/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright 2012 Jason King.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright 2020 Joyent, Inc.
 * Copyright 2020 Robert Mustacchi
 * Copyright 2021 OmniOS Community Edition (OmniOSce) Association.
 */

/*
 * CTF DWARF conversion theory.
 *
 * DWARF data contains a series of compilation units. Each compilation unit
 * generally refers to an object file or what once was, in the case of linked
 * binaries and shared objects. Each compilation unit has a series of what DWARF
 * calls a DIE (Debugging Information Entry). The set of entries that we care
 * about have type information stored in a series of attributes. Each DIE also
 * has a tag that identifies the kind of attributes that it has.
 *
 * A given DIE may itself have children. For example, a DIE that represents a
 * structure has children which represent members. Whenever we encounter a DIE
 * that has children or other values or types associated with it, we recursively
 * process those children first so that way we can then refer to the generated
 * CTF type id while processing its parent. This reduces the amount of unknowns
 * and fixups that we need. It also ensures that we don't accidentally add types
 * that an overzealous compiler might add to the DWARF data but aren't used by
 * anything in the system.
 *
 * Once we do a conversion, we store a mapping in an AVL tree that goes from the
 * DWARF's die offset, which is relative to the given compilation unit, to a
 * ctf_id_t.
 *
 * Unfortunately, some compilers actually will emit duplicate entries for a
 * given type that look similar, but aren't quite. To that end, we go through
 * and do a variant on a merge once we're done processing a single compilation
 * unit which deduplicates all of the types that are in the unit.
 *
 * Finally, if we encounter an object that has multiple compilation units, then
 * we'll convert all of the compilation units separately and then do a merge, so
 * that way we can result in one single ctf_file_t that represents everything
 * for the object.
 *
 * Conversion Steps
 * ----------------
 *
 * Because a given object we've been given to convert may have multiple
 * compilation units, we break the work into two halves. The first half
 * processes each compilation unit (potentially in parallel) and then the second
 * half optionally merges all of the dies in the first half. First, we'll cover
 * what's involved in converting a single ctf_cu_t's dwarf to CTF. This covers
 * the work done in ctf_dwarf_convert_one().
 *
 * An individual ctf_cu_t, which represents a compilation unit, is converted to
 * CTF in a series of multiple passes.
 *
 * Pass 1: During the first pass we walk all of the top-level dies and if we
 * find a function, variable, struct, union, enum or typedef, we recursively
 * transform all of its types. We don't recurse or process everything, because
 * we don't want to add some of the types that compilers may add which are
 * effectively unused.
 *
 * During pass 1, if we encounter any structures or unions we mark them for
 * fixing up later. This is necessary because we may not be able to determine
 * the full size of a structure at the beginning of time. This will happen if
 * the DWARF attribute DW_AT_byte_size is not present for a member. Because of
 * this possibility we defer adding members to structures or even converting
 * them during pass 1 and save that for pass 2. Adding all of the base
 * structures without any of their members helps deal with any circular
 * dependencies that we might encounter.
 *
 * Pass 2: This pass is used to do the first half of fixing up structures and
 * unions. Rather than walk the entire type space again, we actually walk the
 * list of structures and unions that we marked for later fixing up. Here, we
 * iterate over every structure and add members to the underlying ctf_file_t,
 * but not to the structs themselves. One might wonder why we don't, and the
 * main reason is that libctf requires a ctf_update() be done before adding the
 * members to structures or unions.
 *
 * Pass 3: This pass is used to do the second half of fixing up structures and
 * unions. During this part we always go through and add members to structures
 * and unions that we added to the container in the previous pass. In addition,
 * we set the structure and union's actual size, which may have additional
 * padding added by the compiler, it isn't simply the last offset. DWARF always
 * guarantees an attribute exists for this. Importantly no ctf_id_t's change
 * during pass 2.
 *
 * Pass 4: The next phase is to add CTF entries for all of the symbols and
 * variables that are present in this die. During pass 1 we added entries to a
 * map for each variable and function. During this pass, we iterate over the
 * symbol table and when we encounter a symbol that we have in our lists of
 * translated information which matches, we then add it to the ctf_file_t.
 *
 * Pass 5: Here we go and look for any weak symbols and functions and see if
 * they match anything that we recognize. If so, then we add type information
 * for them at this point based on the matching type.
 *
 * Pass 6: This pass is actually a variant on a merge. The traditional merge
 * process expects there to be no duplicate types. As such, at the end of
 * conversion, we do a dedup on all of the types in the system. The
 * deduplication process is described in lib/libctf/common/ctf_merge.c.
 *
 * Once pass 6 is done, we've finished processing the individual compilation
 * unit.
 *
 * The following steps reflect the general process of doing a conversion.
 *
 * 1) Walk the dwarf section and determine the number of compilation units
 * 2) Create a ctf_cu_t for each compilation unit
 * 3) Add all ctf_cu_t's to a workq
 * 4) Have the workq process each die with ctf_dwarf_convert_one. This itself
 *    is comprised of several steps, which were already enumerated.
 * 5) If we have multiple cu's, we do a ctf merge of all the dies. The mechanics
 *    of the merge are discussed in lib/libctf/common/ctf_merge.c.
 * 6) Free everything up and return a ctf_file_t to the user. If we only had a
 *    single compilation unit, then we give that to the user. Otherwise, we
 *    return the merged ctf_file_t.
 *
 * Threading
 * ---------
 *
 * The process has been designed to be amenable to threading. Each compilation
 * unit has its own type stream, therefore the logical place to divide and
 * conquer is at the compilation unit. Each ctf_cu_t has been built to be able
 * to be processed independently of the others. It has its own libdwarf handle,
 * as a given libdwarf handle may only be used by a single thread at a time.
 * This allows the various ctf_cu_t's to be processed in parallel by different
 * threads.
 *
 * All of the ctf_cu_t's are loaded into a workq which allows for a number of
 * threads to be specified and used as a thread pool to process all of the
 * queued work. We set the number of threads to use in the workq equal to the
 * number of threads that the user has specified.
 *
 * After all of the compilation units have been drained, we use the same number
 * of threads when performing a merge of multiple compilation units, if they
 * exist.
 *
 * While all of these different parts do support and allow for multiple threads,
 * it's important that when only a single thread is specified, that it be the
 * calling thread. This allows the conversion routines to be used in a context
 * that doesn't allow additional threads, such as rtld.
 *
 * Common DWARF Mechanics and Notes
 * --------------------------------
 *
 * At this time, we really only support DWARFv2, though support for DWARFv4 is
 * mostly there. There is no intent to support DWARFv3.
 *
 * Generally types for something are stored in the DW_AT_type attribute. For
 * example, a function's return type will be stored in the local DW_AT_type
 * attribute while the arguments will be in child DIEs. There are also various
 * times when we don't have any DW_AT_type. In that case, the lack of a type
 * implies, at least for C, that its C type is void. Because DWARF doesn't emit
 * one, we have a synthetic void type that we create and manipulate instead and
 * pass it off to consumers on an as-needed basis. If nothing has a void type,
 * it will not be emitted.
 *
 * Architecture Specific Parts
 * ---------------------------
 *
 * The CTF tooling encodes various information about the various architectures
 * in the system. Importantly, the tool assumes that every architecture has a
 * data model where long and pointer are the same size. This is currently the
 * case, as the two data models illumos supports are ILP32 and LP64.
 *
 * In addition, we encode the mapping of various floating point sizes to various
 * types for each architecture. If a new architecture is being added, it should
 * be added to the list. The general design of the ctf conversion tools is to be
 * architecture independent. eg. any of the tools here should be able to convert
 * any architecture's DWARF into ctf; however, this has not been rigorously
 * tested and more importantly, the ctf routines don't currently write out the
 * data in an endian-aware form, they only use that of the currently running
 * library.
 */

#include <libctf_impl.h>
#include <sys/avl.h>
#include <sys/debug.h>
#include <sys/list.h>
#include <gelf.h>
#include <libdwarf.h>
#include <dwarf.h>
#include <libgen.h>
#include <workq.h>
#include <thread.h>
#include <macros.h>
#include <errno.h>

#define DWARF_VERSION_TWO       2
#define DWARF_VERSION_FOUR      4
#define DWARF_VARARGS_NAME      "..."

/*
 * Dwarf may refer recursively to other types that we've already processed. To
 * see if we've already converted them, we look them up in an AVL tree that's
 * sorted by the DWARF id.
 */
typedef struct ctf_dwmap {
        avl_node_t      cdm_avl;
        Dwarf_Off       cdm_off;
        Dwarf_Die       cdm_die;
        ctf_id_t        cdm_id;
        boolean_t       cdm_fix;
} ctf_dwmap_t;

typedef struct ctf_dwvar {
        ctf_list_t      cdv_list;
        char            *cdv_name;
        ctf_id_t        cdv_type;
        boolean_t       cdv_global;
} ctf_dwvar_t;

typedef struct ctf_dwfunc {
        ctf_list_t      cdf_list;
        char            *cdf_name;
        ctf_funcinfo_t  cdf_fip;
        ctf_id_t        *cdf_argv;
        boolean_t       cdf_global;
} ctf_dwfunc_t;

typedef struct ctf_dwbitf {
        ctf_list_t      cdb_list;
        ctf_id_t        cdb_base;
        uint_t          cdb_nbits;
        ctf_id_t        cdb_id;
} ctf_dwbitf_t;

/*
 * The ctf_cu_t represents a single top-level DWARF die unit. While generally,
 * the typical object file has only a single die, if we're asked to convert
 * something that's been linked from multiple sources, multiple dies will exist.
 */
typedef struct ctf_die {
        Elf             *cu_elf;        /* shared libelf handle */
        int             cu_fd;          /* shared file descriptor */
        char            *cu_name;       /* basename of the DIE */
        ctf_merge_t     *cu_cmh;        /* merge handle */
        ctf_list_t      cu_vars;        /* List of variables */
        ctf_list_t      cu_funcs;       /* List of functions */
        ctf_list_t      cu_bitfields;   /* Bit field members */
        Dwarf_Debug     cu_dwarf;       /* libdwarf handle */
        mutex_t         *cu_dwlock;     /* libdwarf lock */
        Dwarf_Die       cu_cu;          /* libdwarf compilation unit */
        Dwarf_Off       cu_cuoff;       /* cu's offset */
        Dwarf_Off       cu_maxoff;      /* maximum offset */
        Dwarf_Half      cu_vers;        /* Dwarf Version */
        Dwarf_Half      cu_addrsz;      /* Dwarf Address Size */
        ctf_file_t      *cu_ctfp;       /* output CTF file */
        avl_tree_t      cu_map;         /* map die offsets to CTF types */
        char            *cu_errbuf;     /* error message buffer */
        size_t          cu_errlen;      /* error message buffer length */
        ctf_convert_t   *cu_handle;     /* ctf convert handle */
        size_t          cu_ptrsz;       /* object's pointer size */
        boolean_t       cu_bigend;      /* is it big endian */
        boolean_t       cu_doweaks;     /* should we convert weak symbols? */
        uint_t          cu_mach;        /* machine type */
        ctf_id_t        cu_voidtid;     /* void pointer */
        ctf_id_t        cu_longtid;     /* id for a 'long' */
} ctf_cu_t;

static int ctf_dwarf_init_die(ctf_cu_t *);
static int ctf_dwarf_offset(ctf_cu_t *, Dwarf_Die, Dwarf_Off *);
static int ctf_dwarf_convert_die(ctf_cu_t *, Dwarf_Die);
static int ctf_dwarf_convert_type(ctf_cu_t *, Dwarf_Die, ctf_id_t *, int);

static int ctf_dwarf_function_count(ctf_cu_t *, Dwarf_Die, ctf_funcinfo_t *,
    boolean_t);
static int ctf_dwarf_convert_fargs(ctf_cu_t *, Dwarf_Die, ctf_funcinfo_t *,
    ctf_id_t *);

#define DWARF_LOCK(cup) \
        if ((cup)->cu_dwlock != NULL) \
                mutex_enter((cup)->cu_dwlock)
#define DWARF_UNLOCK(cup) \
        if ((cup)->cu_dwlock != NULL) \
                mutex_exit((cup)->cu_dwlock)

/*
 * This is a generic way to set a CTF Conversion backend error depending on what
 * we were doing. Unless it was one of a specific set of errors that don't
 * indicate a programming / translation bug, eg. ENOMEM, then we transform it
 * into a CTF backend error and fill in the error buffer.
 */
static int
ctf_dwarf_error(ctf_cu_t *cup, ctf_file_t *cfp, int err, const char *fmt, ...)
{
        va_list ap;
        int ret;
        size_t off = 0;
        ssize_t rem = cup->cu_errlen;
        if (cfp != NULL)
                err = ctf_errno(cfp);

        if (err == ENOMEM)
                return (err);

        ret = snprintf(cup->cu_errbuf, rem, "die %s: ",
            cup->cu_name != NULL ? cup->cu_name : "NULL");
        if (ret < 0)
                goto err;
        off += ret;
        rem = MAX(rem - ret, 0);

        va_start(ap, fmt);
        ret = vsnprintf(cup->cu_errbuf + off, rem, fmt, ap);
        va_end(ap);
        if (ret < 0)
                goto err;

        off += ret;
        rem = MAX(rem - ret, 0);
        if (fmt[strlen(fmt) - 1] != '\n') {
                (void) snprintf(cup->cu_errbuf + off, rem,
                    ": %s\n", ctf_errmsg(err));
        }
        va_end(ap);
        return (ECTF_CONVBKERR);

err:
        cup->cu_errbuf[0] = '\0';
        return (ECTF_CONVBKERR);
}

/*
 * DWARF often opts to put no explicit type to describe a void type. eg. if we
 * have a reference type whose DW_AT_type member doesn't exist, then we should
 * instead assume it points to void. Because this isn't represented, we
 * instead cause it to come into existence.
 */
static ctf_id_t
ctf_dwarf_void(ctf_cu_t *cup)
{
        if (cup->cu_voidtid == CTF_ERR) {
                ctf_encoding_t enc = { CTF_INT_SIGNED, 0, 0 };
                cup->cu_voidtid = ctf_add_integer(cup->cu_ctfp, CTF_ADD_ROOT,
                    "void", &enc);
                if (cup->cu_voidtid == CTF_ERR) {
                        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                            "failed to create void type: %s\n",
                            ctf_errmsg(ctf_errno(cup->cu_ctfp)));
                }
        }

        return (cup->cu_voidtid);
}

/*
 * There are many different forms that an array index may take. However, we just
 * always force it to be of a type long no matter what. Therefore we use this to
 * have a single instance of long across everything.
 */
static ctf_id_t
ctf_dwarf_long(ctf_cu_t *cup)
{
        if (cup->cu_longtid == CTF_ERR) {
                ctf_encoding_t enc;

                enc.cte_format = CTF_INT_SIGNED;
                enc.cte_offset = 0;
                /* All illumos systems are LP */
                enc.cte_bits = cup->cu_ptrsz * 8;
                cup->cu_longtid = ctf_add_integer(cup->cu_ctfp, CTF_ADD_NONROOT,
                    "long", &enc);
                if (cup->cu_longtid == CTF_ERR) {
                        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                            "failed to create long type: %s\n",
                            ctf_errmsg(ctf_errno(cup->cu_ctfp)));
                }

        }

        return (cup->cu_longtid);
}

static int
ctf_dwmap_comp(const void *a, const void *b)
{
        const ctf_dwmap_t *ca = a;
        const ctf_dwmap_t *cb = b;

        if (ca->cdm_off > cb->cdm_off)
                return (1);
        if (ca->cdm_off < cb->cdm_off)
                return (-1);
        return (0);
}

static int
ctf_dwmap_add(ctf_cu_t *cup, ctf_id_t id, Dwarf_Die die, boolean_t fix)
{
        int ret;
        avl_index_t index;
        ctf_dwmap_t *dwmap;
        Dwarf_Off off;

        VERIFY(id > 0 && id < CTF_MAX_TYPE);

        if ((ret = ctf_dwarf_offset(cup, die, &off)) != 0)
                return (ret);

        if ((dwmap = ctf_alloc(sizeof (ctf_dwmap_t))) == NULL)
                return (ENOMEM);

        dwmap->cdm_die = die;
        dwmap->cdm_off = off;
        dwmap->cdm_id = id;
        dwmap->cdm_fix = fix;

        ctf_dprintf("dwmap: %p %" DW_PR_DUx "->%d\n", dwmap, off, id);
        VERIFY(avl_find(&cup->cu_map, dwmap, &index) == NULL);
        avl_insert(&cup->cu_map, dwmap, index);
        return (0);
}

static int
ctf_dwarf_attribute(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name,
    Dwarf_Attribute *attrp)
{
        int ret;
        Dwarf_Error derr;

        DWARF_LOCK(cup);
        ret = dwarf_attr(die, name, attrp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK)
                return (0);
        if (ret == DW_DLV_NO_ENTRY) {
                *attrp = NULL;
                return (ENOENT);
        }
        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get attribute for type: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

static void
ctf_dwarf_dealloc(ctf_cu_t *cup, Dwarf_Ptr ptr, Dwarf_Unsigned type)
{
        DWARF_LOCK(cup);
        dwarf_dealloc(cup->cu_dwarf, ptr, type);
        DWARF_UNLOCK(cup);
}

static int
ctf_dwarf_ref(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name, Dwarf_Off *refp)
{
        int ret;
        Dwarf_Attribute attr;
        Dwarf_Error derr;

        if ((ret = ctf_dwarf_attribute(cup, die, name, &attr)) != 0)
                return (ret);

        DWARF_LOCK(cup);
        ret = dwarf_formref(attr, refp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK) {
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (0);
        }

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get attribute descriptor offset: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

static int
ctf_dwarf_refdie(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name,
    Dwarf_Die *diep)
{
        int ret;
        Dwarf_Off off;
        Dwarf_Error derr;

        if ((ret = ctf_dwarf_ref(cup, die, name, &off)) != 0)
                return (ret);

        off += cup->cu_cuoff;
        DWARF_LOCK(cup);
        ret = dwarf_offdie(cup->cu_dwarf, off, diep, &derr);
        DWARF_UNLOCK(cup);
        if (ret != DW_DLV_OK) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "failed to get die from offset %" DW_PR_DUu ": %s\n",
                    off, dwarf_errmsg(derr));
                return (ECTF_CONVBKERR);
        }

        return (0);
}

static int
ctf_dwarf_signed(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name,
    Dwarf_Signed *valp)
{
        int ret;
        Dwarf_Attribute attr;
        Dwarf_Error derr;

        if ((ret = ctf_dwarf_attribute(cup, die, name, &attr)) != 0)
                return (ret);

        DWARF_LOCK(cup);
        ret = dwarf_formsdata(attr, valp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK) {
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (0);
        }

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get signed attribute for type: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

static int
ctf_dwarf_unsigned(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name,
    Dwarf_Unsigned *valp)
{
        int ret;
        Dwarf_Attribute attr;
        Dwarf_Error derr;

        if ((ret = ctf_dwarf_attribute(cup, die, name, &attr)) != 0)
                return (ret);

        DWARF_LOCK(cup);
        ret = dwarf_formudata(attr, valp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK) {
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (0);
        }

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get unsigned attribute for type: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

static int
ctf_dwarf_boolean(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name,
    Dwarf_Bool *val)
{
        int ret;
        Dwarf_Attribute attr;
        Dwarf_Error derr;

        if ((ret = ctf_dwarf_attribute(cup, die, name, &attr)) != 0)
                return (ret);

        DWARF_LOCK(cup);
        ret = dwarf_formflag(attr, val, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK) {
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (0);
        }

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get boolean attribute for type: %s\n",
            dwarf_errmsg(derr));

        return (ECTF_CONVBKERR);
}

static int
ctf_dwarf_string(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half name, char **strp)
{
        int ret;
        char *s;
        Dwarf_Attribute attr;
        Dwarf_Error derr;

        *strp = NULL;
        if ((ret = ctf_dwarf_attribute(cup, die, name, &attr)) != 0)
                return (ret);

        DWARF_LOCK(cup);
        ret = dwarf_formstring(attr, &s, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK) {
                if ((*strp = ctf_strdup(s)) == NULL)
                        ret = ENOMEM;
                else
                        ret = 0;
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (ret);
        }

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get string attribute for type: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

/*
 * The encoding of a DW_AT_data_member_location has changed between different
 * revisions of the specification. It may be a general udata form or it may be
 * location data information. In DWARF 2, it is only the latter. In later
 * revisions of the spec, it may be either. To determine the form, we ask the
 * class, which will be of type CONSTANT.
 */
static int
ctf_dwarf_member_location(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Unsigned *valp)
{
        int ret;
        Dwarf_Error derr;
        Dwarf_Attribute attr;
        Dwarf_Locdesc *loc;
        Dwarf_Signed locnum;
        Dwarf_Half form;
        enum Dwarf_Form_Class class;

        if ((ret = ctf_dwarf_attribute(cup, die, DW_AT_data_member_location,
            &attr)) != 0) {
                return (ret);
        }

        DWARF_LOCK(cup);
        ret = dwarf_whatform(attr, &form, &derr);
        DWARF_UNLOCK(cup);
        if (ret != DW_DLV_OK) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "failed to get dwarf attribute for for member "
                    "location: %s\n",
                    dwarf_errmsg(derr));
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (ECTF_CONVBKERR);
        }

        DWARF_LOCK(cup);
        class = dwarf_get_form_class(cup->cu_vers, DW_AT_data_member_location,
            cup->cu_addrsz, form);
        if (class == DW_FORM_CLASS_CONSTANT) {
                Dwarf_Signed sign;

                /*
                 * We have a constant. We need to try to get both this as signed
                 * and unsigned data, as unfortunately, DWARF doesn't define the
                 * sign. Which is a joy. We try unsigned first. If neither
                 * match, fall through to the normal path.
                 */
                if (dwarf_formudata(attr, valp, &derr) == DW_DLV_OK) {
                        DWARF_UNLOCK(cup);
                        ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                        return (0);
                }

                if (dwarf_formsdata(attr, &sign, &derr) == DW_DLV_OK) {
                        DWARF_UNLOCK(cup);
                        ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                        if (sign < 0) {
                                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                                    "encountered negative member data "
                                    "location: %lld\n", sign);
                        }
                        *valp = (Dwarf_Unsigned)sign;
                        return (0);
                }
        }

        if (dwarf_loclist(attr, &loc, &locnum, &derr) != DW_DLV_OK) {
                DWARF_UNLOCK(cup);
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "failed to obtain location list for member offset: %s\n",
                    dwarf_errmsg(derr));
                ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
                return (ECTF_CONVBKERR);
        }
        DWARF_UNLOCK(cup);
        ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);

        if (locnum != 1 || loc->ld_s->lr_atom != DW_OP_plus_uconst) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "failed to parse location structure for member\n");
                ctf_dwarf_dealloc(cup, loc->ld_s, DW_DLA_LOC_BLOCK);
                ctf_dwarf_dealloc(cup, loc, DW_DLA_LOCDESC);
                return (ECTF_CONVBKERR);
        }

        *valp = loc->ld_s->lr_number;

        ctf_dwarf_dealloc(cup, loc->ld_s, DW_DLA_LOC_BLOCK);
        ctf_dwarf_dealloc(cup, loc, DW_DLA_LOCDESC);
        return (0);
}


static int
ctf_dwarf_offset(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Off *offsetp)
{
        Dwarf_Error derr;
        int ret;

        DWARF_LOCK(cup);
        ret = dwarf_dieoffset(die, offsetp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK)
                return (0);

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get die offset: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

/* simpler variant for debugging output */
static Dwarf_Off
ctf_die_offset(ctf_cu_t *cup, Dwarf_Die die)
{
        Dwarf_Off off = -1;
        Dwarf_Error derr;

        DWARF_LOCK(cup);
        (void) dwarf_dieoffset(die, &off, &derr);
        DWARF_UNLOCK(cup);
        return (off);
}

static int
ctf_dwarf_tag(ctf_cu_t *cup, Dwarf_Die die, Dwarf_Half *tagp)
{
        Dwarf_Error derr;
        int ret;

        DWARF_LOCK(cup);
        ret = dwarf_tag(die, tagp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK)
                return (0);

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get tag type: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

static int
ctf_dwarf_sib(ctf_cu_t *cup, Dwarf_Die base, Dwarf_Die *sibp)
{
        Dwarf_Error derr;
        int ret;

        *sibp = NULL;
        DWARF_LOCK(cup);
        ret = dwarf_siblingof(cup->cu_dwarf, base, sibp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK || ret == DW_DLV_NO_ENTRY)
                return (0);

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to sibling from die: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

static int
ctf_dwarf_child(ctf_cu_t *cup, Dwarf_Die base, Dwarf_Die *childp)
{
        Dwarf_Error derr;
        int ret;

        *childp = NULL;
        DWARF_LOCK(cup);
        ret = dwarf_child(base, childp, &derr);
        DWARF_UNLOCK(cup);
        if (ret == DW_DLV_OK || ret == DW_DLV_NO_ENTRY)
                return (0);

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to child from die: %s\n",
            dwarf_errmsg(derr));
        return (ECTF_CONVBKERR);
}

/*
 * Compilers disagree on what to do to determine if something has global
 * visiblity. Traditionally gcc has used DW_AT_external to indicate this while
 * Studio has used DW_AT_visibility. We check DW_AT_visibility first and then
 * fall back to DW_AT_external. Lack of DW_AT_external implies that it is not.
 */
static int
ctf_dwarf_isglobal(ctf_cu_t *cup, Dwarf_Die die, boolean_t *igp)
{
        int ret;
        Dwarf_Signed vis;
        Dwarf_Bool ext;

        if ((ret = ctf_dwarf_signed(cup, die, DW_AT_visibility, &vis)) == 0) {
                *igp = vis == DW_VIS_exported;
                return (0);
        } else if (ret != ENOENT) {
                return (ret);
        }

        if ((ret = ctf_dwarf_boolean(cup, die, DW_AT_external, &ext)) != 0) {
                if (ret == ENOENT) {
                        *igp = B_FALSE;
                        return (0);
                }
                return (ret);
        }
        *igp = ext != 0 ? B_TRUE : B_FALSE;
        return (0);
}

static int
ctf_dwarf_die_elfenc(Elf *elf, ctf_cu_t *cup, char *errbuf, size_t errlen)
{
        GElf_Ehdr ehdr;

        if (gelf_getehdr(elf, &ehdr) == NULL) {
                (void) snprintf(errbuf, errlen,
                    "failed to get ELF header: %s\n",
                    elf_errmsg(elf_errno()));
                return (ECTF_CONVBKERR);
        }

        cup->cu_mach = ehdr.e_machine;

        if (ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
                cup->cu_ptrsz = 4;
                VERIFY(ctf_setmodel(cup->cu_ctfp, CTF_MODEL_ILP32) == 0);
        } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
                cup->cu_ptrsz = 8;
                VERIFY(ctf_setmodel(cup->cu_ctfp, CTF_MODEL_LP64) == 0);
        } else {
                (void) snprintf(errbuf, errlen,
                    "unknown ELF class %d\n", ehdr.e_ident[EI_CLASS]);
                return (ECTF_CONVBKERR);
        }

        if (ehdr.e_ident[EI_DATA] == ELFDATA2LSB) {
                cup->cu_bigend = B_FALSE;
        } else if (ehdr.e_ident[EI_DATA] == ELFDATA2MSB) {
                cup->cu_bigend = B_TRUE;
        } else {
                (void) snprintf(errbuf, errlen,
                    "unknown ELF data encoding: %hhu\n", ehdr.e_ident[EI_DATA]);
                return (ECTF_CONVBKERR);
        }

        return (0);
}

typedef struct ctf_dwarf_fpent {
        size_t  cdfe_size;
        uint_t  cdfe_enc[3];
} ctf_dwarf_fpent_t;

typedef struct ctf_dwarf_fpmap {
        uint_t                  cdf_mach;
        ctf_dwarf_fpent_t       cdf_ents[5];
} ctf_dwarf_fpmap_t;

static const ctf_dwarf_fpmap_t ctf_dwarf_fpmaps[] = {
        { EM_SPARC, {
                { 4, { CTF_FP_SINGLE, CTF_FP_CPLX, CTF_FP_IMAGRY } },
                { 8, { CTF_FP_DOUBLE, CTF_FP_DCPLX, CTF_FP_DIMAGRY } },
                { 16, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
                { 0, { 0 } }
        } },
        { EM_SPARC32PLUS, {
                { 4, { CTF_FP_SINGLE, CTF_FP_CPLX, CTF_FP_IMAGRY } },
                { 8, { CTF_FP_DOUBLE, CTF_FP_DCPLX, CTF_FP_DIMAGRY } },
                { 16, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
                { 0, { 0 } }
        } },
        { EM_SPARCV9, {
                { 4, { CTF_FP_SINGLE, CTF_FP_CPLX, CTF_FP_IMAGRY } },
                { 8, { CTF_FP_DOUBLE, CTF_FP_DCPLX, CTF_FP_DIMAGRY } },
                { 16, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
                { 0, { 0 } }
        } },
        { EM_386, {
                { 4, { CTF_FP_SINGLE, CTF_FP_CPLX, CTF_FP_IMAGRY } },
                { 8, { CTF_FP_DOUBLE, CTF_FP_DCPLX, CTF_FP_DIMAGRY } },
                { 12, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
                /*
                 * ISO/IEC TS-18661-3:2015 defines several types with analogues
                 * to existing C types. However, in the i386 ABI there is no
                 * corresponding type for a _Float128. While, ideally we would
                 * add this as a discrete type, when C2x formally standardizes
                 * this and a number of additional extensions, we'll want to
                 * change that around. In the interim, we'll encode it as a
                 * weirdly sized long-double, even though not all the tools
                 * will expect an off-abi encoding.
                 */
                { 16, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
                { 0, { 0 } }
        } },
        { EM_X86_64, {
                { 4, { CTF_FP_SINGLE, CTF_FP_CPLX, CTF_FP_IMAGRY } },
                { 8, { CTF_FP_DOUBLE, CTF_FP_DCPLX, CTF_FP_DIMAGRY } },
                { 16, { CTF_FP_LDOUBLE, CTF_FP_LDCPLX, CTF_FP_LDIMAGRY } },
                { 0, { 0 } }
        } },
        { EM_NONE }
};

/*
 * We want to normalize the type names that are used between compilers in the
 * case of complex. gcc prefixes things with types like 'long complex' where as
 * clang only calls them 'complex' in the dwarf even if in the C they are long
 * complex or similar.
 */
static int
ctf_dwarf_fixup_complex(ctf_cu_t *cup, ctf_encoding_t *enc, char **namep)
{
        const char *name;
        *namep = NULL;

        switch (enc->cte_format) {
        case CTF_FP_CPLX:
                name = "complex float";
                break;
        case CTF_FP_DCPLX:
                name = "complex double";
                break;
        case CTF_FP_LDCPLX:
                name = "complex long double";
                break;
        default:
                return (0);
        }

        *namep = ctf_strdup(name);
        if (*namep == NULL) {
                return (ENOMEM);
        }

        return (0);
}

static int
ctf_dwarf_float_base(ctf_cu_t *cup, Dwarf_Signed type, ctf_encoding_t *enc)
{
        const ctf_dwarf_fpmap_t *map = &ctf_dwarf_fpmaps[0];
        const ctf_dwarf_fpent_t *ent;
        uint_t col = 0, mult = 1;

        for (map = &ctf_dwarf_fpmaps[0]; map->cdf_mach != EM_NONE; map++) {
                if (map->cdf_mach == cup->cu_mach)
                        break;
        }

        if (map->cdf_mach == EM_NONE) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "Unsupported machine type: %d\n", cup->cu_mach);
                return (ENOTSUP);
        }

        if (type == DW_ATE_complex_float) {
                mult = 2;
                col = 1;
        } else if (type == DW_ATE_imaginary_float ||
            type == DW_ATE_SUN_imaginary_float) {
                col = 2;
        }

        ent = &map->cdf_ents[0];
        for (ent = &map->cdf_ents[0]; ent->cdfe_size != 0; ent++) {
                if (ent->cdfe_size * mult * 8 == enc->cte_bits) {
                        enc->cte_format = ent->cdfe_enc[col];
                        return (0);
                }
        }

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to find valid fp mapping for encoding %lld, size %d bits\n",
            type, enc->cte_bits);
        return (EINVAL);
}

static int
ctf_dwarf_dwarf_base(ctf_cu_t *cup, Dwarf_Die die, int *kindp,
    ctf_encoding_t *enc)
{
        int ret;
        Dwarf_Signed type;

        if ((ret = ctf_dwarf_signed(cup, die, DW_AT_encoding, &type)) != 0)
                return (ret);

        switch (type) {
        case DW_ATE_unsigned:
        case DW_ATE_address:
                *kindp = CTF_K_INTEGER;
                enc->cte_format = 0;
                break;
        case DW_ATE_unsigned_char:
                *kindp = CTF_K_INTEGER;
                enc->cte_format = CTF_INT_CHAR;
                break;
        case DW_ATE_signed:
                *kindp = CTF_K_INTEGER;
                enc->cte_format = CTF_INT_SIGNED;
                break;
        case DW_ATE_signed_char:
                *kindp = CTF_K_INTEGER;
                enc->cte_format = CTF_INT_SIGNED | CTF_INT_CHAR;
                break;
        case DW_ATE_boolean:
                *kindp = CTF_K_INTEGER;
                enc->cte_format = CTF_INT_SIGNED | CTF_INT_BOOL;
                break;
        case DW_ATE_float:
        case DW_ATE_complex_float:
        case DW_ATE_imaginary_float:
        case DW_ATE_SUN_imaginary_float:
        case DW_ATE_SUN_interval_float:
                *kindp = CTF_K_FLOAT;
                if ((ret = ctf_dwarf_float_base(cup, type, enc)) != 0)
                        return (ret);
                break;
        default:
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "encountered unknown DWARF encoding: %lld\n", type);
                return (ECTF_CONVBKERR);
        }

        return (0);
}

/*
 * Different compilers (at least GCC and Studio) use different names for types.
 * This parses the types and attempts to unify them. If this fails, we just fall
 * back to using the DWARF itself.
 */
static int
ctf_dwarf_parse_int(const char *name, int *kindp, ctf_encoding_t *enc,
    char **newnamep)
{
        char buf[256];
        char *base, *c, *last;
        int nlong = 0, nshort = 0, nchar = 0, nint = 0;
        int sign = 1;

        if (strlen(name) + 1 > sizeof (buf))
                return (EINVAL);

        (void) strlcpy(buf, name, sizeof (buf));
        for (c = strtok_r(buf, " ", &last); c != NULL;
            c = strtok_r(NULL, " ", &last)) {
                if (strcmp(c, "signed") == 0) {
                        sign = 1;
                } else if (strcmp(c, "unsigned") == 0) {
                        sign = 0;
                } else if (strcmp(c, "long") == 0) {
                        nlong++;
                } else if (strcmp(c, "char") == 0) {
                        nchar++;
                } else if (strcmp(c, "short") == 0) {
                        nshort++;
                } else if (strcmp(c, "int") == 0) {
                        nint++;
                } else {
                        /*
                         * If we don't recognize any of the tokens, we'll tell
                         * the caller to fall back to the dwarf-provided
                         * encoding information.
                         */
                        return (EINVAL);
                }
        }

        if (nchar > 1 || nshort > 1 || nint > 1 || nlong > 2)
                return (EINVAL);

        if (nchar > 0) {
                if (nlong > 0 || nshort > 0 || nint > 0)
                        return (EINVAL);
                base = "char";
        } else if (nshort > 0) {
                if (nlong > 0)
                        return (EINVAL);
                base = "short";
        } else if (nlong > 0) {
                base = "long";
        } else {
                base = "int";
        }

        if (nchar > 0)
                enc->cte_format = CTF_INT_CHAR;
        else
                enc->cte_format = 0;

        if (sign > 0)
                enc->cte_format |= CTF_INT_SIGNED;

        (void) snprintf(buf, sizeof (buf), "%s%s%s",
            (sign ? "" : "unsigned "),
            (nlong > 1 ? "long " : ""),
            base);

        *newnamep = ctf_strdup(buf);
        if (*newnamep == NULL)
                return (ENOMEM);
        *kindp = CTF_K_INTEGER;
        return (0);
}

static int
ctf_dwarf_create_base(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp, int isroot,
    Dwarf_Off off)
{
        int ret;
        char *name, *nname = NULL;
        Dwarf_Unsigned sz;
        int kind;
        ctf_encoding_t enc;
        ctf_id_t id;

        if ((ret = ctf_dwarf_string(cup, die, DW_AT_name, &name)) != 0)
                return (ret);
        if ((ret = ctf_dwarf_unsigned(cup, die, DW_AT_byte_size, &sz)) != 0) {
                goto out;
        }
        ctf_dprintf("Creating base type %s from off %llu, size: %d\n", name,
            off, sz);

        bzero(&enc, sizeof (ctf_encoding_t));
        enc.cte_bits = sz * 8;
        if ((ret = ctf_dwarf_parse_int(name, &kind, &enc, &nname)) == 0) {
                ctf_strfree(name);
                name = nname;
        } else {
                if (ret != EINVAL) {
                        goto out;
                }
                ctf_dprintf("falling back to dwarf for base type %s\n", name);
                if ((ret = ctf_dwarf_dwarf_base(cup, die, &kind, &enc)) != 0) {
                        goto out;
                }

                if (kind == CTF_K_FLOAT && (ret = ctf_dwarf_fixup_complex(cup,
                    &enc, &nname)) != 0) {
                        goto out;
                } else if (nname != NULL) {
                        ctf_strfree(name);
                        name = nname;
                }
        }

        id = ctf_add_encoded(cup->cu_ctfp, isroot, name, &enc, kind);
        if (id == CTF_ERR) {
                ret = ctf_errno(cup->cu_ctfp);
        } else {
                *idp = id;
                ret = ctf_dwmap_add(cup, id, die, B_FALSE);
        }
out:
        ctf_strfree(name);
        return (ret);
}

/*
 * Getting a member's offset is a surprisingly intricate dance. It works as
 * follows:
 *
 * 1) If we're in DWARFv4, then we either have a DW_AT_data_bit_offset or we
 * have a DW_AT_data_member_location. We won't have both. Thus we check first
 * for DW_AT_data_bit_offset, and if it exists, we're set.
 *
 * Next, if we have a bitfield and we don't have a DW_AT_data_bit_offset, then
 * we have to grab the data location and use the following dance:
 *
 * 2) Gather the set of DW_AT_byte_size, DW_AT_bit_offset, and DW_AT_bit_size.
 * Of course, the DW_AT_byte_size may be omitted, even though it isn't always.
 * When it's been omitted, we then have to say that the size is that of the
 * underlying type, which forces that to be after a ctf_update(). Here, we have
 * to do different things based on whether or not we're using big endian or
 * little endian to obtain the proper offset.
 */
static int
ctf_dwarf_member_offset(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t mid,
    ulong_t *offp)
{
        int ret;
        Dwarf_Unsigned loc, bitsz, bytesz;
        Dwarf_Signed bitoff;
        size_t off;
        ssize_t tsz;

        if ((ret = ctf_dwarf_unsigned(cup, die, DW_AT_data_bit_offset,
            &loc)) == 0) {
                *offp = loc;
                return (0);
        } else if (ret != ENOENT) {
                return (ret);
        }

        if ((ret = ctf_dwarf_member_location(cup, die, &loc)) != 0)
                return (ret);
        off = loc * 8;

        if ((ret = ctf_dwarf_signed(cup, die, DW_AT_bit_offset,
            &bitoff)) != 0) {
                if (ret != ENOENT)
                        return (ret);
                *offp = off;
                return (0);
        }

        /* At this point we have to have DW_AT_bit_size */
        if ((ret = ctf_dwarf_unsigned(cup, die, DW_AT_bit_size, &bitsz)) != 0)
                return (ret);

        if ((ret = ctf_dwarf_unsigned(cup, die, DW_AT_byte_size,
            &bytesz)) != 0) {
                if (ret != ENOENT)
                        return (ret);
                if ((tsz = ctf_type_size(cup->cu_ctfp, mid)) == CTF_ERR) {
                        int e = ctf_errno(cup->cu_ctfp);
                        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                            "failed to get type size: %s\n", ctf_errmsg(e));
                        return (ECTF_CONVBKERR);
                }
        } else {
                tsz = bytesz;
        }
        tsz *= 8;
        if (cup->cu_bigend == B_TRUE) {
                *offp = off + bitoff;
        } else {
                *offp = off + tsz - bitoff - bitsz;
        }

        return (0);
}

/*
 * We need to determine if the member in question is a bitfield. If it is, then
 * we need to go through and create a new type that's based on the actual base
 * type, but has a different size. We also rename the type as a result to help
 * deal with future collisions.
 *
 * Here we need to look and see if we have a DW_AT_bit_size value. If we have a
 * bit size member and it does not equal the byte size member, then we need to
 * create a bitfield type based on this.
 *
 * Note: When we support DWARFv4, there may be a chance that we need to also
 * search for the DW_AT_byte_size if we don't have a DW_AT_bit_size member.
 */
static int
ctf_dwarf_member_bitfield(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp)
{
        int ret;
        Dwarf_Unsigned bitsz;
        ctf_encoding_t e;
        ctf_dwbitf_t *cdb;
        ctf_dtdef_t *dtd;
        ctf_id_t base = *idp;
        int kind;

        if ((ret = ctf_dwarf_unsigned(cup, die, DW_AT_bit_size, &bitsz)) != 0) {
                if (ret == ENOENT)
                        return (0);
                return (ret);
        }

        ctf_dprintf("Trying to deal with bitfields on %d:%d\n", base, bitsz);
        /*
         * Given that we now have a bitsize, time to go do something about it.
         * We're going to create a new type based on the current one, but first
         * we need to find the base type. This means we need to traverse any
         * typedef's, consts, and volatiles until we get to what should be
         * something of type integer or enumeration.
         */
        VERIFY(bitsz < UINT32_MAX);
        dtd = ctf_dtd_lookup(cup->cu_ctfp, base);
        VERIFY(dtd != NULL);
        kind = CTF_INFO_KIND(dtd->dtd_data.ctt_info);
        while (kind == CTF_K_TYPEDEF || kind == CTF_K_CONST ||
            kind == CTF_K_VOLATILE) {
                dtd = ctf_dtd_lookup(cup->cu_ctfp, dtd->dtd_data.ctt_type);
                VERIFY(dtd != NULL);
                kind = CTF_INFO_KIND(dtd->dtd_data.ctt_info);
        }
        ctf_dprintf("got kind %d\n", kind);
        VERIFY(kind == CTF_K_INTEGER || kind == CTF_K_ENUM);

        /*
         * As surprising as it may be, it is strictly possible to create a
         * bitfield that is based on an enum. Of course, the C standard leaves
         * enums sizing as an ABI concern more or less. To that effect, today on
         * all illumos platforms the size of an enum is generally that of an
         * int as our supported data models and ABIs all agree on that. So what
         * we'll do is fake up a CTF encoding here to use. In this case, we'll
         * treat it as an unsigned value of whatever size the underlying enum
         * currently has (which is in the ctt_size member of its dynamic type
         * data).
         */
        if (kind == CTF_K_INTEGER) {
                e = dtd->dtd_u.dtu_enc;
        } else {
                bzero(&e, sizeof (ctf_encoding_t));
                e.cte_bits = dtd->dtd_data.ctt_size * NBBY;
        }

        for (cdb = ctf_list_next(&cup->cu_bitfields); cdb != NULL;
            cdb = ctf_list_next(cdb)) {
                if (cdb->cdb_base == base && cdb->cdb_nbits == bitsz)
                        break;
        }

        /*
         * Create a new type if none exists. We name all types in a way that is
         * guaranteed not to conflict with the corresponding C type. We do this
         * by using the ':' operator.
         */
        if (cdb == NULL) {
                size_t namesz;
                char *name;

                e.cte_bits = bitsz;
                namesz = snprintf(NULL, 0, "%s:%d", dtd->dtd_name,
                    (uint32_t)bitsz);
                name = ctf_alloc(namesz + 1);
                if (name == NULL)
                        return (ENOMEM);
                cdb = ctf_alloc(sizeof (ctf_dwbitf_t));
                if (cdb == NULL) {
                        ctf_free(name, namesz + 1);
                        return (ENOMEM);
                }
                (void) snprintf(name, namesz + 1, "%s:%d", dtd->dtd_name,
                    (uint32_t)bitsz);

                cdb->cdb_base = base;
                cdb->cdb_nbits = bitsz;
                cdb->cdb_id = ctf_add_integer(cup->cu_ctfp, CTF_ADD_NONROOT,
                    name, &e);
                if (cdb->cdb_id == CTF_ERR) {
                        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                            "failed to get add bitfield type %s: %s\n", name,
                            ctf_errmsg(ctf_errno(cup->cu_ctfp)));
                        ctf_free(name, namesz + 1);
                        ctf_free(cdb, sizeof (ctf_dwbitf_t));
                        return (ECTF_CONVBKERR);
                }
                ctf_free(name, namesz + 1);
                ctf_list_append(&cup->cu_bitfields, cdb);
        }

        *idp = cdb->cdb_id;

        return (0);
}

static int
ctf_dwarf_fixup_sou(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t base, boolean_t add)
{
        int ret, kind;
        Dwarf_Die child, memb;
        Dwarf_Unsigned size;

        kind = ctf_type_kind(cup->cu_ctfp, base);
        VERIFY(kind != CTF_ERR);
        VERIFY(kind == CTF_K_STRUCT || kind == CTF_K_UNION);

        /*
         * Members are in children. However, gcc also allows empty ones.
         */
        if ((ret = ctf_dwarf_child(cup, die, &child)) != 0)
                return (ret);
        if (child == NULL)
                return (0);

        memb = child;
        while (memb != NULL) {
                Dwarf_Die sib, tdie;
                Dwarf_Half tag;
                ctf_id_t mid;
                char *mname;
                ulong_t memboff = 0;

                if ((ret = ctf_dwarf_tag(cup, memb, &tag)) != 0)
                        return (ret);

                if (tag != DW_TAG_member)
                        goto next;

                if ((ret = ctf_dwarf_refdie(cup, memb, DW_AT_type, &tdie)) != 0)
                        return (ret);

                if ((ret = ctf_dwarf_convert_type(cup, tdie, &mid,
                    CTF_ADD_NONROOT)) != 0)
                        return (ret);
                ctf_dprintf("Got back type id: %d\n", mid);

                /*
                 * If we're not adding a member, just go ahead and return.
                 */
                if (add == B_FALSE) {
                        if ((ret = ctf_dwarf_member_bitfield(cup, memb,
                            &mid)) != 0)
                                return (ret);
                        goto next;
                }

                if ((ret = ctf_dwarf_string(cup, memb, DW_AT_name,
                    &mname)) != 0 && ret != ENOENT)
                        return (ret);
                if (ret == ENOENT)
                        mname = NULL;

                if (kind == CTF_K_UNION) {
                        memboff = 0;
                } else if ((ret = ctf_dwarf_member_offset(cup, memb, mid,
                    &memboff)) != 0) {
                        if (mname != NULL)
                                ctf_strfree(mname);
                        return (ret);
                }

                if ((ret = ctf_dwarf_member_bitfield(cup, memb, &mid)) != 0)
                        return (ret);

                ret = ctf_add_member(cup->cu_ctfp, base, mname, mid, memboff);
                if (ret == CTF_ERR) {
                        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                            "failed to add member %s: %s\n",
                            mname, ctf_errmsg(ctf_errno(cup->cu_ctfp)));
                        if (mname != NULL)
                                ctf_strfree(mname);
                        return (ECTF_CONVBKERR);
                }

                if (mname != NULL)
                        ctf_strfree(mname);

next:
                if ((ret = ctf_dwarf_sib(cup, memb, &sib)) != 0)
                        return (ret);
                memb = sib;
        }

        /*
         * If we're not adding members, then we don't know the final size of the
         * structure, so end here.
         */
        if (add == B_FALSE)
                return (0);

        /* Finally set the size of the structure to the actual byte size */
        if ((ret = ctf_dwarf_unsigned(cup, die, DW_AT_byte_size, &size)) != 0)
                return (ret);
        if ((ctf_set_size(cup->cu_ctfp, base, size)) == CTF_ERR) {
                int e = ctf_errno(cup->cu_ctfp);
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "failed to set type size for %d to 0x%x: %s\n", base,
                    (uint32_t)size, ctf_errmsg(e));
                return (ECTF_CONVBKERR);
        }

        return (0);
}

static int
ctf_dwarf_create_sou(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp,
    int kind, int isroot)
{
        int ret;
        char *name;
        ctf_id_t base;
        Dwarf_Die child;
        Dwarf_Bool decl;

        /*
         * Deal with the terribly annoying case of anonymous structs and unions.
         * If they don't have a name, set the name to the empty string.
         */
        if ((ret = ctf_dwarf_string(cup, die, DW_AT_name, &name)) != 0 &&
            ret != ENOENT)
                return (ret);
        if (ret == ENOENT)
                name = NULL;

        /*
         * We need to check if we just have a declaration here. If we do, then
         * instead of creating an actual structure or union, we're just going to
         * go ahead and create a forward. During a dedup or merge, the forward
         * will be replaced with the real thing.
         */
        if ((ret = ctf_dwarf_boolean(cup, die, DW_AT_declaration,
            &decl)) != 0) {
                if (ret != ENOENT)
                        return (ret);
                decl = 0;
        }

        if (decl == B_TRUE) {
                base = ctf_add_forward(cup->cu_ctfp, isroot, name, kind);
        } else if (kind == CTF_K_STRUCT) {
                base = ctf_add_struct(cup->cu_ctfp, isroot, name);
        } else {
                base = ctf_add_union(cup->cu_ctfp, isroot, name);
        }
        ctf_dprintf("added sou %s (%d) (%ld) forward=%d\n",
            name, kind, base, decl == B_TRUE);
        if (name != NULL)
                ctf_strfree(name);
        if (base == CTF_ERR)
                return (ctf_errno(cup->cu_ctfp));
        *idp = base;

        /*
         * If it's just a declaration, we're not going to mark it for fix up or
         * do anything else.
         */
        if (decl == B_TRUE)
                return (ctf_dwmap_add(cup, base, die, B_FALSE));
        if ((ret = ctf_dwmap_add(cup, base, die, B_TRUE)) != 0)
                return (ret);

        /*
         * The children of a structure or union are generally members. However,
         * some compilers actually insert structs and unions there and not as a
         * top-level die. Therefore, to make sure we honor our pass 1 contract
         * of having all the base types, but not members, we need to walk this
         * for instances of a DW_TAG_union_type.
         */
        if ((ret = ctf_dwarf_child(cup, die, &child)) != 0)
                return (ret);

        while (child != NULL) {
                Dwarf_Half tag;
                Dwarf_Die sib;

                if ((ret = ctf_dwarf_tag(cup, child, &tag)) != 0)
                        return (ret);

                switch (tag) {
                case DW_TAG_union_type:
                case DW_TAG_structure_type:
                        ret = ctf_dwarf_convert_type(cup, child, NULL,
                            CTF_ADD_NONROOT);
                        if (ret != 0) {
                                return (ret);
                        }
                        break;
                default:
                        break;
                }

                if ((ret = ctf_dwarf_sib(cup, child, &sib)) != 0)
                        return (ret);
                child = sib;
        }

        return (0);
}

static int
ctf_dwarf_array_upper_bound(ctf_cu_t *cup, Dwarf_Die range, ctf_arinfo_t *ar)
{
        Dwarf_Attribute attr;
        Dwarf_Unsigned uval;
        Dwarf_Signed sval;
        Dwarf_Half attrnum, form;
        Dwarf_Error derr;
        enum Dwarf_Form_Class class;
        const char *formstr = NULL;
        uint_t adj = 0;
        int ret = 0;

        ctf_dprintf("setting array upper bound\n");

        ar->ctr_nelems = 0;

        /*
         * Different compilers use different attributes to indicate the size of
         * an array. GCC has traditionally used DW_AT_upper_bound, while Clang
         * uses DW_AT_count. They have slightly different semantics. DW_AT_count
         * indicates the total number of elements that are present, while
         * DW_AT_upper_bound indicates the last index, hence we need to add one
         * to that index to get the count.
         *
         * We first search for DW_AT_count and then for DW_AT_upper_bound. If we
         * find neither, then we treat the lack of this as a zero element array.
         * Our value is initialized assuming we find a DW_AT_count value.
         */
        attrnum = DW_AT_count;
        ret = ctf_dwarf_attribute(cup, range, DW_AT_count, &attr);
        if (ret != 0 && ret != ENOENT) {
                return (ret);
        } else if (ret == ENOENT) {
                attrnum = DW_AT_upper_bound;
                ret = ctf_dwarf_attribute(cup, range, DW_AT_upper_bound, &attr);
                if (ret != 0 && ret != ENOENT) {
                        return (ret);
                } else if (ret == ENOENT) {
                        return (0);
                } else {
                        adj = 1;
                }
        }

        DWARF_LOCK(cup);
        ret = dwarf_whatform(attr, &form, &derr);
        if (ret != DW_DLV_OK) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "failed to get DW_AT_upper_bound attribute form: %s\n",
                    dwarf_errmsg(derr));
                ret = ECTF_CONVBKERR;
                goto done;
        }

        /*
         * Compilers can indicate array bounds using signed or unsigned values.
         * Additionally, some compilers may also store the array bounds
         * using as DW_FORM_data{1,2,4,8} (which DWARF treats as raw data and
         * expects the caller to understand how to interpret the value).
         *
         * GCC 4.4.4 appears to always use unsigned values to encode the
         * array size (using '(unsigned)-1' to represent a zero-length or
         * unknown length array). Later versions of GCC use a signed value of
         * -1 for zero/unknown length arrays, and unsigned values to encode
         * known array sizes.
         *
         * Both dwarf_formsdata() and dwarf_formudata() will retrieve values
         * as their respective signed/unsigned forms, but both will also
         * retreive DW_FORM_data{1,2,4,8} values and treat them as signed or
         * unsigned integers (i.e. dwarf_formsdata() treats DW_FORM_dataXX
         * as signed integers and dwarf_formudata() treats DW_FORM_dataXX as
         * unsigned integers). Both will return an error if the form is not
         * their respective signed/unsigned form, or DW_FORM_dataXX.
         *
         * To obtain the upper bound, we use the appropriate
         * dwarf_form[su]data() function based on the form of DW_AT_upper_bound.
         * Additionally, we let dwarf_formudata() handle the DW_FORM_dataXX
         * forms (via the default option in the switch). If the value is in an
         * unexpected form (i.e. not DW_FORM_udata or DW_FORM_dataXX),
         * dwarf_formudata() will return failure (i.e. not DW_DLV_OK) and set
         * derr with the specific error value.
         */
        switch (form) {
        case DW_FORM_sdata:
                if (dwarf_formsdata(attr, &sval, &derr) == DW_DLV_OK) {
                        ar->ctr_nelems = sval + adj;
                        goto done;
                }
                break;
        case DW_FORM_udata:
        default:
                if (dwarf_formudata(attr, &uval, &derr) == DW_DLV_OK) {
                        ar->ctr_nelems = uval + adj;
                        goto done;
                }
                break;
        }

        /*
         * The value of attr is not always a constant value. For things
         * such as C99 variable length arrays, it can be a reference to another
         * entity or a DWARF expression. In either of these cases, we treat
         * this as a zero length array.
         */
        class = dwarf_get_form_class(cup->cu_vers, attrnum, cup->cu_addrsz,
            form);

        if (class == DW_FORM_CLASS_REFERENCE || class == DW_FORM_CLASS_BLOCK)
                goto done;

        if (dwarf_get_FORM_name(form, &formstr) != DW_DLV_OK)
                formstr = "unknown DWARF form";

        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
            "failed to get %s (%hu) value for DW_AT_upper_bound: %s\n",
            formstr, form, dwarf_errmsg(derr));
        ret = ECTF_CONVBKERR;

done:
        DWARF_UNLOCK(cup);
        ctf_dwarf_dealloc(cup, attr, DW_DLA_ATTR);
        return (ret);
}

static int
ctf_dwarf_create_array_range(ctf_cu_t *cup, Dwarf_Die range, ctf_id_t *idp,
    ctf_id_t base, int isroot)
{
        int ret;
        Dwarf_Die sib;
        ctf_arinfo_t ar;

        ctf_dprintf("creating array range\n");

        if ((ret = ctf_dwarf_sib(cup, range, &sib)) != 0)
                return (ret);
        if (sib != NULL) {
                ctf_id_t id;
                if ((ret = ctf_dwarf_create_array_range(cup, sib, &id,
                    base, CTF_ADD_NONROOT)) != 0)
                        return (ret);
                ar.ctr_contents = id;
        } else {
                ar.ctr_contents = base;
        }

        if ((ar.ctr_index = ctf_dwarf_long(cup)) == CTF_ERR)
                return (ctf_errno(cup->cu_ctfp));

        if ((ret = ctf_dwarf_array_upper_bound(cup, range, &ar)) != 0)
                return (ret);

        if ((*idp = ctf_add_array(cup->cu_ctfp, isroot, &ar)) == CTF_ERR)
                return (ctf_errno(cup->cu_ctfp));

        return (0);
}

/*
 * Try and create an array type. First, the kind of the array is specified in
 * the DW_AT_type entry. Next, the number of entries is stored in a more
 * complicated form, we should have a child that has the DW_TAG_subrange type.
 */
static int
ctf_dwarf_create_array(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp, int isroot)
{
        int ret;
        Dwarf_Die tdie, rdie;
        ctf_id_t tid;
        Dwarf_Half rtag;

        if ((ret = ctf_dwarf_refdie(cup, die, DW_AT_type, &tdie)) != 0)
                return (ret);
        if ((ret = ctf_dwarf_convert_type(cup, tdie, &tid,
            CTF_ADD_NONROOT)) != 0)
                return (ret);

        if ((ret = ctf_dwarf_child(cup, die, &rdie)) != 0)
                return (ret);
        if ((ret = ctf_dwarf_tag(cup, rdie, &rtag)) != 0)
                return (ret);
        if (rtag != DW_TAG_subrange_type) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "encountered array without DW_TAG_subrange_type child\n");
                return (ECTF_CONVBKERR);
        }

        /*
         * The compiler may opt to describe a multi-dimensional array as one
         * giant array or it may opt to instead encode it as a series of
         * subranges. If it's the latter, then for each subrange we introduce a
         * type. We can always use the base type.
         */
        if ((ret = ctf_dwarf_create_array_range(cup, rdie, idp, tid,
            isroot)) != 0)
                return (ret);
        ctf_dprintf("Got back id %d\n", *idp);
        return (ctf_dwmap_add(cup, *idp, die, B_FALSE));
}

/*
 * Given "const int const_array3[11]", GCC7 at least will create a DIE tree of
 * DW_TAG_const_type:DW_TAG_array_type:DW_Tag_const_type:<member_type>.
 *
 * Given C's syntax, this renders out as "const const int const_array3[11]".  To
 * get closer to round-tripping (and make the unit tests work), we'll peek for
 * this case, and avoid adding the extraneous qualifier if we see that the
 * underlying array referent already has the same qualifier.
 *
 * This is unfortunately less trivial than it could be: this issue applies to
 * qualifier sets like "const volatile", as well as multi-dimensional arrays, so
 * we need to descend down those.
 *
 * Returns CTF_ERR on error, or a boolean value otherwise.
 */
static int
needed_array_qualifier(ctf_cu_t *cup, int kind, ctf_id_t ref_id)
{
        const ctf_type_t *t;
        ctf_arinfo_t arinfo;
        int akind;

        if (kind != CTF_K_CONST && kind != CTF_K_VOLATILE &&
            kind != CTF_K_RESTRICT)
                return (1);

        if ((t = ctf_dyn_lookup_by_id(cup->cu_ctfp, ref_id)) == NULL)
                return (CTF_ERR);

        if (LCTF_INFO_KIND(cup->cu_ctfp, t->ctt_info) != CTF_K_ARRAY)
                return (1);

        if (ctf_dyn_array_info(cup->cu_ctfp, ref_id, &arinfo) != 0)
                return (CTF_ERR);

        ctf_id_t id = arinfo.ctr_contents;

        for (;;) {
                if ((t = ctf_dyn_lookup_by_id(cup->cu_ctfp, id)) == NULL)
                        return (CTF_ERR);

                akind = LCTF_INFO_KIND(cup->cu_ctfp, t->ctt_info);

                if (akind == kind)
                        break;

                if (akind == CTF_K_ARRAY) {
                        if (ctf_dyn_array_info(cup->cu_ctfp,
                            id, &arinfo) != 0)
                                return (CTF_ERR);
                        id = arinfo.ctr_contents;
                        continue;
                }

                if (akind != CTF_K_CONST && akind != CTF_K_VOLATILE &&
                    akind != CTF_K_RESTRICT)
                        break;

                id = t->ctt_type;
        }

        if (kind == akind) {
                ctf_dprintf("ignoring extraneous %s qualifier for array %d\n",
                    ctf_kind_name(cup->cu_ctfp, kind), ref_id);
        }

        return (kind != akind);
}

static int
ctf_dwarf_create_reference(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp,
    int kind, int isroot)
{
        int ret;
        ctf_id_t id;
        Dwarf_Die tdie;
        char *name;

        if ((ret = ctf_dwarf_string(cup, die, DW_AT_name, &name)) != 0 &&
            ret != ENOENT)
                return (ret);
        if (ret == ENOENT)
                name = NULL;

        ctf_dprintf("reference kind %d %s\n", kind, name != NULL ? name : "<>");

        if ((ret = ctf_dwarf_refdie(cup, die, DW_AT_type, &tdie)) != 0) {
                if (ret != ENOENT) {
                        ctf_strfree(name);
                        return (ret);
                }
                if ((id = ctf_dwarf_void(cup)) == CTF_ERR) {
                        ctf_strfree(name);
                        return (ctf_errno(cup->cu_ctfp));
                }
        } else {
                if ((ret = ctf_dwarf_convert_type(cup, tdie, &id,
                    CTF_ADD_NONROOT)) != 0) {
                        ctf_strfree(name);
                        return (ret);
                }
        }

        if ((ret = needed_array_qualifier(cup, kind, id)) <= 0) {
                if (ret != 0) {
                        ret = (ctf_errno(cup->cu_ctfp));
                } else {
                        *idp = id;
                }

                ctf_strfree(name);
                return (ret);
        }

        if ((*idp = ctf_add_reftype(cup->cu_ctfp, isroot, name, id, kind)) ==
            CTF_ERR) {
                ctf_strfree(name);
                return (ctf_errno(cup->cu_ctfp));
        }

        ctf_strfree(name);
        return (ctf_dwmap_add(cup, *idp, die, B_FALSE));
}

static int
ctf_dwarf_create_enum(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp, int isroot)
{
        size_t size = 0;
        Dwarf_Die child;
        Dwarf_Unsigned dw;
        ctf_id_t id;
        char *enumname;
        int ret;

        ret = ctf_dwarf_string(cup, die, DW_AT_name, &enumname);
        if (ret != 0 && ret != ENOENT)
                return (ret);
        if (ret == ENOENT)
                enumname = NULL;

        /*
         * Enumerations may have a size associated with them, particularly if
         * they're packed. Note, a Dwarf_Unsigned is larger than a size_t on an
         * ILP32 system.
         */
        if (ctf_dwarf_unsigned(cup, die, DW_AT_byte_size, &dw) == 0 &&
            dw < SIZE_MAX) {
                size = (size_t)dw;
        }

        id = ctf_add_enum(cup->cu_ctfp, isroot, enumname, size);
        ctf_dprintf("added enum %s (%d)\n",
            enumname == NULL ? "<anon>" : enumname, id);
        if (id == CTF_ERR) {
                ret = ctf_errno(cup->cu_ctfp);
                goto out;
        }
        *idp = id;
        if ((ret = ctf_dwmap_add(cup, id, die, B_FALSE)) != 0)
                goto out;

        if ((ret = ctf_dwarf_child(cup, die, &child)) != 0) {
                if (ret == ENOENT)
                        ret = 0;
                goto out;
        }

        while (child != NULL) {
                Dwarf_Half tag;
                Dwarf_Signed sval;
                Dwarf_Unsigned uval;
                Dwarf_Die arg = child;
                char *name;
                int eval;

                if ((ret = ctf_dwarf_sib(cup, arg, &child)) != 0)
                        break;

                if ((ret = ctf_dwarf_tag(cup, arg, &tag)) != 0)
                        break;

                if (tag != DW_TAG_enumerator) {
                        if ((ret = ctf_dwarf_convert_type(cup, arg, NULL,
                            CTF_ADD_NONROOT)) != 0) {
                                break;
                        }
                        continue;
                }

                /*
                 * DWARF v4 section 5.7 tells us we'll always have names.
                 */
                if ((ret = ctf_dwarf_string(cup, arg, DW_AT_name, &name)) != 0)
                        break;

                /*
                 * We have to be careful here: newer GCCs generate DWARF where
                 * an unsigned value will happily pass ctf_dwarf_signed().
                 * Since negative values will fail ctf_dwarf_unsigned(), we try
                 * that first to make sure we get the right value.
                 */
                if ((ret = ctf_dwarf_unsigned(cup, arg, DW_AT_const_value,
                    &uval)) == 0) {
                        eval = (int)uval;
                } else {
                        /*
                         * ctf_dwarf_unsigned will have left an error in the
                         * buffer
                         */
                        *cup->cu_errbuf = '\0';

                        if ((ret = ctf_dwarf_signed(cup, arg, DW_AT_const_value,
                            &sval)) == 0) {
                                eval = sval;
                        }
                }

                if (ret != 0) {
                        if (ret == ENOENT) {
                                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                                    "encountered enumeration without constant "
                                    "value\n");
                                ret = ECTF_CONVBKERR;
                        }
                        ctf_strfree(name);
                        break;
                }

                ret = ctf_add_enumerator(cup->cu_ctfp, id, name, eval);
                if (ret == CTF_ERR) {
                        ret = ctf_errno(cup->cu_ctfp);

                        if (ret == ECTF_DTFULL && (cup->cu_handle->cch_flags &
                            CTF_ALLOW_TRUNCATION)) {
                                if (cup->cu_handle->cch_warncb != NULL) {
                                        cup->cu_handle->cch_warncb(
                                            cup->cu_handle->cch_warncb_arg,
                                            "truncating enumeration %s at %s\n",
                                            name, enumname == NULL ? "<anon>" :
                                            enumname);
                                }
                                ret = 0;
                        } else {
                                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                                    "failed to add enumerator %s (%d) "
                                    "to %s (%d)\n", name, eval,
                                    enumname == NULL ? "<anon>" : enumname, id);
                        }
                        ctf_strfree(name);
                        break;
                }
                ctf_strfree(name);
        }

out:

        if (enumname != NULL)
                ctf_strfree(enumname);

        return (ret);
}

/*
 * For a function pointer, walk over and process all of its children, unless we
 * encounter one that's just a declaration. In which case, we error on it.
 */
static int
ctf_dwarf_create_fptr(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp, int isroot)
{
        int ret;
        Dwarf_Bool b;
        ctf_funcinfo_t fi;
        Dwarf_Die retdie;
        ctf_id_t *argv = NULL;

        bzero(&fi, sizeof (ctf_funcinfo_t));

        if ((ret = ctf_dwarf_boolean(cup, die, DW_AT_declaration, &b)) != 0) {
                if (ret != ENOENT)
                        return (ret);
        } else {
                if (b != 0)
                        return (EPROTOTYPE);
        }

        /*
         * Return type is in DW_AT_type, if none, it returns void.
         */
        if ((ret = ctf_dwarf_refdie(cup, die, DW_AT_type, &retdie)) != 0) {
                if (ret != ENOENT)
                        return (ret);
                if ((fi.ctc_return = ctf_dwarf_void(cup)) == CTF_ERR)
                        return (ctf_errno(cup->cu_ctfp));
        } else {
                if ((ret = ctf_dwarf_convert_type(cup, retdie, &fi.ctc_return,
                    CTF_ADD_NONROOT)) != 0)
                        return (ret);
        }

        if ((ret = ctf_dwarf_function_count(cup, die, &fi, B_TRUE)) != 0) {
                return (ret);
        }

        if (fi.ctc_argc != 0) {
                argv = ctf_alloc(sizeof (ctf_id_t) * fi.ctc_argc);
                if (argv == NULL)
                        return (ENOMEM);

                if ((ret = ctf_dwarf_convert_fargs(cup, die, &fi, argv)) != 0) {
                        ctf_free(argv, sizeof (ctf_id_t) * fi.ctc_argc);
                        return (ret);
                }
        }

        if ((*idp = ctf_add_funcptr(cup->cu_ctfp, isroot, &fi, argv)) ==
            CTF_ERR) {
                ctf_free(argv, sizeof (ctf_id_t) * fi.ctc_argc);
                return (ctf_errno(cup->cu_ctfp));
        }

        ctf_free(argv, sizeof (ctf_id_t) * fi.ctc_argc);
        return (ctf_dwmap_add(cup, *idp, die, B_FALSE));
}

static int
ctf_dwarf_convert_type(ctf_cu_t *cup, Dwarf_Die die, ctf_id_t *idp,
    int isroot)
{
        int ret;
        Dwarf_Off offset;
        Dwarf_Half tag;
        ctf_dwmap_t lookup, *map;
        ctf_id_t id;

        if (idp == NULL)
                idp = &id;

        if ((ret = ctf_dwarf_offset(cup, die, &offset)) != 0)
                return (ret);

        if (offset > cup->cu_maxoff) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "die offset %llu beyond maximum for header %llu\n",
                    offset, cup->cu_maxoff);
                return (ECTF_CONVBKERR);
        }

        /*
         * If we've already added an entry for this offset, then we're done.
         */
        lookup.cdm_off = offset;
        if ((map = avl_find(&cup->cu_map, &lookup, NULL)) != NULL) {
                *idp = map->cdm_id;
                return (0);
        }

        if ((ret = ctf_dwarf_tag(cup, die, &tag)) != 0)
                return (ret);

        ret = ENOTSUP;
        switch (tag) {
        case DW_TAG_base_type:
                ctf_dprintf("base\n");
                ret = ctf_dwarf_create_base(cup, die, idp, isroot, offset);
                break;
        case DW_TAG_array_type:
                ctf_dprintf("array\n");
                ret = ctf_dwarf_create_array(cup, die, idp, isroot);
                break;
        case DW_TAG_enumeration_type:
                ctf_dprintf("enum\n");
                ret = ctf_dwarf_create_enum(cup, die, idp, isroot);
                break;
        case DW_TAG_pointer_type:
                ctf_dprintf("pointer\n");
                ret = ctf_dwarf_create_reference(cup, die, idp, CTF_K_POINTER,
                    isroot);
                break;
        case DW_TAG_structure_type:
                ctf_dprintf("struct\n");
                ret = ctf_dwarf_create_sou(cup, die, idp, CTF_K_STRUCT,
                    isroot);
                break;
        case DW_TAG_subroutine_type:
                ctf_dprintf("fptr\n");
                ret = ctf_dwarf_create_fptr(cup, die, idp, isroot);
                break;
        case DW_TAG_typedef:
                ctf_dprintf("typedef\n");
                ret = ctf_dwarf_create_reference(cup, die, idp, CTF_K_TYPEDEF,
                    isroot);
                break;
        case DW_TAG_union_type:
                ctf_dprintf("union\n");
                ret = ctf_dwarf_create_sou(cup, die, idp, CTF_K_UNION,
                    isroot);
                break;
        case DW_TAG_const_type:
                ctf_dprintf("const\n");
                ret = ctf_dwarf_create_reference(cup, die, idp, CTF_K_CONST,
                    isroot);
                break;
        case DW_TAG_volatile_type:
                ctf_dprintf("volatile\n");
                ret = ctf_dwarf_create_reference(cup, die, idp, CTF_K_VOLATILE,
                    isroot);
                break;
        case DW_TAG_restrict_type:
                ctf_dprintf("restrict\n");
                ret = ctf_dwarf_create_reference(cup, die, idp, CTF_K_RESTRICT,
                    isroot);
                break;
        default:
                ctf_dprintf("ignoring tag type %x\n", tag);
                *idp = CTF_ERR;
                ret = 0;
                break;
        }
        ctf_dprintf("ctf_dwarf_convert_type tag specific handler returned %d\n",
            ret);

        return (ret);
}

static int
ctf_dwarf_walk_lexical(ctf_cu_t *cup, Dwarf_Die die)
{
        int ret;
        Dwarf_Die child;

        if ((ret = ctf_dwarf_child(cup, die, &child)) != 0)
                return (ret);

        if (child == NULL)
                return (0);

        return (ctf_dwarf_convert_die(cup, die));
}

static int
ctf_dwarf_function_count(ctf_cu_t *cup, Dwarf_Die die, ctf_funcinfo_t *fip,
    boolean_t fptr)
{
        int ret;
        Dwarf_Die child, sib, arg;

        if ((ret = ctf_dwarf_child(cup, die, &child)) != 0)
                return (ret);

        arg = child;
        while (arg != NULL) {
                Dwarf_Half tag;

                if ((ret = ctf_dwarf_tag(cup, arg, &tag)) != 0)
                        return (ret);

                /*
                 * We have to check for a varargs type declaration. This will
                 * happen in one of two ways. If we have a function pointer
                 * type, then it'll be done with a tag of type
                 * DW_TAG_unspecified_parameters. However, it only means we have
                 * a variable number of arguments, if we have more than one
                 * argument found so far. Otherwise, when we have a function
                 * type, it instead uses a formal parameter whose name is '...'
                 * to indicate a variable arguments member.
                 *
                 * Also, if we have a function pointer, then we have to expect
                 * that we might not get a name at all.
                 */
                if (tag == DW_TAG_formal_parameter && fptr == B_FALSE) {
                        char *name;
                        if ((ret = ctf_dwarf_string(cup, die, DW_AT_name,
                            &name)) != 0)
                                return (ret);
                        if (strcmp(name, DWARF_VARARGS_NAME) == 0)
                                fip->ctc_flags |= CTF_FUNC_VARARG;
                        else
                                fip->ctc_argc++;
                        ctf_strfree(name);
                } else if (tag == DW_TAG_formal_parameter) {
                        fip->ctc_argc++;
                } else if (tag == DW_TAG_unspecified_parameters &&
                    fip->ctc_argc > 0) {
                        fip->ctc_flags |= CTF_FUNC_VARARG;
                }
                if ((ret = ctf_dwarf_sib(cup, arg, &sib)) != 0)
                        return (ret);
                arg = sib;
        }

        return (0);
}

static int
ctf_dwarf_convert_fargs(ctf_cu_t *cup, Dwarf_Die die, ctf_funcinfo_t *fip,
    ctf_id_t *argv)
{
        int ret;
        int i = 0;
        Dwarf_Die child, sib, arg;

        if ((ret = ctf_dwarf_child(cup, die, &child)) != 0)
                return (ret);

        arg = child;
        while (arg != NULL) {
                Dwarf_Half tag;

                if ((ret = ctf_dwarf_tag(cup, arg, &tag)) != 0)
                        return (ret);
                if (tag == DW_TAG_formal_parameter) {
                        Dwarf_Die tdie;

                        if ((ret = ctf_dwarf_refdie(cup, arg, DW_AT_type,
                            &tdie)) != 0)
                                return (ret);

                        if ((ret = ctf_dwarf_convert_type(cup, tdie, &argv[i],
                            CTF_ADD_ROOT)) != 0)
                                return (ret);
                        i++;

                        /*
                         * Once we hit argc entries, we're done. This ensures we
                         * don't accidentally hit a varargs which should be the
                         * last entry.
                         */
                        if (i == fip->ctc_argc)
                                break;
                }

                if ((ret = ctf_dwarf_sib(cup, arg, &sib)) != 0)
                        return (ret);
                arg = sib;
        }

        return (0);
}

static int
ctf_dwarf_convert_function(ctf_cu_t *cup, Dwarf_Die die)
{
        ctf_dwfunc_t *cdf;
        Dwarf_Die tdie;
        Dwarf_Bool b;
        char *name;
        int ret;

        /*
         * Functions that don't have a name are generally functions that have
         * been inlined and thus most information about them has been lost. If
         * we can't get a name, then instead of returning ENOENT, we silently
         * swallow the error.
         */
        if ((ret = ctf_dwarf_string(cup, die, DW_AT_name, &name)) != 0) {
                if (ret == ENOENT)
                        return (0);
                return (ret);
        }

        ctf_dprintf("beginning work on function %s (die %llx)\n",
            name, ctf_die_offset(cup, die));

        if ((ret = ctf_dwarf_boolean(cup, die, DW_AT_declaration, &b)) != 0) {
                if (ret != ENOENT) {
                        ctf_strfree(name);
                        return (ret);
                }
        } else if (b != 0) {
                /*
                 * GCC7 at least creates empty DW_AT_declarations for functions
                 * defined in headers.  As they lack details on the function
                 * prototype, we need to ignore them.  If we later actually
                 * see the relevant function's definition, we will see another
                 * DW_TAG_subprogram that is more complete.
                 */
                ctf_dprintf("ignoring declaration of function %s (die %llx)\n",
                    name, ctf_die_offset(cup, die));
                ctf_strfree(name);
                return (0);
        }

        if ((cdf = ctf_alloc(sizeof (ctf_dwfunc_t))) == NULL) {
                ctf_strfree(name);
                return (ENOMEM);
        }
        bzero(cdf, sizeof (ctf_dwfunc_t));
        cdf->cdf_name = name;

        if ((ret = ctf_dwarf_refdie(cup, die, DW_AT_type, &tdie)) == 0) {
                if ((ret = ctf_dwarf_convert_type(cup, tdie,
                    &(cdf->cdf_fip.ctc_return), CTF_ADD_ROOT)) != 0) {
                        ctf_strfree(name);
                        ctf_free(cdf, sizeof (ctf_dwfunc_t));
                        return (ret);
                }
        } else if (ret != ENOENT) {
                ctf_strfree(name);
                ctf_free(cdf, sizeof (ctf_dwfunc_t));
                return (ret);
        } else {
                if ((cdf->cdf_fip.ctc_return = ctf_dwarf_void(cup)) ==
                    CTF_ERR) {
                        ctf_strfree(name);
                        ctf_free(cdf, sizeof (ctf_dwfunc_t));
                        return (ctf_errno(cup->cu_ctfp));
                }
        }

        /*
         * A function has a number of children, some of which may not be ones we
         * care about. Children that we care about have a type of
         * DW_TAG_formal_parameter. We're going to do two passes, the first to
         * count the arguments, the second to process them. Afterwards, we
         * should be good to go ahead and add this function.
         *
         * Note, we already got the return type by going in and grabbing it out
         * of the DW_AT_type.
         */
        if ((ret = ctf_dwarf_function_count(cup, die, &cdf->cdf_fip,
            B_FALSE)) != 0) {
                ctf_strfree(name);
                ctf_free(cdf, sizeof (ctf_dwfunc_t));
                return (ret);
        }

        ctf_dprintf("beginning to convert function arguments %s\n", name);
        if (cdf->cdf_fip.ctc_argc != 0) {
                uint_t argc = cdf->cdf_fip.ctc_argc;
                cdf->cdf_argv = ctf_alloc(sizeof (ctf_id_t) * argc);
                if (cdf->cdf_argv == NULL) {
                        ctf_strfree(name);
                        ctf_free(cdf, sizeof (ctf_dwfunc_t));
                        return (ENOMEM);
                }
                if ((ret = ctf_dwarf_convert_fargs(cup, die,
                    &cdf->cdf_fip, cdf->cdf_argv)) != 0) {
                        ctf_free(cdf->cdf_argv, sizeof (ctf_id_t) * argc);
                        ctf_strfree(name);
                        ctf_free(cdf, sizeof (ctf_dwfunc_t));
                        return (ret);
                }
        } else {
                cdf->cdf_argv = NULL;
        }

        if ((ret = ctf_dwarf_isglobal(cup, die, &cdf->cdf_global)) != 0) {
                ctf_free(cdf->cdf_argv, sizeof (ctf_id_t) *
                    cdf->cdf_fip.ctc_argc);
                ctf_strfree(name);
                ctf_free(cdf, sizeof (ctf_dwfunc_t));
                return (ret);
        }

        ctf_list_append(&cup->cu_funcs, cdf);
        return (ret);
}

/*
 * Convert variables, but only if they're not prototypes and have names.
 */
static int
ctf_dwarf_convert_variable(ctf_cu_t *cup, Dwarf_Die die)
{
        int ret;
        char *name;
        Dwarf_Bool b;
        Dwarf_Die tdie;
        ctf_id_t id;
        ctf_dwvar_t *cdv;

        /* Skip "Non-Defining Declarations" */
        if ((ret = ctf_dwarf_boolean(cup, die, DW_AT_declaration, &b)) == 0) {
                if (b != 0)
                        return (0);
        } else if (ret != ENOENT) {
                return (ret);
        }

        /*
         * If we find a DIE of "Declarations Completing Non-Defining
         * Declarations", we will use the referenced type's DIE.  This isn't
         * quite correct, e.g. DW_AT_decl_line will be the forward declaration
         * not this site.  It's sufficient for what we need, however: in
         * particular, we should find DW_AT_external as needed there.
         */
        if ((ret = ctf_dwarf_refdie(cup, die, DW_AT_specification,
            &tdie)) == 0) {
                Dwarf_Off offset;
                if ((ret = ctf_dwarf_offset(cup, tdie, &offset)) != 0)
                        return (ret);
                ctf_dprintf("die 0x%llx DW_AT_specification -> die 0x%llx\n",
                    ctf_die_offset(cup, die), ctf_die_offset(cup, tdie));
                die = tdie;
        } else if (ret != ENOENT) {
                return (ret);
        }

        if ((ret = ctf_dwarf_string(cup, die, DW_AT_name, &name)) != 0 &&
            ret != ENOENT)
                return (ret);
        if (ret == ENOENT)
                return (0);

        if ((ret = ctf_dwarf_refdie(cup, die, DW_AT_type, &tdie)) != 0) {
                ctf_strfree(name);
                return (ret);
        }

        if ((ret = ctf_dwarf_convert_type(cup, tdie, &id,
            CTF_ADD_ROOT)) != 0)
                return (ret);

        if ((cdv = ctf_alloc(sizeof (ctf_dwvar_t))) == NULL) {
                ctf_strfree(name);
                return (ENOMEM);
        }

        cdv->cdv_name = name;
        cdv->cdv_type = id;

        if ((ret = ctf_dwarf_isglobal(cup, die, &cdv->cdv_global)) != 0) {
                ctf_free(cdv, sizeof (ctf_dwvar_t));
                ctf_strfree(name);
                return (ret);
        }

        ctf_list_append(&cup->cu_vars, cdv);
        return (0);
}

/*
 * Walk through our set of top-level types and process them.
 */
static int
ctf_dwarf_walk_toplevel(ctf_cu_t *cup, Dwarf_Die die)
{
        int ret;
        Dwarf_Off offset;
        Dwarf_Half tag;

        if ((ret = ctf_dwarf_offset(cup, die, &offset)) != 0)
                return (ret);

        if (offset > cup->cu_maxoff) {
                (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                    "die offset %llu beyond maximum for header %llu\n",
                    offset, cup->cu_maxoff);
                return (ECTF_CONVBKERR);
        }

        if ((ret = ctf_dwarf_tag(cup, die, &tag)) != 0)
                return (ret);

        ret = 0;
        switch (tag) {
        case DW_TAG_subprogram:
                ctf_dprintf("top level func\n");
                ret = ctf_dwarf_convert_function(cup, die);
                break;
        case DW_TAG_variable:
                ctf_dprintf("top level var\n");
                ret = ctf_dwarf_convert_variable(cup, die);
                break;
        case DW_TAG_lexical_block:
                ctf_dprintf("top level block\n");
                ret = ctf_dwarf_walk_lexical(cup, die);
                break;
        case DW_TAG_enumeration_type:
        case DW_TAG_structure_type:
        case DW_TAG_typedef:
        case DW_TAG_union_type:
                ctf_dprintf("top level type\n");
                ret = ctf_dwarf_convert_type(cup, die, NULL, B_TRUE);
                break;
        default:
                break;
        }

        return (ret);
}


/*
 * We're given a node. At this node we need to convert it and then proceed to
 * convert any siblings that are associaed with this die.
 */
static int
ctf_dwarf_convert_die(ctf_cu_t *cup, Dwarf_Die die)
{
        while (die != NULL) {
                int ret;
                Dwarf_Die sib;

                if ((ret = ctf_dwarf_walk_toplevel(cup, die)) != 0)
                        return (ret);

                if ((ret = ctf_dwarf_sib(cup, die, &sib)) != 0)
                        return (ret);
                die = sib;
        }
        return (0);
}

static int
ctf_dwarf_fixup_die(ctf_cu_t *cup, boolean_t addpass)
{
        ctf_dwmap_t *map;

        for (map = avl_first(&cup->cu_map); map != NULL;
            map = AVL_NEXT(&cup->cu_map, map)) {
                int ret;
                if (map->cdm_fix == B_FALSE)
                        continue;
                if ((ret = ctf_dwarf_fixup_sou(cup, map->cdm_die, map->cdm_id,
                    addpass)) != 0)
                        return (ret);
        }

        return (0);
}

/*
 * The DWARF information about a symbol and the information in the symbol table
 * may not be the same due to symbol reduction that is performed by ld due to a
 * mapfile or other such directive. We process weak symbols at a later time.
 *
 * The following are the rules that we employ:
 *
 * 1. A DWARF function that is considered exported matches STB_GLOBAL entries
 * with the same name.
 *
 * 2. A DWARF function that is considered exported matches STB_LOCAL entries
 * with the same name and the same file. This case may happen due to mapfile
 * reduction.
 *
 * 3. A DWARF function that is not considered exported matches STB_LOCAL entries
 * with the same name and the same file.
 *
 * 4. A DWARF function that has the same name as the symbol table entry, but the
 * files do not match. This is considered a 'fuzzy' match. This may also happen
 * due to a mapfile reduction. Fuzzy matching is only used when we know that the
 * file in question refers to the primary object. This is because when a symbol
 * is reduced in a mapfile, it's always going to be tagged as a local value in
 * the generated output and it is considered as to belong to the primary file
 * which is the first STT_FILE symbol we see.
 */
static boolean_t
ctf_dwarf_symbol_match(const char *symtab_file, const char *symtab_name,
    uint_t symtab_bind, const char *dwarf_file, const char *dwarf_name,
    boolean_t dwarf_global, boolean_t *is_fuzzy)
{
        *is_fuzzy = B_FALSE;

        if (symtab_bind != STB_LOCAL && symtab_bind != STB_GLOBAL) {
                return (B_FALSE);
        }

        if (strcmp(symtab_name, dwarf_name) != 0) {
                return (B_FALSE);
        }

        if (symtab_bind == STB_GLOBAL) {
                return (dwarf_global);
        }

        if (strcmp(symtab_file, dwarf_file) == 0) {
                return (B_TRUE);
        }

        if (dwarf_global) {
                *is_fuzzy = B_TRUE;
                return (B_TRUE);
        }

        return (B_FALSE);
}

static ctf_dwfunc_t *
ctf_dwarf_match_func(ctf_cu_t *cup, const char *file, const char *name,
    uint_t bind, boolean_t primary)
{
        ctf_dwfunc_t *cdf, *fuzzy = NULL;

        if (bind == STB_WEAK)
                return (NULL);

        if (bind == STB_LOCAL && (file == NULL || cup->cu_name == NULL))
                return (NULL);

        for (cdf = ctf_list_next(&cup->cu_funcs); cdf != NULL;
            cdf = ctf_list_next(cdf)) {
                boolean_t is_fuzzy = B_FALSE;

                if (ctf_dwarf_symbol_match(file, name, bind, cup->cu_name,
                    cdf->cdf_name, cdf->cdf_global, &is_fuzzy)) {
                        if (is_fuzzy) {
                                if (primary) {
                                        fuzzy = cdf;
                                }
                                continue;
                        } else {
                                return (cdf);
                        }
                }
        }

        return (fuzzy);
}

static ctf_dwvar_t *
ctf_dwarf_match_var(ctf_cu_t *cup, const char *file, const char *name,
    uint_t bind, boolean_t primary)
{
        ctf_dwvar_t *cdv, *fuzzy = NULL;

        if (bind == STB_WEAK)
                return (NULL);

        if (bind == STB_LOCAL && (file == NULL || cup->cu_name == NULL))
                return (NULL);

        for (cdv = ctf_list_next(&cup->cu_vars); cdv != NULL;
            cdv = ctf_list_next(cdv)) {
                boolean_t is_fuzzy = B_FALSE;

                if (ctf_dwarf_symbol_match(file, name, bind, cup->cu_name,
                    cdv->cdv_name, cdv->cdv_global, &is_fuzzy)) {
                        if (is_fuzzy) {
                                if (primary) {
                                        fuzzy = cdv;
                                }
                        } else {
                                return (cdv);
                        }
                }
        }

        return (fuzzy);
}

static int
ctf_dwarf_conv_funcvars_cb(const Elf64_Sym *symp, ulong_t idx,
    const char *file, const char *name, boolean_t primary, void *arg)
{
        int ret;
        uint_t bind, type;
        ctf_cu_t *cup = arg;

        bind = GELF_ST_BIND(symp->st_info);
        type = GELF_ST_TYPE(symp->st_info);

        /*
         * Come back to weak symbols in another pass
         */
        if (bind == STB_WEAK)
                return (0);

        if (type == STT_OBJECT) {
                ctf_dwvar_t *cdv = ctf_dwarf_match_var(cup, file, name,
                    bind, primary);
                if (cdv == NULL)
                        return (0);
                ret = ctf_add_object(cup->cu_ctfp, idx, cdv->cdv_type);
                ctf_dprintf("added object %s->%ld\n", name, cdv->cdv_type);
        } else {
                ctf_dwfunc_t *cdf = ctf_dwarf_match_func(cup, file, name,
                    bind, primary);
                if (cdf == NULL)
                        return (0);
                ret = ctf_add_function(cup->cu_ctfp, idx, &cdf->cdf_fip,
                    cdf->cdf_argv);
                ctf_dprintf("added function %s\n", name);
        }

        if (ret == CTF_ERR) {
                return (ctf_errno(cup->cu_ctfp));
        }

        return (0);
}

static int
ctf_dwarf_conv_funcvars(ctf_cu_t *cup)
{
        return (ctf_symtab_iter(cup->cu_ctfp, ctf_dwarf_conv_funcvars_cb, cup));
}

/*
 * If we have a weak symbol, attempt to find the strong symbol it will resolve
 * to.  Note: the code where this actually happens is in sym_process() in
 * cmd/sgs/libld/common/syms.c
 *
 * Finding the matching symbol is unfortunately not trivial.  For a symbol to be
 * a candidate, it must:
 *
 * - have the same type (function, object)
 * - have the same value (address)
 * - have the same size
 * - not be another weak symbol
 * - belong to the same section (checked via section index)
 *
 * To perform this check, we first iterate over the symbol table. For each weak
 * symbol that we encounter, we then do a second walk over the symbol table,
 * calling ctf_dwarf_conv_check_weak(). If a symbol matches the above, then it's
 * either a local or global symbol. If we find a global symbol then we go with
 * it and stop searching for additional matches.
 *
 * If instead, we find a local symbol, things are more complicated. The first
 * thing we do is to try and see if we have file information about both symbols
 * (STT_FILE). If they both have file information and it matches, then we treat
 * that as a good match and stop searching for additional matches.
 *
 * Otherwise, this means we have a non-matching file and a local symbol. We
 * treat this as a candidate and if we find a better match (one of the two cases
 * above), use that instead. There are two different ways this can happen.
 * Either this is a completely different symbol, or it's a once-global symbol
 * that was scoped to local via a mapfile.  In the former case, curfile is
 * likely inaccurate since the linker does not preserve the needed curfile in
 * the order of the symbol table (see the comments about locally scoped symbols
 * in libld's update_osym()).  As we can't tell this case from the former one,
 * we use this symbol iff no other matching symbol is found.
 *
 * What we really need here is a SUNW section containing weak<->strong mappings
 * that we can consume.
 */
typedef struct ctf_dwarf_weak_arg {
        const Elf64_Sym *cweak_symp;
        const char *cweak_file;
        boolean_t cweak_candidate;
        ulong_t cweak_idx;
} ctf_dwarf_weak_arg_t;

static int
ctf_dwarf_conv_check_weak(const Elf64_Sym *symp, ulong_t idx, const char *file,
    const char *name, boolean_t primary, void *arg)
{
        ctf_dwarf_weak_arg_t *cweak = arg;

        const Elf64_Sym *wsymp = cweak->cweak_symp;

        ctf_dprintf("comparing weak to %s\n", name);

        if (GELF_ST_BIND(symp->st_info) == STB_WEAK) {
                return (0);
        }

        if (GELF_ST_TYPE(wsymp->st_info) != GELF_ST_TYPE(symp->st_info)) {
                return (0);
        }

        if (wsymp->st_value != symp->st_value) {
                return (0);
        }

        if (wsymp->st_size != symp->st_size) {
                return (0);
        }

        if (wsymp->st_shndx != symp->st_shndx) {
                return (0);
        }

        /*
         * Check if it's a weak candidate.
         */
        if (GELF_ST_BIND(symp->st_info) == STB_LOCAL &&
            (file == NULL || cweak->cweak_file == NULL ||
            strcmp(file, cweak->cweak_file) != 0)) {
                cweak->cweak_candidate = B_TRUE;
                cweak->cweak_idx = idx;
                return (0);
        }

        /*
         * Found a match, break.
         */
        cweak->cweak_idx = idx;
        return (1);
}

static int
ctf_dwarf_duplicate_sym(ctf_cu_t *cup, ulong_t idx, ulong_t matchidx)
{
        ctf_id_t id = ctf_lookup_by_symbol(cup->cu_ctfp, matchidx);

        /*
         * If we matched something that for some reason didn't have type data,
         * we don't consider that a fatal error and silently swallow it.
         */
        if (id == CTF_ERR) {
                if (ctf_errno(cup->cu_ctfp) == ECTF_NOTYPEDAT)
                        return (0);
                else
                        return (ctf_errno(cup->cu_ctfp));
        }

        if (ctf_add_object(cup->cu_ctfp, idx, id) == CTF_ERR)
                return (ctf_errno(cup->cu_ctfp));

        return (0);
}

static int
ctf_dwarf_duplicate_func(ctf_cu_t *cup, ulong_t idx, ulong_t matchidx)
{
        int ret;
        ctf_funcinfo_t fip;
        ctf_id_t *args = NULL;

        if (ctf_func_info(cup->cu_ctfp, matchidx, &fip) == CTF_ERR) {
                if (ctf_errno(cup->cu_ctfp) == ECTF_NOFUNCDAT)
                        return (0);
                else
                        return (ctf_errno(cup->cu_ctfp));
        }

        if (fip.ctc_argc != 0) {
                args = ctf_alloc(sizeof (ctf_id_t) * fip.ctc_argc);
                if (args == NULL)
                        return (ENOMEM);

                if (ctf_func_args(cup->cu_ctfp, matchidx, fip.ctc_argc, args) ==
                    CTF_ERR) {
                        ctf_free(args, sizeof (ctf_id_t) * fip.ctc_argc);
                        return (ctf_errno(cup->cu_ctfp));
                }
        }

        ret = ctf_add_function(cup->cu_ctfp, idx, &fip, args);
        if (args != NULL)
                ctf_free(args, sizeof (ctf_id_t) * fip.ctc_argc);
        if (ret == CTF_ERR)
                return (ctf_errno(cup->cu_ctfp));

        return (0);
}

static int
ctf_dwarf_conv_weaks_cb(const Elf64_Sym *symp, ulong_t idx, const char *file,
    const char *name, boolean_t primary, void *arg)
{
        int ret, type;
        ctf_dwarf_weak_arg_t cweak;
        ctf_cu_t *cup = arg;

        /*
         * We only care about weak symbols.
         */
        if (GELF_ST_BIND(symp->st_info) != STB_WEAK)
                return (0);

        type = GELF_ST_TYPE(symp->st_info);
        ASSERT(type == STT_OBJECT || type == STT_FUNC);

        /*
         * For each weak symbol we encounter, we need to do a second iteration
         * to try and find a match. We should probably think about other
         * techniques to try and save us time in the future.
         */
        cweak.cweak_symp = symp;
        cweak.cweak_file = file;
        cweak.cweak_candidate = B_FALSE;
        cweak.cweak_idx = 0;

        ctf_dprintf("Trying to find weak equiv for %s\n", name);

        ret = ctf_symtab_iter(cup->cu_ctfp, ctf_dwarf_conv_check_weak, &cweak);
        VERIFY(ret == 0 || ret == 1);

        /*
         * Nothing was ever found, we're not going to add anything for this
         * entry.
         */
        if (ret == 0 && cweak.cweak_candidate == B_FALSE) {
                ctf_dprintf("found no weak match for %s\n", name);
                return (0);
        }

        /*
         * Now, finally go and add the type based on the match.
         */
        ctf_dprintf("matched weak symbol %lu to %lu\n", idx, cweak.cweak_idx);
        if (type == STT_OBJECT) {
                ret = ctf_dwarf_duplicate_sym(cup, idx, cweak.cweak_idx);
        } else {
                ret = ctf_dwarf_duplicate_func(cup, idx, cweak.cweak_idx);
        }

        return (ret);
}

static int
ctf_dwarf_conv_weaks(ctf_cu_t *cup)
{
        return (ctf_symtab_iter(cup->cu_ctfp, ctf_dwarf_conv_weaks_cb, cup));
}

static int
ctf_dwarf_convert_one(void *arg, void *unused)
{
        int ret;
        ctf_file_t *dedup;
        ctf_cu_t *cup = arg;
        const char *name = cup->cu_name != NULL ? cup->cu_name : "NULL";

        VERIFY(cup != NULL);

        if ((ret = ctf_dwarf_init_die(cup)) != 0)
                return (ret);

        ctf_dprintf("converting die: %s - max offset: %x\n", name,
            cup->cu_maxoff);

        ret = ctf_dwarf_convert_die(cup, cup->cu_cu);
        ctf_dprintf("ctf_dwarf_convert_die (%s) returned %d\n", name,
            ret);
        if (ret != 0)
                return (ret);

        if (ctf_update(cup->cu_ctfp) != 0) {
                return (ctf_dwarf_error(cup, cup->cu_ctfp, 0,
                    "failed to update output ctf container"));
        }

        ret = ctf_dwarf_fixup_die(cup, B_FALSE);
        ctf_dprintf("ctf_dwarf_fixup_die (%s, FALSE) returned %d\n", name,
            ret);
        if (ret != 0)
                return (ret);

        if (ctf_update(cup->cu_ctfp) != 0) {
                return (ctf_dwarf_error(cup, cup->cu_ctfp, 0,
                    "failed to update output ctf container"));
        }

        ret = ctf_dwarf_fixup_die(cup, B_TRUE);
        ctf_dprintf("ctf_dwarf_fixup_die (%s, TRUE) returned %d\n", name,
            ret);
        if (ret != 0)
                return (ret);

        if (ctf_update(cup->cu_ctfp) != 0) {
                return (ctf_dwarf_error(cup, cup->cu_ctfp, 0,
                    "failed to update output ctf container"));
        }

        if ((ret = ctf_dwarf_conv_funcvars(cup)) != 0) {
                ctf_dprintf("ctf_dwarf_conv_funcvars (%s) returned %d\n",
                    name, ret);
                return (ctf_dwarf_error(cup, NULL, ret,
                    "failed to convert strong functions and variables"));
        }

        if (ctf_update(cup->cu_ctfp) != 0) {
                return (ctf_dwarf_error(cup, cup->cu_ctfp, 0,
                    "failed to update output ctf container"));
        }

        if (cup->cu_doweaks == B_TRUE) {
                if ((ret = ctf_dwarf_conv_weaks(cup)) != 0) {
                        ctf_dprintf("ctf_dwarf_conv_weaks (%s) returned %d\n",
                            name, ret);
                        return (ctf_dwarf_error(cup, NULL, ret,
                            "failed to convert weak functions and variables"));
                }

                if (ctf_update(cup->cu_ctfp) != 0) {
                        return (ctf_dwarf_error(cup, cup->cu_ctfp, 0,
                            "failed to update output ctf container"));
                }
        }

        ctf_phase_dump(cup->cu_ctfp, "pre-dwarf-dedup", name);
        ctf_dprintf("adding inputs for dedup\n");
        if ((ret = ctf_merge_add(cup->cu_cmh, cup->cu_ctfp)) != 0) {
                return (ctf_dwarf_error(cup, NULL, ret,
                    "failed to add inputs for merge"));
        }

        ctf_dprintf("starting dedup of %s\n", name);
        if ((ret = ctf_merge_dedup(cup->cu_cmh, &dedup)) != 0) {
                return (ctf_dwarf_error(cup, NULL, ret,
                    "failed to deduplicate die"));
        }

        ctf_close(cup->cu_ctfp);
        cup->cu_ctfp = dedup;
        ctf_phase_dump(cup->cu_ctfp, "post-dwarf-dedup", name);

        return (0);
}

static void
ctf_dwarf_free_die(ctf_cu_t *cup)
{
        ctf_dwfunc_t *cdf, *ndf;
        ctf_dwvar_t *cdv, *ndv;
        ctf_dwbitf_t *cdb, *ndb;
        ctf_dwmap_t *map;
        void *cookie;

        ctf_dprintf("Beginning to free die: %p\n", cup);

        VERIFY3P(cup->cu_elf, !=, NULL);
        cup->cu_elf = NULL;

        ctf_dprintf("Trying to free name: %p\n", cup->cu_name);
        if (cup->cu_name != NULL) {
                ctf_strfree(cup->cu_name);
                cup->cu_name = NULL;
        }

        ctf_dprintf("Trying to free merge handle: %p\n", cup->cu_cmh);
        if (cup->cu_cmh != NULL) {
                ctf_merge_fini(cup->cu_cmh);
                cup->cu_cmh = NULL;
        }

        ctf_dprintf("Trying to free functions\n");
        for (cdf = ctf_list_next(&cup->cu_funcs); cdf != NULL; cdf = ndf) {
                ndf = ctf_list_next(cdf);
                ctf_strfree(cdf->cdf_name);
                if (cdf->cdf_fip.ctc_argc != 0) {
                        ctf_free(cdf->cdf_argv,
                            sizeof (ctf_id_t) * cdf->cdf_fip.ctc_argc);
                }
                ctf_free(cdf, sizeof (ctf_dwfunc_t));
        }

        ctf_dprintf("Trying to free variables\n");
        for (cdv = ctf_list_next(&cup->cu_vars); cdv != NULL; cdv = ndv) {
                ndv = ctf_list_next(cdv);
                ctf_strfree(cdv->cdv_name);
                ctf_free(cdv, sizeof (ctf_dwvar_t));
        }

        ctf_dprintf("Trying to free bitfields\n");
        for (cdb = ctf_list_next(&cup->cu_bitfields); cdb != NULL; cdb = ndb) {
                ndb = ctf_list_next(cdb);
                ctf_free(cdb, sizeof (ctf_dwbitf_t));
        }

        if (cup->cu_ctfp != NULL) {
                ctf_close(cup->cu_ctfp);
                cup->cu_ctfp = NULL;
        }

        cookie = NULL;
        while ((map = avl_destroy_nodes(&cup->cu_map, &cookie)) != NULL)
                ctf_free(map, sizeof (ctf_dwmap_t));
        avl_destroy(&cup->cu_map);
        cup->cu_errbuf = NULL;

        if (cup->cu_cu != NULL) {
                ctf_dwarf_dealloc(cup, cup->cu_cu, DW_DLA_DIE);
                cup->cu_cu = NULL;
        }
}

static int
ctf_dwarf_count_dies(Dwarf_Debug dw, Dwarf_Error *derr, uint_t *ndies,
    char *errbuf, size_t errlen)
{
        int ret;
        Dwarf_Half vers;
        Dwarf_Unsigned nexthdr;

        while ((ret = dwarf_next_cu_header(dw, NULL, &vers, NULL, NULL,
            &nexthdr, derr)) != DW_DLV_NO_ENTRY) {
                if (ret != DW_DLV_OK) {
                        (void) snprintf(errbuf, errlen,
                            "file does not contain valid DWARF data: %s\n",
                            dwarf_errmsg(*derr));
                        return (ECTF_CONVBKERR);
                }

                switch (vers) {
                case DWARF_VERSION_TWO:
                case DWARF_VERSION_FOUR:
                        break;
                default:
                        (void) snprintf(errbuf, errlen,
                            "unsupported DWARF version: %d\n", vers);
                        return (ECTF_CONVBKERR);
                }
                *ndies = *ndies + 1;
        }

        return (0);
}

/*
 * Fill out just enough of each ctf_cu_t for the conversion process to
 * be able to finish the rest in a (potentially) multithreaded context.
 */
static int
ctf_dwarf_preinit_dies(ctf_convert_t *cch, int fd, Elf *elf, Dwarf_Debug dw,
    mutex_t *dwlock, Dwarf_Error *derr, uint_t ndies, ctf_cu_t *cdies,
    char *errbuf, size_t errlen)
{
        Dwarf_Unsigned hdrlen, abboff, nexthdr;
        Dwarf_Half addrsz, vers;
        Dwarf_Unsigned offset = 0;
        uint_t added = 0;
        int ret, i = 0;

        while ((ret = dwarf_next_cu_header(dw, &hdrlen, &vers, &abboff,
            &addrsz, &nexthdr, derr)) != DW_DLV_NO_ENTRY) {
                Dwarf_Die cu;
                ctf_cu_t *cup;
                char *name;

                VERIFY3U(i, <, ndies);

                cup = &cdies[i++];

                cup->cu_handle = cch;
                cup->cu_fd = fd;
                cup->cu_elf = elf;
                cup->cu_dwarf = dw;
                cup->cu_errbuf = errbuf;
                cup->cu_errlen = errlen;
                cup->cu_dwarf = dw;
                if (ndies > 1) {
                        /*
                         * Only need to lock calls into libdwarf if there are
                         * multiple CUs.
                         */
                        cup->cu_dwlock = dwlock;
                        cup->cu_doweaks = B_FALSE;
                } else {
                        cup->cu_doweaks = B_TRUE;
                }

                cup->cu_voidtid = CTF_ERR;
                cup->cu_longtid = CTF_ERR;
                cup->cu_cuoff = offset;
                cup->cu_maxoff = nexthdr - 1;
                cup->cu_vers = vers;
                cup->cu_addrsz = addrsz;

                if ((ret = ctf_dwarf_sib(cup, NULL, &cu)) != 0) {
                        ctf_dprintf("cu %d - no cu %d\n", i, ret);
                        return (ret);
                }

                if (cu == NULL) {
                        ctf_dprintf("cu %d - no cu data\n", i);
                        (void) snprintf(cup->cu_errbuf, cup->cu_errlen,
                            "file does not contain DWARF data\n");
                        return (ECTF_CONVNODEBUG);
                }

                if (ctf_dwarf_string(cup, cu, DW_AT_name, &name) == 0) {
                        char *b = basename(name);

                        cup->cu_name = strdup(b);
                        ctf_strfree(name);
                        if (cup->cu_name == NULL)
                                return (ENOMEM);
                }

                ret = ctf_dwarf_child(cup, cu, &cup->cu_cu);
                dwarf_dealloc(cup->cu_dwarf, cu, DW_DLA_DIE);
                if (ret != 0) {
                        ctf_dprintf("cu %d - no child '%s' %d\n",
                            i, cup->cu_name != NULL ? cup->cu_name : "NULL",
                            ret);
                        return (ret);
                }

                if (cup->cu_cu == NULL) {
                        size_t len;

                        ctf_dprintf("cu %d - no child data '%s' %d\n",
                            i, cup->cu_name != NULL ? cup->cu_name : "NULL",
                            ret);
                        if (cup->cu_name != NULL &&
                            (len = strlen(cup->cu_name)) > 2 &&
                            strncmp(".c", &cup->cu_name[len - 2], 2) == 0) {
                                /*
                                 * Missing DEBUG data for a .c file, return an
                                 * error unless this is permitted.
                                 */
                                if (!(cch->cch_flags &
                                    CTF_ALLOW_MISSING_DEBUG)) {
                                        (void) snprintf(
                                            cup->cu_errbuf, cup->cu_errlen,
                                            "missing debug information "
                                            "(first seen in %s)\n",
                                            cup->cu_name);
                                        return (ECTF_CONVNODEBUG);
                                }
                                if (cch->cch_warncb != NULL) {
                                        cch->cch_warncb(cch->cch_warncb_arg,
                                            "file %s is missing debug "
                                            "information\n", cup->cu_name);
                                }
                        }
                } else {
                        added++;
                }

                ctf_dprintf("Pre-initialised cu %d - '%s'\n", i,
                    cup->cu_name != NULL ? cup->cu_name : "NULL");

                offset = nexthdr;
        }

        /*
         * If none of the CUs had debug data, return an error.
         */
        if (added == 0)
                return (ECTF_CONVNODEBUG);

        return (0);
}

static int
ctf_dwarf_init_die(ctf_cu_t *cup)
{
        int ret;

        cup->cu_ctfp = ctf_fdcreate(cup->cu_fd, &ret);
        if (cup->cu_ctfp == NULL)
                return (ret);

        avl_create(&cup->cu_map, ctf_dwmap_comp, sizeof (ctf_dwmap_t),
            offsetof(ctf_dwmap_t, cdm_avl));

        if ((ret = ctf_dwarf_die_elfenc(cup->cu_elf, cup,
            cup->cu_errbuf, cup->cu_errlen)) != 0) {
                return (ret);
        }

        if ((cup->cu_cmh = ctf_merge_init(cup->cu_fd, &ret)) == NULL)
                return (ret);

        return (0);
}

/*
 * This is our only recourse to identify a C source file that is missing debug
 * info: it will be mentioned as an STT_FILE, but not have a compile unit entry.
 * (A traditional ctfmerge works on individual files, so can identify missing
 * DWARF more directly, via ctf_has_c_source() on the .o file.)
 *
 * As we operate on basenames, this can of course miss some cases, but it's
 * better than not checking at all.
 *
 * We explicitly whitelist some CRT components.  Failing that, there's always
 * the -m option.
 */
static boolean_t
c_source_has_debug(ctf_convert_t *cch, const char *file,
    ctf_cu_t *cus, size_t nr_cus)
{
        const char *basename = strrchr(file, '/');
        ctf_convert_filelist_t *ccf;

        if (basename == NULL)
                basename = file;
        else
                basename++;

        if (strcmp(basename, "common-crt.c") == 0 ||
            strcmp(basename, "gmon.c") == 0 ||
            strcmp(basename, "dlink_init.c") == 0 ||
            strcmp(basename, "dlink_common.c") == 0 ||
            strcmp(basename, "ssp_ns.c") == 0 ||
            strncmp(basename, "crt", strlen("crt")) == 0 ||
            strncmp(basename, "values-", strlen("values-")) == 0)
                return (B_TRUE);

        for (ccf = list_head(&cch->cch_nodebug); ccf != NULL;
            ccf = list_next(&cch->cch_nodebug, ccf)) {
                if (ccf->ccf_basename != NULL &&
                    strcmp(basename, ccf->ccf_basename) == 0) {
                        return (B_TRUE);
                }
        }

        for (size_t i = 0; i < nr_cus; i++) {
                if (cus[i].cu_name != NULL &&
                    strcmp(basename, cus[i].cu_name) == 0) {
                        return (B_TRUE);
                }
        }

        return (B_FALSE);
}

static int
ctf_dwarf_check_missing(ctf_convert_t *cch, ctf_cu_t *cus, size_t nr_cus,
    Elf *elf, char *errmsg, size_t errlen)
{
        Elf_Scn *scn, *strscn;
        Elf_Data *data, *strdata;
        GElf_Shdr shdr;
        ulong_t i;
        int ret = 0;

        scn = NULL;
        while ((scn = elf_nextscn(elf, scn)) != NULL) {
                if (gelf_getshdr(scn, &shdr) == NULL) {
                        (void) snprintf(errmsg, errlen,
                            "failed to get section header: %s\n",
                            elf_errmsg(elf_errno()));
                        return (EINVAL);
                }

                if (shdr.sh_type == SHT_SYMTAB)
                        break;
        }

        if (scn == NULL)
                return (0);

        if ((strscn = elf_getscn(elf, shdr.sh_link)) == NULL) {
                (void) snprintf(errmsg, errlen,
                    "failed to get str section: %s\n",
                    elf_errmsg(elf_errno()));
                return (EINVAL);
        }

        if ((data = elf_getdata(scn, NULL)) == NULL) {
                (void) snprintf(errmsg, errlen, "failed to read section: %s\n",
                    elf_errmsg(elf_errno()));
                return (EINVAL);
        }

        if ((strdata = elf_getdata(strscn, NULL)) == NULL) {
                (void) snprintf(errmsg, errlen,
                    "failed to read string table: %s\n",
                    elf_errmsg(elf_errno()));
                return (EINVAL);
        }

        for (i = 0; i < shdr.sh_size / shdr.sh_entsize; i++) {
                GElf_Sym sym;
                const char *file;
                size_t len;

                if (gelf_getsym(data, i, &sym) == NULL) {
                        (void) snprintf(errmsg, errlen,
                            "failed to read sym %lu: %s\n",
                            i, elf_errmsg(elf_errno()));
                        return (EINVAL);
                }

                if (GELF_ST_TYPE(sym.st_info) != STT_FILE)
                        continue;

                file = (const char *)((uintptr_t)strdata->d_buf + sym.st_name);
                len = strlen(file);
                if (len < 2 || strncmp(".c", &file[len - 2], 2) != 0)
                        continue;

                if (!c_source_has_debug(cch, file, cus, nr_cus)) {
                        if (cch->cch_warncb != NULL) {
                                cch->cch_warncb(
                                    cch->cch_warncb_arg,
                                    "file %s is missing debug information\n",
                                    file);
                        }
                        if (ret != ECTF_CONVNODEBUG) {
                                (void) snprintf(errmsg, errlen,
                                    "missing debug information "
                                    "(first seen in %s)\n", file);
                                ret = ECTF_CONVNODEBUG;
                        }
                }
        }

        return (ret);
}

static int
ctf_dwarf_convert_batch(uint_t start, uint_t end, int fd, uint_t nthrs,
    workq_t *wqp, ctf_cu_t *cdies, ctf_file_t **fpp)
{
        ctf_file_t *fpprev = NULL;
        uint_t i, added;
        ctf_cu_t *cup;
        int ret, err;

        ctf_dprintf("Processing CU batch %u - %u\n", start, end - 1);

        added = 0;
        for (i = start; i < end; i++) {
                cup = &cdies[i];
                if (cup->cu_cu == NULL)
                        continue;
                ctf_dprintf("adding cu %s: %p, %x %x\n",
                    cup->cu_name != NULL ? cup->cu_name : "NULL",
                    cup->cu_cu, cup->cu_cuoff, cup->cu_maxoff);
                if (workq_add(wqp, cup) == -1) {
                        err = errno;
                        goto out;
                }
                added++;
        }

        /*
         * No debug data found in this batch, move on to the next.
         * NB:  ctf_dwarf_preinit_dies() has already checked that there is at
         *      least one CU with debug data present.
         */
        if (added == 0) {
                err = 0;
                goto out;
        }

        ctf_dprintf("Running conversion phase\n");

        /* Run the conversions */
        ret = workq_work(wqp, ctf_dwarf_convert_one, NULL, &err);
        if (ret == WORKQ_ERROR) {
                err = errno;
                goto out;
        } else if (ret == WORKQ_UERROR) {
                ctf_dprintf("internal convert failed: %s\n",
                    ctf_errmsg(err));
                goto out;
        }

        ctf_dprintf("starting merge phase\n");

        ctf_merge_t *cmp = ctf_merge_init(fd, &err);
        if (cmp == NULL)
                goto out;

        if ((err = ctf_merge_set_nthreads(cmp, nthrs)) != 0) {
                ctf_merge_fini(cmp);
                goto out;
        }

        /*
         * If we have the result of a previous merge then add it as an input to
         * the next one.
         */
        if (*fpp != NULL) {
                ctf_dprintf("adding previous merge CU\n");
                fpprev = *fpp;
                *fpp = NULL;
                if ((err = ctf_merge_add(cmp, fpprev)) != 0) {
                        ctf_merge_fini(cmp);
                        goto out;
                }
        }

        ctf_dprintf("adding CUs to merge\n");
        for (i = start; i < end; i++) {
                cup = &cdies[i];
                if (cup->cu_cu == NULL)
                        continue;
                if ((err = ctf_merge_add(cmp, cup->cu_ctfp)) != 0) {
                        ctf_merge_fini(cmp);
                        *fpp = NULL;
                        goto out;
                }
        }

        ctf_dprintf("performing merge\n");
        err = ctf_merge_merge(cmp, fpp);
        if (err != 0) {
                ctf_dprintf("failed merge!\n");
                *fpp = NULL;
                ctf_merge_fini(cmp);
                goto out;
        }

        ctf_merge_fini(cmp);

        ctf_dprintf("freeing CUs\n");
        for (i = start; i < end; i++) {
                cup = &cdies[i];
                ctf_dprintf("freeing cu %d\n", i);
                ctf_dwarf_free_die(cup);
        }

out:
        ctf_close(fpprev);
        return (err);
}

int
ctf_dwarf_convert(ctf_convert_t *cch, int fd, Elf *elf, ctf_file_t **fpp,
    char *errbuf, size_t errlen)
{
        int err, ret;
        uint_t ndies, i, bsize, nthrs;
        Dwarf_Debug dw;
        Dwarf_Error derr;
        ctf_cu_t *cdies = NULL, *cup;
        workq_t *wqp = NULL;
        mutex_t dwlock = ERRORCHECKMUTEX;

        *fpp = NULL;

        ret = dwarf_elf_init(elf, DW_DLC_READ, NULL, NULL, &dw, &derr);
        if (ret != DW_DLV_OK) {
                if (ret == DW_DLV_NO_ENTRY ||
                    dwarf_errno(derr) == DW_DLE_DEBUG_INFO_NULL) {
                        (void) snprintf(errbuf, errlen,
                            "file does not contain DWARF data\n");
                        return (ECTF_CONVNODEBUG);
                }

                (void) snprintf(errbuf, errlen,
                    "dwarf_elf_init() failed: %s\n", dwarf_errmsg(derr));
                return (ECTF_CONVBKERR);
        }

        /*
         * Iterate over all of the compilation units and create a ctf_cu_t for
         * each of them.  This is used to determine if we have zero, one, or
         * multiple dies to convert. If we have zero, that's an error. If
         * there's only one die, that's the simple case.  No merge needed and
         * only a single Dwarf_Debug as well.
         */
        ndies = 0;
        err = ctf_dwarf_count_dies(dw, &derr, &ndies, errbuf, errlen);

        ctf_dprintf("found %d DWARF CUs\n", ndies);

        if (ndies == 0) {
                (void) snprintf(errbuf, errlen,
                    "file does not contain DWARF data\n");
                (void) dwarf_finish(dw, &derr);
                return (ECTF_CONVNODEBUG);
        }

        cdies = ctf_alloc(sizeof (ctf_cu_t) * ndies);
        if (cdies == NULL) {
                (void) dwarf_finish(dw, &derr);
                return (ENOMEM);
        }

        bzero(cdies, sizeof (ctf_cu_t) * ndies);

        if ((err = ctf_dwarf_preinit_dies(cch, fd, elf, dw, &dwlock, &derr,
            ndies, cdies, errbuf, errlen)) != 0) {
                goto out;
        }

        if ((err = ctf_dwarf_check_missing(cch, cdies, ndies, elf,
            errbuf, errlen)) != 0) {
                if (!(cch->cch_flags & CTF_ALLOW_MISSING_DEBUG)) {
                        goto out;
                }
                if (err != ECTF_CONVNODEBUG && *errbuf != '\0' &&
                    cch->cch_warncb != NULL) {
                        cch->cch_warncb(cch->cch_warncb_arg, "%s", errbuf);
                        *errbuf = '\0';
                }
        }

        /* Only one cu, no merge required */
        if (ndies == 1) {
                cup = cdies;

                if ((err = ctf_dwarf_convert_one(cup, NULL)) != 0)
                        goto out;

                *fpp = cup->cu_ctfp;
                cup->cu_ctfp = NULL;
                ctf_dwarf_free_die(cup);
                goto success;
        }

        /*
         * There's no need to have either more threads or a batch size larger
         * than the total number of dies, even if the user requested them.
         */
        nthrs = min(ndies, cch->cch_nthreads);
        bsize = min(ndies, cch->cch_batchsize);

        if (workq_init(&wqp, nthrs) == -1) {
                err = errno;
                goto out;
        }

        /*
         * In order to avoid exhausting memory limits when converting files
         * with a large number of dies, we process them in batches.
         */
        for (i = 0; i < ndies; i += bsize) {
                err = ctf_dwarf_convert_batch(i, min(i + bsize, ndies),
                    fd, nthrs, wqp, cdies, fpp);
                if (err != 0) {
                        *fpp = NULL;
                        goto out;
                }
        }

success:
        err = 0;
        ctf_dprintf("successfully converted!\n");

out:
        (void) dwarf_finish(dw, &derr);
        workq_fini(wqp);
        ctf_free(cdies, sizeof (ctf_cu_t) * ndies);
        return (err);
}