/*
 * 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 (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include        <stdio.h>
#include        <string.h>
#include        <link.h>
#include        <debug.h>
#include        "msg.h"
#include        "_libld.h"

/*
 * Determine whether a (COMDAT) group has already been encountered.  If so,
 * indicate that the group descriptor has an overriding group (gd_oisc).  This
 * indication triggers the ld_place_section() to discard this group, while the
 * gd_oisc information provides for complete diagnostics of the override.
 * Otherwise, this is the first occurrence of this group, therefore the group
 * descriptor is saved for future comparisons.
 */
static uintptr_t
gpavl_loaded(Ofl_desc *ofl, Group_desc *gdp)
{
        Isd_node        isd, *isdp;
        avl_tree_t      *avlt;
        avl_index_t     where;

        /*
         * Create a groups avl tree if required.
         */
        if ((avlt = ofl->ofl_groups) == NULL) {
                if ((avlt = libld_calloc(1, sizeof (avl_tree_t))) == NULL)
                        return (S_ERROR);
                avl_create(avlt, isdavl_compare, sizeof (Isd_node),
                    SGSOFFSETOF(Isd_node, isd_avl));
                ofl->ofl_groups = avlt;
        }

        /*
         * An SHT_GROUP section is identified by the name of its signature
         * symbol rather than section name. Although the section names are
         * often unique, this is not required, and some compilers set it to
         * a generic name like ".group".
         */
        isd.isd_name = gdp->gd_name;
        isd.isd_hash = sgs_str_hash(isd.isd_name);

        if ((isdp = avl_find(avlt, &isd, &where)) != NULL) {
                gdp->gd_oisc = isdp->isd_isp;
                return (1);
        }

        /*
         * This is a new group - so keep it.
         */
        if ((isdp = libld_calloc(1, sizeof (Isd_node))) == NULL)
                return (S_ERROR);

        isdp->isd_name = isd.isd_name;
        isdp->isd_hash = isd.isd_hash;
        isdp->isd_isp = gdp->gd_isc;

        avl_insert(avlt, isdp, where);
        return (0);
}

Group_desc *
ld_get_group(Ofl_desc *ofl, Is_desc *isp)
{
        Ifl_desc        *ifl = isp->is_file;
        uint_t          scnndx = isp->is_scnndx;
        Group_desc      *gdp;
        Aliste          idx;

        /*
         * Scan the GROUP sections associated with this file to find the
         * matching group section.
         */
        for (ALIST_TRAVERSE(ifl->ifl_groups, idx, gdp)) {
                size_t  ndx;
                Word    *data;

                if (isp->is_shdr->sh_type == SHT_GROUP) {
                        if (isp->is_scnndx == gdp->gd_isc->is_scnndx)
                                return (gdp);
                        continue;
                }

                data = gdp->gd_data;
                for (ndx = 1; ndx < gdp->gd_cnt; ndx++) {
                        if (data[ndx] == scnndx)
                                return (gdp);
                }
        }

        ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_ELF_NOGROUPSECT),
            ifl->ifl_name, EC_WORD(isp->is_scnndx), isp->is_name);
        return (NULL);
}

/*
 * When creating a .debug_macro section, in an attempt to make certain DWARF
 * macro information shareable, the GNU compiler must construct group sections
 * with a repeatable signature symbol while nevertheless having no actual
 * symbol to refer to (because it relates to macros).
 *
 * We use this as yet another way to clue ourselves in that sloppy relocation
 * will likely be required.
 *
 * The format of these gensym'd names is:
 *    wm<offset size>.<encoded path name>.<lineno>.<32byte hash>
 * Where the encoded file name may be absent.
 */
static boolean_t
is_header_gensym(const char *name)
{
        const char      *c = NULL;
        size_t          len = strlen(name);

        /* No room for leader, hash, and periods */
        if (len < 37)
                return (B_FALSE);

        if ((strncmp(name, "wm4.", 4) != 0) &&
            strncmp(name, "wm8.", 4) != 0)
                return (B_FALSE);

        c = &name[len - 33];
        if (*c++ != '.')
                return (B_FALSE);

        for (; *c != '\0'; c++) {
                if (!(((*c >= 'a') && (*c <= 'f')) ||
                    ((*c >= '0') && (*c <= '9')))) {
                        return (B_FALSE);
                }
        }

        return (B_TRUE);
}

uintptr_t
ld_group_process(Is_desc *gisc, Ofl_desc *ofl)
{
        Ifl_desc        *gifl = gisc->is_file;
        Shdr            *sshdr, *gshdr = gisc->is_shdr;
        Word            *new_data = NULL;
        Shdr            *new_shdr = NULL;
        Is_desc         *isc;
        Sym             *sym;
        const char      *str;
        Group_desc      gd;
        size_t          ndx;
        int             gnu_stt_section;

        /*
         * Confirm that the sh_link points to a valid section.
         */
        if ((gshdr->sh_link == SHN_UNDEF) ||
            (gshdr->sh_link >= gifl->ifl_shnum) ||
            ((isc = gifl->ifl_isdesc[gshdr->sh_link]) == NULL)) {
                ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHLINK),
                    gifl->ifl_name, EC_WORD(gisc->is_scnndx),
                    gisc->is_name, EC_XWORD(gshdr->sh_link));
                return (0);
        }
        if (gshdr->sh_entsize == 0) {
                ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHENTSIZE),
                    gifl->ifl_name, EC_WORD(gisc->is_scnndx), gisc->is_name,
                    EC_XWORD(gshdr->sh_entsize));
                return (0);
        }

        /*
         * Get the associated symbol table.  Sanity check the sh_info field
         * (which points to the signature symbol table entry) against the size
         * of the symbol table.
         */
        sshdr = isc->is_shdr;
        sym = (Sym *)isc->is_indata->d_buf;

        if ((sshdr->sh_info == SHN_UNDEF) ||
            (gshdr->sh_info >= (Word)(sshdr->sh_size / sshdr->sh_entsize)) ||
            ((isc = gifl->ifl_isdesc[sshdr->sh_link]) == NULL)) {
                ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHINFO),
                    gifl->ifl_name, EC_WORD(gisc->is_scnndx), gisc->is_name,
                    EC_XWORD(gshdr->sh_info));
                return (0);
        }

        sym += gshdr->sh_info;

        /*
         * Get the symbol name from the associated string table.
         */
        str = (char *)isc->is_indata->d_buf;
        str += sym->st_name;

        /*
         * The GNU assembler can use section symbols as the signature symbol
         * as described by this comment in the gold linker (found via google):
         *
         *      It seems that some versions of gas will create a section group
         *      associated with a section symbol, and then fail to give a name
         *      to the section symbol.  In such a case, use the name of the
         *      section.
         *
         * In order to support such objects, we do the same.
         */
        gnu_stt_section = ((sym->st_name == 0) || (*str == '\0')) &&
            (ELF_ST_TYPE(sym->st_info) == STT_SECTION);
        if (gnu_stt_section)
                str = gisc->is_name;


        /*
         * Generate a group descriptor.
         */
        gd.gd_isc = gisc;
        gd.gd_oisc = NULL;
        gd.gd_name = str;
        gd.gd_data = gisc->is_indata->d_buf;
        gd.gd_cnt = gisc->is_indata->d_size / sizeof (Word);

        /*
         * If the signature symbol is a name generated by the GNU compiler to
         * refer to a header, we need sloppy relocation.
         */
        if (is_header_gensym(str)) {
                if ((ofl->ofl_flags1 & FLG_OF1_NRLXREL) == 0)
                        ofl->ofl_flags1 |= FLG_OF1_RLXREL;
                DBG_CALL(Dbg_sec_gnu_comdat(ofl->ofl_lml, gisc, TRUE,
                    (ofl->ofl_flags1 & FLG_OF1_RLXREL) != 0));
        }

        /*
         * Validate the section indices within the group.  If this is a COMDAT
         * group, mark each section as COMDAT.
         */
        for (ndx = (gd.gd_cnt - 1); ndx >= 1; ndx--) {
                Word    gndx = gd.gd_data[ndx];

                if ((gndx == 0) || (gndx >= gifl->ifl_shnum)) {
                        ld_eprintf(ofl, ERR_FATAL,
                            MSG_INTL(MSG_GRP_INVALNDX), gifl->ifl_name,
                            EC_WORD(gisc->is_scnndx), gisc->is_name, ndx, gndx);
                        return (0);
                }

                /*
                 * If we reach here the group was valid but has been damaged
                 * by FLG_OF_STRIP.  That is, this section in the group exists
                 * but was ignored during input processing.
                 *
                 * If this entry is NULL, remove it from the group.  You might
                 * think we can make consuming code careful to be aware that
                 * entries in a group may not exist, but if we are linking a
                 * relocatable object (-r -s), the group must survive, and a
                 * bogus entry must not be written out.
                 */
                if (gifl->ifl_isdesc[gndx] == NULL) {
                        /*
                         * We need to allocate new data for the group and the
                         * shdr, the existing data is mapped from the file.
                         */
                        if (new_data == NULL) {
                                if ((new_data = libld_calloc(sizeof (Word),
                                    gd.gd_cnt)) == NULL)
                                        return (S_ERROR);

                                /*
                                 * Copy up the whole thing, we'll shrink it in
                                 * a moment.
                                 */
                                memcpy(new_data, gd.gd_data,
                                    sizeof (Word) * gd.gd_cnt);
                                gisc->is_indata->d_buf = gd.gd_data = new_data;

                                new_shdr = libld_malloc(sizeof (Shdr));
                                if (new_shdr == NULL)
                                        return (S_ERROR);

                                memcpy(new_shdr, gisc->is_shdr, sizeof (Shdr));
                                gisc->is_shdr = new_shdr;
                        }

                        /* If there're entries after us, copy them down */
                        if (ndx < (gd.gd_cnt - 1)) {
                                memmove(&gd.gd_data[ndx], &gd.gd_data[ndx + 1],
                                    (gd.gd_cnt - (ndx + 1)) * sizeof (Word));
                        }

                        gisc->is_indata->d_size -= sizeof (Word);
                        gisc->is_shdr->sh_size -= sizeof (Word);
                        gd.gd_cnt -= 1;
                        continue;
                }

                if (gd.gd_data[0] & GRP_COMDAT)
                        gifl->ifl_isdesc[gndx]->is_flags |= FLG_IS_COMDAT;
        }

        /*
         * If we're left with only one item in the group -- the header --
         * discard it.
         */
        if (gd.gd_cnt == 1)
                gisc->is_flags |= FLG_IS_DISCARD;

        /*
         * If this is a COMDAT group, determine whether this group has already
         * been encountered, or whether this is the first instance of the group.
         */
        if ((gd.gd_data[0] & GRP_COMDAT) &&
            (gpavl_loaded(ofl, &gd) == S_ERROR))
                return (S_ERROR);

        /*
         * Associate the group descriptor with this input file.
         */
        if (alist_append(&(gifl->ifl_groups), &gd, sizeof (Group_desc),
            AL_CNT_IFL_GROUPS) == NULL)
                return (S_ERROR);

        return (1);
}