/*      $OpenBSD: dw.c,v 1.6 2024/02/21 13:16:14 claudio Exp $ */

/*
 * Copyright (c) 2016 Martin Pieuchot
 * Copyright (c) 2014 Matthew Dempsky <matthew@dempsky.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/queue.h>

#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "dw.h"
#include "dwarf.h"
#include "pool.h"

#ifndef NOPOOL
struct pool dcu_pool, die_pool, dav_pool, dab_pool, dat_pool;
#endif /* NOPOOL */

#ifndef nitems
#define nitems(_a)      (sizeof((_a)) / sizeof((_a)[0]))
#endif

static int       dw_read_u8(struct dwbuf *, uint8_t *);
static int       dw_read_u16(struct dwbuf *, uint16_t *);
static int       dw_read_u32(struct dwbuf *, uint32_t *);
static int       dw_read_u64(struct dwbuf *, uint64_t *);

static int       dw_read_sleb128(struct dwbuf *, int64_t *);
static int       dw_read_uleb128(struct dwbuf *, uint64_t *);

static int       dw_read_bytes(struct dwbuf *, void *, size_t);
static int       dw_read_string(struct dwbuf *, const char **);
static int       dw_read_buf(struct dwbuf *, struct dwbuf *, size_t);

static int       dw_skip_bytes(struct dwbuf *, size_t);

static int       dw_attr_parse(struct dwbuf *, struct dwattr *, uint8_t,
                     struct dwaval_queue *);
static void      dw_attr_purge(struct dwaval_queue *);
static int       dw_die_parse(struct dwbuf *, size_t, uint8_t,
                     struct dwabbrev_queue *, struct dwdie_queue *);
static void      dw_die_purge(struct dwdie_queue *);

static int
dw_read_bytes(struct dwbuf *d, void *v, size_t n)
{
        if (d->len < n)
                return -1;
        memcpy(v, d->buf, n);
        d->buf += n;
        d->len -= n;
        return 0;
}

static int
dw_read_u8(struct dwbuf *d, uint8_t *v)
{
        return dw_read_bytes(d, v, sizeof(*v));
}

static int
dw_read_u16(struct dwbuf *d, uint16_t *v)
{
        return dw_read_bytes(d, v, sizeof(*v));
}

static int
dw_read_u32(struct dwbuf *d, uint32_t *v)
{
        return dw_read_bytes(d, v, sizeof(*v));
}

static int
dw_read_u64(struct dwbuf *d, uint64_t *v)
{
        return dw_read_bytes(d, v, sizeof(*v));
}

/* Read a DWARF LEB128 (little-endian base-128) value. */
static inline int
dw_read_leb128(struct dwbuf *d, uint64_t *v, int signextend)
{
        unsigned int shift = 0;
        uint64_t res = 0;
        uint8_t x;

        while (shift < 64 && !dw_read_u8(d, &x)) {
                res |= (uint64_t)(x & 0x7f) << shift;
                shift += 7;
                if ((x & 0x80) == 0) {
                        if (signextend && shift < 64 && (x & 0x40) != 0)
                                res |= ~(uint64_t)0 << shift;
                        *v = res;
                        return 0;
                }
        }
        return -1;
}

static int
dw_read_sleb128(struct dwbuf *d, int64_t *v)
{
        return dw_read_leb128(d, (uint64_t *)v, 1);
}

static int
dw_read_uleb128(struct dwbuf *d, uint64_t *v)
{
        return dw_read_leb128(d, v, 0);
}

/* Read a NUL terminated string. */
static int
dw_read_string(struct dwbuf *d, const char **s)
{
        const char *end = memchr(d->buf, '\0', d->len);
        size_t n;

        if (end == NULL)
                return -1;

        n = end - d->buf + 1;
        *s = d->buf;
        d->buf += n;
        d->len -= n;
        return 0;
}

static int
dw_read_buf(struct dwbuf *d, struct dwbuf *v, size_t n)
{
        if (d->len < n)
                return -1;
        v->buf = d->buf;
        v->len = n;
        d->buf += n;
        d->len -= n;
        return 0;
}

static int
dw_skip_bytes(struct dwbuf *d, size_t n)
{
        if (d->len < n)
                return -1;
        d->buf += n;
        d->len -= n;
        return 0;
}

const char *
dw_tag2name(uint64_t tag)
{
        static const char *dw_tags[] = { DW_TAG_NAMES };

        if (tag <= nitems(dw_tags))
                return dw_tags[tag - 1];

        if (tag == DW_TAG_lo_user)
                return "DW_TAG_lo_user";
        if (tag == DW_TAG_hi_user)
                return "DW_TAG_hi_user";

        return NULL;
}

const char *
dw_at2name(uint64_t at)
{
        static const char *dw_attrs[] = { DW_AT_NAMES };
        static char buf[64];

        if (at <= nitems(dw_attrs))
                return dw_attrs[at - 1];

        if (at == DW_AT_lo_user)
                return "DW_AT_lo_user";
        if (at == DW_AT_hi_user)
                return "DW_AT_hi_user";

        snprintf(buf, sizeof(buf), "#%llu", at);
        return buf;
}

const char *
dw_form2name(uint64_t form)
{
        static const char *dw_forms[] = { DW_FORM_NAMES };

        if (form <= nitems(dw_forms))
                return dw_forms[form - 1];

        if (form == DW_FORM_GNU_ref_alt)
                return "DW_FORM_GNU_ref_alt";
        if (form == DW_FORM_GNU_strp_alt)
                return "DW_FORM_GNU_strp_alt";

        return NULL;
}

const char *
dw_op2name(uint8_t op)
{
        static const char *dw_ops[] = { DW_OP_NAMES };

        if (op <= nitems(dw_ops))
                return dw_ops[op - 1];

        if (op == DW_OP_lo_user)
                return "DW_OP_lo_user";
        if (op == DW_OP_hi_user)
                return "DW_OP_hi_user";

        return NULL;
}

static int
dw_attr_parse(struct dwbuf *dwbuf, struct dwattr *dat, uint8_t psz,
    struct dwaval_queue *davq)
{
        struct dwaval   *dav;
        uint64_t         form = dat->dat_form;
        int              error = 0, i = 0;

        while (form == DW_FORM_indirect) {
                /* XXX loop prevention not strict enough? */
                if (dw_read_uleb128(dwbuf, &form) || (++i > 3))
                        return ELOOP;
        }

        dav = pzalloc(&dav_pool, sizeof(*dav));
        if (dav == NULL)
                return ENOMEM;

        dav->dav_dat = dat;

        switch (form) {
        case DW_FORM_addr:
        case DW_FORM_ref_addr:
                if (psz == sizeof(uint32_t))
                        error = dw_read_u32(dwbuf, &dav->dav_u32);
                else
                        error = dw_read_u64(dwbuf, &dav->dav_u64);
                break;
        case DW_FORM_block1:
                error = dw_read_u8(dwbuf, &dav->dav_u8);
                if (error == 0)
                        error = dw_read_buf(dwbuf, &dav->dav_buf, dav->dav_u8);
                break;
        case DW_FORM_block2:
                error = dw_read_u16(dwbuf, &dav->dav_u16);
                if (error == 0)
                        error = dw_read_buf(dwbuf, &dav->dav_buf, dav->dav_u16);
                break;
        case DW_FORM_block4:
                error = dw_read_u32(dwbuf, &dav->dav_u32);
                if (error == 0)
                        error = dw_read_buf(dwbuf, &dav->dav_buf, dav->dav_u32);
                break;
        case DW_FORM_block:
                error = dw_read_uleb128(dwbuf, &dav->dav_u64);
                if (error == 0)
                        error = dw_read_buf(dwbuf, &dav->dav_buf, dav->dav_u64);
                break;
        case DW_FORM_data1:
        case DW_FORM_flag:
        case DW_FORM_ref1:
                error = dw_read_u8(dwbuf, &dav->dav_u8);
                break;
        case DW_FORM_data2:
        case DW_FORM_ref2:
                error = dw_read_u16(dwbuf, &dav->dav_u16);
                break;
        case DW_FORM_data4:
        case DW_FORM_ref4:
                error = dw_read_u32(dwbuf, &dav->dav_u32);
                break;
        case DW_FORM_data8:
        case DW_FORM_ref8:
                error = dw_read_u64(dwbuf, &dav->dav_u64);
                break;
        case DW_FORM_ref_udata:
        case DW_FORM_udata:
                error = dw_read_uleb128(dwbuf, &dav->dav_u64);
                break;
        case DW_FORM_sdata:
                error = dw_read_sleb128(dwbuf, &dav->dav_s64);
                break;
        case DW_FORM_string:
                error = dw_read_string(dwbuf, &dav->dav_str);
                break;
        case DW_FORM_strp:
                error = dw_read_u32(dwbuf, &dav->dav_u32);
                break;
        case DW_FORM_flag_present:
                dav->dav_u8 = 1;
                break;
        default:
                error = ENOENT;
                break;
        }

        if (error) {
                pfree(&dav_pool, dav);
                return error;
        }

        SIMPLEQ_INSERT_TAIL(davq, dav, dav_next);
        return 0;
}

static void
dw_attr_purge(struct dwaval_queue *davq)
{
        struct dwaval   *dav;

        while ((dav = SIMPLEQ_FIRST(davq)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(davq, dav_next);
                pfree(&dav_pool, dav);
        }

        SIMPLEQ_INIT(davq);
}

static int
dw_die_parse(struct dwbuf *dwbuf, size_t nextoff, uint8_t psz,
    struct dwabbrev_queue *dabq, struct dwdie_queue *dieq)
{
        struct dwdie    *die;
        struct dwabbrev *dab;
        struct dwattr   *dat;
        uint64_t         code;
        size_t           doff;
        uint8_t          lvl = 0;
        int              error;


        while (dwbuf->len > 0) {
                doff = nextoff - dwbuf->len;
                if (dw_read_uleb128(dwbuf, &code))
                        return -1;

                if (code == 0) {
                        lvl--;
                        continue;
                }

                SIMPLEQ_FOREACH(dab, dabq, dab_next) {
                        if (dab->dab_code == code)
                                break;
                }
                if (dab == NULL)
                        return ESRCH;

                die = pmalloc(&die_pool, sizeof(*die));
                if (die == NULL)
                        return ENOMEM;

                die->die_lvl = lvl;
                die->die_dab = dab;
                die->die_offset = doff;
                SIMPLEQ_INIT(&die->die_avals);

                SIMPLEQ_FOREACH(dat, &dab->dab_attrs, dat_next) {
                        error = dw_attr_parse(dwbuf, dat, psz, &die->die_avals);
                        if (error != 0) {
                                dw_attr_purge(&die->die_avals);
                                return error;
                        }
                }

                if (dab->dab_children == DW_CHILDREN_yes)
                        lvl++;

                SIMPLEQ_INSERT_TAIL(dieq, die, die_next);
        }

        return 0;
}

static void
dw_die_purge(struct dwdie_queue *dieq)
{
        struct dwdie    *die;

        while ((die = SIMPLEQ_FIRST(dieq)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(dieq, die_next);
                dw_attr_purge(&die->die_avals);
                pfree(&die_pool, die);
        }

        SIMPLEQ_INIT(dieq);
}

int
dw_ab_parse(struct dwbuf *abseg, struct dwabbrev_queue *dabq)
{
        struct dwabbrev *dab;
        uint64_t         code, tag;
        uint8_t          children;

        if (abseg->len == 0)
                return EINVAL;

        for (;;) {
                if (dw_read_uleb128(abseg, &code) || (code == 0))
                        break;

                if (dw_read_uleb128(abseg, &tag) ||
                    dw_read_u8(abseg, &children))
                        return -1;

                dab = pmalloc(&dab_pool, sizeof(*dab));
                if (dab == NULL)
                        return ENOMEM;

                dab->dab_code = code;
                dab->dab_tag = tag;
                dab->dab_children = children;
                SIMPLEQ_INIT(&dab->dab_attrs);

                SIMPLEQ_INSERT_TAIL(dabq, dab, dab_next);

                for (;;) {
                        struct dwattr *dat;
                        uint64_t attr = 0, form = 0;

                        if (dw_read_uleb128(abseg, &attr) ||
                            dw_read_uleb128(abseg, &form))
                                return -1;

                        if ((attr == 0) && (form == 0))
                                break;

                        dat = pmalloc(&dat_pool, sizeof(*dat));
                        if (dat == NULL)
                                return ENOMEM;

                        dat->dat_attr = attr;
                        dat->dat_form = form;

                        SIMPLEQ_INSERT_TAIL(&dab->dab_attrs, dat, dat_next);
                }
        }

        return 0;
}

void
dw_dabq_purge(struct dwabbrev_queue *dabq)
{
        struct dwabbrev *dab;

        while ((dab = SIMPLEQ_FIRST(dabq)) != NULL) {
                struct dwattr *dat;

                SIMPLEQ_REMOVE_HEAD(dabq, dab_next);
                while ((dat = SIMPLEQ_FIRST(&dab->dab_attrs)) != NULL) {
                        SIMPLEQ_REMOVE_HEAD(&dab->dab_attrs, dat_next);
                        pfree(&dat_pool, dat);
                }

                pfree(&dab_pool, dab);
        }

        SIMPLEQ_INIT(dabq);
}

int
dw_cu_parse(struct dwbuf *info, struct dwbuf *abbrev, size_t seglen,
    struct dwcu **dcup)
{
        struct dwbuf     abseg = *abbrev;
        struct dwbuf     dwbuf;
        size_t           segoff, nextoff, addrsize;
        struct dwcu     *dcu = NULL;
        uint32_t         length = 0, abbroff = 0;
        uint16_t         version;
        uint8_t          psz;
        int              error;
#ifndef NOPOOL
        static int       dw_pool_inited = 0;

        if (!dw_pool_inited) {
                pool_init(&dcu_pool, "dcu", 1, sizeof(struct dwcu));
                pool_init(&dab_pool, "dab", 32, sizeof(struct dwabbrev));
                pool_init(&dat_pool, "dat", 32, sizeof(struct dwattr));
                pool_init(&die_pool, "die", 512, sizeof(struct dwdie));
                pool_init(&dav_pool, "dav", 1024, sizeof(struct dwaval));
                dw_pool_inited = 1;
        }
#endif /* NOPOOL */

        if (info->len == 0 || abbrev->len == 0)
                return EINVAL;

        /* Offset in the segment of the current Compile Unit. */
        segoff = seglen - info->len;

        if (dw_read_u32(info, &length))
                return -1;

        if (length >= 0xfffffff0 || length > info->len)
                return EOVERFLOW;

        /* Offset of the next Compile Unit. */
        nextoff = segoff + length + sizeof(uint32_t);

        if (dw_read_buf(info, &dwbuf, length))
                return -1;

        addrsize = 4; /* XXX */

        if (dw_read_u16(&dwbuf, &version) ||
            dw_read_bytes(&dwbuf, &abbroff, addrsize) ||
            dw_read_u8(&dwbuf, &psz))
                return -1;

        if (dw_skip_bytes(&abseg, abbroff))
                return -1;

        /* Only DWARF2 until extended. */
        if (version != 2)
                return ENOTSUP;

        dcu = pmalloc(&dcu_pool, sizeof(*dcu));
        if (dcu == NULL)
                return ENOMEM;

        dcu->dcu_offset = segoff;
        dcu->dcu_length = length;
        dcu->dcu_version = version;
        dcu->dcu_abbroff = abbroff;
        dcu->dcu_psize = psz;
        SIMPLEQ_INIT(&dcu->dcu_abbrevs);
        SIMPLEQ_INIT(&dcu->dcu_dies);

        error = dw_ab_parse(&abseg, &dcu->dcu_abbrevs);
        if (error != 0) {
                dw_dcu_free(dcu);
                return error;
        }

        error = dw_die_parse(&dwbuf, nextoff, psz, &dcu->dcu_abbrevs,
            &dcu->dcu_dies);
        if (error != 0) {
                dw_dcu_free(dcu);
                return error;
        }

        if (dcup != NULL)
                *dcup = dcu;
        else
                dw_dcu_free(dcu);

        return 0;
}

void
dw_dcu_free(struct dwcu *dcu)
{
        if (dcu == NULL)
                return;

        dw_die_purge(&dcu->dcu_dies);
        dw_dabq_purge(&dcu->dcu_abbrevs);
        pfree(&dcu_pool, dcu);
}

int
dw_loc_parse(struct dwbuf *dwbuf, uint8_t *pop, uint64_t *poper1,
    uint64_t *poper2)
{
        uint64_t oper1 = 0, oper2 = 0;
        uint8_t op;

        if (dw_read_u8(dwbuf, &op))
                return -1;

        if (pop != NULL)
                *pop = op;

        switch (op) {
        case DW_OP_constu:
        case DW_OP_plus_uconst:
        case DW_OP_regx:
        case DW_OP_piece:
                dw_read_uleb128(dwbuf, &oper1);
                break;

        case DW_OP_consts:
        case DW_OP_breg0 ... DW_OP_breg31:
        case DW_OP_fbreg:
                dw_read_sleb128(dwbuf, &oper1);
                break;
        default:
                return ENOTSUP;
        }

        if (poper1 != NULL)
                *poper1 = oper1;
        if (poper2 != NULL)
                *poper2 = oper2;

        return 0;
}