ext/libelf/elf_data.c

/*-
 * Copyright (c) 2006 Joseph Koshy
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


#include <assert.h>
#include <errno.h>
#include "libelf.h"
#include <stdlib.h>

#include "_libelf.h"


Elf_Data *
elf_getdata(Elf_Scn *s, Elf_Data *d)
{
        Elf *e;
        char *dst;
        size_t fsz, msz, count;
        int elfclass, elftype;
        unsigned int sh_type;
        uint64_t sh_align, sh_offset, sh_size;
        void (*xlate)(char *_d, char *_s, size_t _c, int _swap);

        if (s == NULL || (e = s->s_elf) == NULL || e->e_kind != ELF_K_ELF ||
            (d != NULL && s != d->d_scn)) {
                LIBELF_SET_ERROR(ARGUMENT, 0);
                return (NULL);
        }

        if (d == NULL && (d = STAILQ_FIRST(&s->s_data)) != NULL)
                return (d);

        if (d != NULL)
                return (STAILQ_NEXT(d, d_next));

        if (e->e_rawfile == NULL) {
                LIBELF_SET_ERROR(SEQUENCE, 0);
                return (NULL);
        }

        elfclass = e->e_class;

        assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);

        if (elfclass == ELFCLASS32) {
                sh_type   = s->s_shdr.s_shdr32.sh_type;
                sh_offset = (uint64_t) s->s_shdr.s_shdr32.sh_offset;
                sh_size   = (uint64_t) s->s_shdr.s_shdr32.sh_size;
                sh_align  = (uint64_t) s->s_shdr.s_shdr32.sh_addralign;
        } else {
                sh_type   = s->s_shdr.s_shdr64.sh_type;
                sh_offset = s->s_shdr.s_shdr64.sh_offset;
                sh_size   = s->s_shdr.s_shdr64.sh_size;
                sh_align  = s->s_shdr.s_shdr64.sh_addralign;
        }

        if ((elftype = _libelf_xlate_shtype(sh_type)) < ELF_T_FIRST ||
            elftype > ELF_T_LAST ||
            sh_offset + sh_size > (uint64_t) e->e_rawsize) {
                LIBELF_SET_ERROR(SECTION, 0);
                return (NULL);
        }

        if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)(elftype,
                 (size_t) 1, e->e_version)) == 0) {
                LIBELF_SET_ERROR(UNIMPL, 0);
                return (NULL);
        }


        if (sh_size % fsz) {
                LIBELF_SET_ERROR(SECTION, 0);
                return (NULL);
        }

        count = sh_size / fsz;

        msz = _libelf_msize(elftype, elfclass, e->e_version);

        assert(msz > 0);

        if ((dst = malloc(msz*count)) == NULL) {
                LIBELF_SET_ERROR(RESOURCE, 0);
                return (NULL);
        }

        if ((d = _libelf_allocate_data(s)) == NULL)
                return (NULL);

        d->d_buf     = dst;
        d->d_off     = 0;
        d->d_align   = sh_align;
        d->d_size    = msz * count;
        d->d_type    = elftype;
        d->d_version = e->e_version;

        d->d_flags  |= LIBELF_F_MALLOCED;
        STAILQ_INSERT_TAIL(&s->s_data, d, d_next);

        xlate = _libelf_get_translator(elftype, ELF_TOMEMORY, elfclass);
        (*xlate)(d->d_buf, e->e_rawfile + sh_offset, count, e->e_byteorder !=
            LIBELF_PRIVATE(byteorder));

        return (d);
}

Elf_Data *
elf_newdata(Elf_Scn *s)
{
        Elf *e;
        Elf_Data *d;

        if (s == NULL || (e = s->s_elf) == NULL ||
            e->e_kind != ELF_K_ELF) {
                LIBELF_SET_ERROR(ARGUMENT, 0);
                return (NULL);
        }

        /*
         * elf_newdata() has to append a data descriptor, so
         * bring in existing section data if not already present.
         */
        if (e->e_rawfile && s->s_size > 0 && STAILQ_EMPTY(&s->s_data))
                if (elf_getdata(s, NULL) == NULL)
                        return (NULL);

        if ((d = malloc(sizeof(Elf_Data))) == NULL) {
                LIBELF_SET_ERROR(RESOURCE, errno);
                return (NULL);
        }

        STAILQ_INSERT_TAIL(&s->s_data, d, d_next);
        d->d_flags = 0;
        d->d_scn = s;

        d->d_align = 1;
        d->d_buf = NULL;
        d->d_off = (uint64_t) ~0;
        d->d_size = 0;
        d->d_type = ELF_T_BYTE;
        d->d_version = LIBELF_PRIVATE(version);

        (void) elf_flagscn(s, ELF_C_SET, ELF_F_DIRTY);

        return (d);
}

/*
 * Retrieve a data descriptor for raw (untranslated) data for section
 * `s'.
 */

Elf_Data *
elf_rawdata(Elf_Scn *s, Elf_Data *d)
{
        Elf *e;
        int elf_class;
        uint64_t sh_align, sh_offset, sh_size;

        if (s == NULL || (e = s->s_elf) == NULL ||
            e->e_kind != ELF_K_ELF || e->e_rawfile == NULL) {
                LIBELF_SET_ERROR(ARGUMENT, 0);
                return (NULL);
        }

        if (d == NULL && (d = STAILQ_FIRST(&s->s_rawdata)) != NULL)
                return (d);

        if (d != NULL)
                return (STAILQ_NEXT(d, d_next));

        elf_class = e->e_class;

        assert(elf_class == ELFCLASS32 || elf_class == ELFCLASS64);

        if (elf_class == ELFCLASS32) {
                sh_offset = (uint64_t) s->s_shdr.s_shdr32.sh_offset;
                sh_size   = (uint64_t) s->s_shdr.s_shdr32.sh_size;
                sh_align  = (uint64_t) s->s_shdr.s_shdr32.sh_addralign;
        } else {
                sh_offset = s->s_shdr.s_shdr64.sh_offset;
                sh_size   = s->s_shdr.s_shdr64.sh_size;
                sh_align  = s->s_shdr.s_shdr64.sh_addralign;
        }

        if ((d = _libelf_allocate_data(s)) == NULL)
                return (NULL);

        d->d_buf     = e->e_rawfile + sh_offset;
        d->d_off     = 0;
        d->d_align   = sh_align;
        d->d_size    = sh_size;
        d->d_type    = ELF_T_BYTE;
        d->d_version = e->e_version;

        STAILQ_INSERT_TAIL(&s->s_rawdata, d, d_next);

        return (d);
}