ext/libelf/libelf_phdr.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.
 *
 * $FreeBSD: src/lib/libelf/libelf_phdr.c,v 1.2 2006/12/25 02:22:22 jkoshy Exp $
 */

#include <assert.h>
#include <stdlib.h>

#include "gelf.h"
#include "libelf.h"
#include "_libelf.h"

void *
_libelf_getphdr(Elf *e, int ec)
{
        size_t phnum, phentsize;
        size_t fsz, msz;
        uint64_t phoff;
        Elf32_Ehdr *eh32;
        Elf64_Ehdr *eh64;
        void *ehdr, *phdr;
        void (*xlator)(char *_d, char *_s, size_t _c, int _swap);

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

        if (e == NULL) {
                LIBELF_SET_ERROR(ARGUMENT, 0);
                return (NULL);
        }

        if ((phdr = (ec == ELFCLASS32 ?
                 (void *) e->e_u.e_elf.e_phdr.e_phdr32 :
                 (void *) e->e_u.e_elf.e_phdr.e_phdr64)) != NULL)
                return (phdr);

        /*
         * Check the PHDR related fields in the EHDR for sanity.
         */

        if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
                return (NULL);

        phnum = e->e_u.e_elf.e_nphdr;

        if (ec == ELFCLASS32) {
                eh32      = (Elf32_Ehdr *) ehdr;
                phentsize = eh32->e_phentsize;
                phoff     = (uint64_t) eh32->e_phoff;
        } else {
                eh64      = (Elf64_Ehdr *) ehdr;
                phentsize = eh64->e_phentsize;
                phoff     = (uint64_t) eh64->e_phoff;
        }

        fsz = gelf_fsize(e, ELF_T_PHDR, phnum, e->e_version);

        assert(fsz > 0);

        if ((uint64_t) e->e_rawsize < (phoff + fsz)) {
                LIBELF_SET_ERROR(HEADER, 0);
                return (NULL);
        }

        msz = _libelf_msize(ELF_T_PHDR, ec, EV_CURRENT);

        assert(msz > 0);

        if ((phdr = calloc(phnum, msz)) == NULL) {
                LIBELF_SET_ERROR(RESOURCE, 0);
                return (NULL);
        }

        if (ec == ELFCLASS32)
                e->e_u.e_elf.e_phdr.e_phdr32 = phdr;
        else
                e->e_u.e_elf.e_phdr.e_phdr64 = phdr;


        xlator = _libelf_get_translator(ELF_T_PHDR, ELF_TOMEMORY, ec);
        (*xlator)(phdr, e->e_rawfile + phoff, phnum,
            e->e_byteorder != LIBELF_PRIVATE(byteorder));

        return (phdr);
}

void *
_libelf_newphdr(Elf *e, int ec, size_t count)
{
        void *ehdr, *newphdr, *oldphdr;
        size_t msz;

        if (e == NULL) {
                LIBELF_SET_ERROR(ARGUMENT, 0);
                return (NULL);
        }

        if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) {
                LIBELF_SET_ERROR(SEQUENCE, 0);
                return (NULL);
        }

        assert(e->e_class == ec);
        assert(ec == ELFCLASS32 || ec == ELFCLASS64);
        assert(e->e_version == EV_CURRENT);

        msz = _libelf_msize(ELF_T_PHDR, ec, e->e_version);

        assert(msz > 0);

        newphdr = NULL;
        if (count > 0 && (newphdr = calloc(count, msz)) == NULL) {
                LIBELF_SET_ERROR(RESOURCE, 0);
                return (NULL);
        }

        if (ec == ELFCLASS32) {
                if ((oldphdr = (void *) e->e_u.e_elf.e_phdr.e_phdr32) != NULL)
                        free(oldphdr);
                e->e_u.e_elf.e_phdr.e_phdr32 = (Elf32_Phdr *) newphdr;
        } else {
                if ((oldphdr = (void *) e->e_u.e_elf.e_phdr.e_phdr64) != NULL)
                        free(oldphdr);
                e->e_u.e_elf.e_phdr.e_phdr64 = (Elf64_Phdr *) newphdr;
        }

        e->e_u.e_elf.e_nphdr = count;

        elf_flagphdr(e, ELF_C_SET, ELF_F_DIRTY);

        return (newphdr);
}