xref: /bionic/libc/arch-x86/bionic/dl_iterate_phdr_static.c

/* bionic/arch-x86/bionic/dl_iterate_phdr_static.c
**
** Copyright 2006, The Android Open Source Project
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met:
**     * Redistributions of source code must retain the above copyright
**       notice, this list of conditions and the following disclaimer.
**     * 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.
**     * Neither the name of Google Inc. nor the names of its contributors may
**       be used to endorse or promote products derived from this software
**       without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY Google Inc. ``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 Google Inc. 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 <sys/types.h>
#include <linux/elf.h>

/* TODO: Move this into a header that linker.h can also pull it in.
 * Silly to have same struct in 2 places. This is temporary. */
struct dl_phdr_info
{
    Elf32_Addr dlpi_addr;
    const char *dlpi_name;
    const Elf32_Phdr *dlpi_phdr;
    Elf32_Half dlpi_phnum;
};

/* Dynamic binaries get this from the dynamic linker (system/linker), which
 * we don't pull in for static bins. We also don't have a list of so's to
 * iterate over, since there's really only a single monolithic blob of
 * code/data.
 *
 * All we need to do is to find where the executable is in memory, and grab the
 * phdr and phnum from there.
 */

/* ld provides this to us in the default link script */
extern void *__executable_start;

int
dl_iterate_phdr(int (*cb)(struct dl_phdr_info *info, size_t size, void *data),
                void *data)
{
    struct dl_phdr_info dl_info;
    Elf32_Ehdr *ehdr = (Elf32_Ehdr *) &__executable_start;
    Elf32_Phdr *phdr = (Elf32_Phdr *)((unsigned long)ehdr + ehdr->e_phoff);

    /* TODO: again, copied from linker.c. Find a better home for this
     * later. */
    if (ehdr->e_ident[EI_MAG0] != ELFMAG0) return -1;
    if (ehdr->e_ident[EI_MAG1] != ELFMAG1) return -1;
    if (ehdr->e_ident[EI_MAG2] != ELFMAG2) return -1;
    if (ehdr->e_ident[EI_MAG3] != ELFMAG3) return -1;

    dl_info.dlpi_addr = 0;
    dl_info.dlpi_name = NULL;
    dl_info.dlpi_phdr = phdr;
    dl_info.dlpi_phnum = ehdr->e_phnum;
    return cb(&dl_info, sizeof (struct dl_phdr_info), data);
}