diff options
Diffstat (limited to 'tests/addsections.c')
| -rw-r--r-- | tests/addsections.c | 286 |
1 files changed, 286 insertions, 0 deletions
diff --git a/tests/addsections.c b/tests/addsections.c new file mode 100644 index 00000000..66266624 --- /dev/null +++ b/tests/addsections.c @@ -0,0 +1,286 @@ +/* Test program for adding (more than SHN_LORESERVE) sections. + Copyright (C) 2018 Red Hat, Inc. + This file is part of elfutils. + + This file is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + elfutils is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <errno.h> +#include <fcntl.h> +#include <inttypes.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <sys/types.h> +#include <sys/stat.h> + +#include ELFUTILS_HEADER(elf) +#include <gelf.h> + + +/* shstrndx is special, might overflow into section zero header sh_link. */ +static int +setshstrndx (Elf *elf, size_t ndx) +{ + printf ("setshstrndx: %zd\n", ndx); + + GElf_Ehdr ehdr_mem; + GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem); + if (ehdr == NULL) + return -1; + + if (ndx < SHN_LORESERVE) + ehdr->e_shstrndx = ndx; + else + { + ehdr->e_shstrndx = SHN_XINDEX; + Elf_Scn *zscn = elf_getscn (elf, 0); + GElf_Shdr zshdr_mem; + GElf_Shdr *zshdr = gelf_getshdr (zscn, &zshdr_mem); + if (zshdr == NULL) + return -1; + zshdr->sh_link = ndx; + if (gelf_update_shdr (zscn, zshdr) == 0) + return -1; + } + + if (gelf_update_ehdr (elf, ehdr) == 0) + return -1; + + return 0; +} + +/* Will add nr new '.extra' sections and a new '.new_shstrtab' section + at the end. */ +static void +add_sections (const char *name, size_t nr, int use_mmap) +{ + printf ("add_sections '%s': %zd\n", name, nr); + + int fd = open (name, O_RDWR | O_BINARY); + if (fd < 0) + { + fprintf (stderr, "Couldn't open file '%s': %s\n", + name, strerror (errno)); + exit (1); + } + + Elf *elf = elf_begin (fd, use_mmap ? ELF_C_RDWR_MMAP : ELF_C_RDWR, NULL); + if (elf == NULL) + { + fprintf (stderr, "Couldn't open ELF file '%s': %s\n", + name, elf_errmsg (-1)); + exit (1); + } + + /* We will add a new shstrtab section with two new names at the end. + Just get the current shstrtab table and add two entries '.extra' + and '.new_shstrtab' at the end of the table, so all existing indexes + are still valid. */ + size_t shstrndx; + if (elf_getshdrstrndx (elf, &shstrndx) < 0) + { + printf ("cannot get shstrndx: %s\n", elf_errmsg (-1)); + exit (1); + } + + Elf_Scn *shstrtab_scn = elf_getscn (elf, shstrndx); + if (shstrtab_scn == NULL) + { + printf ("couldn't get shstrtab scn: %s\n", elf_errmsg (-1)); + exit (1); + } + Elf_Data *shstrtab_data = elf_getdata (shstrtab_scn, NULL); + if (shstrtab_data == NULL) + { + printf ("couldn't get shstrtab data: %s\n", elf_errmsg (-1)); + exit (1); + } + size_t new_shstrtab_size = (shstrtab_data->d_size + + strlen (".extra") + 1 + + strlen (".new_shstrtab") + 1); + void *new_shstrtab_buf = malloc (new_shstrtab_size); + if (new_shstrtab_buf == NULL) + { + printf ("couldn't allocate new shstrtab data d_buf\n"); + exit (1); + } + memcpy (new_shstrtab_buf, shstrtab_data->d_buf, shstrtab_data->d_size); + size_t extra_idx = shstrtab_data->d_size; + size_t new_shstrtab_idx = extra_idx + strlen (".extra") + 1; + strcpy (new_shstrtab_buf + extra_idx, ".extra"); + strcpy (new_shstrtab_buf + new_shstrtab_idx, ".new_shstrtab"); + + // Add lots of .extra sections... + size_t cnt = 0; + while (cnt++ < nr) + { + Elf_Scn *scn = elf_newscn (elf); + if (scn == NULL) + { + printf ("cannot create .extra section (%zd): %s\n", cnt, + elf_errmsg (-1)); + exit (1); + } + + Elf_Data *data = elf_newdata (scn); + if (data == NULL) + { + printf ("couldn't create new section data (%zd): %s\n", cnt, + elf_errmsg (-1)); + exit (1); + } + + data->d_size = strlen ("extra") + 1; + data->d_buf = "extra"; + data->d_type = ELF_T_BYTE; + data->d_align = 1; + + GElf_Shdr shdr_mem; + GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); + if (shdr == NULL) + { + printf ("cannot get header for new section (%zd): %s\n", cnt, + elf_errmsg (-1)); + exit (1); + } + + shdr->sh_type = SHT_PROGBITS; + shdr->sh_flags = 0; + shdr->sh_addr = 0; + shdr->sh_link = SHN_UNDEF; + shdr->sh_info = SHN_UNDEF; + shdr->sh_addralign = 1; + shdr->sh_entsize = 0; + shdr->sh_size = data->d_size; + shdr->sh_name = extra_idx; + + if (gelf_update_shdr (scn, shdr) == 0) + { + printf ("cannot update new section header (%zd): %s\n", cnt, + elf_errmsg (-1)); + exit (1); + } + } + + // Create new shstrtab section. + Elf_Scn *new_shstrtab_scn = elf_newscn (elf); + if (new_shstrtab_scn == NULL) + { + printf ("cannot create new shstrtab section: %s\n", elf_errmsg (-1)); + exit (1); + } + + Elf_Data *new_shstrtab_data = elf_newdata (new_shstrtab_scn); + if (new_shstrtab_data == NULL) + { + printf ("couldn't create new shstrtab section data: %s\n", + elf_errmsg (-1)); + exit (1); + } + + new_shstrtab_data->d_size = new_shstrtab_size; + new_shstrtab_data->d_buf = new_shstrtab_buf; + new_shstrtab_data->d_type = ELF_T_BYTE; + new_shstrtab_data->d_align = 1; + + GElf_Shdr shdr_mem; + GElf_Shdr *shdr = gelf_getshdr (new_shstrtab_scn, &shdr_mem); + if (shdr == NULL) + { + printf ("cannot get header for new shstrtab section: %s\n", + elf_errmsg (-1)); + exit (1); + } + + shdr->sh_type = SHT_STRTAB; + shdr->sh_flags = 0; + shdr->sh_addr = 0; + shdr->sh_link = SHN_UNDEF; + shdr->sh_info = SHN_UNDEF; + shdr->sh_addralign = 1; + shdr->sh_entsize = 0; + shdr->sh_size = new_shstrtab_size; + shdr->sh_name = new_shstrtab_idx; + + // Finished new shstrtab section, update the header. + if (gelf_update_shdr (new_shstrtab_scn, shdr) == 0) + { + printf ("cannot update new shstrtab section header: %s\n", + elf_errmsg (-1)); + exit (1); + } + + // Set it as the new shstrtab section to get the names correct. + size_t new_shstrndx = elf_ndxscn (new_shstrtab_scn); + if (setshstrndx (elf, new_shstrndx) < 0) + { + printf ("cannot set shstrndx: %s\n", elf_errmsg (-1)); + exit (1); + } + + // Write everything to disk. + if (elf_update (elf, ELF_C_WRITE) < 0) + { + printf ("failure in elf_update: %s\n", elf_errmsg (-1)); + exit (1); + } + + if (elf_end (elf) != 0) + { + printf ("couldn't cleanup elf '%s': %s\n", name, elf_errmsg (-1)); + exit (1); + } + + if (close (fd) != 0) + { + printf ("couldn't close '%s': %s\n", name, strerror (errno)); + exit (1); + } + + free (new_shstrtab_buf); +} + +int +main (int argc, char *argv[]) +{ + elf_version (EV_CURRENT); + + /* Takes the given file, and adds the given number of sections. */ + if (argc < 3 || argc > 4) + { + fprintf (stderr, "addsections [--mmap] nr elf.file\n"); + exit (1); + } + + int argn = 1; + bool use_mmap = false; + if (strcmp (argv[argn], "--mmap") == 0) + { + use_mmap = true; + argn++; + } + + size_t nr = atoi (argv[argn++]); + const char *file = argv[argn]; + add_sections (file, nr, use_mmap); + + return 0; +} |