diff options
Diffstat (limited to 'tests/elfcopy.c')
| -rw-r--r-- | tests/elfcopy.c | 286 |
1 files changed, 286 insertions, 0 deletions
diff --git a/tests/elfcopy.c b/tests/elfcopy.c new file mode 100644 index 00000000..82b3763e --- /dev/null +++ b/tests/elfcopy.c @@ -0,0 +1,286 @@ +/* Test program for copying a whole ELF file using libelf. + 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; +} + +/* Copies all elements of an ELF file either using mmap or read. */ +static void +copy_elf (const char *in, const char *out, bool use_mmap) +{ + printf ("\ncopy_elf: %s -> %s (%s)\n", in, out, use_mmap ? "mmap" : "read"); + + /* Existing ELF file. */ + int fda = open (in, O_RDONLY | O_BINARY); + if (fda < 0) + { + fprintf (stderr, "Couldn't open file '%s': %s\n", + in, strerror (errno)); + exit (1); + } + + Elf *elfa = elf_begin (fda, use_mmap ? ELF_C_READ_MMAP : ELF_C_READ, NULL); + if (elfa == NULL) + { + fprintf (stderr, "Couldn't open ELF file '%s': %s\n", + in, elf_errmsg (-1)); + exit (1); + } + + /* Open new file. */ + int fdb = open (out, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0644); + if (fdb < 0) + { + fprintf (stderr, "Couldn't create file '%s': %s\n", + out, strerror (errno)); + exit (1); + } + + Elf *elfb = elf_begin (fdb, use_mmap ? ELF_C_WRITE_MMAP : ELF_C_WRITE, NULL); + if (elfb == NULL) + { + fprintf (stderr, "Couldn't create ELF file '%s': %s\n", + out, elf_errmsg (-1)); + exit (1); + } + + // Copy ELF header. + GElf_Ehdr ehdr_mema; + GElf_Ehdr *ehdra = gelf_getehdr (elfa, &ehdr_mema); + if (ehdra == NULL) + { + printf ("cannot get ELF header: %s\n", elf_errmsg (-1)); + exit (1); + } + + int class = gelf_getclass (elfa); + // Create an ELF header. + if (gelf_newehdr (elfb, class) == 0) + { + printf ("cannot create ELF header: %s\n", elf_errmsg (-1)); + exit (1); + } + + /* New elf header is an exact copy. */ + GElf_Ehdr ehdr_memb; + GElf_Ehdr *ehdrb = &ehdr_memb; + *ehdrb = *ehdra; + if (gelf_update_ehdr (elfb, ehdrb) == 0) + { + printf ("cannot update ELF header: %s\n", elf_errmsg (-1)); + exit (1); + } + + /* shstrndx is special. (Technically phdrnum and shdrnum are also + special, but they are handled by libelf.) */ + size_t shstrndx; + if (elf_getshdrstrndx (elfa, &shstrndx) < 0) + { + printf ("cannot get shstrndx: %s\n", elf_errmsg (-1)); + exit (1); + } + if (setshstrndx (elfb, shstrndx) < 0) + { + printf ("cannot set shstrndx: %s\n", elf_errmsg (-1)); + exit (1); + } + + /* If there are phdrs, copy them over. */ + size_t phnum; + if (elf_getphdrnum (elfa, &phnum) != 0) + { + printf ("cannot get phdrs: %s\n", elf_errmsg (-1)); + exit (1); + } + + if (phnum > 0) + { + if (gelf_newphdr (elfb, phnum) == 0) + { + printf ("cannot create phdrs: %s\n", elf_errmsg (-1)); + exit (1); + } + + for (size_t cnt = 0; cnt < phnum; ++cnt) + { + GElf_Phdr phdr_mem; + GElf_Phdr *phdr = gelf_getphdr (elfa, cnt, &phdr_mem); + if (phdr == NULL) + { + printf ("couldn't get phdr %zd: %s\n", cnt, elf_errmsg (-1)); + exit (1); + } + + if (gelf_update_phdr (elfb, cnt, phdr) == 0) + { + printf ("couldn't update phdr %zd: %s\n", cnt, elf_errmsg (-1)); + exit (1); + } + } + } + + /* Copy all sections, headers and data. */ + Elf_Scn *scn = NULL; + while ((scn = elf_nextscn (elfa, scn)) != NULL) + { + /* Get the header. */ + GElf_Shdr shdr; + if (gelf_getshdr (scn, &shdr) == NULL) + { + printf ("couldn't get shdr: %s\n", elf_errmsg (-1)); + exit (1); + } + + /* Create new section. */ + Elf_Scn *new_scn = elf_newscn (elfb); + if (new_scn == NULL) + { + printf ("couldn't create new section: %s\n", elf_errmsg (-1)); + exit (1); + } + + if (gelf_update_shdr (new_scn, &shdr) == 0) + { + printf ("couldn't update shdr: %s\n", elf_errmsg (-1)); + exit (1); + } + + /* Copy over section data. */ + Elf_Data *data = NULL; + while ((data = elf_getdata (scn, data)) != NULL) + { + Elf_Data *new_data = elf_newdata (new_scn); + if (new_data == NULL) + { + printf ("couldn't create new section data: %s\n", + elf_errmsg (-1)); + exit (1); + } + *new_data = *data; + } + } + + /* Write everything to disk. If there are any phdrs then we want + the exact same layout. Do we want ELF_F_PERMISSIVE? */ + if (phnum > 0) + elf_flagelf (elfb, ELF_C_SET, ELF_F_LAYOUT); + if (elf_update (elfb, ELF_C_WRITE) < 0) + { + printf ("failure in elf_update: %s\n", elf_errmsg (-1)); + exit (1); + } + + if (elf_end (elfa) != 0) + { + printf ("couldn't cleanup elf '%s': %s\n", in, elf_errmsg (-1)); + exit (1); + } + + if (close (fda) != 0) + { + printf ("couldn't close '%s': %s\n", in, strerror (errno)); + exit (1); + } + + if (elf_end (elfb) != 0) + { + printf ("couldn't cleanup elf '%s': %s\n", out, elf_errmsg (-1)); + exit (1); + } + + if (close (fdb) != 0) + { + printf ("couldn't close '%s': %s\n", out, strerror (errno)); + exit (1); + } +} + +int +main (int argc, const char *argv[]) +{ + elf_version (EV_CURRENT); + + /* Takes the given file, and create a new identical one. */ + if (argc < 3 || argc > 4) + { + fprintf (stderr, "elfcopy [--mmap] in.elf out.elf\n"); + exit (1); + } + + int argn = 1; + bool use_mmap = false; + if (strcmp (argv[argn], "--mmap") == 0) + { + use_mmap = true; + argn++; + } + + const char *in = argv[argn++]; + const char *out = argv[argn]; + copy_elf (in, out, use_mmap); + + return 0; +} |