diff options
Diffstat (limited to 'src/libdwelf/dwelf_elf_gnu_build_id.c')
| -rw-r--r-- | src/libdwelf/dwelf_elf_gnu_build_id.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/src/libdwelf/dwelf_elf_gnu_build_id.c b/src/libdwelf/dwelf_elf_gnu_build_id.c new file mode 100644 index 00000000..1ed501d9 --- /dev/null +++ b/src/libdwelf/dwelf_elf_gnu_build_id.c @@ -0,0 +1,147 @@ +/* Returns the build id if found in a NT_GNU_BUILD_ID note. + Copyright (C) 2014 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 either + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at + your option) any later version + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at + your option) any later version + + or both in parallel, as here. + + 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 copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see <http://www.gnu.org/licenses/>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include "libdwelfP.h" +#include "libdwflP.h" + +#define NO_VADDR ((GElf_Addr) -1l) + +/* Defined here for reuse. The dwelf interface doesn't care about the + address of the note, but libdwfl does. */ +static int +find_elf_build_id (Dwfl_Module *mod, int e_type, Elf *elf, + const void **build_id_bits, GElf_Addr *build_id_elfaddr, + int *build_id_len) +{ + int check_notes (Elf_Data *data, GElf_Addr data_elfaddr) + { + size_t pos = 0; + GElf_Nhdr nhdr; + size_t name_pos; + size_t desc_pos; + while ((pos = gelf_getnote (data, pos, &nhdr, &name_pos, &desc_pos)) > 0) + if (nhdr.n_type == NT_GNU_BUILD_ID + && nhdr.n_namesz == sizeof "GNU" && !memcmp (data->d_buf + name_pos, + "GNU", sizeof "GNU")) + { + *build_id_bits = data->d_buf + desc_pos; + *build_id_elfaddr = (data_elfaddr == NO_VADDR + ? 0 : data_elfaddr + desc_pos); + *build_id_len = nhdr.n_descsz; + return 1; + } + return 0; + } + + size_t shstrndx = SHN_UNDEF; + int result = 0; + + Elf_Scn *scn = elf_nextscn (elf, NULL); + + if (scn == NULL) + { + /* No sections, have to look for phdrs. */ + size_t phnum; + if (unlikely (elf_getphdrnum (elf, &phnum) != 0)) + { + if (mod != NULL) + __libdwfl_seterrno (DWFL_E_LIBELF); + return -1; + } + for (size_t i = 0; result == 0 && i < phnum; ++i) + { + GElf_Phdr phdr_mem; + GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem); + if (likely (phdr != NULL) && phdr->p_type == PT_NOTE) + result = check_notes (elf_getdata_rawchunk (elf, + phdr->p_offset, + phdr->p_filesz, + ELF_T_NHDR), + phdr->p_vaddr); + } + } + else + do + { + GElf_Shdr shdr_mem; + GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); + if (likely (shdr != NULL) && shdr->sh_type == SHT_NOTE) + { + /* Determine the right sh_addr in this module. */ + GElf_Addr vaddr = 0; + if (!(shdr->sh_flags & SHF_ALLOC)) + vaddr = NO_VADDR; + else if (mod == NULL || e_type != ET_REL) + vaddr = shdr->sh_addr; + else if (__libdwfl_relocate_value (mod, elf, &shstrndx, + elf_ndxscn (scn), &vaddr)) + vaddr = NO_VADDR; + result = check_notes (elf_getdata (scn, NULL), vaddr); + } + } + while (result == 0 && (scn = elf_nextscn (elf, scn)) != NULL); + + return result; +} + +int +internal_function +__libdwfl_find_elf_build_id (Dwfl_Module *mod, Elf *elf, + const void **build_id_bits, + GElf_Addr *build_id_elfaddr, int *build_id_len) +{ + GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem); + if (unlikely (ehdr == NULL)) + { + __libdwfl_seterrno (DWFL_E_LIBELF); + return -1; + } + // MOD->E_TYPE is zero here. + assert (ehdr->e_type != ET_REL || mod != NULL); + + return find_elf_build_id (mod, ehdr->e_type, elf, + build_id_bits, build_id_elfaddr, build_id_len); +} + +ssize_t +dwelf_elf_gnu_build_id (Elf *elf, const void **build_idp) +{ + GElf_Addr build_id_elfaddr; + int build_id_len; + int result = find_elf_build_id (NULL, ET_NONE, elf, build_idp, + &build_id_elfaddr, &build_id_len); + if (result > 0) + return build_id_len; + + return result; +} +INTDEF(dwelf_elf_gnu_build_id) |