Elliott Hughes | 0333382 | 2015-02-18 22:19:45 -0800 | [diff] [blame] | 1 | /* Returns the build id if found in a NT_GNU_BUILD_ID note. |
| 2 | Copyright (C) 2014 Red Hat, Inc. |
| 3 | This file is part of elfutils. |
| 4 | |
| 5 | This file is free software; you can redistribute it and/or modify |
| 6 | it under the terms of either |
| 7 | |
| 8 | * the GNU Lesser General Public License as published by the Free |
| 9 | Software Foundation; either version 3 of the License, or (at |
| 10 | your option) any later version |
| 11 | |
| 12 | or |
| 13 | |
| 14 | * the GNU General Public License as published by the Free |
| 15 | Software Foundation; either version 2 of the License, or (at |
| 16 | your option) any later version |
| 17 | |
| 18 | or both in parallel, as here. |
| 19 | |
| 20 | elfutils is distributed in the hope that it will be useful, but |
| 21 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 22 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 23 | General Public License for more details. |
| 24 | |
| 25 | You should have received copies of the GNU General Public License and |
| 26 | the GNU Lesser General Public License along with this program. If |
| 27 | not, see <http://www.gnu.org/licenses/>. */ |
| 28 | |
| 29 | #ifdef HAVE_CONFIG_H |
| 30 | # include <config.h> |
| 31 | #endif |
| 32 | |
| 33 | #include "libdwelfP.h" |
| 34 | #include "libdwflP.h" |
| 35 | |
| 36 | #define NO_VADDR ((GElf_Addr) -1l) |
| 37 | |
| 38 | /* Defined here for reuse. The dwelf interface doesn't care about the |
| 39 | address of the note, but libdwfl does. */ |
| 40 | static int |
| 41 | find_elf_build_id (Dwfl_Module *mod, int e_type, Elf *elf, |
| 42 | const void **build_id_bits, GElf_Addr *build_id_elfaddr, |
| 43 | int *build_id_len) |
| 44 | { |
| 45 | int check_notes (Elf_Data *data, GElf_Addr data_elfaddr) |
| 46 | { |
| 47 | size_t pos = 0; |
| 48 | GElf_Nhdr nhdr; |
| 49 | size_t name_pos; |
| 50 | size_t desc_pos; |
| 51 | while ((pos = gelf_getnote (data, pos, &nhdr, &name_pos, &desc_pos)) > 0) |
| 52 | if (nhdr.n_type == NT_GNU_BUILD_ID |
| 53 | && nhdr.n_namesz == sizeof "GNU" && !memcmp (data->d_buf + name_pos, |
| 54 | "GNU", sizeof "GNU")) |
| 55 | { |
| 56 | *build_id_bits = data->d_buf + desc_pos; |
| 57 | *build_id_elfaddr = (data_elfaddr == NO_VADDR |
| 58 | ? 0 : data_elfaddr + desc_pos); |
| 59 | *build_id_len = nhdr.n_descsz; |
| 60 | return 1; |
| 61 | } |
| 62 | return 0; |
| 63 | } |
| 64 | |
| 65 | size_t shstrndx = SHN_UNDEF; |
| 66 | int result = 0; |
| 67 | |
| 68 | Elf_Scn *scn = elf_nextscn (elf, NULL); |
| 69 | |
| 70 | if (scn == NULL) |
| 71 | { |
| 72 | /* No sections, have to look for phdrs. */ |
| 73 | size_t phnum; |
| 74 | if (unlikely (elf_getphdrnum (elf, &phnum) != 0)) |
| 75 | { |
| 76 | if (mod != NULL) |
| 77 | __libdwfl_seterrno (DWFL_E_LIBELF); |
| 78 | return -1; |
| 79 | } |
| 80 | for (size_t i = 0; result == 0 && i < phnum; ++i) |
| 81 | { |
| 82 | GElf_Phdr phdr_mem; |
| 83 | GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem); |
| 84 | if (likely (phdr != NULL) && phdr->p_type == PT_NOTE) |
| 85 | result = check_notes (elf_getdata_rawchunk (elf, |
| 86 | phdr->p_offset, |
| 87 | phdr->p_filesz, |
| 88 | ELF_T_NHDR), |
| 89 | phdr->p_vaddr); |
| 90 | } |
| 91 | } |
| 92 | else |
| 93 | do |
| 94 | { |
| 95 | GElf_Shdr shdr_mem; |
| 96 | GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); |
| 97 | if (likely (shdr != NULL) && shdr->sh_type == SHT_NOTE) |
| 98 | { |
| 99 | /* Determine the right sh_addr in this module. */ |
| 100 | GElf_Addr vaddr = 0; |
| 101 | if (!(shdr->sh_flags & SHF_ALLOC)) |
| 102 | vaddr = NO_VADDR; |
| 103 | else if (mod == NULL || e_type != ET_REL) |
| 104 | vaddr = shdr->sh_addr; |
| 105 | else if (__libdwfl_relocate_value (mod, elf, &shstrndx, |
| 106 | elf_ndxscn (scn), &vaddr)) |
| 107 | vaddr = NO_VADDR; |
| 108 | result = check_notes (elf_getdata (scn, NULL), vaddr); |
| 109 | } |
| 110 | } |
| 111 | while (result == 0 && (scn = elf_nextscn (elf, scn)) != NULL); |
| 112 | |
| 113 | return result; |
| 114 | } |
| 115 | |
| 116 | int |
| 117 | internal_function |
| 118 | __libdwfl_find_elf_build_id (Dwfl_Module *mod, Elf *elf, |
| 119 | const void **build_id_bits, |
| 120 | GElf_Addr *build_id_elfaddr, int *build_id_len) |
| 121 | { |
| 122 | GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem); |
| 123 | if (unlikely (ehdr == NULL)) |
| 124 | { |
| 125 | __libdwfl_seterrno (DWFL_E_LIBELF); |
| 126 | return -1; |
| 127 | } |
| 128 | // MOD->E_TYPE is zero here. |
| 129 | assert (ehdr->e_type != ET_REL || mod != NULL); |
| 130 | |
| 131 | return find_elf_build_id (mod, ehdr->e_type, elf, |
| 132 | build_id_bits, build_id_elfaddr, build_id_len); |
| 133 | } |
| 134 | |
| 135 | ssize_t |
| 136 | dwelf_elf_gnu_build_id (Elf *elf, const void **build_idp) |
| 137 | { |
| 138 | GElf_Addr build_id_elfaddr; |
| 139 | int build_id_len; |
| 140 | int result = find_elf_build_id (NULL, ET_NONE, elf, build_idp, |
| 141 | &build_id_elfaddr, &build_id_len); |
| 142 | if (result > 0) |
| 143 | return build_id_len; |
| 144 | |
| 145 | return result; |
| 146 | } |
| 147 | INTDEF(dwelf_elf_gnu_build_id) |