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.
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of either
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
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
18 or both in parallel, as here.
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.
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/>. */
33 #include "libdwelfP.h"
36 #define NO_VADDR ((GElf_Addr) -1l)
38 /* Defined here for reuse. The dwelf interface doesn't care about the
39 address of the note, but libdwfl does. */
41 find_elf_build_id (Dwfl_Module *mod, int e_type, Elf *elf,
42 const void **build_id_bits, GElf_Addr *build_id_elfaddr,
45 int check_notes (Elf_Data *data, GElf_Addr data_elfaddr)
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,
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;
65 size_t shstrndx = SHN_UNDEF;
68 Elf_Scn *scn = elf_nextscn (elf, NULL);
72 /* No sections, have to look for phdrs. */
74 if (unlikely (elf_getphdrnum (elf, &phnum) != 0))
77 __libdwfl_seterrno (DWFL_E_LIBELF);
80 for (size_t i = 0; result == 0 && i < phnum; ++i)
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,
96 GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
97 if (likely (shdr != NULL) && shdr->sh_type == SHT_NOTE)
99 /* Determine the right sh_addr in this module. */
101 if (!(shdr->sh_flags & SHF_ALLOC))
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))
108 result = check_notes (elf_getdata (scn, NULL), vaddr);
111 while (result == 0 && (scn = elf_nextscn (elf, scn)) != NULL);
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)
122 GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);
123 if (unlikely (ehdr == NULL))
125 __libdwfl_seterrno (DWFL_E_LIBELF);
128 // MOD->E_TYPE is zero here.
129 assert (ehdr->e_type != ET_REL || mod != NULL);
131 return find_elf_build_id (mod, ehdr->e_type, elf,
132 build_id_bits, build_id_elfaddr, build_id_len);
136 dwelf_elf_gnu_build_id (Elf *elf, const void **build_idp)
138 GElf_Addr build_id_elfaddr;
140 int result = find_elf_build_id (NULL, ET_NONE, elf, build_idp,
141 &build_id_elfaddr, &build_id_len);
147 INTDEF(dwelf_elf_gnu_build_id)