Line data Source code
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 : static int
39 328 : check_notes (Elf_Data *data, GElf_Addr data_elfaddr,
40 : const void **build_id_bits, GElf_Addr *build_id_elfaddr,
41 : int *build_id_len)
42 : {
43 328 : size_t pos = 0;
44 : GElf_Nhdr nhdr;
45 : size_t name_pos;
46 : size_t desc_pos;
47 769 : while ((pos = gelf_getnote (data, pos, &nhdr, &name_pos, &desc_pos)) > 0)
48 332 : if (nhdr.n_type == NT_GNU_BUILD_ID
49 219 : && nhdr.n_namesz == sizeof "GNU"
50 219 : && !memcmp (data->d_buf + name_pos, "GNU", sizeof "GNU"))
51 : {
52 219 : *build_id_bits = data->d_buf + desc_pos;
53 219 : *build_id_elfaddr = (data_elfaddr == NO_VADDR
54 219 : ? 0 : data_elfaddr + desc_pos);
55 219 : *build_id_len = nhdr.n_descsz;
56 219 : return 1;
57 : }
58 : return 0;
59 : }
60 :
61 : /* Defined here for reuse. The dwelf interface doesn't care about the
62 : address of the note, but libdwfl does. */
63 : static int
64 234 : find_elf_build_id (Dwfl_Module *mod, int e_type, Elf *elf,
65 : const void **build_id_bits, GElf_Addr *build_id_elfaddr,
66 : int *build_id_len)
67 : {
68 234 : size_t shstrndx = SHN_UNDEF;
69 234 : int result = 0;
70 :
71 234 : Elf_Scn *scn = elf_nextscn (elf, NULL);
72 :
73 234 : if (scn == NULL)
74 : {
75 : /* No sections, have to look for phdrs. */
76 : size_t phnum;
77 7 : if (unlikely (elf_getphdrnum (elf, &phnum) != 0))
78 : {
79 0 : if (mod != NULL)
80 0 : __libdwfl_seterrno (DWFL_E_LIBELF);
81 0 : return -1;
82 : }
83 29 : for (size_t i = 0; result == 0 && i < phnum; ++i)
84 : {
85 : GElf_Phdr phdr_mem;
86 29 : GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
87 29 : if (likely (phdr != NULL) && phdr->p_type == PT_NOTE)
88 14 : result = check_notes (elf_getdata_rawchunk (elf,
89 7 : phdr->p_offset,
90 : phdr->p_filesz,
91 : ELF_T_NHDR),
92 : phdr->p_vaddr,
93 : build_id_bits,
94 : build_id_elfaddr,
95 : build_id_len);
96 : }
97 : }
98 : else
99 : do
100 : {
101 : GElf_Shdr shdr_mem;
102 712 : GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
103 712 : if (likely (shdr != NULL) && shdr->sh_type == SHT_NOTE)
104 : {
105 : /* Determine the right sh_addr in this module. */
106 321 : GElf_Addr vaddr = 0;
107 321 : if (!(shdr->sh_flags & SHF_ALLOC))
108 8 : vaddr = NO_VADDR;
109 313 : else if (mod == NULL || e_type != ET_REL)
110 313 : vaddr = shdr->sh_addr;
111 0 : else if (__libdwfl_relocate_value (mod, elf, &shstrndx,
112 0 : elf_ndxscn (scn), &vaddr))
113 0 : vaddr = NO_VADDR;
114 321 : result = check_notes (elf_getdata (scn, NULL), vaddr,
115 : build_id_bits,
116 : build_id_elfaddr,
117 : build_id_len);
118 : }
119 : }
120 712 : while (result == 0 && (scn = elf_nextscn (elf, scn)) != NULL);
121 :
122 : return result;
123 : }
124 :
125 : int
126 : internal_function
127 157 : __libdwfl_find_elf_build_id (Dwfl_Module *mod, Elf *elf,
128 : const void **build_id_bits,
129 : GElf_Addr *build_id_elfaddr, int *build_id_len)
130 : {
131 157 : GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);
132 157 : if (unlikely (ehdr == NULL))
133 : {
134 0 : __libdwfl_seterrno (DWFL_E_LIBELF);
135 0 : return -1;
136 : }
137 : // MOD->E_TYPE is zero here.
138 157 : assert (ehdr->e_type != ET_REL || mod != NULL);
139 :
140 157 : return find_elf_build_id (mod, ehdr->e_type, elf,
141 : build_id_bits, build_id_elfaddr, build_id_len);
142 : }
143 :
144 : ssize_t
145 77 : dwelf_elf_gnu_build_id (Elf *elf, const void **build_idp)
146 : {
147 : GElf_Addr build_id_elfaddr;
148 : int build_id_len;
149 77 : int result = find_elf_build_id (NULL, ET_NONE, elf, build_idp,
150 : &build_id_elfaddr, &build_id_len);
151 77 : if (result > 0)
152 76 : return build_id_len;
153 :
154 1 : return result;
155 : }
156 : INTDEF(dwelf_elf_gnu_build_id)
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