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
39 391 : 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 : {
43 391 : size_t pos = 0;
44 391 : GElf_Nhdr nhdr;
45 391 : size_t name_pos;
46 391 : size_t desc_pos;
47 535 : while ((pos = gelf_getnote (data, pos, &nhdr, &name_pos, &desc_pos)) > 0)
48 399 : if (nhdr.n_type == NT_GNU_BUILD_ID
49 255 : && nhdr.n_namesz == sizeof "GNU"
50 255 : && !memcmp (data->d_buf + name_pos, "GNU", sizeof "GNU"))
51 : {
52 255 : *build_id_bits = data->d_buf + desc_pos;
53 510 : *build_id_elfaddr = (data_elfaddr == NO_VADDR
54 255 : ? 0 : data_elfaddr + desc_pos);
55 255 : *build_id_len = nhdr.n_descsz;
56 255 : 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
64 270 : 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 : {
68 270 : size_t shstrndx = SHN_UNDEF;
69 270 : int result = 0;
70 :
71 270 : Elf_Scn *scn = elf_nextscn (elf, NULL);
72 :
73 270 : if (scn == NULL)
74 : {
75 : /* No sections, have to look for phdrs. */
76 9 : size_t phnum;
77 9 : 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 46 : for (size_t i = 0; result == 0 && i < phnum; ++i)
84 : {
85 37 : GElf_Phdr phdr_mem;
86 37 : GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
87 37 : if (likely (phdr != NULL) && phdr->p_type == PT_NOTE)
88 9 : result = check_notes (elf_getdata_rawchunk (elf,
89 9 : phdr->p_offset,
90 : phdr->p_filesz,
91 9 : (phdr->p_align == 8
92 : ? ELF_T_NHDR8
93 : : ELF_T_NHDR)),
94 : phdr->p_vaddr,
95 : build_id_bits,
96 : build_id_elfaddr,
97 : build_id_len);
98 : }
99 : }
100 : else
101 787 : do
102 : {
103 787 : GElf_Shdr shdr_mem;
104 787 : GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
105 787 : if (likely (shdr != NULL) && shdr->sh_type == SHT_NOTE)
106 : {
107 : /* Determine the right sh_addr in this module. */
108 382 : GElf_Addr vaddr = 0;
109 382 : if (!(shdr->sh_flags & SHF_ALLOC))
110 14 : vaddr = NO_VADDR;
111 368 : else if (mod == NULL || e_type != ET_REL)
112 368 : vaddr = shdr->sh_addr;
113 0 : else if (__libdwfl_relocate_value (mod, elf, &shstrndx,
114 0 : elf_ndxscn (scn), &vaddr))
115 0 : vaddr = NO_VADDR;
116 382 : result = check_notes (elf_getdata (scn, NULL), vaddr,
117 : build_id_bits,
118 : build_id_elfaddr,
119 : build_id_len);
120 : }
121 : }
122 788 : while (result == 0 && (scn = elf_nextscn (elf, scn)) != NULL);
123 :
124 : return result;
125 : }
126 :
127 : int
128 : internal_function
129 167 : __libdwfl_find_elf_build_id (Dwfl_Module *mod, Elf *elf,
130 : const void **build_id_bits,
131 : GElf_Addr *build_id_elfaddr, int *build_id_len)
132 : {
133 167 : GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);
134 167 : if (unlikely (ehdr == NULL))
135 : {
136 0 : __libdwfl_seterrno (DWFL_E_LIBELF);
137 0 : return -1;
138 : }
139 : // MOD->E_TYPE is zero here.
140 167 : assert (ehdr->e_type != ET_REL || mod != NULL);
141 :
142 167 : return find_elf_build_id (mod, ehdr->e_type, elf,
143 : build_id_bits, build_id_elfaddr, build_id_len);
144 : }
145 :
146 : ssize_t
147 103 : dwelf_elf_gnu_build_id (Elf *elf, const void **build_idp)
148 : {
149 103 : GElf_Addr build_id_elfaddr;
150 103 : int build_id_len;
151 103 : int result = find_elf_build_id (NULL, ET_NONE, elf, build_idp,
152 : &build_id_elfaddr, &build_id_len);
153 103 : if (result > 0)
154 102 : return build_id_len;
155 :
156 1 : return result;
157 : }
158 : INTDEF(dwelf_elf_gnu_build_id)
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