1 /* Find the split (or skeleton) unit for a given unit.
2 Copyright (C) 2018 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 "libdwP.h"
34 #include "libelfP.h"
35
36 #include <limits.h>
37 #include <search.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <sys/types.h>
41 #include <sys/stat.h>
42 #include <fcntl.h>
43 #include <unistd.h>
44
45 void
try_split_file(Dwarf_CU * cu,const char * dwo_path)46 try_split_file (Dwarf_CU *cu, const char *dwo_path)
47 {
48 int split_fd = open (dwo_path, O_RDONLY);
49 if (split_fd != -1)
50 {
51 Dwarf *split_dwarf = dwarf_begin (split_fd, DWARF_C_READ);
52 if (split_dwarf != NULL)
53 {
54 Dwarf_CU *split = NULL;
55 while (dwarf_get_units (split_dwarf, split, &split,
56 NULL, NULL, NULL, NULL) == 0)
57 {
58 if (split->unit_type == DW_UT_split_compile
59 && cu->unit_id8 == split->unit_id8)
60 {
61 if (tsearch (split->dbg, &cu->dbg->split_tree,
62 __libdw_finddbg_cb) == NULL)
63 {
64 /* Something went wrong. Don't link. */
65 __libdw_seterrno (DWARF_E_NOMEM);
66 break;
67 }
68
69 /* Link skeleton and split compile units. */
70 __libdw_link_skel_split (cu, split);
71
72 /* We have everything we need from this ELF
73 file. And we are going to close the fd to
74 not run out of file descriptors. */
75 elf_cntl (split_dwarf->elf, ELF_C_FDDONE);
76 break;
77 }
78 }
79 if (cu->split == (Dwarf_CU *) -1)
80 dwarf_end (split_dwarf);
81 }
82 /* Always close, because we don't want to run out of file
83 descriptors. See also the elf_fcntl ELF_C_FDDONE call
84 above. */
85 close (split_fd);
86 }
87 }
88
89 Dwarf_CU *
90 internal_function
__libdw_find_split_unit(Dwarf_CU * cu)91 __libdw_find_split_unit (Dwarf_CU *cu)
92 {
93 /* Only try once. */
94 if (cu->split != (Dwarf_CU *) -1)
95 return cu->split;
96
97 /* We need a skeleton unit with a comp_dir and [GNU_]dwo_name attributes.
98 The split unit will be the first in the dwo file and should have the
99 same id as the skeleton. */
100 if (cu->unit_type == DW_UT_skeleton)
101 {
102 Dwarf_Die cudie = CUDIE (cu);
103 Dwarf_Attribute dwo_name;
104 /* It is fine if dwo_dir doesn't exists, but then dwo_name needs
105 to be an absolute path. */
106 if (dwarf_attr (&cudie, DW_AT_dwo_name, &dwo_name) != NULL
107 || dwarf_attr (&cudie, DW_AT_GNU_dwo_name, &dwo_name) != NULL)
108 {
109 /* First try the dwo file name in the same directory
110 as we found the skeleton file. */
111 const char *dwo_file = dwarf_formstring (&dwo_name);
112 const char *debugdir = cu->dbg->debugdir;
113 char *dwo_path = __libdw_filepath (debugdir, NULL, dwo_file);
114 if (dwo_path != NULL)
115 {
116 try_split_file (cu, dwo_path);
117 free (dwo_path);
118 }
119
120 if (cu->split == (Dwarf_CU *) -1)
121 {
122 /* Try compdir plus dwo_name. */
123 Dwarf_Attribute compdir;
124 dwarf_attr (&cudie, DW_AT_comp_dir, &compdir);
125 const char *dwo_dir = dwarf_formstring (&compdir);
126 if (dwo_dir != NULL)
127 {
128 dwo_path = __libdw_filepath (debugdir, dwo_dir, dwo_file);
129 if (dwo_path != NULL)
130 {
131 try_split_file (cu, dwo_path);
132 free (dwo_path);
133 }
134 }
135 }
136 /* XXX If still not found we could try stripping dirs from the
137 comp_dir and adding them from the comp_dir, assuming
138 someone moved a whole build tree around. */
139 }
140 }
141
142 /* If we found nothing, make sure we don't try again. */
143 if (cu->split == (Dwarf_CU *) -1)
144 cu->split = NULL;
145
146 return cu->split;
147 }
148