1/* Copyright (C) 1999-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published
6 by the Free Software Foundation; version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, see <https://www.gnu.org/licenses/>. */
16
17/* The code in this file and in readelflib is a heavily simplified
18 version of the readelf program that's part of the current binutils
19 development version. Besides the simplification, it has also been
20 modified to read some other file formats. */
21
22#include <a.out.h>
23#include <elf.h>
24#include <error.h>
25#include <libintl.h>
26#include <link.h>
27#include <stdio.h>
28#include <string.h>
29#include <unistd.h>
30#include <sys/mman.h>
31#include <sys/param.h>
32#include <sys/stat.h>
33#include <gnu/lib-names.h>
34
35#include <ldconfig.h>
36
37#define Elf32_CLASS ELFCLASS32
38#define Elf64_CLASS ELFCLASS64
39
40struct known_names
41{
42 const char *soname;
43 int flag;
44};
45
46static struct known_names interpreters[] =
47{
48 { "/lib/" LD_SO, FLAG_ELF_LIBC6 },
49#ifdef SYSDEP_KNOWN_INTERPRETER_NAMES
50 SYSDEP_KNOWN_INTERPRETER_NAMES
51#endif
52};
53
54static struct known_names known_libs[] =
55{
56 { LIBC_SO, FLAG_ELF_LIBC6 },
57 { LIBM_SO, FLAG_ELF_LIBC6 },
58#ifdef SYSDEP_KNOWN_LIBRARY_NAMES
59 SYSDEP_KNOWN_LIBRARY_NAMES
60#endif
61};
62
63
64/* Check if string corresponds to a GDB Python file. */
65static bool
66is_gdb_python_file (const char *name)
67{
68 size_t len = strlen (name);
69 return len > 7 && strcmp (name + len - 7, "-gdb.py") == 0;
70}
71
72/* Returns 0 if everything is ok, != 0 in case of error. */
73int
74process_file (const char *real_file_name, const char *file_name,
75 const char *lib, int *flag, unsigned int *osversion,
76 unsigned int *isa_level, char **soname, int is_link,
77 struct stat *stat_buf)
78{
79 FILE *file;
80 struct stat statbuf;
81 void *file_contents;
82 int ret;
83 ElfW(Ehdr) *elf_header;
84 struct exec *aout_header;
85
86 ret = 0;
87 *flag = FLAG_ANY;
88 *soname = NULL;
89
90 file = fopen (real_file_name, "rb");
91 if (file == NULL)
92 {
93 /* No error for stale symlink. */
94 if (is_link && strstr (file_name, ".so") != NULL)
95 return 1;
96 error (0, 0, _("Input file %s not found.\n"), file_name);
97 return 1;
98 }
99
100 if (fstat (fileno (file), &statbuf) < 0)
101 {
102 error (0, 0, _("Cannot fstat file %s.\n"), file_name);
103 fclose (file);
104 return 1;
105 }
106
107 /* Check that the file is large enough so that we can access the
108 information. We're only checking the size of the headers here. */
109 if ((size_t) statbuf.st_size < sizeof (struct exec)
110 || (size_t) statbuf.st_size < sizeof (ElfW(Ehdr)))
111 {
112 if (statbuf.st_size == 0)
113 error (0, 0, _("File %s is empty, not checked."), file_name);
114 else
115 {
116 char buf[SELFMAG];
117 size_t n = MIN (statbuf.st_size, SELFMAG);
118 if (fread (buf, n, 1, file) == 1 && memcmp (buf, ELFMAG, n) == 0)
119 error (0, 0, _("File %s is too small, not checked."), file_name);
120 }
121 fclose (file);
122 return 1;
123 }
124
125 file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
126 fileno (file), 0);
127 if (file_contents == MAP_FAILED)
128 {
129 error (0, 0, _("Cannot mmap file %s.\n"), file_name);
130 fclose (file);
131 return 1;
132 }
133
134 /* First check if this is an aout file. */
135 aout_header = (struct exec *) file_contents;
136 if (N_MAGIC (*aout_header) == ZMAGIC
137#ifdef QMAGIC /* Linuxism. */
138 || N_MAGIC (*aout_header) == QMAGIC
139#endif
140 )
141 {
142 /* Aout files don't have a soname, just return the name
143 including the major number. */
144 char *copy, *major, *dot;
145 copy = xstrdup (lib);
146 major = strstr (copy, ".so.");
147 if (major)
148 {
149 dot = strstr (major + 4, ".");
150 if (dot)
151 *dot = '\0';
152 }
153 *soname = copy;
154 *flag = FLAG_LIBC4;
155 goto done;
156 }
157
158 elf_header = (ElfW(Ehdr) *) file_contents;
159 if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
160 {
161 /* The file is neither ELF nor aout. Check if it's a linker
162 script, like libc.so - otherwise complain. Only search the
163 beginning of the file. */
164 size_t len = MIN (statbuf.st_size, 512);
165 if (memmem (file_contents, len, "GROUP", 5) == NULL
166 && memmem (file_contents, len, "GNU ld script", 13) == NULL
167 && !is_gdb_python_file (file_name))
168 error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
169 file_name);
170 ret = 1;
171 }
172 /* Libraries have to be shared object files. */
173 else if (elf_header->e_type != ET_DYN)
174 ret = 1;
175 else if (process_elf_file (file_name, lib, flag, osversion, isa_level,
176 soname, file_contents, statbuf.st_size))
177 ret = 1;
178
179 done:
180 /* Clean up allocated memory and resources. */
181 munmap (file_contents, statbuf.st_size);
182 fclose (file);
183
184 *stat_buf = statbuf;
185 return ret;
186}
187
188/* Returns made up soname if lib doesn't have explicit DT_SONAME. */
189
190char *
191implicit_soname (const char *lib, int flag)
192{
193 char *soname = xstrdup (lib);
194
195 if ((flag & FLAG_TYPE_MASK) != FLAG_LIBC4)
196 return soname;
197
198 /* Aout files don't have a soname, just return the name
199 including the major number. */
200 char *major = strstr (soname, ".so.");
201 if (major)
202 {
203 char *dot = strstr (major + 4, ".");
204 if (dot)
205 *dot = '\0';
206 }
207 return soname;
208}
209
210/* Get architecture specific version of process_elf_file. */
211#include <readelflib.c>
212