File: dlerror.c

package info (click to toggle)
glibc 2.28-10
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, buster-proposed-updates, experimental, sid
  • size: 272,168 kB
  • sloc: ansic: 1,008,602; asm: 259,607; makefile: 11,271; sh: 10,477; python: 6,910; cpp: 4,992; perl: 2,258; awk: 2,005; yacc: 290; pascal: 182; sed: 73
file content (270 lines) | stat: -rw-r--r-- 6,769 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
/* Return error detail for failing <dlfcn.h> functions.
   Copyright (C) 1995-2018 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <dlfcn.h>
#include <libintl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libc-lock.h>
#include <ldsodefs.h>
#include <libc-symbols.h>

#if !defined SHARED && IS_IN (libdl)

char *
dlerror (void)
{
  return __dlerror ();
}

#else

/* Type for storing results of dynamic loading actions.  */
struct dl_action_result
  {
    int errcode;
    int returned;
    bool malloced;
    const char *objname;
    const char *errstring;
  };
static struct dl_action_result last_result;
static struct dl_action_result *static_buf;

/* This is the key for the thread specific memory.  */
static __libc_key_t key;
__libc_once_define (static, once);

/* Destructor for the thread-specific data.  */
static void init (void);
static void free_key_mem (void *mem);


char *
__dlerror (void)
{
  char *buf = NULL;
  struct dl_action_result *result;

# ifdef SHARED
  if (!rtld_active ())
    return _dlfcn_hook->dlerror ();
# endif

  /* If we have not yet initialized the buffer do it now.  */
  __libc_once (once, init);

  /* Get error string.  */
  result = (struct dl_action_result *) __libc_getspecific (key);
  if (result == NULL)
    result = &last_result;

  /* Test whether we already returned the string.  */
  if (result->returned != 0)
    {
      /* We can now free the string.  */
      if (result->errstring != NULL)
	{
	  if (strcmp (result->errstring, "out of memory") != 0)
	    free ((char *) result->errstring);
	  result->errstring = NULL;
	}
    }
  else if (result->errstring != NULL)
    {
      buf = (char *) result->errstring;
      int n;
      if (result->errcode == 0)
	n = __asprintf (&buf, "%s%s%s",
			result->objname,
			result->objname[0] == '\0' ? "" : ": ",
			_(result->errstring));
      else
	n = __asprintf (&buf, "%s%s%s: %s",
			result->objname,
			result->objname[0] == '\0' ? "" : ": ",
			_(result->errstring),
			strerror (result->errcode));
      if (n != -1)
	{
	  /* We don't need the error string anymore.  */
	  if (strcmp (result->errstring, "out of memory") != 0)
	    free ((char *) result->errstring);
	  result->errstring = buf;
	}

      /* Mark the error as returned.  */
      result->returned = 1;
    }

  return buf;
}
# ifdef SHARED
strong_alias (__dlerror, dlerror)
# endif

int
_dlerror_run (void (*operate) (void *), void *args)
{
  struct dl_action_result *result;

  /* If we have not yet initialized the buffer do it now.  */
  __libc_once (once, init);

  /* Get error string and number.  */
  if (static_buf != NULL)
    result = static_buf;
  else
    {
      /* We don't use the static buffer and so we have a key.  Use it
	 to get the thread-specific buffer.  */
      result = __libc_getspecific (key);
      if (result == NULL)
	{
	  result = (struct dl_action_result *) calloc (1, sizeof (*result));
	  if (result == NULL)
	    /* We are out of memory.  Since this is no really critical
	       situation we carry on by using the global variable.
	       This might lead to conflicts between the threads but
	       they soon all will have memory problems.  */
	    result = &last_result;
	  else
	    /* Set the tsd.  */
	    __libc_setspecific (key, result);
	}
    }

  if (result->errstring != NULL)
    {
      /* Free the error string from the last failed command.  This can
	 happen if `dlerror' was not run after an error was found.  */
      if (result->malloced)
	free ((char *) result->errstring);
      result->errstring = NULL;
    }

  result->errcode = _dl_catch_error (&result->objname, &result->errstring,
				     &result->malloced, operate, args);

  /* If no error we mark that no error string is available.  */
  result->returned = result->errstring == NULL;

  return result->errstring != NULL;
}


/* Initialize buffers for results.  */
static void
init (void)
{
  if (__libc_key_create (&key, free_key_mem))
    /* Creating the key failed.  This means something really went
       wrong.  In any case use a static buffer which is better than
       nothing.  */
    static_buf = &last_result;
}


static void
check_free (struct dl_action_result *rec)
{
  if (rec->errstring != NULL
      && strcmp (rec->errstring, "out of memory") != 0)
    {
      /* We can free the string only if the allocation happened in the
	 C library used by the dynamic linker.  This means, it is
	 always the C library in the base namespace.  When we're statically
         linked, the dynamic linker is part of the program and so always
	 uses the same C library we use here.  */
#ifdef SHARED
      struct link_map *map = NULL;
      Dl_info info;
      if (_dl_addr (check_free, &info, &map, NULL) != 0 && map->l_ns == 0)
#endif
	{
	  free ((char *) rec->errstring);
	  rec->errstring = NULL;
	}
    }
}


static void
__attribute__ ((destructor))
fini (void)
{
  check_free (&last_result);
}


/* Free the thread specific data, this is done if a thread terminates.  */
static void
free_key_mem (void *mem)
{
  check_free ((struct dl_action_result *) mem);

  free (mem);
  __libc_setspecific (key, NULL);
}

# ifdef SHARED

/* Free the dlerror-related resources.  */
void
__dlerror_main_freeres (void)
{
  void *mem;
  /* Free the global memory if used.  */
  check_free (&last_result);
  /* Free the TSD memory if used.  */
  mem = __libc_getspecific (key);
  if (mem != NULL)
    free_key_mem (mem);
}

struct dlfcn_hook *_dlfcn_hook __attribute__((nocommon));
libdl_hidden_data_def (_dlfcn_hook)

# else

static struct dlfcn_hook _dlfcn_hooks =
  {
    .dlopen = __dlopen,
    .dlclose = __dlclose,
    .dlsym = __dlsym,
    .dlvsym = __dlvsym,
    .dlerror = __dlerror,
    .dladdr = __dladdr,
    .dladdr1 = __dladdr1,
    .dlinfo = __dlinfo,
    .dlmopen = __dlmopen
  };

void
__libc_register_dlfcn_hook (struct link_map *map)
{
  struct dlfcn_hook **hook;

  hook = (struct dlfcn_hook **) __libc_dlsym_private (map, "_dlfcn_hook");
  if (hook != NULL)
    *hook = &_dlfcn_hooks;
}
# endif
#endif