summaryrefslogtreecommitdiff
path: root/elf/pldd.c
blob: 9e1d82244fc976d8a62bd8ab7d0f577fb5d0374d (plain)
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
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
/* List dynamic shared objects linked into given process.
   Copyright (C) 2011-2015 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.

   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 <alloca.h>
#include <argp.h>
#include <assert.h>
#include <dirent.h>
#include <elf.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <libintl.h>
#include <link.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
#include <sys/wait.h>

#include <ldsodefs.h>
#include <version.h>

/* Global variables.  */
extern char *program_invocation_short_name;
#define PACKAGE _libc_intl_domainname

/* External functions.  */
#include <programs/xmalloc.h>

/* Name and version of program.  */
static void print_version (FILE *stream, struct argp_state *state);
void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;

/* Function to print some extra text in the help message.  */
static char *more_help (int key, const char *text, void *input);

/* Definitions of arguments for argp functions.  */
static const struct argp_option options[] =
{
  { NULL, 0, NULL, 0, NULL }
};

/* Short description of program.  */
static const char doc[] = N_("\
List dynamic shared objects loaded into process.");

/* Strings for arguments in help texts.  */
static const char args_doc[] = N_("PID");

/* Prototype for option handler.  */
static error_t parse_opt (int key, char *arg, struct argp_state *state);

/* Data structure to communicate with argp functions.  */
static struct argp argp =
{
  options, parse_opt, args_doc, doc, NULL, more_help, NULL
};

// File descriptor of /proc/*/mem file.
static int memfd;

/* Name of the executable  */
static char *exe;

/* Local functions.  */
static int get_process_info (int dfd, long int pid);
static void wait_for_ptrace_stop (long int pid);


int
main (int argc, char *argv[])
{
  /* Parse and process arguments.  */
  int remaining;
  argp_parse (&argp, argc, argv, 0, &remaining, NULL);

  if (remaining != argc - 1)
    {
      fprintf (stderr,
	       gettext ("Exactly one parameter with process ID required.\n"));
      argp_help (&argp, stderr, ARGP_HELP_SEE, program_invocation_short_name);
      return 1;
    }

  assert (sizeof (pid_t) == sizeof (int)
	  || sizeof (pid_t) == sizeof (long int));
  char *endp;
  errno = 0;
  long int pid = strtol (argv[remaining], &endp, 10);
  if (pid < 0 || (pid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
      || (sizeof (pid_t) < sizeof (pid) && pid > INT_MAX))
    error (EXIT_FAILURE, 0, gettext ("invalid process ID '%s'"),
	   argv[remaining]);

  /* Determine the program name.  */
  char buf[7 + 3 * sizeof (pid)];
  snprintf (buf, sizeof (buf), "/proc/%lu", pid);
  int dfd = open (buf, O_RDONLY | O_DIRECTORY);
  if (dfd == -1)
    error (EXIT_FAILURE, errno, gettext ("cannot open %s"), buf);

  size_t exesize = 1024;
#ifdef PATH_MAX
  exesize = PATH_MAX;
#endif
  exe = alloca (exesize);
  ssize_t nexe;
  while ((nexe = readlinkat (dfd, "exe", exe, exesize)) == exesize)
    extend_alloca (exe, exesize, 2 * exesize);
  if (nexe == -1)
    exe = (char *) "<program name undetermined>";
  else
    exe[nexe] = '\0';

  /* Stop all threads since otherwise the list of loaded modules might
     change while we are reading it.  */
  struct thread_list
  {
    pid_t tid;
    struct thread_list *next;
  } *thread_list = NULL;

  int taskfd = openat (dfd, "task", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
  if (taskfd == 1)
    error (EXIT_FAILURE, errno, gettext ("cannot open %s/task"), buf);
  DIR *dir = fdopendir (taskfd);
  if (dir == NULL)
    error (EXIT_FAILURE, errno, gettext ("cannot prepare reading %s/task"),
	   buf);

  struct dirent64 *d;
  while ((d = readdir64 (dir)) != NULL)
    {
      if (! isdigit (d->d_name[0]))
	continue;

      errno = 0;
      long int tid = strtol (d->d_name, &endp, 10);
      if (tid < 0 || (tid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
	  || (sizeof (pid_t) < sizeof (pid) && tid > INT_MAX))
	error (EXIT_FAILURE, 0, gettext ("invalid thread ID '%s'"),
	       d->d_name);

      if (ptrace (PTRACE_ATTACH, tid, NULL, NULL) != 0)
	{
	  /* There might be a race between reading the directory and
	     threads terminating.  Ignore errors attaching to unknown
	     threads unless this is the main thread.  */
	  if (errno == ESRCH && tid != pid)
	    continue;

	  error (EXIT_FAILURE, errno, gettext ("cannot attach to process %lu"),
		 tid);
	}

      wait_for_ptrace_stop (tid);

      struct thread_list *newp = alloca (sizeof (*newp));
      newp->tid = tid;
      newp->next = thread_list;
      thread_list = newp;
    }

  closedir (dir);

  int status = get_process_info (dfd, pid);

  assert (thread_list != NULL);
  do
    {
      ptrace (PTRACE_DETACH, thread_list->tid, NULL, NULL);
      thread_list = thread_list->next;
    }
  while (thread_list != NULL);

  close (dfd);

  return status;
}


/* Wait for PID to enter ptrace-stop state after being attached.  */
static void
wait_for_ptrace_stop (long int pid)
{
  int status;

  /* While waiting for SIGSTOP being delivered to the tracee we have to
     reinject any other pending signal.  Ignore all other errors.  */
  while (waitpid (pid, &status, __WALL) == pid && WIFSTOPPED (status))
    {
      /* The STOP signal should not be delivered to the tracee.  */
      if (WSTOPSIG (status) == SIGSTOP)
	return;
      if (ptrace (PTRACE_CONT, pid, NULL,
		  (void *) (uintptr_t) WSTOPSIG (status)))
	/* The only possible error is that the process died.  */
	return;
    }
}


/* Handle program arguments.  */
static error_t
parse_opt (int key, char *arg, struct argp_state *state)
{
  switch (key)
    {
    default:
      return ARGP_ERR_UNKNOWN;
    }
  return 0;
}


/* Print bug-reporting information in the help message.  */
static char *
more_help (int key, const char *text, void *input)
{
  char *tp = NULL;
  switch (key)
    {
    case ARGP_KEY_HELP_EXTRA:
      /* We print some extra information.  */
      if (asprintf (&tp, gettext ("\
For bug reporting instructions, please see:\n\
%s.\n"), REPORT_BUGS_TO) < 0)
	return NULL;
      return tp;
    default:
      break;
    }
  return (char *) text;
}

/* Print the version information.  */
static void
print_version (FILE *stream, struct argp_state *state)
{
  fprintf (stream, "pldd %s%s\n", PKGVERSION, VERSION);
  fprintf (stream, gettext ("\
Copyright (C) %s Free Software Foundation, Inc.\n\
This is free software; see the source for copying conditions.  There is NO\n\
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
"), "2015");
  fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
}


#define CLASS 32
#include "pldd-xx.c"
#define CLASS 64
#include "pldd-xx.c"


static int
get_process_info (int dfd, long int pid)
{
  memfd = openat (dfd, "mem", O_RDONLY);
  if (memfd == -1)
    goto no_info;

  int fd = openat (dfd, "exe", O_RDONLY);
  if (fd == -1)
    {
    no_info:
      error (0, errno, gettext ("cannot get information about process %lu"),
	     pid);
      return EXIT_FAILURE;
    }

  char e_ident[EI_NIDENT];
  if (read (fd, e_ident, EI_NIDENT) != EI_NIDENT)
    goto no_info;

  close (fd);

  if (memcmp (e_ident, ELFMAG, SELFMAG) != 0)
    {
      error (0, 0, gettext ("process %lu is no ELF program"), pid);
      return EXIT_FAILURE;
    }

  fd = openat (dfd, "auxv", O_RDONLY);
  if (fd == -1)
    goto no_info;

  size_t auxv_size = 0;
  void *auxv = NULL;
  while (1)
    {
      auxv_size += 512;
      auxv = xrealloc (auxv, auxv_size);

      ssize_t n = pread (fd, auxv, auxv_size, 0);
      if (n < 0)
	goto no_info;
      if (n < auxv_size)
	{
	  auxv_size = n;
	  break;
	}
    }

  close (fd);

  int retval;
  if (e_ident[EI_CLASS] == ELFCLASS32)
    retval = find_maps32 (pid, auxv, auxv_size);
  else
    retval = find_maps64 (pid, auxv, auxv_size);

  free (auxv);
  close (memfd);

  return retval;
}