elf/pldd.c

   1 /* List dynamic shared objects linked into given process.
   2    Copyright (C) 2011-2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <alloca.h>
  21 #include <argp.h>
  22 #include <assert.h>
  23 #include <dirent.h>
  24 #include <elf.h>
  25 #include <errno.h>
  26 #include <error.h>
  27 #include <fcntl.h>
  28 #include <libintl.h>
  29 #include <link.h>
  30 #include <stddef.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35 #include <sys/ptrace.h>
  36 #include <sys/stat.h>
  37
  38 #include <ldsodefs.h>
  39 #include <version.h>
  40
  41 /* Global variables.  */
  42 extern char *program_invocation_short_name;
  43 #define PACKAGE _libc_intl_domainname
  44
  45 /* External functions.  */
  46 #include <programs/xmalloc.h>
  47
  48 /* Name and version of program.  */
  49 static void print_version (FILE *stream, struct argp_state *state);
  50 void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
  51
  52 /* Function to print some extra text in the help message.  */
  53 static char *more_help (int key, const char *text, void *input);
  54
  55 /* Definitions of arguments for argp functions.  */
  56 static const struct argp_option options[] =
  57 {
  58   { NULL, 0, NULL, 0, NULL }
  59 };
  60
  61 /* Short description of program.  */
  62 static const char doc[] = N_("\
  63 List dynamic shared objects loaded into process.");
  64
  65 /* Strings for arguments in help texts.  */
  66 static const char args_doc[] = N_("PID");
  67
  68 /* Prototype for option handler.  */
  69 static error_t parse_opt (int key, char *arg, struct argp_state *state);
  70
  71 /* Data structure to communicate with argp functions.  */
  72 static struct argp argp =
  73 {
  74   options, parse_opt, args_doc, doc, NULL, more_help, NULL
  75 };
  76
  77 // File descriptor of /proc/*/mem file.
  78 static int memfd;
  79
  80 /* Name of the executable  */
  81 static char *exe;
  82
  83 /* Local functions.  */
  84 static int get_process_info (int dfd, long int pid);
  85
  86
  87 int
  88 main (int argc, char *argv[])
  89 {
  90   /* Parse and process arguments.  */
  91   int remaining;
  92   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
  93
  94   if (remaining != argc - 1)
  95     {
  96       fprintf (stderr,
  97                gettext ("Exactly one parameter with process ID required.\n"));
  98       argp_help (&argp, stderr, ARGP_HELP_SEE, program_invocation_short_name);
  99       return 1;
 100     }
 101
 102   assert (sizeof (pid_t) == sizeof (int)
 103           || sizeof (pid_t) == sizeof (long int));
 104   char *endp;
 105   errno = 0;
 106   long int pid = strtol (argv[remaining], &endp, 10);
 107   if (pid < 0 || (pid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 108       || (sizeof (pid_t) < sizeof (pid) && pid > INT_MAX))
 109     error (EXIT_FAILURE, 0, gettext ("invalid process ID '%s'"),
 110            argv[remaining]);
 111
 112   /* Determine the program name.  */
 113   char buf[7 + 3 * sizeof (pid)];
 114   snprintf (buf, sizeof (buf), "/proc/%lu", pid);
 115   int dfd = open (buf, O_RDONLY | O_DIRECTORY);
 116   if (dfd == -1)
 117     error (EXIT_FAILURE, errno, gettext ("cannot open %s"), buf);
 118
 119   size_t exesize = 1024;
 120 #ifdef PATH_MAX
 121   exesize = PATH_MAX;
 122 #endif
 123   exe = alloca (exesize);
 124   ssize_t nexe;
 125   while ((nexe = readlinkat (dfd, "exe", exe, exesize)) == exesize)
 126     extend_alloca (exe, exesize, 2 * exesize);
 127   if (nexe == -1)
 128     exe = (char *) "<program name undetermined>";
 129   else
 130     exe[nexe] = '\0';
 131
 132   /* Stop all threads since otherwise the list of loaded modules might
 133      change while we are reading it.  */
 134   struct thread_list
 135   {
 136     pid_t tid;
 137     struct thread_list *next;
 138   } *thread_list = NULL;
 139
 140   int taskfd = openat (dfd, "task", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
 141   if (taskfd == 1)
 142     error (EXIT_FAILURE, errno, gettext ("cannot open %s/task"), buf);
 143   DIR *dir = fdopendir (taskfd);
 144   if (dir == NULL)
 145     error (EXIT_FAILURE, errno, gettext ("cannot prepare reading %s/task"),
 146            buf);
 147
 148   struct dirent64 *d;
 149   while ((d = readdir64 (dir)) != NULL)
 150     {
 151       if (! isdigit (d->d_name[0]))
 152         continue;
 153
 154       errno = 0;
 155       long int tid = strtol (d->d_name, &endp, 10);
 156       if (tid < 0 || (tid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 157           || (sizeof (pid_t) < sizeof (pid) && tid > INT_MAX))
 158         error (EXIT_FAILURE, 0, gettext ("invalid thread ID '%s'"),
 159                d->d_name);
 160
 161       if (ptrace (PTRACE_ATTACH, tid, NULL, NULL) != 0)
 162         {
 163           /* There might be a race between reading the directory and
 164              threads terminating.  Ignore errors attaching to unknown
 165              threads unless this is the main thread.  */
 166           if (errno == ESRCH && tid != pid)
 167             continue;
 168
 169           error (EXIT_FAILURE, errno, gettext ("cannot attach to process %lu"),
 170                  tid);
 171         }
 172
 173       struct thread_list *newp = alloca (sizeof (*newp));
 174       newp->tid = tid;
 175       newp->next = thread_list;
 176       thread_list = newp;
 177     }
 178
 179   closedir (dir);
 180
 181   int status = get_process_info (dfd, pid);
 182
 183   assert (thread_list != NULL);
 184   do
 185     {
 186       ptrace (PTRACE_DETACH, thread_list->tid, NULL, NULL);
 187       thread_list = thread_list->next;
 188     }
 189   while (thread_list != NULL);
 190
 191   close (dfd);
 192
 193   return status;
 194 }
 195
 196
 197 /* Handle program arguments.  */
 198 static error_t
 199 parse_opt (int key, char *arg, struct argp_state *state)
 200 {
 201   switch (key)
 202     {
 203     default:
 204       return ARGP_ERR_UNKNOWN;
 205     }
 206   return 0;
 207 }
 208
 209
 210 /* Print bug-reporting information in the help message.  */
 211 static char *
 212 more_help (int key, const char *text, void *input)
 213 {
 214   char *tp = NULL;
 215   switch (key)
 216     {
 217     case ARGP_KEY_HELP_EXTRA:
 218       /* We print some extra information.  */
 219       if (asprintf (&tp, gettext ("\
 220 For bug reporting instructions, please see:\n\
 221 %s.\n"), REPORT_BUGS_TO) < 0)
 222         return NULL;
 223       return tp;
 224     default:
 225       break;
 226     }
 227   return (char *) text;
 228 }
 229
 230 /* Print the version information.  */
 231 static void
 232 print_version (FILE *stream, struct argp_state *state)
 233 {
 234   fprintf (stream, "pldd %s%s\n", PKGVERSION, VERSION);
 235   fprintf (stream, gettext ("\
 236 Copyright (C) %s Free Software Foundation, Inc.\n\
 237 This is free software; see the source for copying conditions.  There is NO\n\
 238 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 239 "), "2013");
 240   fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
 241 }
 242
 243
 244 #define CLASS 32
 245 #include "pldd-xx.c"
 246 #define CLASS 64
 247 #include "pldd-xx.c"
 248
 249
 250 static int
 251 get_process_info (int dfd, long int pid)
 252 {
 253   memfd = openat (dfd, "mem", O_RDONLY);
 254   if (memfd == -1)
 255     goto no_info;
 256
 257   int fd = openat (dfd, "exe", O_RDONLY);
 258   if (fd == -1)
 259     {
 260     no_info:
 261       error (0, errno, gettext ("cannot get information about process %lu"),
 262              pid);
 263       return EXIT_FAILURE;
 264     }
 265
 266   char e_ident[EI_NIDENT];
 267   if (read (fd, e_ident, EI_NIDENT) != EI_NIDENT)
 268     goto no_info;
 269
 270   close (fd);
 271
 272   if (memcmp (e_ident, ELFMAG, SELFMAG) != 0)
 273     {
 274       error (0, 0, gettext ("process %lu is no ELF program"), pid);
 275       return EXIT_FAILURE;
 276     }
 277
 278   fd = openat (dfd, "auxv", O_RDONLY);
 279   if (fd == -1)
 280     goto no_info;
 281
 282   size_t auxv_size = 0;
 283   void *auxv = NULL;
 284   while (1)
 285     {
 286       auxv_size += 512;
 287       auxv = xrealloc (auxv, auxv_size);
 288
 289       ssize_t n = pread (fd, auxv, auxv_size, 0);
 290       if (n < 0)
 291         goto no_info;
 292       if (n < auxv_size)
 293         {
 294           auxv_size = n;
 295           break;
 296         }
 297     }
 298
 299   close (fd);
 300
 301   int retval;
 302   if (e_ident[EI_CLASS] == ELFCLASS32)
 303     retval = find_maps32 (pid, auxv, auxv_size);
 304   else
 305     retval = find_maps64 (pid, auxv, auxv_size);
 306
 307   free (auxv);
 308   close (memfd);
 309
 310   return retval;
 311 }