elf/pldd.c

   1 /* List dynamic shared objects linked into given process.
   2    Copyright (C) 2011-2015 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 #include <sys/wait.h>
  38
  39 #include <ldsodefs.h>
  40 #include <version.h>
  41
  42 /* Global variables.  */
  43 extern char *program_invocation_short_name;
  44 #define PACKAGE _libc_intl_domainname
  45
  46 /* External functions.  */
  47 #include <programs/xmalloc.h>
  48
  49 /* Name and version of program.  */
  50 static void print_version (FILE *stream, struct argp_state *state);
  51 void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
  52
  53 /* Function to print some extra text in the help message.  */
  54 static char *more_help (int key, const char *text, void *input);
  55
  56 /* Definitions of arguments for argp functions.  */
  57 static const struct argp_option options[] =
  58 {
  59   { NULL, 0, NULL, 0, NULL }
  60 };
  61
  62 /* Short description of program.  */
  63 static const char doc[] = N_("\
  64 List dynamic shared objects loaded into process.");
  65
  66 /* Strings for arguments in help texts.  */
  67 static const char args_doc[] = N_("PID");
  68
  69 /* Prototype for option handler.  */
  70 static error_t parse_opt (int key, char *arg, struct argp_state *state);
  71
  72 /* Data structure to communicate with argp functions.  */
  73 static struct argp argp =
  74 {
  75   options, parse_opt, args_doc, doc, NULL, more_help, NULL
  76 };
  77
  78 // File descriptor of /proc/*/mem file.
  79 static int memfd;
  80
  81 /* Name of the executable  */
  82 static char *exe;
  83
  84 /* Local functions.  */
  85 static int get_process_info (int dfd, long int pid);
  86 static void wait_for_ptrace_stop (long int pid);
  87
  88
  89 int
  90 main (int argc, char *argv[])
  91 {
  92   /* Parse and process arguments.  */
  93   int remaining;
  94   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
  95
  96   if (remaining != argc - 1)
  97     {
  98       fprintf (stderr,
  99                gettext ("Exactly one parameter with process ID required.\n"));
 100       argp_help (&argp, stderr, ARGP_HELP_SEE, program_invocation_short_name);
 101       return 1;
 102     }
 103
 104   assert (sizeof (pid_t) == sizeof (int)
 105           || sizeof (pid_t) == sizeof (long int));
 106   char *endp;
 107   errno = 0;
 108   long int pid = strtol (argv[remaining], &endp, 10);
 109   if (pid < 0 || (pid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 110       || (sizeof (pid_t) < sizeof (pid) && pid > INT_MAX))
 111     error (EXIT_FAILURE, 0, gettext ("invalid process ID '%s'"),
 112            argv[remaining]);
 113
 114   /* Determine the program name.  */
 115   char buf[7 + 3 * sizeof (pid)];
 116   snprintf (buf, sizeof (buf), "/proc/%lu", pid);
 117   int dfd = open (buf, O_RDONLY | O_DIRECTORY);
 118   if (dfd == -1)
 119     error (EXIT_FAILURE, errno, gettext ("cannot open %s"), buf);
 120
 121   size_t exesize = 1024;
 122 #ifdef PATH_MAX
 123   exesize = PATH_MAX;
 124 #endif
 125   exe = alloca (exesize);
 126   ssize_t nexe;
 127   while ((nexe = readlinkat (dfd, "exe", exe, exesize)) == exesize)
 128     extend_alloca (exe, exesize, 2 * exesize);
 129   if (nexe == -1)
 130     exe = (char *) "<program name undetermined>";
 131   else
 132     exe[nexe] = '\0';
 133
 134   /* Stop all threads since otherwise the list of loaded modules might
 135      change while we are reading it.  */
 136   struct thread_list
 137   {
 138     pid_t tid;
 139     struct thread_list *next;
 140   } *thread_list = NULL;
 141
 142   int taskfd = openat (dfd, "task", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
 143   if (taskfd == 1)
 144     error (EXIT_FAILURE, errno, gettext ("cannot open %s/task"), buf);
 145   DIR *dir = fdopendir (taskfd);
 146   if (dir == NULL)
 147     error (EXIT_FAILURE, errno, gettext ("cannot prepare reading %s/task"),
 148            buf);
 149
 150   struct dirent64 *d;
 151   while ((d = readdir64 (dir)) != NULL)
 152     {
 153       if (! isdigit (d->d_name[0]))
 154         continue;
 155
 156       errno = 0;
 157       long int tid = strtol (d->d_name, &endp, 10);
 158       if (tid < 0 || (tid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 159           || (sizeof (pid_t) < sizeof (pid) && tid > INT_MAX))
 160         error (EXIT_FAILURE, 0, gettext ("invalid thread ID '%s'"),
 161                d->d_name);
 162
 163       if (ptrace (PTRACE_ATTACH, tid, NULL, NULL) != 0)
 164         {
 165           /* There might be a race between reading the directory and
 166              threads terminating.  Ignore errors attaching to unknown
 167              threads unless this is the main thread.  */
 168           if (errno == ESRCH && tid != pid)
 169             continue;
 170
 171           error (EXIT_FAILURE, errno, gettext ("cannot attach to process %lu"),
 172                  tid);
 173         }
 174
 175       wait_for_ptrace_stop (tid);
 176
 177       struct thread_list *newp = alloca (sizeof (*newp));
 178       newp->tid = tid;
 179       newp->next = thread_list;
 180       thread_list = newp;
 181     }
 182
 183   closedir (dir);
 184
 185   int status = get_process_info (dfd, pid);
 186
 187   assert (thread_list != NULL);
 188   do
 189     {
 190       ptrace (PTRACE_DETACH, thread_list->tid, NULL, NULL);
 191       thread_list = thread_list->next;
 192     }
 193   while (thread_list != NULL);
 194
 195   close (dfd);
 196
 197   return status;
 198 }
 199
 200
 201 /* Wait for PID to enter ptrace-stop state after being attached.  */
 202 static void
 203 wait_for_ptrace_stop (long int pid)
 204 {
 205   int status;
 206
 207   /* While waiting for SIGSTOP being delivered to the tracee we have to
 208      reinject any other pending signal.  Ignore all other errors.  */
 209   while (waitpid (pid, &status, __WALL) == pid && WIFSTOPPED (status))
 210     {
 211       /* The STOP signal should not be delivered to the tracee.  */
 212       if (WSTOPSIG (status) == SIGSTOP)
 213         return;
 214       if (ptrace (PTRACE_CONT, pid, NULL,
 215                   (void *) (uintptr_t) WSTOPSIG (status)))
 216         /* The only possible error is that the process died.  */
 217         return;
 218     }
 219 }
 220
 221
 222 /* Handle program arguments.  */
 223 static error_t
 224 parse_opt (int key, char *arg, struct argp_state *state)
 225 {
 226   switch (key)
 227     {
 228     default:
 229       return ARGP_ERR_UNKNOWN;
 230     }
 231   return 0;
 232 }
 233
 234
 235 /* Print bug-reporting information in the help message.  */
 236 static char *
 237 more_help (int key, const char *text, void *input)
 238 {
 239   char *tp = NULL;
 240   switch (key)
 241     {
 242     case ARGP_KEY_HELP_EXTRA:
 243       /* We print some extra information.  */
 244       if (asprintf (&tp, gettext ("\
 245 For bug reporting instructions, please see:\n\
 246 %s.\n"), REPORT_BUGS_TO) < 0)
 247         return NULL;
 248       return tp;
 249     default:
 250       break;
 251     }
 252   return (char *) text;
 253 }
 254
 255 /* Print the version information.  */
 256 static void
 257 print_version (FILE *stream, struct argp_state *state)
 258 {
 259   fprintf (stream, "pldd %s%s\n", PKGVERSION, VERSION);
 260   fprintf (stream, gettext ("\
 261 Copyright (C) %s Free Software Foundation, Inc.\n\
 262 This is free software; see the source for copying conditions.  There is NO\n\
 263 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 264 "), "2014");
 265   fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
 266 }
 267
 268
 269 #define CLASS 32
 270 #include "pldd-xx.c"
 271 #define CLASS 64
 272 #include "pldd-xx.c"
 273
 274
 275 static int
 276 get_process_info (int dfd, long int pid)
 277 {
 278   memfd = openat (dfd, "mem", O_RDONLY);
 279   if (memfd == -1)
 280     goto no_info;
 281
 282   int fd = openat (dfd, "exe", O_RDONLY);
 283   if (fd == -1)
 284     {
 285     no_info:
 286       error (0, errno, gettext ("cannot get information about process %lu"),
 287              pid);
 288       return EXIT_FAILURE;
 289     }
 290
 291   char e_ident[EI_NIDENT];
 292   if (read (fd, e_ident, EI_NIDENT) != EI_NIDENT)
 293     goto no_info;
 294
 295   close (fd);
 296
 297   if (memcmp (e_ident, ELFMAG, SELFMAG) != 0)
 298     {
 299       error (0, 0, gettext ("process %lu is no ELF program"), pid);
 300       return EXIT_FAILURE;
 301     }
 302
 303   fd = openat (dfd, "auxv", O_RDONLY);
 304   if (fd == -1)
 305     goto no_info;
 306
 307   size_t auxv_size = 0;
 308   void *auxv = NULL;
 309   while (1)
 310     {
 311       auxv_size += 512;
 312       auxv = xrealloc (auxv, auxv_size);
 313
 314       ssize_t n = pread (fd, auxv, auxv_size, 0);
 315       if (n < 0)
 316         goto no_info;
 317       if (n < auxv_size)
 318         {
 319           auxv_size = n;
 320           break;
 321         }
 322     }
 323
 324   close (fd);
 325
 326   int retval;
 327   if (e_ident[EI_CLASS] == ELFCLASS32)
 328     retval = find_maps32 (pid, auxv, auxv_size);
 329   else
 330     retval = find_maps64 (pid, auxv, auxv_size);
 331
 332   free (auxv);
 333   close (memfd);
 334
 335   return retval;
 336 }