elf/pldd.c

   1 /* List dynamic shared objects linked into given process.
   2    Copyright (C) 2011, 2012 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 extern void *xmalloc (size_t n)
  47   __attribute_malloc__ __attribute_alloc_size (1);
  48 extern void *xrealloc (void *o, size_t n)
  49   __attribute_malloc__ __attribute_alloc_size (2);
  50
  51 /* Name and version of program.  */
  52 static void print_version (FILE *stream, struct argp_state *state);
  53 void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
  54
  55 /* Function to print some extra text in the help message.  */
  56 static char *more_help (int key, const char *text, void *input);
  57
  58 /* Definitions of arguments for argp functions.  */
  59 static const struct argp_option options[] =
  60 {
  61   { NULL, 0, NULL, 0, NULL }
  62 };
  63
  64 /* Short description of program.  */
  65 static const char doc[] = N_("\
  66 List dynamic shared objects loaded into process.");
  67
  68 /* Strings for arguments in help texts.  */
  69 static const char args_doc[] = N_("PID");
  70
  71 /* Prototype for option handler.  */
  72 static error_t parse_opt (int key, char *arg, struct argp_state *state);
  73
  74 /* Data structure to communicate with argp functions.  */
  75 static struct argp argp =
  76 {
  77   options, parse_opt, args_doc, doc, NULL, more_help, NULL
  78 };
  79
  80 // File descriptor of /proc/*/mem file.
  81 static int memfd;
  82
  83 /* Name of the executable  */
  84 static char *exe;
  85
  86 /* Local functions.  */
  87 static int get_process_info (int dfd, long int pid);
  88
  89
  90 int
  91 main (int argc, char *argv[])
  92 {
  93   /* Parse and process arguments.  */
  94   int remaining;
  95   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
  96
  97   if (remaining != argc - 1)
  98     {
  99       fprintf (stderr,
 100                gettext ("Exactly one parameter with process ID required.\n"));
 101       argp_help (&argp, stderr, ARGP_HELP_SEE, program_invocation_short_name);
 102       return 1;
 103     }
 104
 105   assert (sizeof (pid_t) == sizeof (int)
 106           || sizeof (pid_t) == sizeof (long int));
 107   char *endp;
 108   errno = 0;
 109   long int pid = strtol (argv[remaining], &endp, 10);
 110   if (pid < 0 || (pid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 111       || (sizeof (pid_t) < sizeof (pid) && pid > INT_MAX))
 112     error (EXIT_FAILURE, 0, gettext ("invalid process ID '%s'"),
 113            argv[remaining]);
 114
 115   /* Determine the program name.  */
 116   char buf[7 + 3 * sizeof (pid)];
 117   snprintf (buf, sizeof (buf), "/proc/%lu", pid);
 118   int dfd = open (buf, O_RDONLY | O_DIRECTORY);
 119   if (dfd == -1)
 120     error (EXIT_FAILURE, errno, gettext ("cannot open %s"), buf);
 121
 122   size_t exesize = 1024;
 123 #ifdef PATH_MAX
 124   exesize = PATH_MAX;
 125 #endif
 126   exe = alloca (exesize);
 127   ssize_t nexe;
 128   while ((nexe = readlinkat (dfd, "exe", exe, exesize)) == exesize)
 129     extend_alloca (exe, exesize, 2 * exesize);
 130   if (nexe == -1)
 131     exe = (char *) "<program name undetermined>";
 132   else
 133     exe[nexe] = '\0';
 134
 135   /* Stop all threads since otherwise the list of loaded modules might
 136      change while we are reading it.  */
 137   struct thread_list
 138   {
 139     pid_t tid;
 140     struct thread_list *next;
 141   } *thread_list = NULL;
 142
 143   int taskfd = openat (dfd, "task", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
 144   if (taskfd == 1)
 145     error (EXIT_FAILURE, errno, gettext ("cannot open %s/task"), buf);
 146   DIR *dir = fdopendir (taskfd);
 147   if (dir == NULL)
 148     error (EXIT_FAILURE, errno, gettext ("cannot prepare reading %s/task"),
 149            buf);
 150
 151   struct dirent64 *d;
 152   while ((d = readdir64 (dir)) != NULL)
 153     {
 154       if (! isdigit (d->d_name[0]))
 155         continue;
 156
 157       errno = 0;
 158       long int tid = strtol (d->d_name, &endp, 10);
 159       if (tid < 0 || (tid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 160           || (sizeof (pid_t) < sizeof (pid) && tid > INT_MAX))
 161         error (EXIT_FAILURE, 0, gettext ("invalid thread ID '%s'"),
 162                d->d_name);
 163
 164       if (ptrace (PTRACE_ATTACH, tid, NULL, NULL) != 0)
 165         {
 166           /* There might be a race between reading the directory and
 167              threads terminating.  Ignore errors attaching to unknown
 168              threads unless this is the main thread.  */
 169           if (errno == ESRCH && tid != pid)
 170             continue;
 171
 172           error (EXIT_FAILURE, errno, gettext ("cannot attach to process %lu"),
 173                  tid);
 174         }
 175
 176       struct thread_list *newp = alloca (sizeof (*newp));
 177       newp->tid = tid;
 178       newp->next = thread_list;
 179       thread_list = newp;
 180     }
 181
 182   closedir (dir);
 183
 184   int status = get_process_info (dfd, pid);
 185
 186   assert (thread_list != NULL);
 187   do
 188     {
 189       ptrace (PTRACE_DETACH, thread_list->tid, NULL, NULL);
 190       thread_list = thread_list->next;
 191     }
 192   while (thread_list != NULL);
 193
 194   close (dfd);
 195
 196   return status;
 197 }
 198
 199
 200 /* Handle program arguments.  */
 201 static error_t
 202 parse_opt (int key, char *arg, struct argp_state *state)
 203 {
 204   switch (key)
 205     {
 206     default:
 207       return ARGP_ERR_UNKNOWN;
 208     }
 209   return 0;
 210 }
 211
 212
 213 /* Print bug-reporting information in the help message.  */
 214 static char *
 215 more_help (int key, const char *text, void *input)
 216 {
 217   char *tp = NULL;
 218   switch (key)
 219     {
 220     case ARGP_KEY_HELP_EXTRA:
 221       /* We print some extra information.  */
 222       if (asprintf (&tp, gettext ("\
 223 For bug reporting instructions, please see:\n\
 224 %s.\n"), REPORT_BUGS_TO) < 0)
 225         return NULL;
 226       return tp;
 227     default:
 228       break;
 229     }
 230   return (char *) text;
 231 }
 232
 233 /* Print the version information.  */
 234 static void
 235 print_version (FILE *stream, struct argp_state *state)
 236 {
 237   fprintf (stream, "pldd %s%s\n", PKGVERSION, VERSION);
 238   fprintf (stream, gettext ("\
 239 Copyright (C) %s Free Software Foundation, Inc.\n\
 240 This is free software; see the source for copying conditions.  There is NO\n\
 241 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 242 "), "2012");
 243   fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
 244 }
 245
 246
 247 #define CLASS 32
 248 #include "pldd-xx.c"
 249 #define CLASS 64
 250 #include "pldd-xx.c"
 251
 252
 253 static int
 254 get_process_info (int dfd, long int pid)
 255 {
 256   memfd = openat (dfd, "mem", O_RDONLY);
 257   if (memfd == -1)
 258     goto no_info;
 259
 260   int fd = openat (dfd, "exe", O_RDONLY);
 261   if (fd == -1)
 262     {
 263     no_info:
 264       error (0, errno, gettext ("cannot get information about process %lu"),
 265              pid);
 266       return EXIT_FAILURE;
 267     }
 268
 269   char e_ident[EI_NIDENT];
 270   if (read (fd, e_ident, EI_NIDENT) != EI_NIDENT)
 271     goto no_info;
 272
 273   close (fd);
 274
 275   if (memcmp (e_ident, ELFMAG, SELFMAG) != 0)
 276     {
 277       error (0, 0, gettext ("process %lu is no ELF program"), pid);
 278       return EXIT_FAILURE;
 279     }
 280
 281   fd = openat (dfd, "auxv", O_RDONLY);
 282   if (fd == -1)
 283     goto no_info;
 284
 285   size_t auxv_size = 0;
 286   void *auxv = NULL;
 287   while (1)
 288     {
 289       auxv_size += 512;
 290       auxv = xrealloc (auxv, auxv_size);
 291
 292       ssize_t n = pread (fd, auxv, auxv_size, 0);
 293       if (n < 0)
 294         goto no_info;
 295       if (n < auxv_size)
 296         {
 297           auxv_size = n;
 298           break;
 299         }
 300     }
 301
 302   close (fd);
 303
 304   int retval;
 305   if (e_ident[EI_CLASS] == ELFCLASS32)
 306     retval = find_maps32 (pid, auxv, auxv_size);
 307   else
 308     retval = find_maps64 (pid, auxv, auxv_size);
 309
 310   free (auxv);
 311   close (memfd);
 312
 313   return retval;
 314 }