elf/pldd.c

   1 /* List dynamic shared objects linked into given process.
   2    Copyright (C) 2011 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <alloca.h>
  22 #include <argp.h>
  23 #include <assert.h>
  24 #include <dirent.h>
  25 #include <elf.h>
  26 #include <errno.h>
  27 #include <error.h>
  28 #include <fcntl.h>
  29 #include <libintl.h>
  30 #include <link.h>
  31 #include <stddef.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <unistd.h>
  36 #include <sys/ptrace.h>
  37 #include <sys/stat.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 extern void *xmalloc (size_t n);
  48 extern void *xrealloc (void *p, size_t n);
  49
  50 /* Name and version of program.  */
  51 static void print_version (FILE *stream, struct argp_state *state);
  52 void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
  53
  54 /* Bug report address.  */
  55 const char *argp_program_bug_address = N_("\
  56 For bug reporting instructions, please see:\n\
  57 <http://www.gnu.org/software/libc/bugs.html>.\n");
  58
  59 /* Definitions of arguments for argp functions.  */
  60 static const struct argp_option options[] =
  61 {
  62   { NULL, 0, NULL, 0, NULL }
  63 };
  64
  65 /* Short description of program.  */
  66 static const char doc[] = N_("\
  67 List dynamic shared objects loaded into process.");
  68
  69 /* Strings for arguments in help texts.  */
  70 static const char args_doc[] = N_("PID");
  71
  72 /* Prototype for option handler.  */
  73 static error_t parse_opt (int key, char *arg, struct argp_state *state);
  74
  75 /* Data structure to communicate with argp functions.  */
  76 static struct argp argp =
  77 {
  78   options, parse_opt, args_doc, doc, NULL, NULL, NULL
  79 };
  80
  81 // File descriptor of /proc/*/mem file.
  82 static int memfd;
  83
  84 /* Name of the executable  */
  85 static char *exe;
  86
  87 /* Local functions.  */
  88 static int get_process_info (int dfd, long int pid);
  89
  90
  91 int
  92 main (int argc, char *argv[])
  93 {
  94   /* Parse and process arguments.  */
  95   int remaining;
  96   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
  97
  98   if (remaining != argc - 1)
  99     {
 100       fprintf (stderr,
 101                gettext ("Exactly one parameter with process ID required.\n"));
 102       argp_help (&argp, stderr, ARGP_HELP_SEE, program_invocation_short_name);
 103       return 1;
 104     }
 105
 106   assert (sizeof (pid_t) == sizeof (int)
 107           || sizeof (pid_t) == sizeof (long int));
 108   char *endp;
 109   errno = 0;
 110   long int pid = strtol (argv[remaining], &endp, 10);
 111   if (pid < 0 || (pid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 112       || (sizeof (pid_t) < sizeof (pid) && pid > INT_MAX))
 113     error (EXIT_FAILURE, 0, gettext ("invalid process ID '%s'"),
 114            argv[remaining]);
 115
 116   /* Determine the program name.  */
 117   char buf[7 + 3 * sizeof (pid)];
 118   snprintf (buf, sizeof (buf), "/proc/%lu", pid);
 119   int dfd = open (buf, O_RDONLY | O_DIRECTORY);
 120   if (dfd == -1)
 121     error (EXIT_FAILURE, errno, gettext ("cannot open %s"), buf);
 122
 123   size_t exesize = 1024;
 124 #ifdef PATH_MAX
 125   exesize = PATH_MAX;
 126 #endif
 127   exe = alloca (exesize);
 128   ssize_t nexe;
 129   while ((nexe = readlinkat (dfd, "exe", exe, exesize)) == exesize)
 130     extend_alloca (exe, exesize, 2 * exesize);
 131   if (nexe == -1)
 132     exe = (char *) "<program name undetermined>";
 133   else
 134     exe[nexe] = '\0';
 135
 136   /* Stop all threads since otherwise the list of loaded modules might
 137      change while we are reading it.  */
 138   struct thread_list
 139   {
 140     pid_t tid;
 141     struct thread_list *next;
 142   } *thread_list = NULL;
 143
 144   int taskfd = openat (dfd, "task", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
 145   if (taskfd == 1)
 146     error (EXIT_FAILURE, errno, gettext ("cannot open %s/task"), buf);
 147   DIR *dir = fdopendir (taskfd);
 148   if (dir == NULL)
 149     error (EXIT_FAILURE, errno, gettext ("cannot prepare reading %s/task"),
 150            buf);
 151
 152   struct dirent64 *d;
 153   while ((d = readdir64 (dir)) != NULL)
 154     {
 155       if (! isdigit (d->d_name[0]))
 156         continue;
 157
 158       errno = 0;
 159       long int tid = strtol (d->d_name, &endp, 10);
 160       if (tid < 0 || (tid == ULONG_MAX && errno == ERANGE) || *endp != '\0'
 161           || (sizeof (pid_t) < sizeof (pid) && tid > INT_MAX))
 162         error (EXIT_FAILURE, 0, gettext ("invalid thread ID '%s'"),
 163                d->d_name);
 164
 165       if (ptrace (PTRACE_ATTACH, tid, NULL, NULL) != 0)
 166         {
 167           /* There might be a race between reading the directory and
 168              threads terminating.  Ignore errors attaching to unknown
 169              threads unless this is the main thread.  */
 170           if (errno == ESRCH && tid != pid)
 171             continue;
 172
 173           error (EXIT_FAILURE, errno, gettext ("cannot attach to process %lu"),
 174                  tid);
 175         }
 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 /* Handle program arguments.  */
 202 static error_t
 203 parse_opt (int key, char *arg, struct argp_state *state)
 204 {
 205   switch (key)
 206     {
 207     default:
 208       return ARGP_ERR_UNKNOWN;
 209     }
 210   return 0;
 211 }
 212
 213
 214 /* Print the version information.  */
 215 static void
 216 print_version (FILE *stream, struct argp_state *state)
 217 {
 218   fprintf (stream, "pldd (GNU %s) %s\n", PACKAGE, VERSION);
 219   fprintf (stream, gettext ("\
 220 Copyright (C) %s Free Software Foundation, Inc.\n\
 221 This is free software; see the source for copying conditions.  There is NO\n\
 222 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 223 "), "2011");
 224   fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
 225 }
 226
 227
 228 #define CLASS 32
 229 #include "pldd-xx.c"
 230 #define CLASS 64
 231 #include "pldd-xx.c"
 232
 233
 234 static int
 235 get_process_info (int dfd, long int pid)
 236 {
 237   memfd = openat (dfd, "mem", O_RDONLY);
 238   if (memfd == -1)
 239     goto no_info;
 240
 241   int fd = openat (dfd, "exe", O_RDONLY);
 242   if (fd == -1)
 243     {
 244     no_info:
 245       error (0, errno, gettext ("cannot get information about process %lu"),
 246              pid);
 247       return EXIT_FAILURE;
 248     }
 249
 250   char e_ident[EI_NIDENT];
 251   if (read (fd, e_ident, EI_NIDENT) != EI_NIDENT)
 252     goto no_info;
 253
 254   close (fd);
 255
 256   if (memcmp (e_ident, ELFMAG, SELFMAG) != 0)
 257     {
 258       error (0, 0, gettext ("process %lu is no ELF program"), pid);
 259       return EXIT_FAILURE;
 260     }
 261
 262   fd = openat (dfd, "auxv", O_RDONLY);
 263   if (fd == -1)
 264     goto no_info;
 265
 266   size_t auxv_size = 0;
 267   void *auxv = NULL;
 268   while (1)
 269     {
 270       auxv_size += 512;
 271       auxv = xrealloc (auxv, auxv_size);
 272
 273       ssize_t n = pread (fd, auxv, auxv_size, 0);
 274       if (n < 0)
 275         goto no_info;
 276       if (n < auxv_size)
 277         {
 278           auxv_size = n;
 279           break;
 280         }
 281     }
 282
 283   close (fd);
 284
 285   int retval;
 286   if (e_ident[EI_CLASS] == ELFCLASS32)
 287     retval = find_maps32 (pid, auxv, auxv_size);
 288   else
 289     retval = find_maps64 (pid, auxv, auxv_size);
 290
 291   free (auxv);
 292   close (memfd);
 293
 294   return retval;
 295 }