support/support_descriptors.c

   1 /* Monitoring file descriptor usage.
   2    Copyright (C) 2018-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <dirent.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <support/check.h>
  24 #include <support/descriptors.h>
  25 #include <support/support.h>
  26 #include <sys/stat.h>
  27 #include <sys/sysmacros.h>
  28 #include <xunistd.h>
  29
  30 struct procfs_descriptor
  31 {
  32   int fd;
  33   char *link_target;
  34   dev_t dev;
  35   ino64_t ino;
  36 };
  37
  38 /* Used with qsort.  */
  39 static int
  40 descriptor_compare (const void *l, const void *r)
  41 {
  42   const struct procfs_descriptor *left = l;
  43   const struct procfs_descriptor *right = r;
  44   /* Cannot overflow due to limited file descriptor range.  */
  45   return left->fd - right->fd;
  46 }
  47
  48 #define DYNARRAY_STRUCT descriptor_list
  49 #define DYNARRAY_ELEMENT struct procfs_descriptor
  50 #define DYNARRAY_PREFIX descriptor_list_
  51 #define DYNARRAY_ELEMENT_FREE(e) free ((e)->link_target)
  52 #define DYNARRAY_INITIAL_SIZE 0
  53 #include <malloc/dynarray-skeleton.c>
  54
  55 struct support_descriptors
  56 {
  57   struct descriptor_list list;
  58 };
  59
  60 struct support_descriptors *
  61 support_descriptors_list (void)
  62 {
  63   struct support_descriptors *result = xmalloc (sizeof (*result));
  64   descriptor_list_init (&result->list);
  65
  66   DIR *fds = opendir ("/proc/self/fd");
  67   if (fds == NULL)
  68     FAIL_EXIT1 ("opendir (\"/proc/self/fd\"): %m");
  69
  70   while (true)
  71     {
  72       errno = 0;
  73       struct dirent64 *e = readdir64 (fds);
  74       if (e == NULL)
  75         {
  76           if (errno != 0)
  77             FAIL_EXIT1 ("readdir: %m");
  78           break;
  79         }
  80
  81       if (e->d_name[0] == '.')
  82         continue;
  83
  84       char *endptr;
  85       long int fd = strtol (e->d_name, &endptr, 10);
  86       if (*endptr != '\0' || fd < 0 || fd > INT_MAX)
  87         FAIL_EXIT1 ("readdir: invalid file descriptor name: /proc/self/fd/%s",
  88                     e->d_name);
  89
  90       /* Skip the descriptor which is used to enumerate the
  91          descriptors.  */
  92       if (fd == dirfd (fds))
  93         continue;
  94
  95       char *target;
  96       {
  97         char *path = xasprintf ("/proc/self/fd/%ld", fd);
  98         target = xreadlink (path);
  99         free (path);
 100       }
 101       struct stat64 st;
 102       if (fstat64 (fd, &st) != 0)
 103         FAIL_EXIT1 ("readdir: fstat64 (%ld) failed: %m", fd);
 104
 105       struct procfs_descriptor *item = descriptor_list_emplace (&result->list);
 106       if (item == NULL)
 107         FAIL_EXIT1 ("descriptor_list_emplace: %m");
 108       item->fd = fd;
 109       item->link_target = target;
 110       item->dev = st.st_dev;
 111       item->ino = st.st_ino;
 112     }
 113
 114   closedir (fds);
 115
 116   /* Perform a merge join between descrs and current.  This assumes
 117      that the arrays are sorted by file descriptor.  */
 118
 119   qsort (descriptor_list_begin (&result->list),
 120          descriptor_list_size (&result->list),
 121          sizeof (struct procfs_descriptor), descriptor_compare);
 122
 123   return result;
 124 }
 125
 126 void
 127 support_descriptors_free (struct support_descriptors *descrs)
 128 {
 129   descriptor_list_free (&descrs->list);
 130   free (descrs);
 131 }
 132
 133 void
 134 support_descriptors_dump (struct support_descriptors *descrs,
 135                           const char *prefix, FILE *fp)
 136 {
 137   struct procfs_descriptor *end = descriptor_list_end (&descrs->list);
 138   for (struct procfs_descriptor *d = descriptor_list_begin (&descrs->list);
 139        d != end; ++d)
 140     {
 141       char *quoted = support_quote_string (d->link_target);
 142       fprintf (fp, "%s%d: target=\"%s\" major=%lld minor=%lld ino=%lld\n",
 143                prefix, d->fd, quoted,
 144                (long long int) major (d->dev),
 145                (long long int) minor (d->dev),
 146                (long long int) d->ino);
 147       free (quoted);
 148     }
 149 }
 150
 151 static void
 152 dump_mismatch (bool *first,
 153                struct support_descriptors *descrs,
 154                struct support_descriptors *current)
 155 {
 156   if (*first)
 157     *first = false;
 158   else
 159     return;
 160
 161   puts ("error: Differences found in descriptor set");
 162   puts ("Reference descriptor set:");
 163   support_descriptors_dump (descrs, "  ", stdout);
 164   puts ("Current descriptor set:");
 165   support_descriptors_dump (current, "  ", stdout);
 166   puts ("Differences:");
 167 }
 168
 169 static void
 170 report_closed_descriptor (bool *first,
 171                           struct support_descriptors *descrs,
 172                           struct support_descriptors *current,
 173                           struct procfs_descriptor *left)
 174 {
 175   support_record_failure ();
 176   dump_mismatch (first, descrs, current);
 177   printf ("error: descriptor %d was closed\n", left->fd);
 178 }
 179
 180 static void
 181 report_opened_descriptor (bool *first,
 182                           struct support_descriptors *descrs,
 183                           struct support_descriptors *current,
 184                           struct procfs_descriptor *right)
 185 {
 186   support_record_failure ();
 187   dump_mismatch (first, descrs, current);
 188   char *quoted = support_quote_string (right->link_target);
 189   printf ("error: descriptor %d was opened (\"%s\")\n", right->fd, quoted);
 190   free (quoted);
 191 }
 192
 193 void
 194 support_descriptors_check (struct support_descriptors *descrs)
 195 {
 196   struct support_descriptors *current = support_descriptors_list ();
 197
 198   /* Perform a merge join between descrs and current.  This assumes
 199      that the arrays are sorted by file descriptor.  */
 200
 201   struct procfs_descriptor *left = descriptor_list_begin (&descrs->list);
 202   struct procfs_descriptor *left_end = descriptor_list_end (&descrs->list);
 203   struct procfs_descriptor *right = descriptor_list_begin (&current->list);
 204   struct procfs_descriptor *right_end = descriptor_list_end (&current->list);
 205
 206   bool first = true;
 207   while (left != left_end && right != right_end)
 208     {
 209       if (left->fd == right->fd)
 210         {
 211           if (strcmp (left->link_target, right->link_target) != 0)
 212             {
 213               support_record_failure ();
 214               char *left_quoted = support_quote_string (left->link_target);
 215               char *right_quoted = support_quote_string (right->link_target);
 216               dump_mismatch (&first, descrs, current);
 217               printf ("error: descriptor %d changed from \"%s\" to \"%s\"\n",
 218                       left->fd, left_quoted, right_quoted);
 219               free (left_quoted);
 220               free (right_quoted);
 221             }
 222           if (left->dev != right->dev)
 223             {
 224               support_record_failure ();
 225               dump_mismatch (&first, descrs, current);
 226               printf ("error: descriptor %d changed device"
 227                       " from %lld:%lld to %lld:%lld\n",
 228                       left->fd,
 229                       (long long int) major (left->dev),
 230                       (long long int) minor (left->dev),
 231                       (long long int) major (right->dev),
 232                       (long long int) minor (right->dev));
 233             }
 234           if (left->ino != right->ino)
 235             {
 236               support_record_failure ();
 237               dump_mismatch (&first, descrs, current);
 238               printf ("error: descriptor %d changed ino from %lld to %lld\n",
 239                       left->fd,
 240                       (long long int) left->ino, (long long int) right->ino);
 241             }
 242           ++left;
 243           ++right;
 244         }
 245       else if (left->fd < right->fd)
 246         {
 247           /* Gap on the right.  */
 248           report_closed_descriptor (&first, descrs, current, left);
 249           ++left;
 250         }
 251       else
 252         {
 253           /* Gap on the left.  */
 254           TEST_VERIFY_EXIT (left->fd > right->fd);
 255           report_opened_descriptor (&first, descrs, current, right);
 256           ++right;
 257         }
 258     }
 259
 260   while (left != left_end)
 261     {
 262       /* Closed descriptors (more descriptors on the left).  */
 263       report_closed_descriptor (&first, descrs, current, left);
 264       ++left;
 265     }
 266
 267   while (right != right_end)
 268     {
 269       /* Opened descriptors (more descriptors on the right).  */
 270       report_opened_descriptor (&first, descrs, current, right);
 271       ++right;
 272     }
 273
 274   support_descriptors_free (current);
 275 }