src/sync.c

   1 /* sync - update the super block
   2    Copyright (C) 1994-2023 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Jim Meyering */
  18
  19 #include <config.h>
  20 #include <assert.h>
  21 #include <getopt.h>
  22 #include <stdio.h>
  23 #include <sys/types.h>
  24
  25 #include "system.h"
  26 #include "die.h"
  27 #include "error.h"
  28
  29 /* The official name of this program (e.g., no 'g' prefix).  */
  30 #define PROGRAM_NAME "sync"
  31
  32 #define AUTHORS                                 \
  33   proper_name ("Jim Meyering"),                 \
  34   proper_name ("Giuseppe Scrivano")
  35
  36 #ifndef HAVE_SYNCFS
  37 # define HAVE_SYNCFS 0
  38 #endif
  39
  40 enum sync_mode
  41 {
  42   MODE_FILE,
  43   MODE_DATA,
  44   MODE_FILE_SYSTEM,
  45   MODE_SYNC
  46 };
  47
  48 static struct option const long_options[] =
  49 {
  50   {"data", no_argument, nullptr, 'd'},
  51   {"file-system", no_argument, nullptr, 'f'},
  52   {GETOPT_HELP_OPTION_DECL},
  53   {GETOPT_VERSION_OPTION_DECL},
  54   {nullptr, 0, nullptr, 0}
  55 };
  56
  57 void
  58 usage (int status)
  59 {
  60   if (status != EXIT_SUCCESS)
  61     emit_try_help ();
  62   else
  63     {
  64       printf (_("Usage: %s [OPTION] [FILE]...\n"), program_name);
  65       fputs (_("\
  66 Synchronize cached writes to persistent storage\n\
  67 \n\
  68 If one or more files are specified, sync only them,\n\
  69 or their containing file systems.\n\
  70 \n\
  71 "), stdout);
  72
  73       fputs (_("\
  74   -d, --data             sync only file data, no unneeded metadata\n\
  75 "), stdout);
  76       fputs (_("\
  77   -f, --file-system      sync the file systems that contain the files\n\
  78 "), stdout);
  79
  80       fputs (HELP_OPTION_DESCRIPTION, stdout);
  81       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  82       emit_ancillary_info (PROGRAM_NAME);
  83     }
  84   exit (status);
  85 }
  86
  87 /* Sync the specified FILE, or file systems associated with FILE.
  88    Return 1 on success.  */
  89
  90 static bool
  91 sync_arg (enum sync_mode mode, char const *file)
  92 {
  93   bool ret = true;
  94   int open_flags = O_RDONLY | O_NONBLOCK;
  95   int fd;
  96
  97 #if defined _AIX || defined __CYGWIN__
  98   /* AIX 7.1, CYGWIN 2.9.0, fsync requires write access to file.  */
  99   if (mode == MODE_FILE)
 100     open_flags = O_WRONLY | O_NONBLOCK;
 101 #endif
 102
 103   /* Note O_PATH might be supported with syncfs(),
 104      though as of Linux 3.18 is not.  */
 105   fd = open (file, open_flags);
 106   if (fd < 0)
 107     {
 108       /* Use the O_RDONLY errno, which is significant
 109          with directories for example.  */
 110       int rd_errno = errno;
 111       if (open_flags != (O_WRONLY | O_NONBLOCK))
 112         fd = open (file, O_WRONLY | O_NONBLOCK);
 113       if (fd < 0)
 114         {
 115           error (0, rd_errno, _("error opening %s"), quoteaf (file));
 116           return false;
 117         }
 118     }
 119
 120   /* We used O_NONBLOCK above to not hang with fifos,
 121      so reset that here.  */
 122   int fdflags = fcntl (fd, F_GETFL);
 123   if (fdflags == -1
 124       || fcntl (fd, F_SETFL, fdflags & ~O_NONBLOCK) < 0)
 125     {
 126       error (0, errno, _("couldn't reset non-blocking mode %s"),
 127              quoteaf (file));
 128       ret = false;
 129     }
 130
 131   if (ret == true)
 132     {
 133       int sync_status = -1;
 134
 135       switch (mode)
 136         {
 137         case MODE_DATA:
 138           sync_status = fdatasync (fd);
 139           break;
 140
 141         case MODE_FILE:
 142           sync_status = fsync (fd);
 143           break;
 144
 145 #if HAVE_SYNCFS
 146         case MODE_FILE_SYSTEM:
 147           sync_status = syncfs (fd);
 148           break;
 149 #endif
 150
 151         default:
 152           assert ("invalid sync_mode");
 153         }
 154
 155       if (sync_status < 0)
 156         {
 157           error (0, errno, _("error syncing %s"), quoteaf (file));
 158           ret = false;
 159         }
 160     }
 161
 162   if (close (fd) < 0)
 163     {
 164       error (0, errno, _("failed to close %s"), quoteaf (file));
 165       ret = false;
 166     }
 167
 168   return ret;
 169 }
 170
 171 int
 172 main (int argc, char **argv)
 173 {
 174   int c;
 175   bool args_specified;
 176   bool arg_data = false, arg_file_system = false;
 177   enum sync_mode mode;
 178   bool ok = true;
 179
 180   initialize_main (&argc, &argv);
 181   set_program_name (argv[0]);
 182   setlocale (LC_ALL, "");
 183   bindtextdomain (PACKAGE, LOCALEDIR);
 184   textdomain (PACKAGE);
 185
 186   atexit (close_stdout);
 187
 188   while ((c = getopt_long (argc, argv, "df", long_options, nullptr))
 189          != -1)
 190     {
 191       switch (c)
 192         {
 193         case 'd':
 194           arg_data = true;
 195           break;
 196
 197         case 'f':
 198           arg_file_system = true;
 199           break;
 200
 201         case_GETOPT_HELP_CHAR;
 202
 203         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 204
 205         default:
 206           usage (EXIT_FAILURE);
 207         }
 208     }
 209
 210   args_specified = optind < argc;
 211
 212   if (arg_data && arg_file_system)
 213     {
 214       die (EXIT_FAILURE, 0,
 215            _("cannot specify both --data and --file-system"));
 216     }
 217
 218   if (!args_specified && arg_data)
 219     die (EXIT_FAILURE, 0, _("--data needs at least one argument"));
 220
 221   if (! args_specified || (arg_file_system && ! HAVE_SYNCFS))
 222     mode = MODE_SYNC;
 223   else if (arg_file_system)
 224     mode = MODE_FILE_SYSTEM;
 225   else if (! arg_data)
 226     mode = MODE_FILE;
 227   else
 228     mode = MODE_DATA;
 229
 230   if (mode == MODE_SYNC)
 231     sync ();
 232   else
 233     {
 234       for (; optind < argc; optind++)
 235         ok &= sync_arg (mode, argv[optind]);
 236     }
 237
 238   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 239 }