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 <getopt.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23
  24 #include "system.h"
  25 #include "die.h"
  26 #include "error.h"
  27
  28 /* The official name of this program (e.g., no 'g' prefix).  */
  29 #define PROGRAM_NAME "sync"
  30
  31 #define AUTHORS                                 \
  32   proper_name ("Jim Meyering"),                 \
  33   proper_name ("Giuseppe Scrivano")
  34
  35 #ifndef HAVE_SYNCFS
  36 # define HAVE_SYNCFS 0
  37 #endif
  38
  39 enum sync_mode
  40 {
  41   MODE_FILE,
  42   MODE_DATA,
  43   MODE_FILE_SYSTEM,
  44   MODE_SYNC
  45 };
  46
  47 static struct option const long_options[] =
  48 {
  49   {"data", no_argument, nullptr, 'd'},
  50   {"file-system", no_argument, nullptr, 'f'},
  51   {GETOPT_HELP_OPTION_DECL},
  52   {GETOPT_VERSION_OPTION_DECL},
  53   {nullptr, 0, nullptr, 0}
  54 };
  55
  56 void
  57 usage (int status)
  58 {
  59   if (status != EXIT_SUCCESS)
  60     emit_try_help ();
  61   else
  62     {
  63       printf (_("Usage: %s [OPTION] [FILE]...\n"), program_name);
  64       fputs (_("\
  65 Synchronize cached writes to persistent storage\n\
  66 \n\
  67 If one or more files are specified, sync only them,\n\
  68 or their containing file systems.\n\
  69 \n\
  70 "), stdout);
  71
  72       fputs (_("\
  73   -d, --data             sync only file data, no unneeded metadata\n\
  74 "), stdout);
  75       fputs (_("\
  76   -f, --file-system      sync the file systems that contain the files\n\
  77 "), stdout);
  78
  79       fputs (HELP_OPTION_DESCRIPTION, stdout);
  80       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  81       emit_ancillary_info (PROGRAM_NAME);
  82     }
  83   exit (status);
  84 }
  85
  86 /* Sync the specified FILE, or file systems associated with FILE.
  87    Return 1 on success.  */
  88
  89 static bool
  90 sync_arg (enum sync_mode mode, char const *file)
  91 {
  92   bool ret = true;
  93   int open_flags = O_RDONLY | O_NONBLOCK;
  94   int fd;
  95
  96 #if defined _AIX || defined __CYGWIN__
  97   /* AIX 7.1, CYGWIN 2.9.0, fsync requires write access to file.  */
  98   if (mode == MODE_FILE)
  99     open_flags = O_WRONLY | O_NONBLOCK;
 100 #endif
 101
 102   /* Note O_PATH might be supported with syncfs(),
 103      though as of Linux 3.18 is not.  */
 104   fd = open (file, open_flags);
 105   if (fd < 0)
 106     {
 107       /* Use the O_RDONLY errno, which is significant
 108          with directories for example.  */
 109       int rd_errno = errno;
 110       if (open_flags != (O_WRONLY | O_NONBLOCK))
 111         fd = open (file, O_WRONLY | O_NONBLOCK);
 112       if (fd < 0)
 113         {
 114           error (0, rd_errno, _("error opening %s"), quoteaf (file));
 115           return false;
 116         }
 117     }
 118
 119   /* We used O_NONBLOCK above to not hang with fifos,
 120      so reset that here.  */
 121   int fdflags = fcntl (fd, F_GETFL);
 122   if (fdflags == -1
 123       || fcntl (fd, F_SETFL, fdflags & ~O_NONBLOCK) < 0)
 124     {
 125       error (0, errno, _("couldn't reset non-blocking mode %s"),
 126              quoteaf (file));
 127       ret = false;
 128     }
 129
 130   if (ret == true)
 131     {
 132       int sync_status = -1;
 133
 134       switch (mode)
 135         {
 136         case MODE_DATA:
 137           sync_status = fdatasync (fd);
 138           break;
 139
 140         case MODE_FILE:
 141           sync_status = fsync (fd);
 142           break;
 143
 144 #if HAVE_SYNCFS
 145         case MODE_FILE_SYSTEM:
 146           sync_status = syncfs (fd);
 147           break;
 148 #endif
 149
 150         default:
 151           unreachable ();
 152         }
 153
 154       if (sync_status < 0)
 155         {
 156           error (0, errno, _("error syncing %s"), quoteaf (file));
 157           ret = false;
 158         }
 159     }
 160
 161   if (close (fd) < 0)
 162     {
 163       error (0, errno, _("failed to close %s"), quoteaf (file));
 164       ret = false;
 165     }
 166
 167   return ret;
 168 }
 169
 170 int
 171 main (int argc, char **argv)
 172 {
 173   int c;
 174   bool args_specified;
 175   bool arg_data = false, arg_file_system = false;
 176   enum sync_mode mode;
 177   bool ok = true;
 178
 179   initialize_main (&argc, &argv);
 180   set_program_name (argv[0]);
 181   setlocale (LC_ALL, "");
 182   bindtextdomain (PACKAGE, LOCALEDIR);
 183   textdomain (PACKAGE);
 184
 185   atexit (close_stdout);
 186
 187   while ((c = getopt_long (argc, argv, "df", long_options, nullptr))
 188          != -1)
 189     {
 190       switch (c)
 191         {
 192         case 'd':
 193           arg_data = true;
 194           break;
 195
 196         case 'f':
 197           arg_file_system = true;
 198           break;
 199
 200         case_GETOPT_HELP_CHAR;
 201
 202         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 203
 204         default:
 205           usage (EXIT_FAILURE);
 206         }
 207     }
 208
 209   args_specified = optind < argc;
 210
 211   if (arg_data && arg_file_system)
 212     {
 213       die (EXIT_FAILURE, 0,
 214            _("cannot specify both --data and --file-system"));
 215     }
 216
 217   if (!args_specified && arg_data)
 218     die (EXIT_FAILURE, 0, _("--data needs at least one argument"));
 219
 220   if (! args_specified || (arg_file_system && ! HAVE_SYNCFS))
 221     mode = MODE_SYNC;
 222   else if (arg_file_system)
 223     mode = MODE_FILE_SYSTEM;
 224   else if (! arg_data)
 225     mode = MODE_FILE;
 226   else
 227     mode = MODE_DATA;
 228
 229   if (mode == MODE_SYNC)
 230     sync ();
 231   else
 232     {
 233       for (; optind < argc; optind++)
 234         ok &= sync_arg (mode, argv[optind]);
 235     }
 236
 237   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 238 }