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