1 /* vi: set sw=4 ts=4: */
2 /*
3 * Mini sync implementation for busybox
4 *
5 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
6 * Copyright (C) 2015 by Ari Sundholm <ari@tuxera.com>
7 *
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
9 */
10 //config:config SYNC
11 //config: bool "sync"
12 //config: default y
13 //config: help
14 //config: sync is used to flush filesystem buffers.
15 //config:config FEATURE_SYNC_FANCY
16 //config: bool "Enable -d and -f flags (requires syncfs(2) in libc)"
17 //config: default y
18 //config: depends on SYNC
19 //config: help
20 //config: sync -d FILE... executes fdatasync() on each FILE.
21 //config: sync -f FILE... executes syncfs() on each FILE.
22
23 //applet:IF_SYNC(APPLET_NOFORK(sync, sync, BB_DIR_BIN, BB_SUID_DROP, sync))
24
25 //kbuild:lib-$(CONFIG_SYNC) += sync.o
26
27 /* BB_AUDIT SUSv3 N/A -- Matches GNU behavior. */
28
29 //usage:#define sync_trivial_usage
30 //usage: ""IF_FEATURE_SYNC_FANCY("[-df] [FILE]...")
31 //usage:#define sync_full_usage "\n\n"
32 //usage: IF_NOT_FEATURE_SYNC_FANCY(
33 //usage: "Write all buffered blocks to disk"
34 //usage: )
35 //usage: IF_FEATURE_SYNC_FANCY(
36 //usage: "Write all buffered blocks (in FILEs) to disk"
37 //usage: "\n -d Avoid syncing metadata"
38 //usage: "\n -f Sync filesystems underlying FILEs"
39 //usage: )
40
41 #include "libbb.h"
42
43 /* This is a NOFORK applet. Be very careful! */
44
45 int sync_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
sync_main(int argc UNUSED_PARAM,char ** argv IF_NOT_DESKTOP (UNUSED_PARAM))46 int sync_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
47 {
48 #if !ENABLE_FEATURE_SYNC_FANCY
49 /* coreutils-6.9 compat */
50 bb_warn_ignoring_args(argv[1]);
51 sync();
52 return EXIT_SUCCESS;
53 #else
54 unsigned opts;
55 int ret = EXIT_SUCCESS;
56
57 enum {
58 OPT_DATASYNC = (1 << 0),
59 OPT_SYNCFS = (1 << 1),
60 };
61
62 opt_complementary = "d--f:f--d";
63 opts = getopt32(argv, "df");
64 argv += optind;
65
66 /* Handle the no-argument case. */
67 if (!argv[0])
68 sync();
69
70 while (*argv) {
71 int fd = open_or_warn(*argv, O_RDONLY);
72
73 if (fd < 0) {
74 ret = EXIT_FAILURE;
75 goto next;
76 }
77 if (opts & OPT_DATASYNC) {
78 if (fdatasync(fd))
79 goto err;
80 goto do_close;
81 }
82 if (opts & OPT_SYNCFS) {
83 /*
84 * syncfs is documented to only fail with EBADF,
85 * which can't happen here. So, no error checks.
86 */
87 syncfs(fd);
88 goto do_close;
89 }
90 if (fsync(fd)) {
91 err:
92 bb_simple_perror_msg(*argv);
93 ret = EXIT_FAILURE;
94 }
95 do_close:
96 close(fd);
97 next:
98 ++argv;
99 }
100
101 return ret;
102 #endif
103 }
104