coreutils/sync.c

   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 (4 kb)"
  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_NOFORK:name  main  location    suid_type     help
  24 //applet:IF_SYNC(APPLET_NOFORK(sync, sync, BB_DIR_BIN, BB_SUID_DROP, sync))
  25
  26 //kbuild:lib-$(CONFIG_SYNC) += sync.o
  27
  28 /* BB_AUDIT SUSv3 N/A -- Matches GNU behavior. */
  29
  30 //usage:#define sync_trivial_usage
  31 //usage:       ""IF_FEATURE_SYNC_FANCY("[-df] [FILE]...")
  32 //usage:#define sync_full_usage "\n\n"
  33 //usage:    IF_NOT_FEATURE_SYNC_FANCY(
  34 //usage:       "Write all buffered blocks to disk"
  35 //usage:    )
  36 //usage:    IF_FEATURE_SYNC_FANCY(
  37 //usage:       "Write all buffered blocks (in FILEs) to disk"
  38 //usage:     "\n        -d      Avoid syncing metadata"
  39 //usage:     "\n        -f      Sync filesystems underlying FILEs"
  40 //usage:    )
  41
  42 #include "libbb.h"
  43
  44 /* This is a NOFORK applet. Be very careful! */
  45
  46 #if ENABLE_FEATURE_SYNC_FANCY || ENABLE_FSYNC
  47 static int sync_common(int opts, char **argv)
  48 {
  49         int ret;
  50         enum {
  51                 OPT_DATASYNC = (1 << 0),
  52                 OPT_SYNCFS   = (1 << 1),
  53         };
  54
  55         ret = EXIT_SUCCESS;
  56         do {
  57                 /* GNU "sync FILE" uses O_NONBLOCK open */
  58                 int fd = open_or_warn(*argv, /*O_NOATIME |*/ O_NOCTTY | O_RDONLY | O_NONBLOCK);
  59                 /* open(NOATIME) can only be used by owner or root, don't use NOATIME here */
  60
  61                 if (fd < 0) {
  62                         ret = EXIT_FAILURE;
  63                         goto next;
  64                 }
  65 # if ENABLE_FEATURE_SYNC_FANCY
  66                 if (opts & OPT_SYNCFS) {
  67                         /*
  68                          * syncfs is documented to only fail with EBADF,
  69                          * which can't happen here. So, no error checks.
  70                          */
  71                         syncfs(fd);
  72                 } else
  73 # endif
  74                 if (((opts & OPT_DATASYNC) ? fdatasync(fd) : fsync(fd)) != 0) {
  75                         bb_simple_perror_msg(*argv);
  76                         ret = EXIT_FAILURE;
  77                 }
  78                 close(fd);
  79  next:
  80                 argv++;
  81         } while (*argv);
  82
  83         return ret;
  84 }
  85 #endif
  86
  87 #if ENABLE_SYNC
  88 int sync_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  89 int sync_main(int argc UNUSED_PARAM, char **argv IF_NOT_DESKTOP(UNUSED_PARAM))
  90 {
  91 # if !ENABLE_FEATURE_SYNC_FANCY
  92         /* coreutils-6.9 compat */
  93         bb_warn_ignoring_args(argv[1]);
  94         sync();
  95         return EXIT_SUCCESS;
  96 # else
  97         unsigned opts = getopt32(argv, "^" "df" "\0" "d--f:f--d");
  98         argv += optind;
  99         if (!argv[0]) {
 100                 sync();
 101                 return EXIT_SUCCESS;
 102         }
 103         return sync_common(opts, argv);
 104 # endif
 105 }
 106 #endif
 107
 108 /*
 109  * Mini fsync implementation for busybox
 110  *
 111  * Copyright (C) 2008 Nokia Corporation. All rights reserved.
 112  *
 113  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 114  */
 115 //config:config FSYNC
 116 //config:       bool "fsync (3.8 kb)"
 117 //config:       default y
 118 //config:       help
 119 //config:       fsync is used to flush file-related cached blocks to disk.
 120
 121 //                APPLET_NOFORK:name   main   location    suid_type     help
 122 //applet:IF_FSYNC(APPLET_NOFORK(fsync, fsync, BB_DIR_BIN, BB_SUID_DROP, fsync))
 123
 124 //kbuild:lib-$(CONFIG_FSYNC) += sync.o
 125
 126 //usage:#define fsync_trivial_usage
 127 //usage:       "[-d] FILE..."
 128 //usage:#define fsync_full_usage "\n\n"
 129 //usage:       "Write all buffered blocks in FILEs to disk\n"
 130 //usage:     "\n        -d      Avoid syncing metadata"
 131
 132 #if ENABLE_FSYNC
 133 int fsync_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 134 int fsync_main(int argc UNUSED_PARAM, char **argv)
 135 {
 136         int opts = getopt32(argv, "^" "d" "\0" "-1"/*min 1 arg*/);
 137         argv += optind;
 138         return sync_common(opts, argv);
 139 }
 140 #endif