LXR busybox/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 (3.8 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
  47static 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
  88int sync_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  89int 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 (3.6 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
 133int fsync_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 134int 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
 141