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