1 | /*
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2 | * Mini truncate implementation for busybox
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3 | *
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4 | * Copyright (C) 2015 by Ari Sundholm <ari@tuxera.com>
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5 | *
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6 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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7 | */
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8 |
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9 | //config:config TRUNCATE
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10 | //config: bool "truncate"
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11 | //config: default y
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12 | //config: help
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13 | //config: truncate truncates files to a given size. If a file does
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14 | //config: not exist, it is created unless told otherwise.
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15 |
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16 | //kbuild:lib-$(CONFIG_TRUNCATE) += truncate.o
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17 | //applet:IF_TRUNCATE(APPLET_NOFORK(truncate, truncate, BB_DIR_USR_BIN, BB_SUID_DROP, truncate))
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18 |
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19 | //usage:#define truncate_trivial_usage
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20 | //usage: "[-c] -s SIZE FILE..."
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21 | //usage:#define truncate_full_usage "\n\n"
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22 | //usage: "Truncate FILEs to the given size\n"
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23 | //usage: "\n -c Do not create files"
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24 | //usage: "\n -s SIZE Truncate to SIZE"
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25 | //usage:
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26 | //usage:#define truncate_example_usage
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27 | //usage: "$ truncate -s 1G foo"
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28 |
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29 | #include "libbb.h"
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30 |
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31 | #if ENABLE_LFS
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32 | # define XATOU_SFX xatoull_sfx
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33 | #else
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34 | # define XATOU_SFX xatoul_sfx
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35 | #endif
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36 |
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37 | /* This is a NOFORK applet. Be very careful! */
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38 |
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39 | int truncate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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40 | int truncate_main(int argc UNUSED_PARAM, char **argv)
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41 | {
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42 | unsigned opts;
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43 | int flags = O_WRONLY | O_NONBLOCK;
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44 | int ret = EXIT_SUCCESS;
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45 | char *size_str;
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46 | off_t size;
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47 |
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48 | enum {
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49 | OPT_NOCREATE = (1 << 0),
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50 | OPT_SIZE = (1 << 1),
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51 | };
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52 |
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53 | opt_complementary = "s:-1";
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54 | opts = getopt32(argv, "cs:", &size_str);
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55 |
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56 | if (!(opts & OPT_NOCREATE))
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57 | flags |= O_CREAT;
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58 |
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59 | // TODO: coreutils 8.17 also support "m" (lowercase) suffix
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60 | // with truncate, but not with dd!
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61 | // We share kMG_suffixes[], so we can't make both tools
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62 | // compatible at once...
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63 | size = XATOU_SFX(size_str, kMG_suffixes);
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64 |
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65 | argv += optind;
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66 | while (*argv) {
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67 | int fd = open(*argv, flags, 0666);
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68 | if (fd < 0) {
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69 | if (errno != ENOENT || !(opts & OPT_NOCREATE)) {
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70 | bb_perror_msg("%s: open", *argv);
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71 | ret = EXIT_FAILURE;
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72 | }
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73 | /* else: ENOENT && OPT_NOCREATE:
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74 | * do not report error, exitcode is also 0.
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75 | */
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76 | } else {
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77 | if (ftruncate(fd, size) == -1) {
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78 | bb_perror_msg("%s: truncate", *argv);
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79 | ret = EXIT_FAILURE;
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80 | }
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81 | xclose(fd);
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82 | }
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83 | ++argv;
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84 | }
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85 |
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86 | return ret;
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87 | }
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