release/src/router/busybox/coreutils/truncate.c

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