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 //config:config TRUNCATE
9 //config: bool "truncate (4.2 kb)"
10 //config: default y
11 //config: help
12 //config: truncate truncates files to a given size. If a file does
13 //config: not exist, it is created unless told otherwise.
14
15 //applet:IF_TRUNCATE(APPLET_NOFORK(truncate, truncate, BB_DIR_USR_BIN, BB_SUID_DROP, truncate))
16
17 //kbuild:lib-$(CONFIG_TRUNCATE) += truncate.o
18
19 //usage:#define truncate_trivial_usage
20 //usage: "[-c] -s SIZE FILE..."
21 //usage:#define truncate_full_usage "\n\n"
22 //usage: "Truncate FILEs to SIZE\n"
23 //usage: "\n -c Do not create files"
24 //usage: "\n -s SIZE"
25 //usage:
26 //usage:#define truncate_example_usage
27 //usage: "$ 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;
truncate_main(int argc UNUSED_PARAM,char ** argv)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 opts = getopt32(argv, "^" "cs:" "\0" "s:-1", &size_str);
54
55 if (!(opts & OPT_NOCREATE))
56 flags |= O_CREAT;
57
58 // TODO: coreutils 8.17 also support "m" (lowercase) suffix
59 // with truncate, but not with dd!
60 // We share kMG_suffixes[], so we can't make both tools
61 // compatible at once...
62 size = XATOU_SFX(size_str, kMG_suffixes);
63
64 argv += optind;
65 while (*argv) {
66 int fd = open(*argv, flags, 0666);
67 if (fd < 0) {
68 if (errno != ENOENT || !(opts & OPT_NOCREATE)) {
69 bb_perror_msg("%s: open", *argv);
70 ret = EXIT_FAILURE;
71 }
72 /* else: ENOENT && OPT_NOCREATE:
73 * do not report error, exitcode is also 0.
74 */
75 } else {
76 if (ftruncate(fd, size) == -1) {
77 bb_perror_msg("%s: truncate", *argv);
78 ret = EXIT_FAILURE;
79 }
80 xclose(fd);
81 }
82 ++argv;
83 }
84
85 return ret;
86 }
87