1 /* truncate -- truncate or extend the length of files.
2 Copyright (C) 2008-2010 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* Written by Pádraig Brady
19 This is backwards compatible with the FreeBSD utility, but is more
20 flexible wrt the size specifications and the use of long options,
21 to better fit the "GNU" environment.
23 Note if !defined(HAVE_FTRUNCATE) then the --skip-ftruncate configure flag
24 was specified or we're in a mingw environment. In these cases gnulib
25 emulation will be used and GNULIB_FTRUNCATE is defined. Note if emulation
26 can't even be provided ftruncate() will return EIO. */
28 #include <config.h> /* sets _FILE_OFFSET_BITS=64 etc. */
31 #include <sys/types.h>
39 /* The official name of this program (e.g., no `g' prefix). */
40 #define PROGRAM_NAME "truncate"
42 #define AUTHORS proper_name_utf8 ("Padraig Brady", "P\303\241draig Brady")
44 /* (-c) If true, don't create if not already there */
45 static bool no_create;
47 /* (-o) If true, --size refers to blocks not bytes */
48 static bool block_mode;
50 /* (-r) Reference file to use size from */
51 static char const *ref_file;
53 static struct option const longopts[] =
55 {"no-create", no_argument, NULL, 'c'},
56 {"io-blocks", no_argument, NULL, 'o'},
57 {"reference", required_argument, NULL, 'r'},
58 {"size", required_argument, NULL, 's'},
59 {GETOPT_HELP_OPTION_DECL},
60 {GETOPT_VERSION_OPTION_DECL},
65 { rm_abs = 0, rm_rel, rm_min, rm_max, rm_rdn, rm_rup } rel_mode_t;
67 /* Set size to the value of STR, interpreted as a decimal integer,
68 optionally multiplied by various values.
69 Return -1 on error, 0 on success.
71 This supports dd BLOCK size suffixes + lowercase g,t,m for bsd compat
72 Note we don't support dd's b=512, c=1, w=2 or 21x512MiB formats. */
74 parse_len (char const *str, off_t *size)
78 e = xstrtoimax (str, NULL, 10, &tmp_size, "EgGkKmMPtTYZ0");
80 && !(OFF_T_MIN <= tmp_size && tmp_size <= OFF_T_MAX))
90 errno = (e == LONGINT_OVERFLOW ? EOVERFLOW : 0);
97 if (status != EXIT_SUCCESS)
98 fprintf (stderr, _("Try `%s --help' for more information.\n"),
102 printf (_("Usage: %s OPTION... FILE...\n"), program_name);
104 Shrink or extend the size of each FILE to the specified size\n\
106 A FILE argument that does not exist is created.\n\
108 If a FILE is larger than the specified size, the extra data is lost.\n\
109 If a FILE is shorter, it is extended and the extended part (hole)\n\
110 reads as zero bytes.\n\
114 Mandatory arguments to long options are mandatory for short options too.\n\
117 -c, --no-create do not create any files\n\
120 -o, --io-blocks Treat SIZE as number of IO blocks instead of bytes\n\
123 -r, --reference=FILE use this FILE's size\n\
124 -s, --size=SIZE use this SIZE\n"), stdout);
125 fputs (HELP_OPTION_DESCRIPTION, stdout);
126 fputs (VERSION_OPTION_DESCRIPTION, stdout);
129 SIZE may also be prefixed by one of the following modifying characters:\n\
130 `+' extend by, `-' reduce by, `<' at most, `>' at least,\n\
131 `/' round down to multiple of, `%' round up to multiple of.\n"), stdout);
134 Note that the -r and -s options are mutually exclusive.\n\
136 emit_ancillary_info ();
141 /* return 1 on error, 0 on success */
143 do_ftruncate (int fd, char const *fname, off_t ssize, rel_mode_t rel_mode)
148 if ((block_mode || rel_mode) && fstat (fd, &sb) != 0)
150 error (0, errno, _("cannot fstat %s"), quote (fname));
155 off_t const blksize = ST_BLKSIZE (sb);
156 if (ssize < OFF_T_MIN / blksize || ssize > OFF_T_MAX / blksize)
159 _("overflow in %" PRIdMAX
160 " * %" PRIdMAX " byte blocks for file %s"),
161 (intmax_t) ssize, (intmax_t) blksize,
169 uintmax_t const fsize = sb.st_size;
173 /* Complain only for a regular file, a directory,
174 or a shared memory object, as POSIX 1003.1-2004 specifies
175 ftruncate's behavior only for these file types. */
176 if (S_ISREG (sb.st_mode) || S_ISDIR (sb.st_mode)
177 || S_TYPEISSHM (&sb))
179 /* overflow is the only reason I can think
180 this would ever go negative for the above types */
181 error (0, 0, _("%s has unusable, apparently negative size"),
188 if (rel_mode == rm_min)
189 nsize = MAX (fsize, (uintmax_t) ssize);
190 else if (rel_mode == rm_max)
191 nsize = MIN (fsize, (uintmax_t) ssize);
192 else if (rel_mode == rm_rdn)
193 /* 0..ssize-1 -> 0 */
194 nsize = (fsize / ssize) * ssize;
195 else if (rel_mode == rm_rup)
196 /* 1..ssize -> ssize */
198 /* Here ssize>=1 && fsize>=0 */
199 uintmax_t const overflow = ((fsize + ssize - 1) / ssize) * ssize;
200 if (overflow > OFF_T_MAX)
202 error (0, 0, _("overflow rounding up size of file %s"),
210 if (ssize > OFF_T_MAX - (off_t)fsize)
212 error (0, 0, _("overflow extending size of file %s"),
216 nsize = fsize + ssize;
224 if (ftruncate (fd, nsize) == -1) /* note updates mtime & ctime */
226 /* Complain only when ftruncate fails on a regular file, a
227 directory, or a shared memory object, as POSIX 1003.1-2004
228 specifies ftruncate's behavior only for these file types.
229 For example, do not complain when Linux kernel 2.4 ftruncate
230 fails on /dev/fd0. */
231 int const ftruncate_errno = errno;
232 if (fstat (fd, &sb) != 0)
234 error (0, errno, _("cannot fstat %s"), quote (fname));
237 else if (S_ISREG (sb.st_mode) || S_ISDIR (sb.st_mode)
238 || S_TYPEISSHM (&sb))
240 error (0, ftruncate_errno,
241 _("truncating %s at %" PRIdMAX " bytes"), quote (fname),
252 main (int argc, char **argv)
254 bool got_size = false;
255 off_t size IF_LINT (= 0);
256 rel_mode_t rel_mode = rm_abs;
258 int c, errors = 0, fd = -1, oflags;
261 initialize_main (&argc, &argv);
262 set_program_name (argv[0]);
263 setlocale (LC_ALL, "");
264 bindtextdomain (PACKAGE, LOCALEDIR);
265 textdomain (PACKAGE);
267 atexit (close_stdout);
269 while ((c = getopt_long (argc, argv, "cor:s:", longopts, NULL)) != -1)
286 /* skip any whitespace */
287 while (isspace (to_uchar (*optarg)))
308 /* skip any whitespace */
309 while (isspace (to_uchar (*optarg)))
311 if (*optarg == '+' || *optarg == '-')
315 error (0, 0, _("multiple relative modifiers specified"));
316 /* Note other combinations are flagged as invalid numbers */
317 usage (EXIT_FAILURE);
321 if (parse_len (optarg, &size) == -1)
322 error (EXIT_FAILURE, errno, _("invalid number %s"),
324 /* Rounding to multiple of 0 is nonsensical */
325 if ((rel_mode == rm_rup || rel_mode == rm_rdn) && size == 0)
326 error (EXIT_FAILURE, 0, _("division by zero"));
330 case_GETOPT_HELP_CHAR;
332 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
335 usage (EXIT_FAILURE);
342 /* must specify either size or reference file */
343 if ((ref_file && got_size) || (!ref_file && !got_size))
345 error (0, 0, _("you must specify one of %s or %s"),
346 quote_n (0, "--size"), quote_n (1, "--reference"));
347 usage (EXIT_FAILURE);
349 /* block_mode without size is not valid */
350 if (block_mode && !got_size)
352 error (0, 0, _("%s was specified but %s was not"),
353 quote_n (0, "--io-blocks"), quote_n (1, "--size"));
354 usage (EXIT_FAILURE);
356 /* must specify at least 1 file */
359 error (0, 0, _("missing file operand"));
360 usage (EXIT_FAILURE);
366 if (stat (ref_file, &sb) != 0)
367 error (EXIT_FAILURE, errno, _("cannot stat %s"), quote (ref_file));
371 oflags = O_WRONLY | (no_create ? 0 : O_CREAT) | O_NONBLOCK;
372 omode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
374 while ((fname = *argv++) != NULL)
376 if ((fd = open (fname, oflags, omode)) == -1)
378 /* `truncate -s0 -c no-such-file` shouldn't gen error
379 `truncate -s0 no-such-dir/file` should gen ENOENT error
380 `truncate -s0 no-such-dir/` should gen EISDIR error
381 `truncate -s0 .` should gen EISDIR error */
382 if (!(no_create && errno == ENOENT))
384 int const open_errno = errno;
386 if (stat (fname, &sb) == 0)
388 /* Complain only for a regular file, a directory,
389 or a shared memory object, as POSIX 1003.1-2004 specifies
390 ftruncate's behavior only for these file types. */
391 if (!S_ISREG (sb.st_mode) && !S_ISDIR (sb.st_mode)
392 && !S_TYPEISSHM (&sb))
395 error (0, open_errno, _("cannot open %s for writing"),
405 errors += do_ftruncate (fd, fname, size, rel_mode);
408 error (0, errno, _("closing %s"), quote (fname));
414 return errors ? EXIT_FAILURE : EXIT_SUCCESS;