1 /* truncate -- truncate or extend the length of files.
2 Copyright (C) 2008-2023 Free Software Foundation, Inc.
3
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.
8
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.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 /* Written by Pádraig Brady
18
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. */
22
23 #include <config.h> /* sets _FILE_OFFSET_BITS=64 etc. */
24 #include <stdckdint.h>
25 #include <stdio.h>
26 #include <getopt.h>
27 #include <sys/types.h>
28
29 #include "system.h"
30 #include "quote.h"
31 #include "stat-size.h"
32 #include "xdectoint.h"
33
34 /* The official name of this program (e.g., no 'g' prefix). */
35 #define PROGRAM_NAME "truncate"
36
37 #define AUTHORS proper_name_lite ("Padraig Brady", "P\303\241draig Brady")
38
39 /* (-c) If true, don't create if not already there */
40 static bool no_create;
41
42 /* (-o) If true, --size refers to blocks not bytes */
43 static bool block_mode;
44
45 /* (-r) Reference file to use size from */
46 static char const *ref_file;
47
48 static struct option const longopts[] =
49 {
50 {"no-create", no_argument, nullptr, 'c'},
51 {"io-blocks", no_argument, nullptr, 'o'},
52 {"reference", required_argument, nullptr, 'r'},
53 {"size", required_argument, nullptr, 's'},
54 {GETOPT_HELP_OPTION_DECL},
55 {GETOPT_VERSION_OPTION_DECL},
56 {nullptr, 0, nullptr, 0}
57 };
58
59 typedef enum
60 { rm_abs = 0, rm_rel, rm_min, rm_max, rm_rdn, rm_rup } rel_mode_t;
61
62 void
usage(int status)63 usage (int status)
64 {
65 if (status != EXIT_SUCCESS)
66 emit_try_help ();
67 else
68 {
69 printf (_("Usage: %s OPTION... FILE...\n"), program_name);
70 fputs (_("\
71 Shrink or extend the size of each FILE to the specified size\n\
72 \n\
73 A FILE argument that does not exist is created.\n\
74 \n\
75 If a FILE is larger than the specified size, the extra data is lost.\n\
76 If a FILE is shorter, it is extended and the sparse extended part (hole)\n\
77 reads as zero bytes.\n\
78 "), stdout);
79
80 emit_mandatory_arg_note ();
81
82 fputs (_("\
83 -c, --no-create do not create any files\n\
84 "), stdout);
85 fputs (_("\
86 -o, --io-blocks treat SIZE as number of IO blocks instead of bytes\n\
87 "), stdout);
88 fputs (_("\
89 -r, --reference=RFILE base size on RFILE\n\
90 -s, --size=SIZE set or adjust the file size by SIZE bytes\n"), stdout);
91 fputs (HELP_OPTION_DESCRIPTION, stdout);
92 fputs (VERSION_OPTION_DESCRIPTION, stdout);
93 emit_size_note ();
94 fputs (_("\n\
95 SIZE may also be prefixed by one of the following modifying characters:\n\
96 '+' extend by, '-' reduce by, '<' at most, '>' at least,\n\
97 '/' round down to multiple of, '%' round up to multiple of.\n"), stdout);
98 emit_ancillary_info (PROGRAM_NAME);
99 }
100 exit (status);
101 }
102
103 /* return true on success, false on error. */
104 static bool
do_ftruncate(int fd,char const * fname,off_t ssize,off_t rsize,rel_mode_t rel_mode)105 do_ftruncate (int fd, char const *fname, off_t ssize, off_t rsize,
106 rel_mode_t rel_mode)
107 {
108 struct stat sb;
109 off_t nsize;
110
111 if ((block_mode || (rel_mode && rsize < 0)) && fstat (fd, &sb) != 0)
112 {
113 error (0, errno, _("cannot fstat %s"), quoteaf (fname));
114 return false;
115 }
116 if (block_mode)
117 {
118 ptrdiff_t blksize = STP_BLKSIZE (&sb);
119 intmax_t ssize0 = ssize;
120 if (ckd_mul (&ssize, ssize, blksize))
121 {
122 error (0, 0,
123 _("overflow in %jd * %td byte blocks for file %s"),
124 ssize0, blksize, quoteaf (fname));
125 return false;
126 }
127 }
128 if (rel_mode)
129 {
130 off_t fsize;
131
132 if (0 <= rsize)
133 fsize = rsize;
134 else
135 {
136 if (usable_st_size (&sb))
137 {
138 fsize = sb.st_size;
139 if (fsize < 0)
140 {
141 /* Sanity check. Overflow is the only reason I can think
142 this would ever go negative. */
143 error (0, 0, _("%s has unusable, apparently negative size"),
144 quoteaf (fname));
145 return false;
146 }
147 }
148 else
149 {
150 fsize = lseek (fd, 0, SEEK_END);
151 if (fsize < 0)
152 {
153 error (0, errno, _("cannot get the size of %s"),
154 quoteaf (fname));
155 return false;
156 }
157 }
158 }
159
160 if (rel_mode == rm_min)
161 nsize = MAX (fsize, ssize);
162 else if (rel_mode == rm_max)
163 nsize = MIN (fsize, ssize);
164 else if (rel_mode == rm_rdn)
165 /* 0..ssize-1 -> 0 */
166 nsize = fsize - fsize % ssize;
167 else
168 {
169 if (rel_mode == rm_rup)
170 {
171 /* 1..ssize -> ssize */
172 off_t r = fsize % ssize;
173 ssize = r == 0 ? 0 : ssize - r;
174 }
175 if (ckd_add (&nsize, fsize, ssize))
176 {
177 error (0, 0, _("overflow extending size of file %s"),
178 quoteaf (fname));
179 return false;
180 }
181 }
182 }
183 else
184 nsize = ssize;
185 if (nsize < 0)
186 nsize = 0;
187
188 if (ftruncate (fd, nsize) != 0)
189 {
190 error (0, errno, _("failed to truncate %s at %jd bytes"),
191 quoteaf (fname), (intmax_t) nsize);
192 return false;
193 }
194
195 return true;
196 }
197
198 int
main(int argc,char ** argv)199 main (int argc, char **argv)
200 {
201 bool got_size = false;
202 off_t size IF_LINT ( = 0);
203 off_t rsize = -1;
204 rel_mode_t rel_mode = rm_abs;
205 int c;
206
207 initialize_main (&argc, &argv);
208 set_program_name (argv[0]);
209 setlocale (LC_ALL, "");
210 bindtextdomain (PACKAGE, LOCALEDIR);
211 textdomain (PACKAGE);
212
213 atexit (close_stdout);
214
215 while ((c = getopt_long (argc, argv, "cor:s:", longopts, nullptr)) != -1)
216 {
217 switch (c)
218 {
219 case 'c':
220 no_create = true;
221 break;
222
223 case 'o':
224 block_mode = true;
225 break;
226
227 case 'r':
228 ref_file = optarg;
229 break;
230
231 case 's':
232 /* skip any whitespace */
233 while (isspace (to_uchar (*optarg)))
234 optarg++;
235 switch (*optarg)
236 {
237 case '<':
238 rel_mode = rm_max;
239 optarg++;
240 break;
241 case '>':
242 rel_mode = rm_min;
243 optarg++;
244 break;
245 case '/':
246 rel_mode = rm_rdn;
247 optarg++;
248 break;
249 case '%':
250 rel_mode = rm_rup;
251 optarg++;
252 break;
253 }
254 /* skip any whitespace */
255 while (isspace (to_uchar (*optarg)))
256 optarg++;
257 if (*optarg == '+' || *optarg == '-')
258 {
259 if (rel_mode)
260 {
261 error (0, 0, _("multiple relative modifiers specified"));
262 /* Note other combinations are flagged as invalid numbers */
263 usage (EXIT_FAILURE);
264 }
265 rel_mode = rm_rel;
266 }
267 /* Support dd BLOCK size suffixes + lowercase g,t,m for bsd compat.
268 Note we don't support dd's b=512, c=1, w=2 or 21x512MiB formats. */
269 size = xdectoimax (optarg, OFF_T_MIN, OFF_T_MAX, "EgGkKmMPQRtTYZ0",
270 _("Invalid number"), 0);
271 /* Rounding to multiple of 0 is nonsensical */
272 if ((rel_mode == rm_rup || rel_mode == rm_rdn) && size == 0)
273 error (EXIT_FAILURE, 0, _("division by zero"));
274 got_size = true;
275 break;
276
277 case_GETOPT_HELP_CHAR;
278
279 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
280
281 default:
282 usage (EXIT_FAILURE);
283 }
284 }
285
286 argv += optind;
287 argc -= optind;
288
289 /* must specify either size or reference file */
290 if (!ref_file && !got_size)
291 {
292 error (0, 0, _("you must specify either %s or %s"),
293 quote_n (0, "--size"), quote_n (1, "--reference"));
294 usage (EXIT_FAILURE);
295 }
296 /* must specify a relative size with a reference file */
297 if (ref_file && got_size && !rel_mode)
298 {
299 error (0, 0, _("you must specify a relative %s with %s"),
300 quote_n (0, "--size"), quote_n (1, "--reference"));
301 usage (EXIT_FAILURE);
302 }
303 /* block_mode without size is not valid */
304 if (block_mode && !got_size)
305 {
306 error (0, 0, _("%s was specified but %s was not"),
307 quote_n (0, "--io-blocks"), quote_n (1, "--size"));
308 usage (EXIT_FAILURE);
309 }
310 /* must specify at least 1 file */
311 if (argc < 1)
312 {
313 error (0, 0, _("missing file operand"));
314 usage (EXIT_FAILURE);
315 }
316
317 if (ref_file)
318 {
319 struct stat sb;
320 off_t file_size = -1;
321 if (stat (ref_file, &sb) != 0)
322 error (EXIT_FAILURE, errno, _("cannot stat %s"), quoteaf (ref_file));
323 if (usable_st_size (&sb))
324 file_size = sb.st_size;
325 else
326 {
327 int ref_fd = open (ref_file, O_RDONLY);
328 if (0 <= ref_fd)
329 {
330 off_t file_end = lseek (ref_fd, 0, SEEK_END);
331 int saved_errno = errno;
332 close (ref_fd); /* ignore failure */
333 if (0 <= file_end)
334 file_size = file_end;
335 else
336 {
337 /* restore, in case close clobbered it. */
338 errno = saved_errno;
339 }
340 }
341 }
342 if (file_size < 0)
343 error (EXIT_FAILURE, errno, _("cannot get the size of %s"),
344 quoteaf (ref_file));
345 if (!got_size)
346 size = file_size;
347 else
348 rsize = file_size;
349 }
350
351 int oflags = O_WRONLY | (no_create ? 0 : O_CREAT) | O_NONBLOCK;
352 bool errors = false;
353
354 for (char const *fname; (fname = *argv); argv++)
355 {
356 int fd = open (fname, oflags, MODE_RW_UGO);
357 if (fd < 0)
358 {
359 /* 'truncate -s0 -c no-such-file' shouldn't gen error
360 'truncate -s0 no-such-dir/file' should gen ENOENT error
361 'truncate -s0 no-such-dir/' should gen EISDIR error
362 'truncate -s0 .' should gen EISDIR error */
363 if (!(no_create && errno == ENOENT))
364 {
365 error (0, errno, _("cannot open %s for writing"),
366 quoteaf (fname));
367 errors = true;
368 }
369 }
370 else
371 {
372 errors |= !do_ftruncate (fd, fname, size, rsize, rel_mode);
373 if (close (fd) != 0)
374 {
375 error (0, errno, _("failed to close %s"), quoteaf (fname));
376 errors = true;
377 }
378 }
379 }
380
381 return errors ? EXIT_FAILURE : EXIT_SUCCESS;
382 }
383