1/*
2 * Copyright (c) 2000 Sheldon Hearn <sheldonh@FreeBSD.org>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 */
27
28#ifndef lint
29static const char rcsid[] =
30 "$FreeBSD: head/usr.bin/truncate/truncate.c 63790 2000-07-24 08:56:42Z sheldonh $";
31#endif
32
33#include <sys/stat.h>
34
35#include <ctype.h>
36#include <err.h>
37#include <errno.h>
38#include <fcntl.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include <unistd.h>
42
43static off_t parselength __P((char *, off_t *));
44static void usage __P((void));
45
46static int no_create;
47static int do_relative;
48static int do_refer;
49static int got_size;
50
51int
52main(int argc, char **argv)
53{
54 struct stat sb;
55 mode_t omode;
56 off_t oflow, rsize, sz, tsize;
57 int ch, error, fd, oflags;
58 char *fname, *rname;
59
60 error = 0;
61 while ((ch = getopt(argc, argv, "cr:s:")) != -1)
62 switch (ch) {
63 case 'c':
64 no_create++;
65 break;
66 case 'r':
67 do_refer++;
68 rname = optarg;
69 break;
70 case 's':
71 if (parselength(optarg, &sz) == -1)
72 errx(EXIT_FAILURE,
73 "invalid size argument `%s'", optarg);
74 if (*optarg == '+' || *optarg == '-')
75 do_relative++;
76 got_size++;
77 break;
78 default:
79 usage();
80 /* NOTREACHED */
81 }
82
83 argv += optind;
84 argc -= optind;
85
86 /*
87 * Exactly one of do_refer or got_size must be specified. Since
88 * do_relative implies got_size, do_relative and do_refer are
89 * also mutually exclusive. See usage() for allowed invocations.
90 */
91 if (!(do_refer || got_size) || (do_refer && got_size) || argc < 1)
92 usage();
93 if (do_refer) {
94 if (stat(rname, &sb) == -1)
95 err(EXIT_FAILURE, "%s", rname);
96 tsize = sb.st_size;
97 } else if (got_size) {
98 if (do_relative)
99 rsize = sz;
100 else
101 tsize = sz;
102 }
103
104 if (no_create)
105 oflags = O_WRONLY;
106 else
107 oflags = O_WRONLY | O_CREAT;
108 omode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
109
110 while ((fname = *argv++) != NULL) {
111 if ((fd = open(fname, oflags, omode)) == -1) {
112 if (errno != ENOENT) {
113 warn("%s", fname);
114 error++;
115 }
116 continue;
117 }
118 if (do_relative) {
119 if (fstat(fd, &sb) == -1) {
120 warn("%s", fname);
121 error++;
122 continue;
123 }
124 oflow = sb.st_size + rsize;
125 if (oflow < (sb.st_size + rsize)) {
126 errno = EFBIG;
127 warn("%s", fname);
128 error++;
129 continue;
130 }
131 tsize = oflow;
132 }
133 if (tsize < 0)
134 tsize = 0;
135
136 if (ftruncate(fd, tsize) == -1) {
137 warn("%s", fname);
138 error++;
139 continue;
140 }
141
142 close(fd);
143 }
144
145 return error ? EXIT_FAILURE : EXIT_SUCCESS;
146}
147
148/*
149 * Return the numeric value of a string given in the form [+-][0-9]+[GMK]
150 * or -1 on format error or overflow.
151 */
152static off_t
153parselength(char *ls, off_t *sz)
154{
155 off_t length, oflow;
156 int lsign;
157
158 length = 0;
159 lsign = 1;
160
161 switch (*ls) {
162 case '-':
163 lsign = -1;
164 case '+':
165 ls++;
166 }
167
168#define ASSIGN_CHK_OFLOW(x, y) if (x < y) return -1; y = x
169 /*
170 * Calculate the value of the decimal digit string, failing
171 * on overflow.
172 */
173 while (isdigit(*ls)) {
174 oflow = length * 10 + *ls++ - '0';
175 ASSIGN_CHK_OFLOW(oflow, length);
176 }
177
178 switch (*ls) {
179 case 'G':
180 oflow = length * 1024;
181 ASSIGN_CHK_OFLOW(oflow, length);
182 case 'M':
183 oflow = length * 1024;
184 ASSIGN_CHK_OFLOW(oflow, length);
185 case 'K':
186 if (ls[1] != '\0')
187 return -1;
188 oflow = length * 1024;
189 ASSIGN_CHK_OFLOW(oflow, length);
190 case '\0':
191 break;
192 default:
193 return -1;
194 }
195
196 *sz = length * lsign;
197 return 0;
198}
199
200static void
201usage(void)
202{
203 fprintf(stderr, "%s\n%s\n",
204 "usage: truncate [-c] -s [+|-]size[K|M|G] file ...",
205 " truncate [-c] -r rfile file ...");
206 exit(EXIT_FAILURE);
207}