usr.bin/truncate/truncate.c

   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  * $FreeBSD: src/usr.bin/truncate/truncate.c,v 1.6.2.1 2000/08/04 08:05:52 sheldonh Exp $
  27  */
  28
  29 #include <sys/stat.h>
  30
  31 #include <ctype.h>
  32 #include <err.h>
  33 #include <errno.h>
  34 #include <fcntl.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <unistd.h>
  38
  39 static off_t    parselength(char *, off_t *);
  40 static void     usage(void);
  41
  42 static int      no_create;
  43 static int      do_relative;
  44 static int      do_refer;
  45 static int      got_size;
  46
  47 int
  48 main(int argc, char **argv)
  49 {
  50         struct stat     sb;
  51         mode_t  omode;
  52         off_t   oflow, rsize, sz, tsize;
  53         int     ch, error, fd, oflags;
  54         char   *fname, *rname;
  55
  56         rsize = tsize = sz = 0;
  57         error = 0;
  58         rname = NULL;
  59         while ((ch = getopt(argc, argv, "cr:s:")) != -1)
  60                 switch (ch) {
  61                 case 'c':
  62                         no_create = 1;
  63                         break;
  64                 case 'r':
  65                         do_refer = 1;
  66                         rname = optarg;
  67                         break;
  68                 case 's':
  69                         if (parselength(optarg, &sz) == -1)
  70                                 errx(EXIT_FAILURE,
  71                                     "invalid size argument `%s'", optarg);
  72                         if (*optarg == '+' || *optarg == '-')
  73                                 do_relative = 1;
  74                         got_size = 1;
  75                         break;
  76                 default:
  77                         usage();
  78                         /* NOTREACHED */
  79                 }
  80
  81         argv += optind;
  82         argc -= optind;
  83
  84         /*
  85          * Exactly one of do_refer or got_size must be specified.  Since
  86          * do_relative implies got_size, do_relative and do_refer are
  87          * also mutually exclusive.  See usage() for allowed invocations.
  88          */
  89         if (do_refer + got_size != 1 || argc < 1)
  90                 usage();
  91         if (do_refer) {
  92                 if (stat(rname, &sb) == -1)
  93                         err(EXIT_FAILURE, "%s", rname);
  94                 tsize = sb.st_size;
  95         } else if (do_relative)
  96                 rsize = sz;
  97         else
  98                 tsize = sz;
  99
 100         if (no_create)
 101                 oflags = O_WRONLY;
 102         else
 103                 oflags = O_WRONLY | O_CREAT;
 104         omode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
 105
 106         while ((fname = *argv++) != NULL) {
 107                 if ((fd = open(fname, oflags, omode)) == -1) {
 108                         if (errno != ENOENT) {
 109                                 warn("%s", fname);
 110                                 error++;
 111                         }
 112                         continue;
 113                 }
 114                 if (do_relative) {
 115                         if (fstat(fd, &sb) == -1) {
 116                                 warn("%s", fname);
 117                                 error++;
 118                                 continue;
 119                         }
 120                         oflow = sb.st_size + rsize;
 121                         if (oflow < (sb.st_size + rsize)) {
 122                                 errno = EFBIG;
 123                                 warn("%s", fname);
 124                                 error++;
 125                                 continue;
 126                         }
 127                         tsize = oflow;
 128                 }
 129                 if (tsize < 0)
 130                         tsize = 0;
 131
 132                 if (ftruncate(fd, tsize) == -1) {
 133                         warn("%s", fname);
 134                         error++;
 135                         continue;
 136                 }
 137
 138                 close(fd);
 139         }
 140
 141         return error ? EXIT_FAILURE : EXIT_SUCCESS;
 142 }
 143
 144 /*
 145  * Return the numeric value of a string given in the form [+-][0-9]+[GMK]
 146  * or -1 on format error or overflow.
 147  */
 148 static off_t
 149 parselength(char *ls, off_t *sz)
 150 {
 151         off_t   length, oflow;
 152         int     lsign;
 153
 154         length = 0;
 155         lsign = 1;
 156
 157         switch (*ls) {
 158         case '-':
 159                 lsign = -1;
 160                 /* FALLTHROUGH */
 161         case '+':
 162                 ls++;
 163         }
 164
 165 #define ASSIGN_CHK_OFLOW(x, y)  if (x < y) return -1; y = x
 166         /*
 167          * Calculate the value of the decimal digit string, failing
 168          * on overflow.
 169          */
 170         while (isdigit(*ls)) {
 171                 oflow = length * 10 + *ls++ - '0';
 172                 ASSIGN_CHK_OFLOW(oflow, length);
 173         }
 174
 175         switch (*ls) {
 176         case 'T':
 177                 oflow = length * 1024;
 178                 ASSIGN_CHK_OFLOW(oflow, length);
 179                 /* FALLTHROUGH */
 180         case 'G':
 181                 oflow = length * 1024;
 182                 ASSIGN_CHK_OFLOW(oflow, length);
 183                 /* FALLTHROUGH */
 184         case 'M':
 185                 oflow = length * 1024;
 186                 ASSIGN_CHK_OFLOW(oflow, length);
 187                 /* FALLTHROUGH */
 188         case 'K':
 189                 if (ls[1] != '\0')
 190                         return -1;
 191                 oflow = length * 1024;
 192                 ASSIGN_CHK_OFLOW(oflow, length);
 193         case '\0':
 194                 break;
 195         default:
 196                 return -1;
 197         }
 198
 199         *sz = length * lsign;
 200         return 0;
 201 }
 202
 203 static void
 204 usage(void)
 205 {
 206         fprintf(stderr, "%s\n%s\n",
 207             "usage: truncate [-c] -s [+|-]size[K|M|G|T] file ...",
 208             "       truncate [-c] -r rfile file ...");
 209         exit(EXIT_FAILURE);
 210 }