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  * $DragonFly: src/usr.bin/truncate/truncate.c,v 1.3 2003/10/04 20:36:53 hmp Exp $
  28  */
  29
  30 #include <sys/stat.h>
  31
  32 #include <ctype.h>
  33 #include <err.h>
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <unistd.h>
  39
  40 static off_t    parselength(char *, off_t *);
  41 static void     usage(void);
  42
  43 static int      no_create;
  44 static int      do_relative;
  45 static int      do_refer;
  46 static int      got_size;
  47
  48 int
  49 main(int argc, char **argv)
  50 {
  51         struct stat     sb;
  52         mode_t  omode;
  53         off_t   oflow, rsize, sz, tsize;
  54         int     ch, error, fd, oflags;
  55         char   *fname, *rname;
  56
  57         rsize = tsize = sz = 0;
  58         error = 0;
  59         rname = NULL;
  60         while ((ch = getopt(argc, argv, "cr:s:")) != -1)
  61                 switch (ch) {
  62                 case 'c':
  63                         no_create = 1;
  64                         break;
  65                 case 'r':
  66                         do_refer = 1;
  67                         rname = optarg;
  68                         break;
  69                 case 's':
  70                         if (parselength(optarg, &sz) == -1)
  71                                 errx(EXIT_FAILURE,
  72                                     "invalid size argument `%s'", optarg);
  73                         if (*optarg == '+' || *optarg == '-')
  74                                 do_relative = 1;
  75                         got_size = 1;
  76                         break;
  77                 default:
  78                         usage();
  79                         /* NOTREACHED */
  80                 }
  81
  82         argv += optind;
  83         argc -= optind;
  84
  85         /*
  86          * Exactly one of do_refer or got_size must be specified.  Since
  87          * do_relative implies got_size, do_relative and do_refer are
  88          * also mutually exclusive.  See usage() for allowed invocations.
  89          */
  90         if (do_refer + got_size != 1 || argc < 1)
  91                 usage();
  92         if (do_refer) {
  93                 if (stat(rname, &sb) == -1)
  94                         err(EXIT_FAILURE, "%s", rname);
  95                 tsize = sb.st_size;
  96         } else if (do_relative)
  97                 rsize = sz;
  98         else
  99                 tsize = sz;
 100
 101         if (no_create)
 102                 oflags = O_WRONLY;
 103         else
 104                 oflags = O_WRONLY | O_CREAT;
 105         omode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
 106
 107         while ((fname = *argv++) != NULL) {
 108                 if ((fd = open(fname, oflags, omode)) == -1) {
 109                         if (errno != ENOENT) {
 110                                 warn("%s", fname);
 111                                 error++;
 112                         }
 113                         continue;
 114                 }
 115                 if (do_relative) {
 116                         if (fstat(fd, &sb) == -1) {
 117                                 warn("%s", fname);
 118                                 error++;
 119                                 continue;
 120                         }
 121                         oflow = sb.st_size + rsize;
 122                         if (oflow < (sb.st_size + rsize)) {
 123                                 errno = EFBIG;
 124                                 warn("%s", fname);
 125                                 error++;
 126                                 continue;
 127                         }
 128                         tsize = oflow;
 129                 }
 130                 if (tsize < 0)
 131                         tsize = 0;
 132
 133                 if (ftruncate(fd, tsize) == -1) {
 134                         warn("%s", fname);
 135                         error++;
 136                         continue;
 137                 }
 138
 139                 close(fd);
 140         }
 141
 142         return error ? EXIT_FAILURE : EXIT_SUCCESS;
 143 }
 144
 145 /*
 146  * Return the numeric value of a string given in the form [+-][0-9]+[GMK]
 147  * or -1 on format error or overflow.
 148  */
 149 static off_t
 150 parselength(char *ls, off_t *sz)
 151 {
 152         off_t   length, oflow;
 153         int     lsign;
 154
 155         length = 0;
 156         lsign = 1;
 157
 158         switch (*ls) {
 159         case '-':
 160                 lsign = -1;
 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 'G':
 177                 oflow = length * 1024;
 178                 ASSIGN_CHK_OFLOW(oflow, length);
 179         case 'M':
 180                 oflow = length * 1024;
 181                 ASSIGN_CHK_OFLOW(oflow, length);
 182         case 'K':
 183                 if (ls[1] != '\0')
 184                         return -1;
 185                 oflow = length * 1024;
 186                 ASSIGN_CHK_OFLOW(oflow, length);
 187         case '\0':
 188                 break;
 189         default:
 190                 return -1;
 191         }
 192
 193         *sz = length * lsign;
 194         return 0;
 195 }
 196
 197 static void
 198 usage(void)
 199 {
 200         fprintf(stderr, "%s\n%s\n",
 201             "usage: truncate [-c] -s [+|-]size[K|M|G] file ...",
 202             "       truncate [-c] -r rfile file ...");
 203         exit(EXIT_FAILURE);
 204 }