commands/simple/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  */
  27
  28 #include <sys/stat.h>
  29
  30 #include <ctype.h>
  31 #include <errno.h>
  32 #include <fcntl.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <unistd.h>
  36
  37 static off_t    parselength(char *, off_t *);
  38 static void     usage(void);
  39
  40 static int      no_create;
  41 static int      do_relative;
  42 static int      do_refer;
  43 static int      got_size;
  44
  45 int
  46 main(int argc, char **argv)
  47 {
  48         struct stat     sb;
  49         mode_t  omode;
  50         off_t   oflow, rsize, sz, tsize;
  51         int     ch, error, fd, oflags;
  52         char   *fname, *rname;
  53
  54         rsize = tsize = 0;
  55         error = 0;
  56         rname = NULL;
  57         while ((ch = getopt(argc, argv, "cr:s:")) != -1)
  58                 switch (ch) {
  59                 case 'c':
  60                         no_create = 1;
  61                         break;
  62                 case 'r':
  63                         do_refer = 1;
  64                         rname = optarg;
  65                         break;
  66                 case 's':
  67                         if (parselength(optarg, &sz) == -1) {
  68                                 fprintf(stderr,
  69                                     "invalid size argument `%s'", optarg);
  70                                    exit(EXIT_FAILURE);
  71                                   }
  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                         fprintf(stderr, "%s", rname);
  94                         exit(EXIT_FAILURE);
  95                 }
  96                 tsize = sb.st_size;
  97         } else if (do_relative)
  98                 rsize = sz;
  99         else
 100                 tsize = sz;
 101
 102         if (no_create)
 103                 oflags = O_WRONLY;
 104         else
 105                 oflags = O_WRONLY | O_CREAT;
 106         omode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
 107
 108         while ((fname = *argv++) != NULL) {
 109                 if ((fd = open(fname, oflags, omode)) == -1) {
 110                         if (errno != ENOENT) {
 111                                 perror(fname);
 112                                 error++;
 113                         }
 114                         continue;
 115                 }
 116                 if (do_relative) {
 117                         if (fstat(fd, &sb) == -1) {
 118                                 perror(fname);
 119                                 error++;
 120                                 continue;
 121                         }
 122                         oflow = sb.st_size + rsize;
 123                         if (oflow < (sb.st_size + rsize)) {
 124                                 errno = EFBIG;
 125                                 perror(fname);
 126                                 error++;
 127                                 continue;
 128                         }
 129                         tsize = oflow;
 130                 }
 131                 if (tsize < 0)
 132                         tsize = 0;
 133
 134                 if (ftruncate(fd, tsize) == -1) {
 135                         perror(fname);
 136                         error++;
 137                         continue;
 138                 }
 139
 140                 close(fd);
 141         }
 142
 143         return error ? EXIT_FAILURE : EXIT_SUCCESS;
 144 }
 145
 146 /*
 147  * Return the numeric value of a string given in the form [+-][0-9]+[GMK]
 148  * or -1 on format error or overflow.
 149  */
 150 static off_t
 151 parselength(char *ls, off_t *sz)
 152 {
 153         off_t   length, oflow;
 154         int     lsign;
 155
 156         length = 0;
 157         lsign = 1;
 158
 159         switch (*ls) {
 160         case '-':
 161                 lsign = -1;
 162         case '+':
 163                 ls++;
 164         }
 165
 166 #define ASSIGN_CHK_OFLOW(x, y)  if (x < y) return -1; y = x
 167         /*
 168          * Calculate the value of the decimal digit string, failing
 169          * on overflow.
 170          */
 171         while (isdigit(*ls)) {
 172                 oflow = length * 10 + *ls++ - '0';
 173                 ASSIGN_CHK_OFLOW(oflow, length);
 174         }
 175
 176         switch (*ls) {
 177         case 'G':
 178         case 'g':
 179                 oflow = length * 1024;
 180                 ASSIGN_CHK_OFLOW(oflow, length);
 181         case 'M':
 182         case 'm':
 183                 oflow = length * 1024;
 184                 ASSIGN_CHK_OFLOW(oflow, length);
 185         case 'K':
 186         case 'k':
 187                 if (ls[1] != '\0')
 188                         return -1;
 189                 oflow = length * 1024;
 190                 ASSIGN_CHK_OFLOW(oflow, length);
 191         case '\0':
 192                 break;
 193         default:
 194                 return -1;
 195         }
 196
 197         *sz = length * lsign;
 198         return 0;
 199 }
 200
 201 static void
 202 usage(void)
 203 {
 204         fprintf(stderr, "%s\n%s\n",
 205             "usage: truncate [-c] -s [+|-]size[K|k|M|m|G|g] file ...",
 206             "       truncate [-c] -r rfile file ...");
 207         exit(EXIT_FAILURE);
 208 }