createsparse/createsparse.c

   1 /******************************************************************************
   2  * createsparse.c
   3  * creates arbitrary sized sparse files
   4  *****************************************************************************/
   5
   6 #define _FILE_OFFSET_BITS 64
   7 #define _GNU_SOURCE
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13
  14 #include <errno.h>
  15
  16 static unsigned long long get_special_number(char *in)
  17 {
  18     unsigned long long ret;
  19     char *unit;
  20
  21     ret = strtoull(in, &unit, 10);
  22     if(*unit == 'k') { ret *= 1024; }
  23     else if(*unit == 'K') { ret *= 1000; }
  24     else if(*unit == 'm') { ret *= 1024*1024; }
  25     else if(*unit == 'M') { ret *= 1000*1000; }
  26     else if(*unit == 'g') { ret *= 1024*1024*1024; }
  27     else if(*unit == 'G') { ret *= 1000*1000*1000; }
  28
  29     return ret;
  30 } /* get_special_number() */
  31
  32
  33 int main(int argc, char ** argv)
  34 {
  35     size_t size;
  36     FILE *f;
  37     int err, i, ret=0;
  38
  39     if(argc < 3)
  40     {
  41         fprintf(stderr, "Usage: createsparse <size[kKmMgG]> <filename> [filenames ...]\n\n");
  42         exit(1);
  43     }
  44
  45     size = get_special_number(argv[1]);
  46
  47     for(i=2; i < argc; i++)
  48     {
  49         f = fopen(argv[i], "w+");
  50         if(!f)
  51         {
  52             ret = 1;
  53             fprintf(stderr, "%s: fopen() failed: %s\n", argv[i], strerror(errno));
  54             continue;
  55         }
  56         err = fseek(f, size-1, SEEK_SET);
  57         if(-1 == err)
  58         {
  59             ret = 1;
  60             fprintf(stderr, "%s: fseek() failed: %s\n", argv[i], strerror(errno));
  61             fclose(f);
  62             continue;
  63         }
  64         err = putc(0, f);
  65         if(EOF == err)
  66         {
  67             ret = 1;
  68             fprintf(stderr, "%s: putc() failed: %s\n", argv[i], strerror(errno));
  69             fclose(f);
  70             continue;
  71         }
  72     } /* for i */
  73
  74     return ret;
  75 } /* main() */
  76