rewrite.c

   1 /*
   2  * Copyright 2013      Ecole Normale Superieure
   3  *
   4  * Use of this software is governed by the MIT license
   5  *
   6  * Written by Sven Verdoolaege,
   7  * Ecole Normale Superieure, 45 rue d’Ulm, 75230 Paris, France
   8  */
   9
  10 #include <assert.h>
  11
  12 #include "rewrite.h"
  13
  14 /* Copy the contents of "input" from offset "start" to "end" to "output".
  15  */
  16 void copy(FILE *input, FILE *output, long start, long end)
  17 {
  18         char buffer[1024];
  19         size_t n, m;
  20
  21         if (end < 0) {
  22                 fseek(input, 0, SEEK_END);
  23                 end = ftell(input);
  24         }
  25
  26         fseek(input, start, SEEK_SET);
  27
  28         while (start < end) {
  29                 n = end - start;
  30                 if (n > 1024)
  31                         n = 1024;
  32                 n = fread(buffer, 1, n, input);
  33                 assert(n > 0);
  34                 m = fwrite(buffer, 1, n, output);
  35                 assert(n == m);
  36                 start += n;
  37         }
  38 }