t/helper/test-genrandom.c

   1 /*
   2  * Simple random data generator used to create reproducible test files.
   3  * This is inspired from POSIX.1-2001 implementation example for rand().
   4  * Copyright (C) 2007 by Nicolas Pitre, licensed under the GPL version 2.
   5  */
   6
   7 #include "git-compat-util.h"
   8
   9 int cmd_main(int argc, const char **argv)
  10 {
  11         unsigned long count, next = 0;
  12         unsigned char *c;
  13
  14         if (argc < 2 || argc > 3) {
  15                 fprintf(stderr, "usage: %s <seed_string> [<size>]\n", argv[0]);
  16                 return 1;
  17         }
  18
  19         c = (unsigned char *) argv[1];
  20         do {
  21                 next = next * 11 + *c;
  22         } while (*c++);
  23
  24         count = (argc == 3) ? strtoul(argv[2], NULL, 0) : -1L;
  25
  26         while (count--) {
  27                 next = next * 1103515245 + 12345;
  28                 if (putchar((next >> 16) & 0xff) == EOF)
  29                         return -1;
  30         }
  31
  32         return 0;
  33 }