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 "test-tool.h"
   8 #include "git-compat-util.h"
   9
  10 int cmd__genrandom(int argc, const char **argv)
  11 {
  12         unsigned long count, next = 0;
  13         unsigned char *c;
  14
  15         if (argc < 2 || argc > 3) {
  16                 fprintf(stderr, "usage: %s <seed_string> [<size>]\n", argv[0]);
  17                 return 1;
  18         }
  19
  20         c = (unsigned char *) argv[1];
  21         do {
  22                 next = next * 11 + *c;
  23         } while (*c++);
  24
  25         count = (argc == 3) ? strtoul(argv[2], NULL, 0) : -1L;
  26
  27         while (count--) {
  28                 next = next * 1103515245 + 12345;
  29                 if (putchar((next >> 16) & 0xff) == EOF)
  30                         return -1;
  31         }
  32
  33         return 0;
  34 }