Delay Pipe: Read a block of data from stdin, write it to stdout with random delay

dpipe.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>

#define PIPE_PROGRESS_SIZE 4096

#define min(a, b)           \
  ({                        \
    __typeof__(a) _a = (a); \
    __typeof__(b) _b = (b); \
    _a < _b ? _a : _b;      \
  })

static int run(unsigned int maxRead, unsigned int maxDelay, FILE *in,
               FILE *out) {
  char buf[PIPE_PROGRESS_SIZE];
  size_t len;

  setvbuf(out, NULL, _IONBF, 0);
  srand(time(NULL));

  // uniform distribution
  while ((len = fread(buf, 1, min((rand() % maxRead) + 1, PIPE_PROGRESS_SIZE),
                      in)) > 0) {
    usleep(rand() % maxDelay);
    fwrite(buf, 1, len, out);
  }

  return 0;
}

static void usage(const char *prog) {
  fprintf(stderr, "usage: %s [-d <max delay>] [-s <max read>]\n", prog);
  exit(EXIT_FAILURE);
}

int main(int argc, char **argv) {
  unsigned int maxDelay = 100000;
  unsigned int maxRead = 10;
  int c;

  while ((c = getopt(argc, argv, "d:s:")) != -1) {
    switch (c) {
      case 'd':
        maxDelay = atoi(optarg);
        break;
      case 's':
        maxRead = atoi(optarg);
        break;
      default:
        usage(argv[0]);
    }
  }

  argv += optind;

  return run(maxRead, maxDelay, stdin, stdout);
}