#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <fcntl.h>

#define CHECK(cond) do { \
	if( !(cond) ) { \
		printf("%s failed at %s:%d\n", #cond, __FILE__, __LINE__); \
		exit(1); \
	} } while(0)

int main(int argc, char *argv[]) {
  if( argc < 2 ) {
    fprintf(stderr, "Syntax: a.exe fname [mode]\n");
    exit(1);
  }

  const char *fname = argv[1];

  int mode = O_CREAT | O_TRUNC;
  if( argc > 2 && 0 == strcmp("rw", argv[2]) )
    mode |= O_RDWR;
  else
    mode |= O_WRONLY;

  const int perm = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
  const unsigned data = -1;

  int fd = open(fname, mode, perm);
  CHECK( -1 != fd );
  close(fd);

  fd = open(fname, mode, perm);
  CHECK( -1 != fd );
  CHECK( sizeof(data) == write(fd, &data, sizeof(data)) );
  CHECK( sizeof(data) == lseek(fd, 0, SEEK_END) );
  CHECK( sizeof(data) == lseek(fd, 0, SEEK_CUR) );

  printf("success\n");

  return 0;
}