#include <sys/stat.h>

#include <assert.h>

#include <fcntl.h>

#include <unistd.h>

#define BASE_DIR "/tmp"

#define OUTPUT_DIR BASE_DIR "/testdir"

#define PATH OUTPUT_DIR "/output.txt"

int main(void) {

struct stat st;

int fd;

(void)st;

assert(0 == mkdir(OUTPUT_DIR, 0755));

fd = open(PATH, O_CREAT | O_WRONLY, 0666);

assert(fd != -1);

/* Verify that the file is initially empty. */

assert(0 == fstat(fd, &st));

assert(st.st_size == 0);

assert(0 == lseek(fd, 0, SEEK_CUR));

/* Increase the file size using ftruncate(). */

assert(0 == ftruncate(fd, 500));

assert(0 == fstat(fd, &st));

assert(st.st_size == 500);

assert(0 == lseek(fd, 0, SEEK_CUR));

/* Truncate the file using ftruncate(). */

assert(0 == ftruncate(fd, 300));

assert(0 == fstat(fd, &st));

assert(st.st_size == 300);

assert(0 == lseek(fd, 0, SEEK_CUR));

assert(0 == close(fd));

return 0;

}