stat.c

// stat.c
//
// TO RUN: cc -Wall stat.c && ./a.out

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>

static const char *path = __FILE__;

static int f(struct timespec times[2])
{
    struct stat st;
    struct timespec initial[] = {
        {11, 0},
        {1, 0}
    };
    printf("%s {{%li, %li}, {%li, %li}}\n",
           path,
           times[0].tv_sec, times[0].tv_nsec,
           times[1].tv_sec, times[1].tv_nsec);
    if (utimensat(AT_FDCWD, path, initial, 0)) {
        perror("utimensat1 failed");
        return 1;
    }
    if (stat(path, &st)) {
        perror("stat1 failed");
        return 1;
    }
    printf("     atime = %li, mtime = %li\n",
           st.st_atime, st.st_mtime);
    if (utimensat(AT_FDCWD, path, times, 0)) {
        perror("utimensat2 failed");
        return 1;
    }
    if (stat(path, &st)) {
        perror("stat2 failed");
        return 1;
    }
    printf("  -> atime = %li, mtime = %li\n",
           st.st_atime, st.st_mtime);
    return 0;
}

int main(void)
{
    return f((struct timespec [2]){{0, UTIME_OMIT}, {0, 0}})
        || f((struct timespec [2]){{12, 0}, {0, UTIME_OMIT}})
        || f((struct timespec [2]){{12, 0}, {0, -1}})
        || f((struct timespec [2]){{12, 0}, {0, -3}});
}