#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>

int main(int argc, char **argv) {
    if (argc < 2) { fprintf(stderr, "Usage: %s MOUNTPOINT\n", argv[0]); return 1; }
    char path1[512];
    snprintf(path1, sizeof(path1), "%s/test1.txt", argv[1]);

    // open then unlink, chmod path vs fchmod fd
    int fd = open(path1, O_CREAT|O_WRONLY|O_TRUNC);
    if (fd < 0) { perror("open2"); return 1; }
    unlink(path1);
    if (chmod(path1, 0600) == -1) {
        printf("chmod(%s) failed as expected: %s\n", path1, strerror(errno));
    }
    else {
        printf("chmod(%s) succeeded WHICH IS BAD\n", path1);
    }
    if (fchmod(fd, 0600) == 0) {
        printf("fchmod(fd) succeeded on unlinked file\n");
    }
    else {
        printf("fchmod(fd) failed, WHICH IS BAD: %s\n", strerror(errno));
    }
    close(fd);
    return 0;
}

chmod(test1.txt) failed as expected: No such file or directory
fchmod(fd) failed, WHICH IS BAD: No such file or directory

chmod(test1.txt) failed as expected: No such file or directory
fchmod(fd) succeeded on unlinked file