text: #include <assert.h>
  #include <dirent.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <signal.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <utime.h>
  #include <sys/stat.h>
  #include <sys/types.h>
  
  void create_file(const char *path, const char *buffer, int mode) {
    int fd = open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
    assert(fd >= 0);
  
    int err = write(fd, buffer, sizeof(char) * strlen(buffer));
    assert(err ==  (sizeof(char) * strlen(buffer)));
  
    close(fd);
  }
  
  void setup() {
    create_file("file", "abcdef", 0777);
    symlink("file", "file-link");
    // some platforms use 777, some use 755 by default for symlinks
    // make sure we're using 777 for the test
    lchmod("file-link", 0777);
    mkdir("folder", 0777);
  }
  
  void cleanup() {
    unlink("file-link");
    unlink("file");
    rmdir("folder");
  }
  
  void test() {
    int err;
    int lastctime;
    struct stat s;
    
    //
    // chmod a file
    //
    // get the current ctime for the file
    memset(&s, 0, sizeof s);
    stat("file", &s);
    lastctime = s.st_ctime;
    sleep(1);
  
    // do the actual chmod
    err = chmod("file", 0200);
    assert(!err);
  
    memset(&s, 0, sizeof s);
    stat("file", &s);
    assert(s.st_mode == (0200 | S_IFREG));
    assert(s.st_ctime != lastctime);
  
    //
    // fchmod a file
    //
    lastctime = s.st_ctime;
    sleep(1);
  
    err = fchmod(open("file", O_WRONLY), 0100);
    assert(!err);
  
    memset(&s, 0, sizeof s);
    stat("file", &s);
    assert(s.st_mode == (0100 | S_IFREG));
    assert(s.st_ctime != lastctime);
  
    //
    // chmod a folder
    //
    // get the current ctime for the folder
    memset(&s, 0, sizeof s);
    stat("folder", &s);
    lastctime = s.st_ctime;
    sleep(1);
  
    // do the actual chmod
    err = chmod("folder", 0300);
    assert(!err);
    memset(&s, 0, sizeof s);
    stat("folder", &s);
    assert(s.st_mode == (0300 | S_IFDIR));
    assert(s.st_ctime != lastctime);
  
    //
    // chmod a symlink's target
    //
    err = chmod("file-link", 0400);
    assert(!err);
  
    // make sure the file it references changed
    stat("file-link", &s);
    assert(s.st_mode == (0400 | S_IFREG));
  
    // but the link didn't
    lstat("file-link", &s);
    assert(s.st_mode == (0777 | S_IFLNK));
  
    //
    // chmod the actual symlink
    //
    err = lchmod("file-link", 0500);
    assert(!err);
  
    // make sure the file it references didn't change
    stat("file-link", &s);
    assert(s.st_mode == (0400 | S_IFREG));
  
    // but the link did
    lstat("file-link", &s);
    assert(s.st_mode == (0500 | S_IFLNK));
  
    puts("success");
  }
  
  int main() {
    atexit(cleanup);
    signal(SIGABRT, cleanup);
    setup();
    test();
    return EXIT_SUCCESS;
  }
  