test-sleep2.c

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

int
main (void)
{
  char const *filename = "test.txt";
  int fd = open(filename, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666);
  if (fd < 0)
    return perror ("open"), 1;
  static char const message[] = "This is a test.\n";
  int messagelen = sizeof message - 1;
  if (write (fd, message, messagelen) != messagelen)
    return perror ("write"), 1;
  if (fsync (fd) != 0)
    return perror ("fsync"), 1;
  struct stat st1, st2, st3;
  if (fstat (fd, &st1) != 0)
    return perror ("fstat"), 1;
  if (close (fd) != 0)
    return perror ("close"), 1;
  int fd2 = open(filename, O_WRONLY|O_CLOEXEC);
  if (fd2 < 0)
    return perror ("open 2"), 1;
  if (fstat (fd2, &st2) != 0)
    return perror ("fstat 2"), 1;
  if (close (fd2) != 0)
    return perror ("close 2"), 1;
  if (! (st1.st_mtim.tv_sec == st2.st_mtim.tv_sec
	 && st1.st_mtim.tv_nsec == st2.st_mtim.tv_nsec))
    printf ("Emacs should work around this POSIX-conformance bug.\n");
  sleep (2);
  if (stat (filename, &st3) != 0)
    return perror ("stat"), 1;
  if (! (st2.st_mtim.tv_sec == st3.st_mtim.tv_sec
	 && st2.st_mtim.tv_nsec == st3.st_mtim.tv_nsec))
    {
      printf ("Emacs does not work around this POSIX-conformance bug.\n");
    }
  printf ("stat #1: %ld.%09ld\n", st1.st_mtim.tv_sec, st1.st_mtim.tv_nsec);
  printf ("stat #2: %ld.%09ld\n", st2.st_mtim.tv_sec, st2.st_mtim.tv_nsec);
  printf ("stat #3: %ld.%09ld\n", st3.st_mtim.tv_sec, st3.st_mtim.tv_nsec);
  return 0;
}