fsync bug

[Eric Blake <eblake at redhat dot com>]

fsync() is required to work on read-only fds (in theory, you can sync 
the atime metadata, which is a write operation triggered by a read-only 
fd).  But cygwin rejects this program, which works on Linux:

$ cat foo.c
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <fcntl.h>
int main (void)
{
  int fd = open("file", O_CREAT|O_EXCL|O_WRONLY, 0600);
  if (fd < 0)
    return 1;
  if (close(fd))
    return 2;
  fd = open("file", O_RDONLY);
  if (fd < 0)
    return 3;
  if (fsync(fd))
    return 4;
  if (unlink("file"))
    return 5;
  puts("success");
  return 0;
}
$ rm -f file && ./foo; echo $?
4

--
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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