Re: Emacs pretest 28.0.90 is out

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org
> Date: Sat, 11 Dec 2021 17:42:31 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > And in any case, even if you want not to go through a temporary file,
> > I'd prefer to edit the original recipe in sed1v2.inp instead of adding
> > a DOS-specific recipe, as the former is safer for changes on the
> > release branch.
> 
> Thanks, I opted to implement this option, and it works well.
> 
> I also implemented futimens (and based on that, utimensat), and fixed
> the rest of the issues you outlined above.
> 
> If the following patch looks good to you, I will install it on
> emacs-28.  Thanks.

A couple of minor gotchas below, and then you can install this.

> +int
> +fchmodat (int fd, const char *path, mode_t mode, int flags)
> +{
> +  if (fd != AT_FDCWD)
> +    {
> +      if (strlen (dir_pathname) + strlen (path) + 1 >= MAXPATHLEN)
> +	{
> +	  errno = ENAMETOOLONG;
> +	  return -1;
> +	}
> +    }
> +
> +  return chmod (path, mode);
> +}

No support for AT_FDCWD here (by using dir_pathname)?

> +int
> +futimens (int fd, const struct timespec times[2])
> +{
> +  struct tm *tm;
> +  struct ftime ft;
> +  time_t t;
> +
> +  block_input ();
> +  if (times[1].tv_sec == UTIME_NOW)
> +    t = time (NULL);
> +  else
> +    t = times[1].tv_sec;
> +
> +  tm = localtime (&t);
> +  ft.ft_tsec = min (59, tm->tm_sec);

ft_sec is 0 to 29, in 2-sec units (as DOS has only 2-sec resolution in
file time stamps), so you need to scale it here.

> +int
> +utimensat (int dirfd, const char *pathname,
> +	   const struct timespec times[2], int flags)
> +{
> +  int fd;
> +  char fullname[MAXPATHLEN];
> +
> +  if (dirfd != AT_FDCWD)
> +    {
> +      if (strlen (dir_pathname) + strlen (pathname) + 1 >= MAXPATHLEN)
> +	{
> +	  errno = ENAMETOOLONG;
> +	  return -1;
> +	}
> +      sprintf (fullname, "%s/%s", dir_pathname, pathname);
> +      pathname = fullname;
> +    }
> +
> +  /* Rely on a hack: dirfd in its current usage in Emacs is always
> +     AT_FDCWD.  */

This comment seems to be out of place, you need to move it higher up,
I believe.

> +  fd = open (pathname, O_WRONLY);
> +
> +  if (fd < 0)
> +    return -1;
> +
> +  return futimens (fd, times);

This leaks a file descriptor, since you open the file, but don't close
it.

Thanks.