Re: POSIX violation by writeback error

[Theodore Y. Ts'o]

On Tue, Sep 25, 2018 at 07:35:11PM +0200, Adam Borowski wrote:
> Isn't this what the snippet for O_TMPFILE in "man 2 open" does?:
> 
>                   char path[PATH_MAX];
>                   fd = open("/path/to/dir", O_TMPFILE | O_RDWR,
>                                           S_IRUSR | S_IWUSR);
> 
>                   /* File I/O on 'fd'... */
> 
>                   snprintf(path, PATH_MAX,  "/proc/self/fd/%d", fd);
>                   linkat(AT_FDCWD, path, AT_FDCWD, "/path/for/file",
>                                           AT_SYMLINK_FOLLOW);

Huh.  I stand corrected.  I had assumed O_TMPFILE worked like any
other file where the link count was zero, and linkat(2) wouldn't allow
this.  But obviously, this does work.  In fact, from the linkat(2) man
page, using:

	linkat(fd, NULL, AT_FDCWD, "/path/for/file", AT_EMPTY_PATH);

is an even simpler way that doesn't /proc being mounted.

TIL...

					- Ted