Applied, thanks!
Sergey Bugaev, le lun. 30 janv. 2023 15:52:15 +0300, a ecrit:
> This is a flag that causes open () to create a new, unnamed file in the
> same filesystem as the given directory. The file descriptor can be
> simply used in the creating process as a temporary file, or shared with
> children processes via fork (), or sent over a Unix socket. The file can
> be left anonymous, in which case it will be deleted from the backing
> file system once all copies of the file descriptor are closed, or given
> a permanent name with a linkat () call, such as the following:
>
> int fd = open ("/tmp", O_TMPFILE | O_RDWR, 0700);
> /* Do something with the file... */
> linkat (fd, "", AT_FDCWD, "/tmp/filename", AT_EMPTY_PATH);
>
> In between creating the file and linking it to the file system, it is
> possible to set the file content, mode, ownership, author, and other
> attributes, so that the file visibly appears in the file system (perhaps
> replacing another file) atomically, with all of its attributes already
> set up.
>
> The Hurd support for O_TMPFILE directly exposes the dir_mkfile RPC to
> user programs. Previously, dir_mkfile was used by glibc internally, in
> particular for implementing tmpfile (), but not exposed to user programs
> through a Unix-level API.
>
> O_TMPFILE was initially introduced by Linux. This implementation is
> intended to be compatible with the Linux implementation, except that the
> O_EXCL flag is not given the special meaning when used together with
> O_TMPFILE, unlike on Linux.
>
> Signed-off-by: Sergey Bugaev <buga...@gmail.com>
> ---
> hurd/lookup-at.c | 21 +++++++++++++++++++++
> sysdeps/mach/hurd/bits/fcntl.h | 4 ++++
> 2 files changed, 25 insertions(+)
>
> diff --git a/hurd/lookup-at.c b/hurd/lookup-at.c
> index 25dab5a1..88c83779 100644
> --- a/hurd/lookup-at.c
> +++ b/hurd/lookup-at.c
> @@ -29,6 +29,7 @@ __file_name_lookup_at (int fd, int at_flags,
> error_t err;
> file_t result;
> int empty = at_flags & AT_EMPTY_PATH;
> + int orig_flags;
>
> at_flags &= ~AT_EMPTY_PATH;
>
> @@ -53,6 +54,10 @@ __file_name_lookup_at (int fd, int at_flags,
> return err ? (__hurd_dfail (fd, err), MACH_PORT_NULL) : result;
> }
>
> + orig_flags = flags;
> + if (flags & O_TMPFILE)
> + flags = O_DIRECTORY;
> +
> if (fd == AT_FDCWD || file_name[0] == '/')
> {
> err = __hurd_file_name_lookup (&_hurd_ports_use, &__getdport, 0,
> @@ -90,6 +95,22 @@ __file_name_lookup_at (int fd, int at_flags,
> }
> }
>
> + if (orig_flags & O_TMPFILE)
> + {
> + /* What we have looked up is not the file itself, but actually
> + the directory to create the file in. Do that now. */
> + file_t dir = result;
> +
> + err = __dir_mkfile (dir, orig_flags & ~(O_TMPFILE | O_DIRECTORY),
> + mode, &result);
> + __mach_port_deallocate (__mach_task_self (), dir);
> + if (err)
> + {
> + __hurd_fail (err);
> + return MACH_PORT_NULL;
> + }
> + }
> +
> return result;
> }
>
> diff --git a/sysdeps/mach/hurd/bits/fcntl.h b/sysdeps/mach/hurd/bits/fcntl.h
> index 970f79b8..c24a819e 100644
> --- a/sysdeps/mach/hurd/bits/fcntl.h
> +++ b/sysdeps/mach/hurd/bits/fcntl.h
> @@ -123,6 +123,10 @@
> # define O_CLOEXEC 0x00400000 /* Set FD_CLOEXEC. */
> #endif
>
> +#ifdef __USE_GNU
> +# define O_TMPFILE 0x00800000 /* Make a new unnamed file. */
> +#endif
> +
>
> /* Controlling terminal flags. These are understood only by `open',
> and are not preserved once the file has been opened. */
> --
> 2.39.1
>
--
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.
