From 65392c84782a53b0d7705ca0207c95c3da41c7dc Mon Sep 17 00:00:00 2001 From: Sergey Bugaev Date: Mon, 30 Jan 2023 15:52:15 +0300 Subject: hurd: Implement O_TMPFILE 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 Message-Id: <20230130125216.6254-3-bugaevc@gmail.com> --- sysdeps/mach/hurd/bits/fcntl.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'sysdeps/mach') diff --git a/sysdeps/mach/hurd/bits/fcntl.h b/sysdeps/mach/hurd/bits/fcntl.h index 970f79b82d..c24a819e02 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. */ -- cgit 1.4.1