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[RFC PATCH 4/5] include/fcntl.h: Define O_IGNORE_CTTY
From: |
Sergey Bugaev |
Subject: |
[RFC PATCH 4/5] include/fcntl.h: Define O_IGNORE_CTTY |
Date: |
Tue, 18 Apr 2023 01:58:56 +0300 |
This internal definition makes it possible to use O_IGNORE_CTTY in
the glibc codebase unconditionally, no matter whether the current port
provides it or not (i.e. both on Hurd and on Linux). Along with the
definition, this adds a small guide on when O_IGNORE_CTTY is to be used.
The following commit will actually make use of O_IGNORE_CTTY
throughout the glibc codebase.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
---
include/fcntl.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/include/fcntl.h b/include/fcntl.h
index be435047..3de40827 100644
--- a/include/fcntl.h
+++ b/include/fcntl.h
@@ -33,6 +33,22 @@ extern int __openat_2 (int __fd, const char *__path, int
__oflag);
extern int __openat64_2 (int __fd, const char *__path, int __oflag);
+/* Makes open () & friends slightly faster on the Hurd, but can only be used
+ (without altering user-visible behavior) when we're sure that the file
+ we're opening is not (at the moment) our controlling terminal. Use this
+ when:
+ - opening well-known files internally (utmp, nss db);
+ - opening files with user-specified names that can not reasonably be ttys
+ (sem_open, shm_open);
+ - opening new (previously unused) ttys (openpty).
+ Don't use this when:
+ - doing a general-purpose open () with a user-controlled path that could
+ well be "/dev/tty" (fopen). */
+#ifndef O_IGNORE_CTTY
+# define O_IGNORE_CTTY 0
+#endif
+
+
#if IS_IN (rtld)
# include <dl-fcntl.h>
#endif
--
2.39.2
[RFC PATCH 4/5] include/fcntl.h: Define O_IGNORE_CTTY,
Sergey Bugaev <=
[RFC PATCH 5/5] Use O_IGNORE_CTTY where appropriate, Sergey Bugaev, 2023/04/17