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 <buga...@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
