This patch adds O_TMPFILE support to tmpfile on Linux. This is
similar to the previous suggestion by Andreas Schwab [1] with the
difference the file descriptor creation is parameterized to
compartmentalize Linux only open flags (O_TMPFILE) on sysdeps.
Checked on x86_64-linux-gnu.
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Andreas Schwab <schwab@suse.de>
[BZ #21530]
* include/stdio.h (__gen_tempfd): New function.
* stdio-common/Makefile (routines): Add gentempfd.
* stdio-common/gentempfd.c: New file.
* sysdeps/unix/sysv/linux/gentempfd.c: Likewise.
* stdio-common/tmpfile.c (tmpfile): First try to use a system specific
unnamed file first.
[1] https://sourceware.org/ml/libc-alpha/2017-06/msg01293.html
