Both open and openat load their last argument 'mode' lazily, using
va_arg() only if O_CREAT is found in oflag. This is wrong, mode is also
necessary if O_TMPFILE is in oflag.
By chance on x86_64, the problem wasn't evident when using O_TMPFILE
with open, as the 3rd argument of open, even when not loaded with
va_arg, is left untouched in RDX, where the syscall expects it.
However, openat was not so lucky, and O_TMPFILE couldn't be used: mode
is the 4th argument, in RCX, but the syscall expects its 4th argument in
a different register than the glibc wrapper, in R10.
Introduce a macro __OPEN_NEEDS_MODE (oflag) to test if either O_CREAT or
O_TMPFILE is set in oflag.
Tested on Linux x86_64.
[BZ #17523]
* io/fcntl.h (__OPEN_NEEDS_MODE): New macro.
* io/bits/fcntl2.h (open): Use it.
(openat): Likewise.
* io/open.c (__libc_open): Likewise.
* io/open64.c (__libc_open64): Likewise.
* io/open64_2.c (__open64_2): Likewise.
* io/open_2.c (__open_2): Likewise.
* io/openat.c (__openat): Likewise.
* io/openat64.c (__openat64): Likewise.
* io/openat64_2.c (__openat64_2): Likewise.
* io/openat_2.c (__openat_2): Likewise.
* sysdeps/mach/hurd/open.c (__libc_open): Likewise.
* sysdeps/mach/hurd/openat.c (__openat): Likewise.
* sysdeps/posix/open64.c (__libc_open64): Likewise.
* sysdeps/unix/sysv/linux/dl-openat64.c (openat64): Likewise.
* sysdeps/unix/sysv/linux/generic/open.c (__libc_open): Likewise.
(__open_nocancel): Likewise.
* sysdeps/unix/sysv/linux/generic/open64.c (__libc_open64): Likewise.
* sysdeps/unix/sysv/linux/open64.c (__libc_open64): Likewise.
* sysdeps/unix/sysv/linux/openat.c (__OPENAT): Likewise.
