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authorEric Rannaud <e@nanocritical.com>2015-02-24 13:12:26 +0530
committerSiddhesh Poyarekar <siddhesh@redhat.com>2015-02-24 13:19:22 +0530
commit65f6f938cd562a614a68e15d0581a34b177ec29d (patch)
treec33b9da9e6b00195e90e87b811a3d7def6529425 /io/fcntl.h
parent3e3002ffead0526d088c353f97475400367087da (diff)
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linux: open and openat ignore 'mode' with O_TMPFILE in flags
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.
Diffstat (limited to 'io/fcntl.h')
-rw-r--r--io/fcntl.h14
1 files changed, 12 insertions, 2 deletions
diff --git a/io/fcntl.h b/io/fcntl.h
index 71f5e52e88..c6812c467b 100644
--- a/io/fcntl.h
+++ b/io/fcntl.h
@@ -34,6 +34,15 @@ __BEGIN_DECLS
    numbers and flag bits for `open', `fcntl', et al.  */
 #include <bits/fcntl.h>
 
+/* Detect if open needs mode as a third argument (or for openat as a fourth
+   argument).  */
+#ifdef __O_TMPFILE
+# define __OPEN_NEEDS_MODE(oflag) \
+  (((oflag) & O_CREAT) != 0 || ((oflag) & __O_TMPFILE) == __O_TMPFILE)
+#else
+# define __OPEN_NEEDS_MODE(oflag) (((oflag) & O_CREAT) != 0)
+#endif
+
 /* POSIX.1-2001 specifies that these types are defined by <fcntl.h>.
    Earlier POSIX standards permitted any type ending in `_t' to be defined
    by any POSIX header, so we don't conditionalize the definitions here.  */
@@ -160,8 +169,9 @@ typedef __pid_t pid_t;
 extern int fcntl (int __fd, int __cmd, ...);
 
 /* Open FILE and return a new file descriptor for it, or -1 on error.
-   OFLAG determines the type of access used.  If O_CREAT is on OFLAG,
-   the third argument is taken as a `mode_t', the mode of the created file.
+   OFLAG determines the type of access used.  If O_CREAT or O_TMPFILE is set
+   in OFLAG, the third argument is taken as a `mode_t', the mode of the
+   created file.
 
    This function is a cancellation point and therefore not marked with
    __THROW.  */