When O_PATH is used with O_DIRECTORY, it only acts as an optimization: the
openat() syscall simply finds the name in the VFS, and doesn't trigger the
underlying filesystem.
On systems that don't define O_PATH, because they have glibc version 2.13
or older for example, we can safely omit it. We don't want to deactivate
O_PATH globally though, in case it is used without O_DIRECTORY. The is done
with a dedicated macro.
Signed-off-by: Greg Kurz <gr...@kaod.org>
---
hw/9pfs/9p-util.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h
index 091f3ce88e15..cb7b2072d3ac 100644
--- a/hw/9pfs/9p-util.h
+++ b/hw/9pfs/9p-util.h
@@ -22,7 +22,12 @@ static inline void close_preserve_errno(int fd)
static inline int openat_dir(int dirfd, const char *name)
{
- return openat(dirfd, name, O_DIRECTORY | O_RDONLY | O_PATH);
+#ifdef O_PATH
+#define OPENAT_DIR_O_PATH O_PATH
+#else
+#define OPENAT_DIR_O_PATH 0
+#endif
+ return openat(dirfd, name, O_DIRECTORY | O_RDONLY | OPENAT_DIR_O_PATH);
}
static inline int openat_file(int dirfd, const char *name, int flags,
