From: Christian Brauner brauner@kernel.org
commit 1bc6d44 upstream.
Make it possible to quickly check whether AT_EMPTY_PATH is valid. Note, after some discussion we decided to also allow NULL to be passed instead of requiring the empty string.
Signed-off-by: Christian Brauner brauner@kernel.org
Cc: stable@vger.kernel.org # 5.10.x-5.15.x Signed-off-by: Miao Wang shankerwangmiao@gmail.com Tested-by: Xi Ruoyao xry111@xry111.site --- include/linux/fs.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/include/linux/fs.h b/include/linux/fs.h index 27da89d0ed5a..6fe2ae89bba6 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3736,4 +3736,21 @@ static inline int inode_drain_writes(struct inode *inode) return filemap_write_and_wait(inode->i_mapping); }
+static inline bool vfs_empty_path(int dfd, const char __user *path) +{ + char c; + + if (dfd < 0) + return false; + + /* We now allow NULL to be used for empty path. */ + if (!path) + return true; + + if (unlikely(get_user(c, path))) + return false; + + return !c; +} + #endif /* _LINUX_FS_H */