tools/nolibc: Fix S_ISxxx macros

[ Upstream commit 16f5cea ]

The mode field has the type encoded as an value in a field, not as a bit
mask. Mask the mode with S_IFMT instead of each type to test. Otherwise,
false positives are possible: eg S_ISDIR will return true for block
devices because S_IFDIR = 0040000 and S_IFBLK = 0060000 since mode is
masked with S_IFDIR instead of S_IFMT. These macros now match the
similar definitions in tools/include/uapi/linux/stat.h.

Signed-off-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

tools/include/nolibc/types.h

@@ -26,13 +26,13 @@
 #define S_IFSOCK       0140000
 #define S_IFMT         0170000
 
-#define S_ISDIR(mode)  (((mode) & S_IFDIR)  == S_IFDIR)
-#define S_ISCHR(mode)  (((mode) & S_IFCHR)  == S_IFCHR)
-#define S_ISBLK(mode)  (((mode) & S_IFBLK)  == S_IFBLK)
-#define S_ISREG(mode)  (((mode) & S_IFREG)  == S_IFREG)
-#define S_ISFIFO(mode) (((mode) & S_IFIFO)  == S_IFIFO)
-#define S_ISLNK(mode)  (((mode) & S_IFLNK)  == S_IFLNK)
-#define S_ISSOCK(mode) (((mode) & S_IFSOCK) == S_IFSOCK)
+#define S_ISDIR(mode)  (((mode) & S_IFMT) == S_IFDIR)
+#define S_ISCHR(mode)  (((mode) & S_IFMT) == S_IFCHR)
+#define S_ISBLK(mode)  (((mode) & S_IFMT) == S_IFBLK)
+#define S_ISREG(mode)  (((mode) & S_IFMT) == S_IFREG)
+#define S_ISFIFO(mode) (((mode) & S_IFMT) == S_IFIFO)
+#define S_ISLNK(mode)  (((mode) & S_IFMT) == S_IFLNK)
+#define S_ISSOCK(mode) (((mode) & S_IFMT) == S_IFSOCK)
 
 /* dirent types */
 #define DT_UNKNOWN     0x0