diff mbox series

[1/5] nolibc: fix fd_set type

Message ID 20221209141939.3634586-2-svens@linux.ibm.com
State New
Headers
Series add s390 support to nolibc and rcutorture |

Commit Message

Sven Schnelle Dec. 9, 2022, 2:19 p.m. UTC 
  The kernel uses unsigned long for the fd_set bitmap,
but nolibc use u32. This works fine on little endian
machines, but fails on big endian. Convert to unsigned
long to fix this.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 tools/include/nolibc/types.h | 53 ++++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 23 deletions(-)

Comments

Willy Tarreau Dec. 10, 2022, 8:46 a.m. UTC | #1 
On Fri, Dec 09, 2022 at 03:19:35PM +0100, Sven Schnelle wrote:
> The kernel uses unsigned long for the fd_set bitmap,
> but nolibc use u32. This works fine on little endian
> machines, but fails on big endian. Convert to unsigned
> long to fix this.

Thank you for spotting and fixing this one! I had been using these for
a long time, including for pure user-land code to manipulate bits and
never thought about the risk of incompatibility when passing them as-is
to the kernel! It's fairly possible that I'm having non-working code for
64-bit BE machines at a few places!

> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>

Acked-by: Willy Tarreau <w@1wt.eu>

Willy
diff mbox series

Patch

diff --git a/tools/include/nolibc/types.h b/tools/include/nolibc/types.h
index 959997034e55..300e0ff1cd58 100644
--- a/tools/include/nolibc/types.h
+++ b/tools/include/nolibc/types.h
@@ -89,39 +89,46 @@ 
 #define EXIT_SUCCESS 0
 #define EXIT_FAILURE 1
 
+#define FD_SETIDXMASK (8 * sizeof(unsigned long))
+#define FD_SETBITMASK (8 * sizeof(unsigned long)-1)
+
 /* for select() */
 typedef struct {
-	uint32_t fd32[(FD_SETSIZE + 31) / 32];
+	unsigned long fds[(FD_SETSIZE + FD_SETBITMASK) / FD_SETIDXMASK];
 } fd_set;
 
-#define FD_CLR(fd, set) do {                                            \
-		fd_set *__set = (set);                                  \
-		int __fd = (fd);                                        \
-		if (__fd >= 0)                                          \
-			__set->fd32[__fd / 32] &= ~(1U << (__fd & 31)); \
+#define FD_CLR(fd, set) do {						\
+		fd_set *__set = (set);					\
+		int __fd = (fd);					\
+		if (__fd >= 0)						\
+			__set->fds[__fd / FD_SETIDXMASK] &=		\
+				~(1U << (__fd & FX_SETBITMASK));	\
 	} while (0)
 
-#define FD_SET(fd, set) do {                                            \
-		fd_set *__set = (set);                                  \
-		int __fd = (fd);                                        \
-		if (__fd >= 0)                                          \
-			__set->fd32[__fd / 32] |= 1U << (__fd & 31);    \
+#define FD_SET(fd, set) do {						\
+		fd_set *__set = (set);					\
+		int __fd = (fd);					\
+		if (__fd >= 0)						\
+			__set->fds[__fd / FD_SETIDXMASK] |=		\
+				1 << (__fd & FD_SETBITMASK);		\
 	} while (0)
 
-#define FD_ISSET(fd, set) ({                                                  \
-		fd_set *__set = (set);                                        \
-		int __fd = (fd);                                              \
-		int __r = 0;                                                  \
-		if (__fd >= 0)                                                \
-			__r = !!(__set->fd32[__fd / 32] & 1U << (__fd & 31)); \
-		__r;                                                          \
+#define FD_ISSET(fd, set) ({						\
+			fd_set *__set = (set);				\
+			int __fd = (fd);				\
+		int __r = 0;						\
+		if (__fd >= 0)						\
+			__r = !!(__set->fds[__fd / FD_SETIDXMASK] &	\
+1U << (__fd & FD_SET_BITMASK));						\
+		__r;							\
 	})
 
-#define FD_ZERO(set) do {                                               \
-		fd_set *__set = (set);                                  \
-		int __idx;                                              \
-		for (__idx = 0; __idx < (FD_SETSIZE+31) / 32; __idx ++) \
-			__set->fd32[__idx] = 0;                         \
+#define FD_ZERO(set) do {						\
+		fd_set *__set = (set);					\
+		int __idx;						\
+		int __size = (FD_SETSIZE+FD_SETBITMASK) / FD_SETIDXMASK;\
+		for (__idx = 0; __idx < __size; __idx++)		\
+			__set->fds[__idx] = 0;				\
 	} while (0)
 
 /* for poll() */