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authorPeter Hutterer <peter.hutterer@who-t.net>2009-06-29 13:09:57 +1000
committerMike DePaulo <mikedep333@gmail.com>2015-02-17 21:23:43 -0500
commit3937db18a203f9936387286b95328f27013a5ffe (patch)
tree8da4e05a2c24642612ad684cb68db76fd220a1b5 /nx-X11/programs/Xserver/include
parentd6ce946f9c0bb5746b8333b3f589aa8527739431 (diff)
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include: introduce byte counting functions.
This patch adds the following three functions: bits_to_bytes(bits) - the number of bytes needed to hold 'bits' bytes_to_int32(bytes) - the number of 4-byte units to hold 'bytes' pad_to_int32(bytes) - the closest multiple of 4 equal to or larger than 'bytes'. All three operations are common in protocol processing and currently the server has ((foo + 7)/8 + 3)/4 operations all over the place. A common set of functions reduce the error rate of these (albeit simple) calculations and improve readability of the code. The functions do not check for overflow. v2: backport to nx-libs 3.6.x as a prereq for the CVE-2015-0255 fix (Mike DePaulo) Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Diffstat (limited to 'nx-X11/programs/Xserver/include')
-rw-r--r--nx-X11/programs/Xserver/include/misc.h30
1 files changed, 30 insertions, 0 deletions
diff --git a/nx-X11/programs/Xserver/include/misc.h b/nx-X11/programs/Xserver/include/misc.h
index 5944a427f..849f1b5cc 100644
--- a/nx-X11/programs/Xserver/include/misc.h
+++ b/nx-X11/programs/Xserver/include/misc.h
@@ -193,6 +193,36 @@ typedef struct _xReq *xReqPtr;
#endif
+/**
+ * Calculate the number of bytes needed to hold bits.
+ * @param bits The minimum number of bits needed.
+ * @return The number of bytes needed to hold bits.
+ */
+static __inline__ int
+bits_to_bytes(const int bits) {
+ return ((bits + 7) >> 3);
+}
+/**
+ * Calculate the number of 4-byte units needed to hold the given number of
+ * bytes.
+ * @param bytes The minimum number of bytes needed.
+ * @return The number of 4-byte units needed to hold bytes.
+ */
+static __inline__ int
+bytes_to_int32(const int bytes) {
+ return (((bytes) + 3) >> 2);
+}
+
+/**
+ * Calculate the number of bytes (in multiples of 4) needed to hold bytes.
+ * @param bytes The minimum number of bytes needed.
+ * @return The closest multiple of 4 that is equal or higher than bytes.
+ */
+static __inline__ int
+pad_to_int32(const int bytes) {
+ return (((bytes) + 3) & ~3);
+}
+
/* some macros to help swap requests, replies, and events */
#define LengthRestB(stuff) \