Improve macro hygiene
This commit improves hygiene and formatting of macro definitions
throughout the library. Specifically:
- It adds brackets around parameters to avoid unintended
interpretation of arguments, e.g. due to operator precedence.
- It adds uses of the `do { ... } while( 0 )` idiom for macros that
can be used as commands.
diff --git a/library/sha256.c b/library/sha256.c
index 8a540ad..09d3fe3 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -172,8 +172,8 @@
0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2,
};
-#define SHR(x,n) ((x & 0xFFFFFFFF) >> n)
-#define ROTR(x,n) (SHR(x,n) | (x << (32 - n)))
+#define SHR(x,n) (((x) & 0xFFFFFFFF) >> (n))
+#define ROTR(x,n) (SHR(x,n) | ((x) << (32 - (n))))
#define S0(x) (ROTR(x, 7) ^ ROTR(x,18) ^ SHR(x, 3))
#define S1(x) (ROTR(x,17) ^ ROTR(x,19) ^ SHR(x,10))
@@ -181,21 +181,22 @@
#define S2(x) (ROTR(x, 2) ^ ROTR(x,13) ^ ROTR(x,22))
#define S3(x) (ROTR(x, 6) ^ ROTR(x,11) ^ ROTR(x,25))
-#define F0(x,y,z) ((x & y) | (z & (x | y)))
-#define F1(x,y,z) (z ^ (x & (y ^ z)))
+#define F0(x,y,z) (((x) & (y)) | ((z) & ((x) | (y))))
+#define F1(x,y,z) ((z) ^ ((x) & ((y) ^ (z))))
#define R(t) \
-( \
- W[t] = S1(W[t - 2]) + W[t - 7] + \
- S0(W[t - 15]) + W[t - 16] \
-)
+ ( \
+ W[t] = S1(W[(t) - 2]) + W[(t) - 7] + \
+ S0(W[(t) - 15]) + W[(t) - 16] \
+ )
-#define P(a,b,c,d,e,f,g,h,x,K) \
-{ \
- temp1 = h + S3(e) + F1(e,f,g) + K + x; \
- temp2 = S2(a) + F0(a,b,c); \
- d += temp1; h = temp1 + temp2; \
-}
+#define P(a,b,c,d,e,f,g,h,x,K) \
+ do \
+ { \
+ temp1 = (h) + S3(e) + F1(e,f,g) + (K) + (x); \
+ temp2 = S2(a) + F0(a,b,c); \
+ (d) += temp1; (h) = temp1 + temp2; \
+ } while( 0 )
int mbedtls_internal_sha256_process( mbedtls_sha256_context *ctx,
const unsigned char data[64] )