From 7780af1e8edf158f503794dbdb87787999daa086 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= Date: Sat, 15 Jul 2017 21:11:14 +0200 Subject: bswap: convert to unsigned before shifting in get_be32 The pointer p is dereferenced and we get an unsigned char. Before shifting it's automatically promoted to int. Left-shifting a signed 32-bit value bigger than 127 by 24 places is undefined. Explicitly convert to a 32-bit unsigned type to avoid undefined behaviour if the highest bit is set. Found with Clang's UBSan. Signed-off-by: Rene Scharfe Signed-off-by: Junio C Hamano --- compat/bswap.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'compat') diff --git a/compat/bswap.h b/compat/bswap.h index d47c003544..4582c1107a 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -166,10 +166,10 @@ static inline uint64_t git_bswap64(uint64_t x) (*((unsigned char *)(p) + 0) << 8) | \ (*((unsigned char *)(p) + 1) << 0) ) #define get_be32(p) ( \ - (*((unsigned char *)(p) + 0) << 24) | \ - (*((unsigned char *)(p) + 1) << 16) | \ - (*((unsigned char *)(p) + 2) << 8) | \ - (*((unsigned char *)(p) + 3) << 0) ) + ((uint32_t)*((unsigned char *)(p) + 0) << 24) | \ + ((uint32_t)*((unsigned char *)(p) + 1) << 16) | \ + ((uint32_t)*((unsigned char *)(p) + 2) << 8) | \ + ((uint32_t)*((unsigned char *)(p) + 3) << 0) ) #define put_be32(p, v) do { \ unsigned int __v = (v); \ *((unsigned char *)(p) + 0) = __v >> 24; \ -- cgit v1.2.3 From 5b114f3bb0820c1f57fb4a9cd14b62b55aa30d31 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= Date: Sat, 15 Jul 2017 21:22:50 +0200 Subject: bswap: convert get_be16, get_be32 and put_be32 to inline functions Simplify the implementation and allow callers to use expressions with side-effects by turning the macros get_be16, get_be32 and put_be32 into inline functions. Signed-off-by: Rene Scharfe Signed-off-by: Junio C Hamano --- compat/bswap.h | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) (limited to 'compat') diff --git a/compat/bswap.h b/compat/bswap.h index 4582c1107a..7d063e9e40 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -162,19 +162,29 @@ static inline uint64_t git_bswap64(uint64_t x) #else -#define get_be16(p) ( \ - (*((unsigned char *)(p) + 0) << 8) | \ - (*((unsigned char *)(p) + 1) << 0) ) -#define get_be32(p) ( \ - ((uint32_t)*((unsigned char *)(p) + 0) << 24) | \ - ((uint32_t)*((unsigned char *)(p) + 1) << 16) | \ - ((uint32_t)*((unsigned char *)(p) + 2) << 8) | \ - ((uint32_t)*((unsigned char *)(p) + 3) << 0) ) -#define put_be32(p, v) do { \ - unsigned int __v = (v); \ - *((unsigned char *)(p) + 0) = __v >> 24; \ - *((unsigned char *)(p) + 1) = __v >> 16; \ - *((unsigned char *)(p) + 2) = __v >> 8; \ - *((unsigned char *)(p) + 3) = __v >> 0; } while (0) +static inline uint16_t get_be16(const void *ptr) +{ + const unsigned char *p = ptr; + return (uint16_t)p[0] << 8 | + (uint16_t)p[1] << 0; +} + +static inline uint32_t get_be32(const void *ptr) +{ + const unsigned char *p = ptr; + return (uint32_t)p[0] << 24 | + (uint32_t)p[1] << 16 | + (uint32_t)p[2] << 8 | + (uint32_t)p[3] << 0; +} + +static inline void put_be32(void *ptr, uint32_t value) +{ + unsigned char *p = ptr; + p[0] = value >> 24; + p[1] = value >> 16; + p[2] = value >> 8; + p[3] = value >> 0; +} #endif -- cgit v1.2.3