From c3d8da571f11b0146e60591c040da399d411c3f2 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Thu, 23 Jan 2014 16:26:42 -0500 Subject: [PATCH] read-cache: use get_be32 instead of hand-rolled ntoh_l Commit d60c49c (read-cache.c: allow unaligned mapping of the index file, 2012-04-03) introduced helpers to access unaligned data. However, we already have get_be32, which has a few advantages: 1. It's already written, so we avoid duplication. 2. It's probably faster, since it does the endian conversion and the alignment fix at the same time. 3. The get_be32 code is well-tested, having been in block-sha1 for a long time. By contrast, our custom helpers were probably almost never used, since the user needed to manually define a macro to enable them. We have to add a get_be16 implementation to the existing get_be32, but that is very simple to do. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- compat/bswap.h | 4 ++++ read-cache.c | 44 ++++++++++++-------------------------------- 2 files changed, 16 insertions(+), 32 deletions(-) diff --git a/compat/bswap.h b/compat/bswap.h index 7d17953a6..120c6c1d3 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -136,11 +136,15 @@ static inline uint64_t git_bswap64(uint64_t x) defined(__powerpc__) || defined(__powerpc64__) || \ defined(__s390__) || defined(__s390x__) +#define get_be16(p) ntohs(*(unsigned short *)(p)) #define get_be32(p) ntohl(*(unsigned int *)(p)) #define put_be32(p, v) do { *(unsigned int *)(p) = htonl(v); } while (0) #else +#define get_be16(p) ( \ + (*((unsigned char *)(p) + 0) << 8) | \ + (*((unsigned char *)(p) + 1) << 0) ) #define get_be32(p) ( \ (*((unsigned char *)(p) + 0) << 24) | \ (*((unsigned char *)(p) + 1) << 16) | \ diff --git a/read-cache.c b/read-cache.c index 33dd676cc..422187262 100644 --- a/read-cache.c +++ b/read-cache.c @@ -1313,26 +1313,6 @@ int read_index(struct index_state *istate) return read_index_from(istate, get_index_file()); } -#ifndef NEEDS_ALIGNED_ACCESS -#define ntoh_s(var) ntohs(var) -#define ntoh_l(var) ntohl(var) -#else -static inline uint16_t ntoh_s_force_align(void *p) -{ - uint16_t x; - memcpy(&x, p, sizeof(x)); - return ntohs(x); -} -static inline uint32_t ntoh_l_force_align(void *p) -{ - uint32_t x; - memcpy(&x, p, sizeof(x)); - return ntohl(x); -} -#define ntoh_s(var) ntoh_s_force_align(&(var)) -#define ntoh_l(var) ntoh_l_force_align(&(var)) -#endif - static struct cache_entry *cache_entry_from_ondisk(struct ondisk_cache_entry *ondisk, unsigned int flags, const char *name, @@ -1340,16 +1320,16 @@ static struct cache_entry *cache_entry_from_ondisk(struct ondisk_cache_entry *on { struct cache_entry *ce = xmalloc(cache_entry_size(len)); - ce->ce_stat_data.sd_ctime.sec = ntoh_l(ondisk->ctime.sec); - ce->ce_stat_data.sd_mtime.sec = ntoh_l(ondisk->mtime.sec); - ce->ce_stat_data.sd_ctime.nsec = ntoh_l(ondisk->ctime.nsec); - ce->ce_stat_data.sd_mtime.nsec = ntoh_l(ondisk->mtime.nsec); - ce->ce_stat_data.sd_dev = ntoh_l(ondisk->dev); - ce->ce_stat_data.sd_ino = ntoh_l(ondisk->ino); - ce->ce_mode = ntoh_l(ondisk->mode); - ce->ce_stat_data.sd_uid = ntoh_l(ondisk->uid); - ce->ce_stat_data.sd_gid = ntoh_l(ondisk->gid); - ce->ce_stat_data.sd_size = ntoh_l(ondisk->size); + ce->ce_stat_data.sd_ctime.sec = get_be32(&ondisk->ctime.sec); + ce->ce_stat_data.sd_mtime.sec = get_be32(&ondisk->mtime.sec); + ce->ce_stat_data.sd_ctime.nsec = get_be32(&ondisk->ctime.nsec); + ce->ce_stat_data.sd_mtime.nsec = get_be32(&ondisk->mtime.nsec); + ce->ce_stat_data.sd_dev = get_be32(&ondisk->dev); + ce->ce_stat_data.sd_ino = get_be32(&ondisk->ino); + ce->ce_mode = get_be32(&ondisk->mode); + ce->ce_stat_data.sd_uid = get_be32(&ondisk->uid); + ce->ce_stat_data.sd_gid = get_be32(&ondisk->gid); + ce->ce_stat_data.sd_size = get_be32(&ondisk->size); ce->ce_flags = flags & ~CE_NAMEMASK; ce->ce_namelen = len; hashcpy(ce->sha1, ondisk->sha1); @@ -1389,14 +1369,14 @@ static struct cache_entry *create_from_disk(struct ondisk_cache_entry *ondisk, unsigned int flags; /* On-disk flags are just 16 bits */ - flags = ntoh_s(ondisk->flags); + flags = get_be16(&ondisk->flags); len = flags & CE_NAMEMASK; if (flags & CE_EXTENDED) { struct ondisk_cache_entry_extended *ondisk2; int extended_flags; ondisk2 = (struct ondisk_cache_entry_extended *)ondisk; - extended_flags = ntoh_s(ondisk2->flags2) << 16; + extended_flags = get_be16(&ondisk2->flags2) << 16; /* We do not yet understand any bit out of CE_EXTENDED_FLAGS */ if (extended_flags & ~CE_EXTENDED_FLAGS) die("Unknown index entry format %08x", extended_flags); -- 2.11.0