From 5f7817c85d4b5f65626c8f49249a6c91292b8513 Mon Sep 17 00:00:00 2001 From: "brian m. carlson" Date: Fri, 13 Mar 2015 23:39:27 +0000 Subject: define a structure for object IDs Many places throughout the code use "unsigned char [20]" to store object IDs (SHA-1 values). This leads to lots of hardcoded numbers throughout the codebase. It also leads to confusion about the purposes of a buffer. Introduce a structure for object IDs. This allows us to obtain the benefits of compile-time checking for misuse. The structure is expected to remain the same size and have the same alignment requirements on all known platforms, compared to the array of unsigned char, although this is not required for correctness. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano --- cache.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'cache.h') diff --git a/cache.h b/cache.h index 4d02efc905..40d06fde03 100644 --- a/cache.h +++ b/cache.h @@ -43,6 +43,14 @@ int git_deflate_end_gently(git_zstream *); int git_deflate(git_zstream *, int flush); unsigned long git_deflate_bound(git_zstream *, unsigned long); +/* The length in bytes and in hex digits of an object name (SHA-1 value). */ +#define GIT_SHA1_RAWSZ 20 +#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ) + +struct object_id { + unsigned char hash[GIT_SHA1_RAWSZ]; +}; + #if defined(DT_UNKNOWN) && !defined(NO_D_TYPE_IN_DIRENT) #define DTYPE(de) ((de)->d_type) #else -- cgit v1.3 From aa1c6fdf478c023180e5ca5f1658b00a72592dc6 Mon Sep 17 00:00:00 2001 From: "brian m. carlson" Date: Fri, 13 Mar 2015 23:39:28 +0000 Subject: define utility functions for object IDs There are several utility functions (hashcmp and friends) that are used for comparing object IDs (SHA-1 values). Using these functions, which take pointers to unsigned char, with struct object_id requires tiresome access to the sha1 member, which bloats code and violates the desired encapsulation. Provide wrappers around these functions for struct object_id for neater, more maintainable code. Use the new constants to avoid the hard-coded 20s and 40s throughout the original functions. These functions simply call the underlying pointer-to-unsigned-char versions to ensure that any performance improvements will be passed through to the new functions. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano --- cache.h | 32 ++++++++++++++++++++++++++++---- hex.c | 16 +++++++++++++--- 2 files changed, 41 insertions(+), 7 deletions(-) (limited to 'cache.h') diff --git a/cache.h b/cache.h index 40d06fde03..04cfb1f8aa 100644 --- a/cache.h +++ b/cache.h @@ -718,13 +718,13 @@ extern char *sha1_pack_name(const unsigned char *sha1); extern char *sha1_pack_index_name(const unsigned char *sha1); extern const char *find_unique_abbrev(const unsigned char *sha1, int); -extern const unsigned char null_sha1[20]; +extern const unsigned char null_sha1[GIT_SHA1_RAWSZ]; static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2) { int i; - for (i = 0; i < 20; i++, sha1++, sha2++) { + for (i = 0; i < GIT_SHA1_RAWSZ; i++, sha1++, sha2++) { if (*sha1 != *sha2) return *sha1 - *sha2; } @@ -732,20 +732,42 @@ static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2) return 0; } +static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2) +{ + return hashcmp(oid1->hash, oid2->hash); +} + static inline int is_null_sha1(const unsigned char *sha1) { return !hashcmp(sha1, null_sha1); } +static inline int is_null_oid(const struct object_id *oid) +{ + return !hashcmp(oid->hash, null_sha1); +} + static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src) { - memcpy(sha_dst, sha_src, 20); + memcpy(sha_dst, sha_src, GIT_SHA1_RAWSZ); +} + +static inline void oidcpy(struct object_id *dst, const struct object_id *src) +{ + hashcpy(dst->hash, src->hash); } + static inline void hashclr(unsigned char *hash) { - memset(hash, 0, 20); + memset(hash, 0, GIT_SHA1_RAWSZ); } +static inline void oidclr(struct object_id *oid) +{ + hashclr(oid->hash); +} + + #define EMPTY_TREE_SHA1_HEX \ "4b825dc642cb6eb9a060e54bf8d69288fbee4904" #define EMPTY_TREE_SHA1_BIN_LITERAL \ @@ -952,8 +974,10 @@ extern int for_each_abbrev(const char *prefix, each_abbrev_fn, void *); * null-terminated string. */ extern int get_sha1_hex(const char *hex, unsigned char *sha1); +extern int get_oid_hex(const char *hex, struct object_id *sha1); extern char *sha1_to_hex(const unsigned char *sha1); /* static buffer result! */ +extern char *oid_to_hex(const struct object_id *oid); /* same static buffer as sha1_to_hex */ extern int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags); extern int read_ref(const char *refname, unsigned char *sha1); diff --git a/hex.c b/hex.c index cfd9d722fd..899b74a08c 100644 --- a/hex.c +++ b/hex.c @@ -38,7 +38,7 @@ const signed char hexval_table[256] = { int get_sha1_hex(const char *hex, unsigned char *sha1) { int i; - for (i = 0; i < 20; i++) { + for (i = 0; i < GIT_SHA1_RAWSZ; i++) { unsigned int val; /* * hex[1]=='\0' is caught when val is checked below, @@ -56,15 +56,20 @@ int get_sha1_hex(const char *hex, unsigned char *sha1) return 0; } +int get_oid_hex(const char *hex, struct object_id *oid) +{ + return get_sha1_hex(hex, oid->hash); +} + char *sha1_to_hex(const unsigned char *sha1) { static int bufno; - static char hexbuffer[4][41]; + static char hexbuffer[4][GIT_SHA1_HEXSZ + 1]; static const char hex[] = "0123456789abcdef"; char *buffer = hexbuffer[3 & ++bufno], *buf = buffer; int i; - for (i = 0; i < 20; i++) { + for (i = 0; i < GIT_SHA1_RAWSZ; i++) { unsigned int val = *sha1++; *buf++ = hex[val >> 4]; *buf++ = hex[val & 0xf]; @@ -73,3 +78,8 @@ char *sha1_to_hex(const unsigned char *sha1) return buffer; } + +char *oid_to_hex(const struct object_id *oid) +{ + return sha1_to_hex(oid->hash); +} -- cgit v1.3