[PATCH] 4/7 Use SHA1 for git-update-cache --refresh

Change git-update-cache --refresh behaviour to use sha1's rather than
comparing byte by byte.

Signed-off-by: Bryan Larsen <redacted>
---

  update-cache.c |   31 +++++--------------------------
  1 files changed, 5 insertions(+), 26 deletions(-)

diff --git a/update-cache.c b/update-cache.c
--- a/update-cache.c
+++ b/update-cache.c

@@ -93,37 +93,16 @@ static int add_file_to_cache(char *path)
  	return add_cache_entry(ce, option);
  }

-static int match_data(int fd, void *buffer, unsigned long size)
-{
-	while (size) {
-		char compare[1024];
-		int ret = read(fd, compare, sizeof(compare));
-
-		if (ret <= 0 || ret > size || memcmp(buffer, compare, ret))
-			return -1;
-		size -= ret;
-		buffer += ret;
-	}
-	return 0;
-}
-
-static int compare_data(struct cache_entry *ce, unsigned long 

expected_size)
+static int compare_data(struct cache_entry *ce, struct stat *st)
  {
  	int match = -1;
  	int fd = open(ce->name, O_RDONLY);

  	if (fd >= 0) {
-		void *buffer;
-		unsigned long size;
-		char type[20];
-
-		buffer = read_sha1_file(ce->sha1, type, &size);
-		if (buffer) {
-			if (size == expected_size && !strcmp(type, "blob"))
-				match = match_data(fd, buffer, size);
-			free(buffer);
+		unsigned char sha1[20];
+		if(!index_fd(sha1, fd, st, 1)) {
+			match = memcmp(sha1, ce->sha1, 20);
  		}
-		close(fd);
  	}
  	return match;
  }

@@ -188,7 +167,7 @@ static struct cache_entry *refresh_entry

  	switch (st.st_mode & S_IFMT) {
  	case S_IFREG:
-		if (compare_data(ce, st.st_size))
+		if (compare_data(ce, &st))
  			return ERR_PTR(-EINVAL);
  		break;
  	case S_IFLNK: