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authorJunio C Hamano <junkio@cox.net>2005-06-02 22:20:54 (GMT)
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-02 22:48:33 (GMT)
commit65c2e0c349aa5c7f605defb52dc67f1b3658a1b9 (patch)
tree011b8aba6186497e2eece190bb560165a9b44f8f /sha1_file.c
parent4a62b61939396c512bd7592f800110bddf45af72 (diff)
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[PATCH] Find size of SHA1 object without inflating everything.
This adds sha1_file_size() helper function and uses it in the rename/copy similarity estimator. The helper function handles deltified object as well. Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'sha1_file.c')
-rw-r--r--sha1_file.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/sha1_file.c b/sha1_file.c
index ccfcca0..a2ba4c8 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -432,6 +432,66 @@ int sha1_delta_base(const unsigned char *sha1, unsigned char *base_sha1)
return ret;
}
+int sha1_file_size(const unsigned char *sha1, unsigned long *sizep)
+{
+ int ret, status;
+ unsigned long mapsize, size;
+ void *map;
+ z_stream stream;
+ char hdr[64], type[20];
+ const unsigned char *data;
+ unsigned char cmd;
+ int i;
+
+ map = map_sha1_file(sha1, &mapsize);
+ if (!map)
+ return -1;
+ ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
+ status = -1;
+ if (ret < Z_OK || parse_sha1_header(hdr, type, &size) < 0)
+ goto out;
+ if (strcmp(type, "delta")) {
+ *sizep = size;
+ status = 0;
+ goto out;
+ }
+
+ /* We are dealing with a delta object. Inflated, the first
+ * 20 bytes hold the base object SHA1, and delta data follows
+ * immediately after it.
+ *
+ * The initial part of the delta starts at delta_data_head +
+ * 20. Borrow code from patch-delta to read the result size.
+ */
+ data = hdr + strlen(hdr) + 1 + 20;
+
+ /* Skip over the source size; we are not interested in
+ * it and we cannot verify it because we do not want
+ * to read the base object.
+ */
+ cmd = *data++;
+ while (cmd) {
+ if (cmd & 1)
+ data++;
+ cmd >>= 1;
+ }
+ /* Read the result size */
+ size = i = 0;
+ cmd = *data++;
+ while (cmd) {
+ if (cmd & 1)
+ size |= *data++ << i;
+ i += 8;
+ cmd >>= 1;
+ }
+ *sizep = size;
+ status = 0;
+ out:
+ inflateEnd(&stream);
+ munmap(map, mapsize);
+ return status;
+}
+
void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
{
unsigned long mapsize;