From 65c2e0c349aa5c7f605defb52dc67f1b3658a1b9 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <junkio@cox.net>
Date: Thu, 2 Jun 2005 15:20:54 -0700
Subject: [PATCH] [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>
---
cache.h | 1 +
diff.c | 11 +++++-----
sha1_file.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 67 insertions(+), 5 deletions(-)
diff --git a/cache.h b/cache.h
index e54176b4b5..481f7c7870 100644
--- a/cache.h
+++ b/cache.h
@@ -154,6 +154,7 @@ extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
extern int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size);
extern int parse_sha1_header(char *hdr, char *type, unsigned long *sizep);
extern int sha1_delta_base(const unsigned char *, unsigned char *);
+extern int sha1_file_size(const unsigned char *, unsigned long *);
extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
extern int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *return_sha1);
diff --git a/diff.c b/diff.c
index 7cf40daee5..5513632b9f 100644
--- a/diff.c
+++ b/diff.c
@@ -333,7 +333,6 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
close(fd);
}
else {
- /* We cannot do size only for SHA1 blobs */
char type[20];
struct sha1_size_cache *e;
@@ -343,11 +342,13 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
s->size = e->size;
return 0;
}
+ if (!sha1_file_size(s->sha1, &s->size))
+ locate_size_cache(s->sha1, s->size);
+ }
+ else {
+ s->data = read_sha1_file(s->sha1, type, &s->size);
+ s->should_free = 1;
}
- s->data = read_sha1_file(s->sha1, type, &s->size);
- s->should_free = 1;
- if (s->data && size_only)
- locate_size_cache(s->sha1, s->size);
}
return 0;
}
diff --git a/sha1_file.c b/sha1_file.c
index ccfcca07c7..a2ba4c81db 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;
--
2.40.0