[PATCH 1/17] Replace unpack_entry_gently with unpack_entry.

["Shawn O. Pearce" <spearce@spearce.org>]

The unpack_entry_gently function currently has only two callers:
the delta base resolution in sha1_file.c and the main loop of
pack-check.c.  Both of these must change to using unpack_entry
directly when we implement sliding window mmap logic, so I'm doing
it earlier to help break down the change set.

This may cause a slight performance decrease for delta base
resolution as well as for pack-check.c's verify_packfile(), as
the pack use counter will be incremented and decremented for every
object that is unpacked.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 cache.h      |    2 +-
 pack-check.c |    2 +-
 sha1_file.c  |   33 ++++++++++++---------------------
 3 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/cache.h b/cache.h
index 4943056..38db1bf 100644
--- a/cache.h
+++ b/cache.h
@@ -394,7 +394,7 @@ extern struct packed_git *add_packed_git(char *, int, int);
 extern int num_packed_objects(const struct packed_git *p);
 extern int nth_packed_object_sha1(const struct packed_git *, int, unsigned char*);
 extern unsigned long find_pack_entry_one(const unsigned char *, struct packed_git *);
-extern void *unpack_entry_gently(struct packed_git *, unsigned long, char *, unsigned long *);
+extern void *unpack_entry(struct packed_git *, unsigned long, char *, unsigned long *);
 extern unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
 extern void packed_object_info_detail(struct packed_git *, unsigned long, char *, unsigned long *, unsigned long *, unsigned int *, unsigned char *);
 
diff --git a/pack-check.c b/pack-check.c
index c0caaee..491bad2 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -51,7 +51,7 @@ static int verify_packfile(struct packed_git *p)
 		offset = find_pack_entry_one(sha1, p);
 		if (!offset)
 			die("internal error pack-check find-pack-entry-one");
-		data = unpack_entry_gently(p, offset, type, &size);
+		data = unpack_entry(p, offset, type, &size);
 		if (!data) {
 			err = error("cannot unpack %s from %s",
 				    sha1_to_hex(sha1), p->pack_name);
diff --git a/sha1_file.c b/sha1_file.c
index 1c4df5b..4824a5d 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1110,7 +1110,7 @@ static void *unpack_delta_entry(struct packed_git *p,
 	unsigned long result_size, base_size, base_offset;
 
 	offset = get_delta_base(p, offset, kind, obj_offset, &base_offset);
-	base = unpack_entry_gently(p, base_offset, type, &base_size);
+	base = unpack_entry(p, base_offset, type, &base_size);
 	if (!base)
 		die("failed to read delta base object at %lu from %s",
 		    base_offset, p->pack_name);
@@ -1127,43 +1127,34 @@ static void *unpack_delta_entry(struct packed_git *p,
 	return result;
 }
 
-static void *unpack_entry(struct pack_entry *entry,
+void *unpack_entry(struct packed_git *p, unsigned long offset,
 			  char *type, unsigned long *sizep)
 {
-	struct packed_git *p = entry->p;
+	unsigned long size, obj_offset = offset;
+	enum object_type kind;
 	void *retval;
 
 	if (use_packed_git(p))
 		die("cannot map packed file");
-	retval = unpack_entry_gently(p, entry->offset, type, sizep);
-	unuse_packed_git(p);
-	if (!retval)
-		die("corrupted pack file %s", p->pack_name);
-	return retval;
-}
-
-/* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
-void *unpack_entry_gently(struct packed_git *p, unsigned long offset,
-			  char *type, unsigned long *sizep)
-{
-	unsigned long size, obj_offset = offset;
-	enum object_type kind;
-
 	offset = unpack_object_header(p, offset, &kind, &size);
 	switch (kind) {
 	case OBJ_OFS_DELTA:
 	case OBJ_REF_DELTA:
-		return unpack_delta_entry(p, offset, size, kind, obj_offset, type, sizep);
+		retval = unpack_delta_entry(p, offset, size, kind, obj_offset, type, sizep);
+		break;
 	case OBJ_COMMIT:
 	case OBJ_TREE:
 	case OBJ_BLOB:
 	case OBJ_TAG:
 		strcpy(type, type_names[kind]);
 		*sizep = size;
-		return unpack_compressed_entry(p, offset, size);
+		retval = unpack_compressed_entry(p, offset, size);
+		break;
 	default:
-		return NULL;
+		die("unknown object type %i in %s", kind, p->pack_name);
 	}
+	unuse_packed_git(p);
+	return retval;
 }
 
 int num_packed_objects(const struct packed_git *p)
@@ -1312,7 +1303,7 @@ static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned lo
 		error("cannot read sha1_file for %s", sha1_to_hex(sha1));
 		return NULL;
 	}
-	return unpack_entry(&e, type, size);
+	return unpack_entry(e.p, e.offset, type, size);
 }
 
 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
-- 
1.4.4.3.g87d8