Create pack-write.c for common pack writing code

Include a generalized fixup_pack_header_footer() in this new file.
Needed by git-repack --max-pack-size feature in a later patchset.

[sp: Moved close(pack_fd) to callers, to support index-pack, and
     changed name to better indicate it is for packfiles.]

Signed-off-by: Dana L. How <danahow@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Makefile

@@ -301,8 +301,8 @@ LIB_OBJS = \
 	interpolate.o \
 	lockfile.o \
 	patch-ids.o \
-	object.o pack-check.o patch-delta.o path.o pkt-line.o sideband.o \
-	reachable.o reflog-walk.o \
+	object.o pack-check.o pack-write.o patch-delta.o path.o pkt-line.o \
+	sideband.o reachable.o reflog-walk.o \
 	quote.o read-cache.o refs.o run-command.o dir.o object-refs.o \
 	server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \
 	tag.o tree.o usage.o config.o environment.o ctype.o copy.o \

fast-import.c

@@ -651,42 +651,6 @@ static void start_packfile(void)
 	all_packs[pack_id] = p;
 }
 
-static void fixup_header_footer(void)
-{
-	static const int buf_sz = 128 * 1024;
-	int pack_fd = pack_data->pack_fd;
-	SHA_CTX c;
-	struct pack_header hdr;
-	char *buf;
-
-	if (lseek(pack_fd, 0, SEEK_SET) != 0)
-		die("Failed seeking to start: %s", strerror(errno));
-	if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
-		die("Unable to reread header of %s", pack_data->pack_name);
-	if (lseek(pack_fd, 0, SEEK_SET) != 0)
-		die("Failed seeking to start: %s", strerror(errno));
-	hdr.hdr_entries = htonl(object_count);
-	write_or_die(pack_fd, &hdr, sizeof(hdr));
-
-	SHA1_Init(&c);
-	SHA1_Update(&c, &hdr, sizeof(hdr));
-
-	buf = xmalloc(buf_sz);
-	for (;;) {
-		ssize_t n = xread(pack_fd, buf, buf_sz);
-		if (!n)
-			break;
-		if (n < 0)
-			die("Failed to checksum %s", pack_data->pack_name);
-		SHA1_Update(&c, buf, n);
-	}
-	free(buf);
-
-	SHA1_Final(pack_data->sha1, &c);
-	write_or_die(pack_fd, pack_data->sha1, sizeof(pack_data->sha1));
-	close(pack_fd);
-}
-
 static int oecmp (const void *a_, const void *b_)
 {
 	struct object_entry *a = *((struct object_entry**)a_);
@@ -802,7 +766,9 @@ static void end_packfile(void)
 		struct branch *b;
 		struct tag *t;
 
-		fixup_header_footer();
+		fixup_pack_header_footer(pack_data->pack_fd, pack_data->sha1,
+				    pack_data->pack_name, object_count);
+		close(pack_data->pack_fd);
 		idx_name = keep_pack(create_index());
 
 		/* Register the packfile with core git's machinary. */

pack-write.c

@@ -0,0 +1,39 @@
+#include "cache.h"
+#include "pack.h"
+
+void fixup_pack_header_footer(int pack_fd,
+			 unsigned char *pack_file_sha1,
+			 const char *pack_name,
+			 uint32_t object_count)
+{
+	static const int buf_sz = 128 * 1024;
+	SHA_CTX c;
+	struct pack_header hdr;
+	char *buf;
+
+	if (lseek(pack_fd, 0, SEEK_SET) != 0)
+		die("Failed seeking to start: %s", strerror(errno));
+	if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
+		die("Unable to reread header of %s: %s", pack_name, strerror(errno));
+	if (lseek(pack_fd, 0, SEEK_SET) != 0)
+		die("Failed seeking to start: %s", strerror(errno));
+	hdr.hdr_entries = htonl(object_count);
+	write_or_die(pack_fd, &hdr, sizeof(hdr));
+
+	SHA1_Init(&c);
+	SHA1_Update(&c, &hdr, sizeof(hdr));
+
+	buf = xmalloc(buf_sz);
+	for (;;) {
+		size_t n = xread(pack_fd, buf, buf_sz);
+		if (!n)
+			break;
+		if (n < 0)
+			die("Failed to checksum %s: %s", pack_name, strerror(errno));
+		SHA1_Update(&c, buf, n);
+	}
+	free(buf);
+
+	SHA1_Final(pack_file_sha1, &c);
+	write_or_die(pack_fd, pack_file_sha1, 20);
+}

pack.h

@@ -44,6 +44,7 @@ struct pack_idx_header {
 
 
 extern int verify_pack(struct packed_git *, int);
+extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t);
 
 #define PH_ERROR_EOF		(-1)
 #define PH_ERROR_PACK_SIGNATURE	(-2)