[PATCH 4/8] git-repack --max-pack-size: add fixup_header_footer()

[Dana How <danahow@gmail.com>]

Add our own version of the one in fast-import.c here.
Will need this later to correct an incorrect object
count in the pack header.

Signed-off-by: Dana How <how@deathvalley.cswitch.com>
---
 builtin-pack-objects.c |   40 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 8415549..7ab0712 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -518,6 +518,46 @@ static off_t write_one(struct sha1file *f,
 	return offset + write_object(f, e);
 }
 
+/*
+ * Move this, the version in fast-import.c,
+ * and index_pack.c:readjust_pack_header_and_sha1 into sha1_file.c ?
+ */
+static void fixup_header_footer(int pack_fd, unsigned char *pack_file_sha1,
+				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", 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 (;;) {
+		size_t n = xread(pack_fd, buf, buf_sz);
+		if (!n)
+			break;
+		if (n < 0)
+			die("Failed to checksum %s", pack_name);
+		SHA1_Update(&c, buf, n);
+	}
+	free(buf);
+
+	SHA1_Final(pack_file_sha1, &c);
+	write_or_die(pack_fd, pack_file_sha1, 20);
+	close(pack_fd);
+}
+
 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 
 static entry_sort_t current_sort;
-- 
1.5.1.89.g8abf0