Move pack_refs() and friends into libgit

This moves pack_refs() and underlying functionality into the library,
to make pack-refs functionality easily available to all git programs.

Most of builtin-pack-refs.c has been moved verbatim into a new file
pack-refs.c that is compiled into libgit.a. A corresponding header
file, pack-refs.h, has also been added, declaring pack_refs() and
the #defines associated with the flags parameter to pack_refs().

This patch introduces no other changes in functionality.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 117 insertions, 0 deletions

diff --git a/pack-refs.c b/pack-refs.c
new file mode 100644
index 000000000..848d311c2
--- /dev/null
+++ b/pack-refs.c
@@ -0,0 +1,117 @@
+#include "cache.h"
+#include "refs.h"
+#include "tag.h"
+#include "pack-refs.h"
+
+struct ref_to_prune {
+	struct ref_to_prune *next;
+	unsigned char sha1[20];
+	char name[FLEX_ARRAY];
+};
+
+struct pack_refs_cb_data {
+	unsigned int flags;
+	struct ref_to_prune *ref_to_prune;
+	FILE *refs_file;
+};
+
+static int do_not_prune(int flags)
+{
+	/* If it is already packed or if it is a symref,
+	 * do not prune it.
+	 */
+	return (flags & (REF_ISSYMREF|REF_ISPACKED));
+}
+
+static int handle_one_ref(const char *path, const unsigned char *sha1,
+			  int flags, void *cb_data)
+{
+	struct pack_refs_cb_data *cb = cb_data;
+	int is_tag_ref;
+
+	/* Do not pack the symbolic refs */
+	if ((flags & REF_ISSYMREF))
+		return 0;
+	is_tag_ref = !prefixcmp(path, "refs/tags/");
+
+	/* ALWAYS pack refs that were already packed or are tags */
+	if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref && !(flags & REF_ISPACKED))
+		return 0;
+
+	fprintf(cb->refs_file, "%s %s\n", sha1_to_hex(sha1), path);
+	if (is_tag_ref) {
+		struct object *o = parse_object(sha1);
+		if (o->type == OBJ_TAG) {
+			o = deref_tag(o, path, 0);
+			if (o)
+				fprintf(cb->refs_file, "^%s\n",
+					sha1_to_hex(o->sha1));
+		}
+	}
+
+	if ((cb->flags & PACK_REFS_PRUNE) && !do_not_prune(flags)) {
+		int namelen = strlen(path) + 1;
+		struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
+		hashcpy(n->sha1, sha1);
+		strcpy(n->name, path);
+		n->next = cb->ref_to_prune;
+		cb->ref_to_prune = n;
+	}
+	return 0;
+}
+
+/* make sure nobody touched the ref, and unlink */
+static void prune_ref(struct ref_to_prune *r)
+{
+	struct ref_lock *lock = lock_ref_sha1(r->name + 5, r->sha1);
+
+	if (lock) {
+		unlink(git_path("%s", r->name));
+		unlock_ref(lock);
+	}
+}
+
+static void prune_refs(struct ref_to_prune *r)
+{
+	while (r) {
+		prune_ref(r);
+		r = r->next;
+	}
+}
+
+static struct lock_file packed;
+
+int pack_refs(unsigned int flags)
+{
+	int fd;
+	struct pack_refs_cb_data cbdata;
+
+	memset(&cbdata, 0, sizeof(cbdata));
+	cbdata.flags = flags;
+
+	fd = hold_lock_file_for_update(&packed, git_path("packed-refs"), 1);
+	cbdata.refs_file = fdopen(fd, "w");
+	if (!cbdata.refs_file)
+		die("unable to create ref-pack file structure (%s)",
+		    strerror(errno));
+
+	/* perhaps other traits later as well */
+	fprintf(cbdata.refs_file, "# pack-refs with: peeled \n");
+
+	for_each_ref(handle_one_ref, &cbdata);
+	if (ferror(cbdata.refs_file))
+		die("failed to write ref-pack file");
+	if (fflush(cbdata.refs_file) || fsync(fd) || fclose(cbdata.refs_file))
+		die("failed to write ref-pack file (%s)", strerror(errno));
+	/*
+	 * Since the lock file was fdopen()'ed and then fclose()'ed above,
+	 * assign -1 to the lock file descriptor so that commit_lock_file()
+	 * won't try to close() it.
+	 */
+	packed.fd = -1;
+	if (commit_lock_file(&packed) < 0)
+		die("unable to overwrite old ref-pack file (%s)", strerror(errno));
+	if (cbdata.flags & PACK_REFS_PRUNE)
+		prune_refs(cbdata.ref_to_prune);
+	return 0;
+}