Modularize commit-walker

This turns the extern functions to be provided by the backend into a
struct of pointers, renames the functions to be more
namespace-friendly, and updates http-fetch to this interface. It
removes the unused include from http-push.c. It makes git-http-fetch a
builtin (with the implementation a separate file, accessible
directly).

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 318 insertions, 0 deletions

diff --git a/walker.c b/walker.c
new file mode 100644
index 0000000000..5c65ea494d
--- /dev/null
+++ b/walker.c
@@ -0,0 +1,318 @@
+#include "cache.h"
+#include "walker.h"
+#include "commit.h"
+#include "tree.h"
+#include "tree-walk.h"
+#include "tag.h"
+#include "blob.h"
+#include "refs.h"
+#include "strbuf.h"
+
+static unsigned char current_commit_sha1[20];
+
+void walker_say(struct walker *walker, const char *fmt, const char *hex)
+{
+	if (walker->get_verbosely)
+		fprintf(stderr, fmt, hex);
+}
+
+static void report_missing(const struct object *obj)
+{
+	char missing_hex[41];
+	strcpy(missing_hex, sha1_to_hex(obj->sha1));;
+	fprintf(stderr, "Cannot obtain needed %s %s\n",
+		obj->type ? typename(obj->type): "object", missing_hex);
+	if (!is_null_sha1(current_commit_sha1))
+		fprintf(stderr, "while processing commit %s.\n",
+			sha1_to_hex(current_commit_sha1));
+}
+
+static int process(struct walker *walker, struct object *obj);
+
+static int process_tree(struct walker *walker, struct tree *tree)
+{
+	struct tree_desc desc;
+	struct name_entry entry;
+
+	if (parse_tree(tree))
+		return -1;
+
+	init_tree_desc(&desc, tree->buffer, tree->size);
+	while (tree_entry(&desc, &entry)) {
+		struct object *obj = NULL;
+
+		/* submodule commits are not stored in the superproject */
+		if (S_ISGITLINK(entry.mode))
+			continue;
+		if (S_ISDIR(entry.mode)) {
+			struct tree *tree = lookup_tree(entry.sha1);
+			if (tree)
+				obj = &tree->object;
+		}
+		else {
+			struct blob *blob = lookup_blob(entry.sha1);
+			if (blob)
+				obj = &blob->object;
+		}
+		if (!obj || process(walker, obj))
+			return -1;
+	}
+	free(tree->buffer);
+	tree->buffer = NULL;
+	tree->size = 0;
+	return 0;
+}
+
+#define COMPLETE	(1U << 0)
+#define SEEN		(1U << 1)
+#define TO_SCAN		(1U << 2)
+
+static struct commit_list *complete = NULL;
+
+static int process_commit(struct walker *walker, struct commit *commit)
+{
+	if (parse_commit(commit))
+		return -1;
+
+	while (complete && complete->item->date >= commit->date) {
+		pop_most_recent_commit(&complete, COMPLETE);
+	}
+
+	if (commit->object.flags & COMPLETE)
+		return 0;
+
+	hashcpy(current_commit_sha1, commit->object.sha1);
+
+	walker_say(walker, "walk %s\n", sha1_to_hex(commit->object.sha1));
+
+	if (walker->get_tree) {
+		if (process(walker, &commit->tree->object))
+			return -1;
+		if (!walker->get_all)
+			walker->get_tree = 0;
+	}
+	if (walker->get_history) {
+		struct commit_list *parents = commit->parents;
+		for (; parents; parents = parents->next) {
+			if (process(walker, &parents->item->object))
+				return -1;
+		}
+	}
+	return 0;
+}
+
+static int process_tag(struct walker *walker, struct tag *tag)
+{
+	if (parse_tag(tag))
+		return -1;
+	return process(walker, tag->tagged);
+}
+
+static struct object_list *process_queue = NULL;
+static struct object_list **process_queue_end = &process_queue;
+
+static int process_object(struct walker *walker, struct object *obj)
+{
+	if (obj->type == OBJ_COMMIT) {
+		if (process_commit(walker, (struct commit *)obj))
+			return -1;
+		return 0;
+	}
+	if (obj->type == OBJ_TREE) {
+		if (process_tree(walker, (struct tree *)obj))
+			return -1;
+		return 0;
+	}
+	if (obj->type == OBJ_BLOB) {
+		return 0;
+	}
+	if (obj->type == OBJ_TAG) {
+		if (process_tag(walker, (struct tag *)obj))
+			return -1;
+		return 0;
+	}
+	return error("Unable to determine requirements "
+		     "of type %s for %s",
+		     typename(obj->type), sha1_to_hex(obj->sha1));
+}
+
+static int process(struct walker *walker, struct object *obj)
+{
+	if (obj->flags & SEEN)
+		return 0;
+	obj->flags |= SEEN;
+
+	if (has_sha1_file(obj->sha1)) {
+		/* We already have it, so we should scan it now. */
+		obj->flags |= TO_SCAN;
+	}
+	else {
+		if (obj->flags & COMPLETE)
+			return 0;
+		walker->prefetch(walker, obj->sha1);
+	}
+
+	object_list_insert(obj, process_queue_end);
+	process_queue_end = &(*process_queue_end)->next;
+	return 0;
+}
+
+static int loop(struct walker *walker)
+{
+	struct object_list *elem;
+
+	while (process_queue) {
+		struct object *obj = process_queue->item;
+		elem = process_queue;
+		process_queue = elem->next;
+		free(elem);
+		if (!process_queue)
+			process_queue_end = &process_queue;
+
+		/* If we are not scanning this object, we placed it in
+		 * the queue because we needed to fetch it first.
+		 */
+		if (! (obj->flags & TO_SCAN)) {
+			if (walker->fetch(walker, obj->sha1)) {
+				report_missing(obj);
+				return -1;
+			}
+		}
+		if (!obj->type)
+			parse_object(obj->sha1);
+		if (process_object(walker, obj))
+			return -1;
+	}
+	return 0;
+}
+
+static int interpret_target(struct walker *walker, char *target, unsigned char *sha1)
+{
+	if (!get_sha1_hex(target, sha1))
+		return 0;
+	if (!check_ref_format(target)) {
+		if (!walker->fetch_ref(walker, target, sha1)) {
+			return 0;
+		}
+	}
+	return -1;
+}
+
+static int mark_complete(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	struct commit *commit = lookup_commit_reference_gently(sha1, 1);
+	if (commit) {
+		commit->object.flags |= COMPLETE;
+		insert_by_date(commit, &complete);
+	}
+	return 0;
+}
+
+int walker_targets_stdin(char ***target, const char ***write_ref)
+{
+	int targets = 0, targets_alloc = 0;
+	struct strbuf buf;
+	*target = NULL; *write_ref = NULL;
+	strbuf_init(&buf);
+	while (1) {
+		char *rf_one = NULL;
+		char *tg_one;
+
+		read_line(&buf, stdin, '\n');
+		if (buf.eof)
+			break;
+		tg_one = buf.buf;
+		rf_one = strchr(tg_one, '\t');
+		if (rf_one)
+			*rf_one++ = 0;
+
+		if (targets >= targets_alloc) {
+			targets_alloc = targets_alloc ? targets_alloc * 2 : 64;
+			*target = xrealloc(*target, targets_alloc * sizeof(**target));
+			*write_ref = xrealloc(*write_ref, targets_alloc * sizeof(**write_ref));
+		}
+		(*target)[targets] = xstrdup(tg_one);
+		(*write_ref)[targets] = rf_one ? xstrdup(rf_one) : NULL;
+		targets++;
+	}
+	return targets;
+}
+
+void walker_targets_free(int targets, char **target, const char **write_ref)
+{
+	while (targets--) {
+		free(target[targets]);
+		if (write_ref && write_ref[targets])
+			free((char *) write_ref[targets]);
+	}
+}
+
+int walker_fetch(struct walker *walker, int targets, char **target,
+		 const char **write_ref, const char *write_ref_log_details)
+{
+	struct ref_lock **lock = xcalloc(targets, sizeof(struct ref_lock *));
+	unsigned char *sha1 = xmalloc(targets * 20);
+	char *msg;
+	int ret;
+	int i;
+
+	save_commit_buffer = 0;
+	track_object_refs = 0;
+
+	for (i = 0; i < targets; i++) {
+		if (!write_ref || !write_ref[i])
+			continue;
+
+		lock[i] = lock_ref_sha1(write_ref[i], NULL);
+		if (!lock[i]) {
+			error("Can't lock ref %s", write_ref[i]);
+			goto unlock_and_fail;
+		}
+	}
+
+	if (!walker->get_recover)
+		for_each_ref(mark_complete, NULL);
+
+	for (i = 0; i < targets; i++) {
+		if (interpret_target(walker, target[i], &sha1[20 * i])) {
+			error("Could not interpret %s as something to pull", target[i]);
+			goto unlock_and_fail;
+		}
+		if (process(walker, lookup_unknown_object(&sha1[20 * i])))
+			goto unlock_and_fail;
+	}
+
+	if (loop(walker))
+		goto unlock_and_fail;
+
+	if (write_ref_log_details) {
+		msg = xmalloc(strlen(write_ref_log_details) + 12);
+		sprintf(msg, "fetch from %s", write_ref_log_details);
+	} else {
+		msg = NULL;
+	}
+	for (i = 0; i < targets; i++) {
+		if (!write_ref || !write_ref[i])
+			continue;
+		ret = write_ref_sha1(lock[i], &sha1[20 * i], msg ? msg : "fetch (unknown)");
+		lock[i] = NULL;
+		if (ret)
+			goto unlock_and_fail;
+	}
+	free(msg);
+
+	return 0;
+
+unlock_and_fail:
+	for (i = 0; i < targets; i++)
+		if (lock[i])
+			unlock_ref(lock[i]);
+
+	return -1;
+}
+
+void walker_free(struct walker *walker)
+{
+	walker->cleanup(walker);
+	free(walker);
+}