Subject: Re: What's cooking in git.git (Aug 2008, #05; Tue, 19)

From: Junio C Hamano <[email-masked]>
Date: Tue, 02 Sep 2008 13:43:30 -0700

Junio C Hamano <[email-masked]> writes:

> Miklos Vajna <[email-masked]> writes:
>
>> I tried to let cmd_revert() use merge_trees() only and not
>> merge_recursive_generic(), but something is fishy with it.
> Here is a partial fix to address the above issues I noticed on
> top of your version; untested.

This has a few fix-ups in addition to the one I sent earlier (not
incremental, this applies directly on top of yours, bypassing the earlier
one), and has passed the self tests.

 builtin-revert.c |   47 +++++++++++++++++++++++++++++++++++++----------
 1 files changed, 37 insertions(+), 10 deletions(-)

diff --git i/builtin-revert.c w/builtin-revert.c
index 3071518..8486539 100644
--- i/builtin-revert.c
+++ w/builtin-revert.c
@@ -234,16 +234,27 @@ static int index_is_dirty(void)
 	return !!DIFF_OPT_TST(&rev.diffopt, HAS_CHANGES);
 }
 
+static struct tree *empty_tree(void)
+{
+	struct tree *tree = xcalloc(1, sizeof(struct tree));
+
+	tree->object.parsed = 1;
+	tree->object.type = OBJ_TREE;
+	pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
+	return tree;
+}
+
 static int revert_or_cherry_pick(int argc, const char **argv)
 {
 	unsigned char head[20];
 	struct commit *base, *next, *parent;
-	int i;
+	int i, index_fd, clean;
 	char *oneline, *reencoded_message = NULL;
 	const char *message, *encoding;
 	const char *defmsg = xstrdup(git_path("MERGE_MSG"));
 	struct merge_options o;
-	struct tree *result;
+	struct tree *result, *next_tree, *base_tree, *head_tree;
+	static struct lock_file index_lock;
 
 	git_config(git_default_config, NULL);
 	me = action == REVERT ? "revert" : "cherry-pick";
@@ -254,6 +265,8 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 	if (action == REVERT && !no_replay)
 		die("revert is incompatible with replay");
 
+	if (read_cache() < 0)
+		die("git %s: failed to read the index", me);
 	if (no_commit) {
 		/*
 		 * We do not intend to commit immediately.  We just want to
@@ -266,12 +279,12 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 	} else {
 		if (get_sha1("HEAD", head))
 			die ("You do not have a valid HEAD");
-		if (read_cache() < 0)
-			die("could not read the index");
 		if (index_is_dirty())
 			die ("Dirty index: cannot %s", me);
-		discard_cache();
 	}
+	discard_cache();
+
+	index_fd = hold_locked_index(&index_lock, 1);
 
 	if (!commit->parents) {
 		if (action == REVERT)
@@ -305,6 +318,10 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 		die ("Cannot get commit message for %s",
 				sha1_to_hex(commit->object.sha1));
 
+	if (parent && parse_commit(parent) < 0)
+		die("%s: cannot parse parent commit %s",
+		    me, sha1_to_hex(parent->object.sha1));
+
 	/*
 	 * "commit" is an existing commit.  We would want to apply
 	 * the difference it introduces since its first parent "prev"
@@ -351,11 +368,21 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 	init_merge_options(&o);
 	o.branch1 = "HEAD";
 	o.branch2 = oneline;
-	parse_commit(next);
-	parse_commit(base);
-	if (!merge_trees(&o, lookup_commit_reference_gently(head, 0)->tree,
-				next->tree, base->tree, &result) ||
-		write_cache_as_tree(head, 0, NULL)) {
+
+	head_tree = parse_tree_indirect(head);
+	next_tree = next ? next->tree : empty_tree();
+	base_tree = base ? base->tree : empty_tree();
+
+	clean = merge_trees(&o,
+			    head_tree,
+			    next_tree, base_tree, &result);
+
+	if (active_cache_changed &&
+	    (write_cache(index_fd, active_cache, active_nr) ||
+	     commit_locked_index(&index_lock)))
+		die("%s: Unable to write new index file", me);
+
+	if (!clean) {
 		add_to_msg("\nConflicts:\n\n");
 		for (i = 0; i < active_nr;) {
 			struct cache_entry *ce = active_cache[i++];