1 files changed, 69 insertions, 11 deletions

diff --git a/merge-recursive.c b/merge-recursive.c
index e1aebd7727..595b0226ac 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -16,6 +16,22 @@
 #include "path-list.h"
 #include "xdiff-interface.h"
 
+static int subtree_merge;
+
+static struct tree *shift_tree_object(struct tree *one, struct tree *two)
+{
+	unsigned char shifted[20];
+
+	/*
+	 * NEEDSWORK: this limits the recursion depth to hardcoded
+	 * value '2' to avoid excessive overhead.
+	 */
+	shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
+	if (!hashcmp(two->object.sha1, shifted))
+		return two;
+	return lookup_tree(shifted);
+}
+
 /*
  * A virtual commit has
  * - (const char *)commit->util set to the name, and
@@ -221,7 +237,7 @@ static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 	struct cache_entry *ce;
 	ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 	if (!ce)
-		return error("cache_addinfo failed: %s", strerror(cache_errno));
+		return error("addinfo_cache failed for path '%s'", path);
 	return add_cache_entry(ce, options);
 }
 
@@ -580,9 +596,31 @@ static void update_file_flags(const unsigned char *sha,
 
 		if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 			int fd;
-			if (mkdir_p(path, 0777))
-				die("failed to create path %s: %s", path, strerror(errno));
-			unlink(path);
+			int status;
+			const char *msg = "failed to create path '%s'%s";
+
+			status = mkdir_p(path, 0777);
+			if (status) {
+				if (status == -3) {
+					/* something else exists */
+					error(msg, path, ": perhaps a D/F conflict?");
+					update_wd = 0;
+					goto update_index;
+				}
+				die(msg, path, "");
+			}
+			if (unlink(path)) {
+				if (errno == EISDIR) {
+					/* something else exists */
+					error(msg, path, ": perhaps a D/F conflict?");
+					update_wd = 0;
+					goto update_index;
+				}
+				if (errno != ENOENT)
+					die("failed to unlink %s "
+					    "in preparation to update: %s",
+					    path, strerror(errno));
+			}
 			if (mode & 0100)
 				mode = 0777;
 			else
@@ -604,6 +642,7 @@ static void update_file_flags(const unsigned char *sha,
 			die("do not know what to do with %06o %s '%s'",
 			    mode, sha1_to_hex(sha), path);
 	}
+ update_index:
 	if (update_cache)
 		add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 }
@@ -1002,9 +1041,9 @@ static int process_renames(struct path_list *a_renames,
 	return clean_merge;
 }
 
-static unsigned char *has_sha(const unsigned char *sha)
+static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
 {
-	return is_null_sha1(sha) ? NULL: (unsigned char *)sha;
+	return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
 }
 
 /* Per entry merge function */
@@ -1017,12 +1056,12 @@ static int process_entry(const char *path, struct stage_data *entry,
 	print_index_entry("\tpath: ", entry);
 	*/
 	int clean_merge = 1;
-	unsigned char *o_sha = has_sha(entry->stages[1].sha);
-	unsigned char *a_sha = has_sha(entry->stages[2].sha);
-	unsigned char *b_sha = has_sha(entry->stages[3].sha);
 	unsigned o_mode = entry->stages[1].mode;
 	unsigned a_mode = entry->stages[2].mode;
 	unsigned b_mode = entry->stages[3].mode;
+	unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
+	unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
+	unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
 
 	if (o_sha && (!a_sha || !b_sha)) {
 		/* Case A: Deleted in one */
@@ -1123,6 +1162,12 @@ static int process_entry(const char *path, struct stage_data *entry,
 				update_file_flags(mfi.sha, mfi.mode, path,
 					      0 /* update_cache */, 1 /* update_working_directory */);
 		}
+	} else if (!o_sha && !a_sha && !b_sha) {
+		/*
+		 * this entry was deleted altogether. a_mode == 0 means
+		 * we had that path and want to actively remove it.
+		 */
+		remove_file(1, path, !a_mode);
 	} else
 		die("Fatal merge failure, shouldn't happen.");
 
@@ -1137,6 +1182,12 @@ static int merge_trees(struct tree *head,
 		       struct tree **result)
 {
 	int code, clean;
+
+	if (subtree_merge) {
+		merge = shift_tree_object(head, merge);
+		common = shift_tree_object(head, common);
+	}
+
 	if (sha_eq(common->object.sha1, merge->object.sha1)) {
 		output(0, "Already uptodate!");
 		*result = head;
@@ -1342,6 +1393,13 @@ int main(int argc, char *argv[])
 	struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 	int index_fd;
 
+	if (argv[0]) {
+		int namelen = strlen(argv[0]);
+		if (8 < namelen &&
+		    !strcmp(argv[0] + namelen - 8, "-subtree"))
+			subtree_merge = 1;
+	}
+
 	git_config(merge_config);
 	if (getenv("GIT_MERGE_VERBOSITY"))
 		verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
@@ -1378,7 +1436,7 @@ int main(int argc, char *argv[])
 	if (show(3))
 		printf("Merging %s with %s\n", branch1, branch2);
 
-	index_fd = hold_lock_file_for_update(lock, get_index_file(), 1);
+	index_fd = hold_locked_index(lock, 1);
 
 	for (i = 0; i < bases_count; i++) {
 		struct commit *ancestor = get_ref(bases[i]);
@@ -1388,7 +1446,7 @@ int main(int argc, char *argv[])
 
 	if (active_cache_changed &&
 	    (write_cache(index_fd, active_cache, active_nr) ||
-	     close(index_fd) || commit_lock_file(lock)))
+	     close(index_fd) || commit_locked_index(lock)))
 			die ("unable to write %s", get_index_file());
 
 	return clean ? 0: 1;