Add git-update-cache --replace option.

When "path" exists as a file or a symlink in the index, an
attempt to add "path/file" is refused because it results in file
vs directory conflict.  Similarly when "path/file1",
"path/file2", etc. exist, an attempt to add "path" as a file or
a symlink is refused.  With git-update-cache --replace, these
existing entries that conflict with the entry being added are
automatically removed from the cache, with warning messages.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 39 insertions, 15 deletions

diff --git a/read-cache.c b/read-cache.c
index 327888b8ad..47aa2d4469 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -127,10 +127,15 @@ int same_name(struct cache_entry *a, struct cache_entry *b)
  * is being added, or we already have path and path/file is being
  * added.  Either one would result in a nonsense tree that has path
  * twice when git-write-tree tries to write it out.  Prevent it.
+ * 
+ * If ok-to-replace is specified, we remove the conflicting entries
+ * from the cache so the caller should recompute the insert position.
+ * When this happens, we return non-zero.
  */
-static int check_file_directory_conflict(const struct cache_entry *ce)
+static int check_file_directory_conflict(const struct cache_entry *ce,
+					 int ok_to_replace)
 {
-	int pos;
+	int pos, replaced = 0;
 	const char *path = ce->name;
 	int namelen = strlen(path);
 	int stage = ce_stage(ce);
@@ -157,8 +162,13 @@ static int check_file_directory_conflict(const struct cache_entry *ce)
 			 * and we are trying to make it a directory.  This is
 			 * bad.
 			 */
-			free(pathbuf);
-			return -1;
+			if (!ok_to_replace) {
+				free(pathbuf);
+				return -1;
+			}
+			fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path);
+			remove_entry_at(pos);
+			replaced = 1;
 		}
 		*ep = '/';  /* then restore it and go downwards */
 		cp = ep + 1;
@@ -185,30 +195,40 @@ static int check_file_directory_conflict(const struct cache_entry *ce)
 	 *
 	 *        1 path
 	 * pos->  3 path
-	 *        2 path/file
-	 *        3 path/file
+	 *        2 path/file1
+	 *        3 path/file1
+	 *        2 path/file2
+	 *        2 patho
 	 *
 	 * We need to examine pos, ignore it because it is at different
 	 * stage, examine next to find the path/file at stage 2, and
-	 * complain.
+	 * complain.  We need to do this until we are not the leading
+	 * path of an existing entry anymore.
 	 */
 
 	while (pos < active_nr) {
 		struct cache_entry *other = active_cache[pos];
 		if (strncmp(other->name, path, namelen))
 			break; /* it is not our "subdirectory" anymore */
-		if ((ce_stage(other) == stage) && other->name[namelen] == '/')
-			return -1;
+		if ((ce_stage(other) == stage) &&
+		    other->name[namelen] == '/') {
+			if (!ok_to_replace)
+				return -1;
+			fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path);
+			remove_entry_at(pos);
+			replaced = 1;
+			continue; /* cycle without updating pos */
+		}
 		pos++;
 	}
-
-	return 0;
+	return replaced;
 }
 
-int add_cache_entry(struct cache_entry *ce, int ok_to_add)
+int add_cache_entry(struct cache_entry *ce, int option)
 {
 	int pos;
-
+	int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
+	int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
 	pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 
 	/* existing match? Just replace it */
@@ -234,8 +254,12 @@ int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 	if (!ok_to_add)
 		return -1;
 
-	if (check_file_directory_conflict(ce))
-		return -1;
+	if (check_file_directory_conflict(ce, ok_to_replace)) {
+		if (!ok_to_replace)
+			return -1;
+		pos = cache_name_pos(ce->name, htons(ce->ce_flags));
+		pos = -pos-1;
+	}
 
 	/* Make sure the array is big enough .. */
 	if (active_nr == active_alloc) {