Add get_merge_bases_clean()

diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index bb50fbd274e2d7e73fc3c6f86a73bd22f636400e..9a2099d7307903d62c85f3483a22969ab5094c84 100644 (file)
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -24,14 +24,14 @@ static int trivial_merges_only = 0;
 static int aggressive = 0;
 static int verbose_update = 0;
 static volatile int progress_update = 0;
+static const char *prefix = NULL;
 
 static int head_idx = -1;
 static int merge_size = 0;
 
 static struct object_list *trees = NULL;
 
-static struct cache_entry df_conflict_entry = {
-};
+static struct cache_entry df_conflict_entry;
 
 struct tree_entry_list {
        struct tree_entry_list *next;
@@ -412,7 +412,8 @@ static int unpack_trees(merge_fn_t fn)
                        posns[i] = create_tree_entry_list((struct tree *) posn->item);
                        posn = posn->next;
                }
-               if (unpack_trees_rec(posns, len, "", fn, &indpos))
+               if (unpack_trees_rec(posns, len, prefix ? prefix : "",
+                                    fn, &indpos))
                        return -1;
        }
 
@@ -761,6 +762,28 @@ static int twoway_merge(struct cache_entry **src)
                return deleted_entry(oldtree, current);
 }
 
+/*
+ * Bind merge.
+ *
+ * Keep the index entries at stage0, collapse stage1 but make sure
+ * stage0 does not have anything there.
+ */
+static int bind_merge(struct cache_entry **src)
+{
+       struct cache_entry *old = src[0];
+       struct cache_entry *a = src[1];
+
+       if (merge_size != 1)
+               return error("Cannot do a bind merge of %d trees\n",
+                            merge_size);
+       if (a && old)
+               die("Entry '%s' overlaps.  Cannot bind.", a->name);
+       if (!a)
+               return keep_entry(old);
+       else
+               return merged_entry(a, NULL);
+}
+
 /*
  * One-way merge.
  *
@@ -851,7 +874,7 @@ static void prime_cache_tree(void)
 
 }
 
-static const char read_tree_usage[] = "git-read-tree (<sha> | -m [--aggressive] [-u | -i] <sha1> [<sha2> [<sha3>]])";
+static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] <sha1> [<sha2> [<sha3>]])";
 
 static struct lock_file lock_file;
 
@@ -896,12 +919,27 @@ int cmd_read_tree(int argc, const char **argv, char **envp)
                        continue;
                }
 
+               /* "--prefix=<subdirectory>/" means keep the current index
+                *  entries and put the entries from the tree under the
+                * given subdirectory.
+                */
+               if (!strncmp(arg, "--prefix=", 9)) {
+                       if (stage || merge || prefix)
+                               usage(read_tree_usage);
+                       prefix = arg + 9;
+                       merge = 1;
+                       stage = 1;
+                       if (read_cache_unmerged())
+                               die("you need to resolve your current index first");
+                       continue;
+               }
+
                /* This differs from "-m" in that we'll silently ignore
                 * unmerged entries and overwrite working tree files that
                 * correspond to them.
                 */
                if (!strcmp(arg, "--reset")) {
-                       if (stage || merge)
+                       if (stage || merge || prefix)
                                usage(read_tree_usage);
                        reset = 1;
                        merge = 1;
@@ -922,7 +960,7 @@ int cmd_read_tree(int argc, const char **argv, char **envp)
 
                /* "-m" stands for "merge", meaning we start in stage 1 */
                if (!strcmp(arg, "-m")) {
-                       if (stage || merge)
+                       if (stage || merge || prefix)
                                usage(read_tree_usage);
                        if (read_cache_unmerged())
                                die("you need to resolve your current index first");
@@ -944,12 +982,31 @@ int cmd_read_tree(int argc, const char **argv, char **envp)
        if ((update||index_only) && !merge)
                usage(read_tree_usage);
 
+       if (prefix) {
+               int pfxlen = strlen(prefix);
+               int pos;
+               if (prefix[pfxlen-1] != '/')
+                       die("prefix must end with /");
+               if (stage != 2)
+                       die("binding merge takes only one tree");
+               pos = cache_name_pos(prefix, pfxlen);
+               if (0 <= pos)
+                       die("corrupt index file");
+               pos = -pos-1;
+               if (pos < active_nr &&
+                   !strncmp(active_cache[pos]->name, prefix, pfxlen))
+                       die("subdirectory '%s' already exists.", prefix);
+               pos = cache_name_pos(prefix, pfxlen-1);
+               if (0 <= pos)
+                       die("file '%.*s' already exists.", pfxlen-1, prefix);
+       }
+
        if (merge) {
                if (stage < 2)
                        die("just how do you expect me to merge %d trees?", stage-1);
                switch (stage - 1) {
                case 1:
-                       fn = oneway_merge;
+                       fn = prefix ? bind_merge : oneway_merge;
                        break;
                case 2:
                        fn = twoway_merge;
@@ -975,7 +1032,7 @@ int cmd_read_tree(int argc, const char **argv, char **envp)
         * valid cache-tree because the index must match exactly
         * what came from the tree.
         */
-       if (trees && trees->item && (!merge || (stage == 2))) {
+       if (trees && trees->item && !prefix && (!merge || (stage == 2))) {
                cache_tree_free(&active_cache_tree);
                prime_cache_tree();
        }