Merge branch 'jc/dirwalk-n-cache-tree' into next

* jc/dirwalk-n-cache-tree:

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

diff --combined read-tree.c
index a3ada55c1571e52fb3edf7c181ebfd000d7b8db6,99e7c750444117fe07b25bd75d454f03da2134fe..55f7f87133c4a310855fe478452dbc51f6d28fca
--- 1/read-tree.c
--- 2/read-tree.c
+++ b/read-tree.c
@@@ -22,7 -22,6 +22,7 @@@ 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;
@@@ -371,8 -370,7 +371,8 @@@ static int unpack_trees(merge_fn_t fn
                        posns[i] = ((struct tree *) posn->item)->entries;
                        posn = posn->next;
                }
 -              if (unpack_trees_rec(posns, len, "", fn, &indpos))
 +              if (unpack_trees_rec(posns, len, prefix ? prefix : "",
 +                                   fn, &indpos))
                        return -1;
        }
  
@@@ -721,28 -719,6 +721,28 @@@ static int twoway_merge(struct cache_en
                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.
   *
@@@ -758,10 -734,8 +758,10 @@@ static int oneway_merge(struct cache_en
                return error("Cannot do a oneway merge of %d trees",
                             merge_size);
  
 -      if (!a)
 +      if (!a) {
 +              invalidate_ce_path(old);
                return deleted_entry(old, old);
 +      }
        if (old && same(old, a)) {
                if (reset) {
                        struct stat st;
@@@ -801,7 -775,7 +801,7 @@@ static void prime_cache_tree_rec(struc
  {
        struct tree_entry_list *ent;
        int cnt;
-       
+ 
        memcpy(it->sha1, tree->object.sha1, 20);
        for (cnt = 0, ent = tree->entries; ent; ent = ent->next) {
                if (!ent->directory)
@@@ -830,7 -804,7 +830,7 @@@ 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 cache_file cache_file;
  
@@@ -875,24 -849,9 +875,24 @@@ int main(int argc, char **argv
                        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 */
                if (!strcmp(arg, "--reset")) {
 -                      if (stage || merge)
 +                      if (stage || merge || prefix)
                                usage(read_tree_usage);
                        reset = 1;
                        merge = 1;
@@@ -913,7 -872,7 +913,7 @@@
  
                /* "-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");
@@@ -935,31 -894,12 +935,31 @@@
        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;