Make "read-tree" know how to do a "1-way merge".

This one just reads one tree, but picks up any matching stat information
from the old index.

diff --git a/read-tree.c b/read-tree.c
index abb5225..46747b5 100644 (file)
--- a/read-tree.c
+++ b/read-tree.c
@@ -169,9 +169,36 @@ static void trivially_merge_cache(struct cache_entry **src, int nr)
                        nr -= 2;
                        active_nr -= 2;
                }
-               *dst = ce;
+               *dst++ = ce;
+               src++;
+               nr--;
+       }
+}
+
+static void merge_stat_info(struct cache_entry **src, int nr)
+{
+       static struct cache_entry null_entry;
+       struct cache_entry **dst = src;
+       struct cache_entry *old = &null_entry;
+
+       while (nr) {
+               struct cache_entry *ce;
+
+               ce = src[0];
+
+               /* We throw away original cache entries except for the stat information */
+               if (!ce_stage(ce)) {
+                       old = ce;
+                       src++;
+                       nr--;
+                       active_nr--;
+                       continue;
+               }
+               if (path_matches(ce, old) && same(ce, old))
+                       *ce = *old;
+               ce->ce_flags &= ~htons(CE_STAGEMASK);
+               *dst++ = ce;
                src++;
-               dst++;
                nr--;
        }
 }
@@ -214,9 +241,16 @@ int main(int argc, char **argv)
                stage++;
        }
        if (merge) {
-               if (stage != 4)
-                       usage("I need three trees to merge: original, branch1 and branch2");
-               trivially_merge_cache(active_cache, active_nr);
+               switch (stage) {
+               case 4: /* Three-way merge */
+                       trivially_merge_cache(active_cache, active_nr);
+                       break;
+               case 2: /* Just read a tree, merge with old cache contents */
+                       merge_stat_info(active_cache, active_nr);
+                       break;
+               default:
+                       die("just how do you expect me to merge %d trees?", stage-1);
+               }
        }
        if (write_cache(newfd, active_cache, active_nr) ||
            rename(".git/index.lock", ".git/index"))