checkout $tree: do not throw away unchanged index entries

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 54f80bd38a7413390ed2093a626b129a1a3e8e7f..8129eee837d68df4238c898829a945a6145f71c3 100644 (file)
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -67,6 +67,7 @@ static int update_some(const unsigned char *sha1, const char *base, int baselen,
 {
        int len;
        struct cache_entry *ce;
+       int pos;
 
        if (S_ISDIR(mode))
                return READ_TREE_RECURSIVE;
@@ -79,6 +80,23 @@ static int update_some(const unsigned char *sha1, const char *base, int baselen,
        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
        ce->ce_namelen = len;
        ce->ce_mode = create_ce_mode(mode);
+
+       /*
+        * If the entry is the same as the current index, we can leave the old
+        * entry in place. Whether it is UPTODATE or not, checkout_entry will
+        * do the right thing.
+        */
+       pos = cache_name_pos(ce->name, ce->ce_namelen);
+       if (pos >= 0) {
+               struct cache_entry *old = active_cache[pos];
+               if (ce->ce_mode == old->ce_mode &&
+                   !hashcmp(ce->sha1, old->sha1)) {
+                       old->ce_flags |= CE_UPDATE;
+                       free(ce);
+                       return 0;
+               }
+       }
+
        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
        return 0;
 }