git-fmt-merge-msg: make it usable from other builtins

diff --git a/read-cache.c b/read-cache.c
index 8e5fbb619295fe3e4d950e8926d8034d6f825e41..d801f9d1cf9eca5ddeff2f0af4549bbc1e72423f 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -138,6 +138,16 @@ static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
        return 0;
 }
 
+static int is_empty_blob_sha1(const unsigned char *sha1)
+{
+       static const unsigned char empty_blob_sha1[20] = {
+               0xe6,0x9d,0xe2,0x9b,0xb2,0xd1,0xd6,0x43,0x4b,0x8b,
+               0x29,0xae,0x77,0x5a,0xd8,0xc2,0xe4,0x8c,0x53,0x91
+       };
+
+       return !hashcmp(sha1, empty_blob_sha1);
+}
+
 static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
 {
        unsigned int changed = 0;
@@ -193,6 +203,12 @@ static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
        if (ce->ce_size != (unsigned int) st->st_size)
                changed |= DATA_CHANGED;
 
+       /* Racily smudged entry? */
+       if (!ce->ce_size) {
+               if (!is_empty_blob_sha1(ce->sha1))
+                       changed |= DATA_CHANGED;
+       }
+
        return changed;
 }
 
@@ -1394,3 +1410,34 @@ int write_index(const struct index_state *istate, int newfd)
        }
        return ce_flush(&c, newfd);
 }
+
+/*
+ * Read the index file that is potentially unmerged into given
+ * index_state, dropping any unmerged entries.  Returns true is
+ * the index is unmerged.  Callers who want to refuse to work
+ * from an unmerged state can call this and check its return value,
+ * instead of calling read_cache().
+ */
+int read_index_unmerged(struct index_state *istate)
+{
+       int i;
+       struct cache_entry **dst;
+       struct cache_entry *last = NULL;
+
+       read_index(istate);
+       dst = istate->cache;
+       for (i = 0; i < istate->cache_nr; i++) {
+               struct cache_entry *ce = istate->cache[i];
+               if (ce_stage(ce)) {
+                       remove_name_hash(ce);
+                       if (last && !strcmp(ce->name, last->name))
+                               continue;
+                       cache_tree_invalidate_path(istate->cache_tree, ce->name);
+                       last = ce;
+                       continue;
+               }
+               *dst++ = ce;
+       }
+       istate->cache_nr = dst - istate->cache;
+       return !!last;
+}