unpack-trees: plug minor memory leak

The allocations made by unpack_nondirectories() using create_ce_entry()
are never freed.

In the non-merge case, we duplicate them using add_entry() and later
only look at the first allocated element (src[0]), perhaps even only
by mistake.  Split out the actual addition from add_entry() into the
new helper do_add_entry() and call this non-duplicating function
instead of add_entry() to avoid the leak.

Valgrind reports this for the command "git archive v1.7.9" without
the patch:

  ==13372== LEAK SUMMARY:
  ==13372==    definitely lost: 230,986 bytes in 2,325 blocks
  ==13372==    indirectly lost: 0 bytes in 0 blocks
  ==13372==      possibly lost: 98 bytes in 1 blocks
  ==13372==    still reachable: 2,259,198 bytes in 3,243 blocks
  ==13372==         suppressed: 0 bytes in 0 blocks

And with the patch applied:

  ==13375== LEAK SUMMARY:
  ==13375==    definitely lost: 65 bytes in 1 blocks
  ==13375==    indirectly lost: 0 bytes in 0 blocks
  ==13375==      possibly lost: 0 bytes in 0 blocks
  ==13375==    still reachable: 2,364,417 bytes in 3,245 blocks
  ==13375==         suppressed: 0 bytes in 0 blocks

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

unpack-trees.c

@@ -102,21 +102,28 @@ void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
 		opts->unpack_rejects[i].strdup_strings = 1;
 }
 
-static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
-	unsigned int set, unsigned int clear)
+static void do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
+			 unsigned int set, unsigned int clear)
 {
-	unsigned int size = ce_size(ce);
-	struct cache_entry *new = xmalloc(size);
-
 	clear |= CE_HASHED | CE_UNHASHED;
 
 	if (set & CE_REMOVE)
 		set |= CE_WT_REMOVE;
 
+	ce->next = NULL;
+	ce->ce_flags = (ce->ce_flags & ~clear) | set;
+	add_index_entry(&o->result, ce,
+			ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
+}
+
+static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
+	unsigned int set, unsigned int clear)
+{
+	unsigned int size = ce_size(ce);
+	struct cache_entry *new = xmalloc(size);
+
 	memcpy(new, ce, size);
-	new->next = NULL;
-	new->ce_flags = (new->ce_flags & ~clear) | set;
-	add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
+	do_add_entry(o, new, set, clear);
 }
 
 /*
@@ -587,7 +594,7 @@ static int unpack_nondirectories(int n, unsigned long mask,
 
 	for (i = 0; i < n; i++)
 		if (src[i] && src[i] != o->df_conflict_entry)
-			add_entry(o, src[i], 0, 0);
+			do_add_entry(o, src[i], 0, 0);
 	return 0;
 }