rerere: Fix use of an empty strbuf.buf

The code incorrectly assumed that strbuf.buf is always an
allocated piece of memory that has NUL at offset strbuf.len.
That assumption does not hold for a freshly initialized empty
strbuf.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-rerere.c b/builtin-rerere.c
index d331772e100d87592d091aa5ad9c38d36bea86c2..b8206744c12307b3efbdebc99e5bcdd4a8632212 100644 (file)
--- a/builtin-rerere.c
+++ b/builtin-rerere.c
@@ -113,8 +113,10 @@ static int handle_file(const char *path,
                                fputs(">>>>>>>\n", out);
                        }
                        if (sha1) {
-                               SHA1_Update(&ctx, one.buf, one.len + 1);
-                               SHA1_Update(&ctx, two.buf, two.len + 1);
+                               SHA1_Update(&ctx, one.buf ? one.buf : "",
+                                           one.len + 1);
+                               SHA1_Update(&ctx, two.buf ? two.buf : "",
+                                           two.len + 1);
                        }
                        strbuf_reset(&one);
                        strbuf_reset(&two);