apply: remove prefix_length member from apply_state

Use a NULL-and-NUL check to see if we have a prefix and consistently use
C string functions on it instead of storing its length in a member of
struct apply_state.  This avoids strlen() calls and simplifies the code.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

apply.c

@@ -79,7 +79,6 @@ int init_apply_state(struct apply_state *state,
 {
 	memset(state, 0, sizeof(*state));
 	state->prefix = prefix;
-	state->prefix_length = state->prefix ? strlen(state->prefix) : 0;
 	state->lock_file = lock_file;
 	state->newfd = -1;
 	state->apply = 1;
@@ -795,11 +794,11 @@ static int guess_p_value(struct apply_state *state, const char *nameline)
 		 * Does it begin with "a/$our-prefix" and such?  Then this is
 		 * very likely to apply to our directory.
 		 */
-		if (!strncmp(name, state->prefix, state->prefix_length))
+		if (starts_with(name, state->prefix))
 			val = count_slashes(state->prefix);
 		else {
 			cp++;
-			if (!strncmp(cp, state->prefix, state->prefix_length))
+			if (starts_with(cp, state->prefix))
 				val = count_slashes(state->prefix) + 1;
 		}
 	}
@@ -2078,10 +2077,9 @@ static int use_patch(struct apply_state *state, struct patch *p)
 	int i;
 
 	/* Paths outside are not touched regardless of "--include" */
-	if (0 < state->prefix_length) {
+	if (state->prefix && *state->prefix) {
-		int pathlen = strlen(pathname);
+		const char *rest;
-		if (pathlen <= state->prefix_length ||
+		if (!skip_prefix(pathname, state->prefix, &rest) || !*rest)
-		    memcmp(state->prefix, pathname, state->prefix_length))
 			return 0;
 	}
 

apply.h

@@ -35,7 +35,6 @@ enum apply_verbosity {
 
 struct apply_state {
 	const char *prefix;
-	int prefix_length;
 
 	/* These are lock_file related */
 	struct lock_file *lock_file;