create_directories(): remove some memcpy() and strchr() calls

Remove the call to memcpy() and strchr() for each path component
tested, and instead add each path component as we go forward inside
the while-loop.

Impact: small optimisation

Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/entry.c b/entry.c
index bb6bdb9..cc8f0c6 100644
--- a/entry.c
+++ b/entry.c
@@ -2,15 +2,19 @@
 #include "blob.h"
 #include "dir.h"
 
-static void create_directories(const char *path, const struct checkout *state)
+static void create_directories(const char *path, int path_len,
+			       const struct checkout *state)
 {
-	int len = strlen(path);
-	char *buf = xmalloc(len + 1);
-	const char *slash = path;
+	char *buf = xmalloc(path_len + 1);
+	int len = 0;
 
-	while ((slash = strchr(slash+1, '/')) != NULL) {
-		len = slash - path;
-		memcpy(buf, path, len);
+	while (len < path_len) {
+		do {
+			buf[len] = path[len];
+			len++;
+		} while (len < path_len && path[len] != '/');
+		if (len >= path_len)
+			break;
 		buf[len] = 0;
 
 		/*
@@ -190,6 +194,7 @@
 
 	memcpy(path, state->base_dir, len);
 	strcpy(path + len, ce->name);
+	len += ce_namelen(ce);
 
 	if (!lstat(path, &st)) {
 		unsigned changed = ce_match_stat(ce, &st, CE_MATCH_IGNORE_VALID);
@@ -218,6 +223,6 @@
 			return error("unable to unlink old '%s' (%s)", path, strerror(errno));
 	} else if (state->not_new)
 		return 0;
-	create_directories(path, state);
+	create_directories(path, len, state);
 	return write_entry(ce, path, state, 0);
 }