url.c: simplify is_url()

The function was implemented in an overly complicated way.
Rewrite it to check from left to right in a single pass.

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

diff --git a/url.c b/url.c
index 6a5495960f03ded65f0f5f8b8bd5c7cd98c0b05e..8d64d902ec5048c7d65ddf5eaa7e99ec3b3a76b7 100644 (file)
--- a/url.c
+++ b/url.c
@@ -17,35 +17,15 @@ int is_urlschemechar(int first_flag, int ch)
 
 int is_url(const char *url)
 {
-       const char *url2, *first_slash;
-
-       if (!url)
-               return 0;
-       url2 = url;
-       first_slash = strchr(url, '/');
-
-       /* Input with no slash at all or slash first can't be URL. */
-       if (!first_slash || first_slash == url)
-               return 0;
-       /* Character before must be : and next must be /. */
-       if (first_slash[-1] != ':' || first_slash[1] != '/')
+       /* Is "scheme" part reasonable? */
+       if (!url || !is_urlschemechar(1, *url++))
                return 0;
-       /* There must be something before the :// */
-       if (first_slash == url + 1)
-               return 0;
-       /*
-        * Check all characters up to first slash - 1. Only alphanum
-        * is allowed.
-        */
-       url2 = url;
-       while (url2 < first_slash - 1) {
-               if (!is_urlschemechar(url2 == url, (unsigned char)*url2))
+       while (*url && *url != ':') {
+               if (!is_urlschemechar(0, *url++))
                        return 0;
-               url2++;
        }
-
-       /* Valid enough. */
-       return 1;
+       /* We've seen "scheme"; we want colon-slash-slash */
+       return (url[0] == ':' && url[1] == '/' && url[2] == '/');
 }
 
 static int url_decode_char(const char *q)