introduce hex2chr() for converting two hexadecimal digits to a character

Add and use a helper function that decodes the char value of two
hexadecimal digits.  It returns a negative number on error, avoids
running over the end of the given string and doesn't shift negative
values.

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

1 files changed, 1 insertions, 20 deletions

diff --git a/url.c b/url.c
index 2d89ad190c..eaf4f07081 100644
--- a/url.c
+++ b/url.c
@@ -29,25 +29,6 @@ int is_url(const char *url)
 	return (url[0] == ':' && url[1] == '/' && url[2] == '/');
 }
 
-static int url_decode_char(const char *q)
-{
-	int i;
-	unsigned char val = 0;
-	for (i = 0; i < 2; i++) {
-		unsigned char c = *q++;
-		val <<= 4;
-		if (c >= '0' && c <= '9')
-			val += c - '0';
-		else if (c >= 'a' && c <= 'f')
-			val += c - 'a' + 10;
-		else if (c >= 'A' && c <= 'F')
-			val += c - 'A' + 10;
-		else
-			return -1;
-	}
-	return val;
-}
-
 static char *url_decode_internal(const char **query, int len,
 				 const char *stop_at, struct strbuf *out,
 				 int decode_plus)
@@ -66,7 +47,7 @@ static char *url_decode_internal(const char **query, int len,
 		}
 
 		if (c == '%') {
-			int val = url_decode_char(q + 1);
+			int val = hex2chr(q + 1);
 			if (0 <= val) {
 				strbuf_addch(out, val);
 				q += 3;