Add trim_end() and use it to remove trailing slashes from repo paths

The new function removes all trailing instances of an arbitrary character
from a copy of the supplied char array. This is then used to remove any
trailing slashes from cgit_query_path.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

shared.c

@@ -228,7 +228,7 @@ void cgit_querystring_cb(const char *name, const char *value)
 	} else if (!strcmp(name, "ofs")) {
 		cgit_query_ofs = atoi(value);
 	} else if (!strcmp(name, "path")) {
-		cgit_query_path = xstrdup(value);
+		cgit_query_path = trim_end(value, '/');
 	} else if (!strcmp(name, "name")) {
 		cgit_query_name = xstrdup(value);
 	}
@@ -257,6 +257,28 @@ int hextoint(char c)
 		return -1;
 }
 
+char *trim_end(const char *str, char c)
+{
+	int len;
+	char *s, *t;
+
+	if (str == NULL)
+		return NULL;
+	t = (char *)str;
+	len = strlen(t);
+	while(len > 0 && t[len - 1] == c)
+		len--;
+
+	if (len == 0)
+		return NULL;
+
+	c = t[len];
+	t[len] = '\0';
+	s = xstrdup(t);
+	t[len] = c;
+	return s;
+}
+
 void cgit_diff_tree_cb(struct diff_queue_struct *q,
 		       struct diff_options *options, void *data)
 {