Support server paths in various path functions

src/host/path_getabsolute.c

@@ -34,6 +34,9 @@ void do_getabsolute(char* result, const char* value, const char* relative_to)
 	result[0] = '\0';
 	if (buffer[0] == '/') {
 		strcat(result, "/");
+		if (buffer[1] == '/') {
+			strcat(result, "/");
+		}
 	}
 
 	prev = NULL;

src/host/path_getrelative.c

@@ -67,6 +67,14 @@ int path_getrelative(lua_State* L)
 		return 1;
 	}
 
+	/* Relative paths within a server can't climb outside the server root.
+	* If the paths don't share server name, return the absolute path. */
+	if (src[0] == '/' && src[1] == '/' && last == 1) {
+		dst[strlen(dst) - 1] = '\0';
+		lua_pushstring(L, dst);
+		return 1;
+	}
+
 	/* count remaining levels in src */
 	count = 0;
 	for (i = last + 1; src[i] != '\0'; ++i) {

src/host/path_normalize.c

@@ -70,8 +70,8 @@ static void* normalize_substring(const char* str, const char* endPtr, char* writ
 			}
 		}
 
-		/* add to the result, filtering out duplicate slashes */
-		if (ch != '/' || last != '/') {
+		/* add to the result, filtering out duplicate slashes, except when they are leading slashes */
+		if (str == &source[1] || (ch != '/' || last != '/')) {
 			*(writePtr++) = ch;
 		}