diff -r 4204db81cdbc -r c89e5edb8eae librazor/path.c
--- a/librazor/path.c	Thu Jul 07 15:17:29 2016 +0100
+++ b/librazor/path.c	Thu Jun 07 18:36:20 2018 +0100
@@ -159,41 +159,129 @@
 
 RAZOR_EXPORT char *razor_path_to_uri(const char *path)
 {
-	char *uri, *p;
+	char *uri, *s;
+	const char *p;
+	int check_dotdot, len;
+	struct razor_uri ru;
 
-	uri = malloc(6 + 3 * strlen(path) + 1);
+	uri = malloc(5 + (4 - 3) + 4 + 3 * strlen(path) + 1);
 
 	strcpy(uri, "file:");
 
-	p = uri + 5;
+	s = uri + 5;
+
+#ifdef MSWIN_API
+	check_dotdot = path[0] != '/' && path[0] != '\\';
+#else
+	check_dotdot = path[0] != '/';
+#endif
+
+	p = path;
 
 #ifdef MSWIN_API
 	/*
 	 * Under MS-Windows, c:/xxx maps to a path of /c:/xxx
+	 * Relative paths that include a drive letter (eg., c:xxx)
+	 * can't be handled directly and have to be converted
+	 * to absolute form.
 	 */
-	if (is_alpha(path[0]) && path[1] == ':' &&
-	    (path[2] == '/' || path[2] == '\\'))
-		*p++ = '/';
+	if (is_alpha(p[0]) && p[1] == ':') {
+		if (p[2] == '/' || p[2] == '\\') {
+			*s++ = '/';
+			*s++ = p[0];
+			*s++ = ':';
+			*s++ = '/';
+			p += 3;
+			/*
+			 * We need to take care that ".." segments don't remove
+			 * the drive letter (eg., c:/../xxx -> file:/c:/../xxx
+			 * which normalizes to file:/xxx).
+			 */
+			check_dotdot = 2;
+		} else {
+			s = razor_abspath(p);
+			uri = razor_path_to_uri(s);
+			free(s);
+			return uri;
+		}
+	}
 #endif
 
-	while(*path) {
-		if (*path == '/' || is_unreserved(*path) ||
-		    is_sub_delim(*path) || *path == ':' || *path == '@')
-			*p++ = *path;
+	/*
+	 * Relative paths are complicated. URIs can't have dot segments
+	 * so these will be removed during normalization. That often does
+	 * the right thing, but where a relative path traverses up the
+	 * tree then the result is a URI that points to somewhere quite
+	 * different to path: eg., file:../dir normalizes to file:dir
+	 * We solve this by inserting a sentinel segment at the beginning.
+	 * If the segment is still present after normalization, then it
+	 * can just be removed. If it is missing, then we need to create
+	 * an absolute path and redo the conversion.
+	 */
+	if (check_dotdot) {
+		*s++ = '%';
+		*s++ = '2';
+		*s++ = 'F';
+		*s++ = '/';
+	}
+
+	while(*p) {
+		if (*p == '/' || is_unreserved(*p) || is_sub_delim(*p) ||
+		    *p == ':' || *p == '@')
+			*s++ = *p;
 #ifdef MSWIN_API
-		else if (*path == '\\')
-			*p++ = '/';
+		else if (*p == '\\')
+			*s++ = '/';
 #endif
 		else {
-			*p++ = '%';
-			*p++ = "0123456789ABCDEF"[(*(unsigned char *)path)/16];
-			*p++ = "0123456789ABCDEF"[(*(unsigned char *)path)%16];
+			*s++ = '%';
+			*s++ = "0123456789ABCDEF"[(*(unsigned char *)p)/16];
+			*s++ = "0123456789ABCDEF"[(*(unsigned char *)p)%16];
 		}
-		path++;
+		p++;
 	}
-	*p++ = '\0';
+	*s++ = '\0';
 
-	return realloc(uri, p - uri);
+	if (razor_uri_parse(&ru, uri, NULL) < 0) {
+		free(uri);
+		return NULL;
+	}
+	free(uri);
+
+	razor_uri_normalize(&ru);
+
+	uri = razor_uri_recompose(&ru);
+
+	razor_uri_destroy(&ru);
+
+	if (check_dotdot == 2) {
+		s = strdup("file:/x:/%2F/");
+		s[6] = path[0];
+		if (str_has_prefix(uri, s)) {
+			free(s);
+			memmove(uri + 5 + 3, uri + 9 + 3,
+				strlen(uri + 9 + 3) + 1);
+			uri = realloc(uri, strlen(uri) + 1);
+		} else {
+			free(s);
+			free(uri);
+			s = razor_abspath(path);
+			uri = razor_path_to_uri(s);
+			free(s);
+		}
+	} else if (check_dotdot) {
+		if (str_has_prefix(uri, "file:%2F/")) {
+			memmove(uri + 5, uri + 9, strlen(uri + 9) + 1);
+			uri = realloc(uri, strlen(uri) + 1);
+		} else {
+			free(uri);
+			s = razor_abspath(path);
+			uri = razor_path_to_uri(s);
+			free(s);
+		}
+	}
+
+	return uri;
 }
 
 RAZOR_EXPORT char *