--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/xps/xps-util.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,185 @@
+// Copyright (C) 2004-2021 Artifex Software, Inc.
+//
+// This file is part of MuPDF.
+//
+// MuPDF is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
+//
+// Alternative licensing terms are available from the licensor.
+// For commercial licensing, see <https://www.artifex.com/> or contact
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+#include "mupdf/fitz.h"
+#include "xps-imp.h"
+
+static inline int xps_tolower(int c)
+{
+	if (c >= 'A' && c <= 'Z')
+		return c + 32;
+	return c;
+}
+
+int
+xps_strcasecmp(char *a, char *b)
+{
+	while (xps_tolower(*a) == xps_tolower(*b))
+	{
+		if (*a++ == 0)
+			return 0;
+		b++;
+	}
+	return xps_tolower(*a) - xps_tolower(*b);
+}
+
+/* A URL is defined as consisting of a:
+ * SCHEME (e.g. http:)
+ * AUTHORITY (username, password, hostname, port, eg //test:passwd@mupdf.com:999)
+ * PATH (e.g. /download)
+ * QUERY (e.g. ?view=page)
+ * FRAGMENT (e.g. #fred) (not strictly part of the URL)
+ */
+static char *
+skip_scheme(char *path)
+{
+	char *p = path;
+
+	/* Skip over: alpha *(alpha | digit | "+" | "-" | ".") looking for : */
+	if (*p >= 'a' && *p <= 'z')
+	{
+		/* Starts with a-z */
+	}
+	else if (*p >= 'A' && *p <= 'Z')
+	{
+		/* Starts with A-Z */
+	}
+	else
+		return path;
+
+	while (*++p)
+	{
+		if (*p >= 'a' && *p <= 'z')
+			continue;
+		if (*p >= 'A' && *p <= 'Z')
+			continue;
+		if (*p >= '0' && *p <= '9')
+			continue;
+		if (*p == '+')
+			continue;
+		if (*p == '-')
+			continue;
+		if (*p == '.')
+			continue;
+		if (*p == ':')
+			return p+1;
+		break;
+	}
+	return path;
+}
+
+static char *
+skip_authority(char *path)
+{
+	char *p = path;
+
+	/* Authority section must start with '//' */
+	if (p[0] != '/' || p[1] != '/')
+		return path;
+	p += 2;
+
+	/* Authority is terminated by end of URL, '/' or '?' */
+	while (*p && *p != '/' && *p != '?')
+		p++;
+
+	return p;
+}
+
+#define SEP(x) ((x)=='/' || (x) == 0)
+
+static char *
+clean_path(char *name)
+{
+	char *p, *q, *dotdot, *start;
+	int rooted;
+
+	start = skip_scheme(name);
+	start = skip_authority(start);
+	rooted = start[0] == '/';
+
+	/*
+	 * invariants:
+	 *		p points at beginning of path element we're considering.
+	 *		q points just past the last path element we wrote (no slash).
+	 *		dotdot points just past the point where .. cannot backtrack
+	 *				any further (no slash).
+	 */
+	p = q = dotdot = start + rooted;
+	while (*p)
+	{
+		if(p[0] == '/') /* null element */
+			p++;
+		else if (p[0] == '.' && SEP(p[1]))
+			p += 1; /* don't count the separator in case it is nul */
+		else if (p[0] == '.' && p[1] == '.' && SEP(p[2]))
+		{
+			p += 2;
+			if (q > dotdot) /* can backtrack */
+			{
+				while(--q > dotdot && *q != '/')
+					;
+			}
+			else if (!rooted) /* /.. is / but ./../ is .. */
+			{
+				if (q != start)
+					*q++ = '/';
+				*q++ = '.';
+				*q++ = '.';
+				dotdot = q;
+			}
+		}
+		else /* real path element */
+		{
+			if (q != start+rooted)
+				*q++ = '/';
+			while ((*q = *p) != '/' && *q != 0)
+				p++, q++;
+		}
+	}
+
+	/* Protect against 'blah:' input, where start = q = the terminator.
+	 * We must not overrun it. */
+	if (q == start && *q != 0) /* empty string is really "." */
+		*q++ = '.';
+	*q = '\0';
+
+	return name;
+}
+
+void
+xps_resolve_url(fz_context *ctx, xps_document *doc, char *output, char *base_uri, char *path, int output_size)
+{
+	char *p = skip_authority(skip_scheme(path));
+
+	if (p != path || path[0] == '/')
+	{
+		fz_strlcpy(output, path, output_size);
+	}
+	else
+	{
+		size_t len = fz_strlcpy(output, base_uri, output_size);
+		if (len == 0 || output[len-1] != '/')
+			fz_strlcat(output, "/", output_size);
+		fz_strlcat(output, path, output_size);
+	}
+	clean_path(output);
+}