--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/fitz/link.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,106 @@
+// Copyright (C) 2004-2023 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 <math.h>
+
+fz_link *
+fz_new_link_of_size(fz_context *ctx, int size, fz_rect rect, const char *uri)
+{
+	fz_link *link = Memento_label(fz_calloc(ctx, 1, size), "fz_link");
+	link->refs = 1;
+	link->rect = rect;
+
+	fz_try(ctx)
+		link->uri = fz_strdup(ctx, uri);
+	fz_catch(ctx)
+	{
+		fz_drop_link(ctx, link);
+		fz_rethrow(ctx);
+	}
+
+	return link;
+}
+
+fz_link *
+fz_keep_link(fz_context *ctx, fz_link *link)
+{
+	return fz_keep_imp(ctx, link, &link->refs);
+}
+
+void
+fz_drop_link(fz_context *ctx, fz_link *link)
+{
+	while (fz_drop_imp(ctx, link, &link->refs))
+	{
+		fz_link *next = link->next;
+
+		if (link->drop)
+			link->drop(ctx, link);
+
+		fz_free(ctx, link->uri);
+		fz_free(ctx, link);
+		link = next;
+	}
+}
+
+int
+fz_is_external_link(fz_context *ctx, const char *uri)
+{
+	const char *mark;
+	/* Basically, this function returns true, if the URI starts with
+	 * a valid 'scheme' followed by ':'. */
+
+	 if (!uri)
+		 return 0;
+
+	/* All schemes must start with a letter; exit if we don't. */
+	if ((*uri < 'a' || *uri > 'z') && (*uri < 'A' || *uri > 'Z'))
+		return 0;
+	uri++;
+
+	mark = uri;
+
+	/* Subsequent characters can be letters, digits, +, -, or . */
+	while ((*uri >= 'a' && *uri <= 'z') ||
+		(*uri >= 'A' && *uri <= 'Z') ||
+		(*uri >= '0' && *uri <= '9') ||
+		(*uri == '+') ||
+		(*uri == '-') ||
+		(*uri == '.'))
+		++uri;
+
+	return uri[0] == ':' && (uri - mark) > 1;
+}
+
+fz_link_dest fz_make_link_dest_none(void)
+{
+	fz_link_dest dest = { { -1, -1 }, FZ_LINK_DEST_XYZ, NAN, NAN, NAN, NAN, NAN };
+	return dest;
+}
+
+fz_link_dest fz_make_link_dest_xyz(int chapter, int page, float x, float y, float z)
+{
+	fz_link_dest dest = { { chapter, page }, FZ_LINK_DEST_XYZ, x, y, NAN, NAN, z };
+	return dest;
+}