--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/fitz/zip.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,163 @@
+// 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 <string.h>
+
+#include <zlib.h>
+
+#if !defined (INT32_MAX)
+#define INT32_MAX 2147483647L
+#endif
+
+#define ZIP_LOCAL_FILE_SIG 0x04034b50
+#define ZIP_CENTRAL_DIRECTORY_SIG 0x02014b50
+#define ZIP_END_OF_CENTRAL_DIRECTORY_SIG 0x06054b50
+
+struct fz_zip_writer
+{
+	fz_output *output;
+	fz_buffer *central;
+	int count;
+	int closed;
+};
+
+void
+fz_write_zip_entry(fz_context *ctx, fz_zip_writer *zip, const char *name, fz_buffer *buf, int compress)
+{
+	int offset = fz_tell_output(ctx, zip->output);
+	int sum;
+
+	sum = crc32(0, NULL, 0);
+	sum = crc32(sum, buf->data, (uInt)buf->len);
+
+	/* bit 11 of general purpose bit flag indicates UTF-8. */
+	fz_append_int32_le(ctx, zip->central, ZIP_CENTRAL_DIRECTORY_SIG);
+	fz_append_int16_le(ctx, zip->central, 0); /* version made by: MS-DOS */
+	fz_append_int16_le(ctx, zip->central, 20); /* version to extract: 2.0 */
+	fz_append_int16_le(ctx, zip->central, 1<<11); /* general purpose bit flag */
+	fz_append_int16_le(ctx, zip->central, 0); /* compression method: store */
+	fz_append_int16_le(ctx, zip->central, 0); /* TODO: last mod file time */
+	fz_append_int16_le(ctx, zip->central, 0); /* TODO: last mod file date */
+	fz_append_int32_le(ctx, zip->central, sum); /* crc-32 */
+	fz_append_int32_le(ctx, zip->central, (int)buf->len); /* csize */
+	fz_append_int32_le(ctx, zip->central, (int)buf->len); /* usize */
+	fz_append_int16_le(ctx, zip->central, (int)strlen(name)); /* file name length */
+	fz_append_int16_le(ctx, zip->central, 0); /* extra field length */
+	fz_append_int16_le(ctx, zip->central, 0); /* file comment length */
+	fz_append_int16_le(ctx, zip->central, 0); /* disk number start */
+	fz_append_int16_le(ctx, zip->central, 0); /* internal file attributes */
+	fz_append_int32_le(ctx, zip->central, 0); /* external file attributes */
+	fz_append_int32_le(ctx, zip->central, offset); /* relative offset of local header */
+	fz_append_string(ctx, zip->central, name);
+
+	fz_write_int32_le(ctx, zip->output, ZIP_LOCAL_FILE_SIG);
+	fz_write_int16_le(ctx, zip->output, 20); /* version to extract: 2.0 */
+	fz_write_int16_le(ctx, zip->output, 1<<11); /* general purpose bit flag */
+	fz_write_int16_le(ctx, zip->output, 0); /* compression method: store */
+	fz_write_int16_le(ctx, zip->output, 0); /* TODO: last mod file time */
+	fz_write_int16_le(ctx, zip->output, 0); /* TODO: last mod file date */
+	fz_write_int32_le(ctx, zip->output, sum); /* crc-32 */
+	fz_write_int32_le(ctx, zip->output, (int)buf->len); /* csize */
+	fz_write_int32_le(ctx, zip->output, (int)buf->len); /* usize */
+	fz_write_int16_le(ctx, zip->output, (int)strlen(name)); /* file name length */
+	fz_write_int16_le(ctx, zip->output, 0); /* extra field length */
+	fz_write_data(ctx, zip->output, name, strlen(name));
+	fz_write_data(ctx, zip->output, buf->data, buf->len);
+
+	++zip->count;
+}
+
+void
+fz_close_zip_writer(fz_context *ctx, fz_zip_writer *zip)
+{
+	int64_t offset = fz_tell_output(ctx, zip->output);
+
+	fz_write_data(ctx, zip->output, zip->central->data, zip->central->len);
+
+	fz_write_int32_le(ctx, zip->output, ZIP_END_OF_CENTRAL_DIRECTORY_SIG);
+	fz_write_int16_le(ctx, zip->output, 0); /* number of this disk */
+	fz_write_int16_le(ctx, zip->output, 0); /* number of disk where central directory starts */
+	fz_write_int16_le(ctx, zip->output, zip->count); /* entries in central directory in this disk */
+	fz_write_int16_le(ctx, zip->output, zip->count); /* entries in central directory in total */
+	fz_write_int32_le(ctx, zip->output, (int)zip->central->len); /* size of the central directory */
+	fz_write_int32_le(ctx, zip->output, (int)offset); /* offset of the central directory */
+	fz_write_int16_le(ctx, zip->output, 5); /* zip file comment length */
+
+	fz_write_data(ctx, zip->output, "MuPDF", 5);
+
+	fz_close_output(ctx, zip->output);
+
+	zip->closed = 1;
+}
+
+void
+fz_drop_zip_writer(fz_context *ctx, fz_zip_writer *zip)
+{
+	if (!zip)
+		return;
+	if (!zip->closed)
+		fz_warn(ctx, "dropping unclosed zip writer");
+	fz_drop_output(ctx, zip->output);
+	fz_drop_buffer(ctx, zip->central);
+	fz_free(ctx, zip);
+}
+
+fz_zip_writer *
+fz_new_zip_writer_with_output(fz_context *ctx, fz_output *out)
+{
+	fz_zip_writer *zip = NULL;
+
+	fz_var(zip);
+
+	fz_try(ctx)
+	{
+		zip = fz_malloc_struct(ctx, fz_zip_writer);
+		zip->output = out;
+		zip->central = fz_new_buffer(ctx, 0);
+	}
+	fz_catch(ctx)
+	{
+		fz_drop_output(ctx, out);
+		if (zip)
+			fz_drop_buffer(ctx, zip->central);
+		fz_free(ctx, zip);
+		fz_rethrow(ctx);
+	}
+	return zip;
+}
+
+fz_zip_writer *
+fz_new_zip_writer(fz_context *ctx, const char *filename)
+{
+	fz_output *out = fz_new_output_with_path(ctx, filename, 0);
+	fz_zip_writer *zip = NULL;
+	fz_try(ctx)
+		zip = fz_new_zip_writer_with_output(ctx, out);
+	fz_catch(ctx)
+	{
+		fz_drop_output(ctx, out);
+		fz_rethrow(ctx);
+	}
+	return zip;
+}