--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/pdf/pdf-graft.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,293 @@
+// 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 "mupdf/pdf.h"
+
+#include <assert.h>
+
+struct pdf_graft_map
+{
+	int refs;
+	int len;
+	pdf_document *src;
+	pdf_document *dst;
+	int *dst_from_src;
+};
+
+pdf_graft_map *
+pdf_new_graft_map(fz_context *ctx, pdf_document *dst)
+{
+	pdf_graft_map *map = NULL;
+
+	if (dst == NULL)
+		fz_throw(ctx, FZ_ERROR_ARGUMENT, "cannot create graft make without a destination document");
+
+	map = fz_malloc_struct(ctx, pdf_graft_map);
+
+	map->dst = pdf_keep_document(ctx, dst);
+	map->refs = 1;
+	return map;
+}
+
+pdf_graft_map *
+pdf_keep_graft_map(fz_context *ctx, pdf_graft_map *map)
+{
+	return fz_keep_imp(ctx, map, &map->refs);
+}
+
+void
+pdf_drop_graft_map(fz_context *ctx, pdf_graft_map *map)
+{
+	if (fz_drop_imp(ctx, map, &map->refs))
+	{
+		pdf_drop_document(ctx, map->src);
+		pdf_drop_document(ctx, map->dst);
+		fz_free(ctx, map->dst_from_src);
+		fz_free(ctx, map);
+	}
+}
+
+pdf_obj *
+pdf_graft_object(fz_context *ctx, pdf_document *dst, pdf_obj *obj)
+{
+	pdf_document *src;
+	pdf_graft_map *map;
+
+	/* Primitive objects are not bound to a document, so can be re-used as is. */
+	src = pdf_get_bound_document(ctx, obj);
+	if (src == NULL)
+		return pdf_keep_obj(ctx, obj);
+
+	map = pdf_new_graft_map(ctx, dst);
+
+	fz_try(ctx)
+		obj = pdf_graft_mapped_object(ctx, map, obj);
+	fz_always(ctx)
+		pdf_drop_graft_map(ctx, map);
+	fz_catch(ctx)
+		fz_rethrow(ctx);
+
+	return obj;
+}
+
+pdf_obj *
+pdf_graft_mapped_object(fz_context *ctx, pdf_graft_map *map, pdf_obj *obj)
+{
+	pdf_obj *val, *key;
+	pdf_obj *new_obj = NULL;
+	pdf_obj *new_dict;
+	pdf_obj *new_array;
+	pdf_obj *ref = NULL;
+	fz_buffer *buffer = NULL;
+	pdf_document *src;
+	int new_num, src_num, len, i;
+
+	/* Primitive objects are not bound to a document, so can be re-used as is. */
+	src = pdf_get_bound_document(ctx, obj);
+	if (!src)
+		return pdf_keep_obj(ctx, obj);
+
+	if (map->src && src != map->src)
+		fz_throw(ctx, FZ_ERROR_ARGUMENT, "grafted objects must all belong to the same source document");
+
+	if (pdf_is_indirect(ctx, obj))
+	{
+		src_num = pdf_to_num(ctx, obj);
+
+		if (map->src == NULL)
+		{
+			fz_try(ctx)
+			{
+				map->src = pdf_keep_document(ctx, src);
+				map->len = pdf_xref_len(ctx, src);
+				map->dst_from_src = fz_calloc(ctx, map->len, sizeof(int));
+			}
+			fz_catch(ctx)
+			{
+				pdf_drop_document(ctx, map->src);
+				map->src = NULL;
+				fz_rethrow(ctx);
+			}
+		}
+
+		if (src_num < 1 || src_num >= map->len)
+			fz_throw(ctx, FZ_ERROR_ARGUMENT, "source object number out of range");
+
+		/* Check if we have done this one.  If yes, then just
+		 * return our indirect ref */
+		if (map->dst_from_src[src_num] != 0)
+		{
+			int dest_num = map->dst_from_src[src_num];
+			return pdf_new_indirect(ctx, map->dst, dest_num, 0);
+		}
+
+		fz_var(buffer);
+		fz_var(ref);
+		fz_var(new_obj);
+
+		fz_try(ctx)
+		{
+			/* Create new slot for our src object, set the mapping and call again
+			 * using the resolved indirect reference */
+			new_num = pdf_create_object(ctx, map->dst);
+			map->dst_from_src[src_num] = new_num;
+			new_obj = pdf_graft_mapped_object(ctx, map, pdf_resolve_indirect(ctx, obj));
+
+			/* Return a ref to the new_obj making sure to attach any stream */
+			pdf_update_object(ctx, map->dst, new_num, new_obj);
+			ref = pdf_new_indirect(ctx, map->dst, new_num, 0);
+			if (pdf_is_stream(ctx, obj))
+			{
+				buffer = pdf_load_raw_stream_number(ctx, src, src_num);
+				pdf_update_stream(ctx, map->dst, ref, buffer, 1);
+			}
+		}
+		fz_always(ctx)
+		{
+			pdf_drop_obj(ctx, new_obj);
+			fz_drop_buffer(ctx, buffer);
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_obj(ctx, ref);
+			fz_rethrow(ctx);
+		}
+		return ref;
+	}
+	else if (pdf_is_dict(ctx, obj))
+	{
+		len = pdf_dict_len(ctx, obj);
+		new_dict = pdf_new_dict(ctx, map->dst, len);
+
+		fz_try(ctx)
+		{
+			for (i = 0; i < len; i++)
+			{
+				key = pdf_dict_get_key(ctx, obj, i);
+				val = pdf_dict_get_val(ctx, obj, i);
+				pdf_dict_put_drop(ctx, new_dict, key, pdf_graft_mapped_object(ctx, map, val));
+			}
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_obj(ctx, new_dict);
+			fz_rethrow(ctx);
+		}
+		return new_dict;
+	}
+	else if (pdf_is_array(ctx, obj))
+	{
+		/* Step through the array items handling indirect refs */
+		len = pdf_array_len(ctx, obj);
+		new_array = pdf_new_array(ctx, map->dst, len);
+
+		fz_try(ctx)
+		{
+			for (i = 0; i < len; i++)
+			{
+				val = pdf_array_get(ctx, obj, i);
+				pdf_array_push_drop(ctx, new_array, pdf_graft_mapped_object(ctx, map, val));
+			}
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_obj(ctx, new_array);
+			fz_rethrow(ctx);
+		}
+		return new_array;
+	}
+	else
+	{
+		assert("This never happens" == NULL);
+		return NULL;
+	}
+}
+
+void pdf_graft_mapped_page(fz_context *ctx, pdf_graft_map *map, int page_to, pdf_document *src, int page_from)
+{
+	pdf_obj *page_ref;
+	pdf_obj *page_dict = NULL;
+	pdf_obj *obj;
+	pdf_obj *ref = NULL;
+	int i;
+	pdf_document *dst = map->dst;
+
+	/* Copy as few key/value pairs as we can. Do not include items that reference other pages. */
+	static pdf_obj * const copy_list[] = {
+		PDF_NAME(Contents),
+		PDF_NAME(Resources),
+		PDF_NAME(MediaBox),
+		PDF_NAME(CropBox),
+		PDF_NAME(BleedBox),
+		PDF_NAME(TrimBox),
+		PDF_NAME(ArtBox),
+		PDF_NAME(Rotate),
+		PDF_NAME(UserUnit)
+	};
+
+	fz_var(ref);
+	fz_var(page_dict);
+
+	fz_try(ctx)
+	{
+		page_ref = pdf_lookup_page_obj(ctx, src, page_from);
+
+		/* Make a new page object dictionary to hold the items we copy from the source page. */
+		page_dict = pdf_new_dict(ctx, dst, 4);
+
+		pdf_dict_put(ctx, page_dict, PDF_NAME(Type), PDF_NAME(Page));
+
+		for (i = 0; i < (int)nelem(copy_list); i++)
+		{
+			obj = pdf_dict_get_inheritable(ctx, page_ref, copy_list[i]);
+			if (obj != NULL)
+				pdf_dict_put_drop(ctx, page_dict, copy_list[i], pdf_graft_mapped_object(ctx, map, obj));
+		}
+
+		/* Add the page object to the destination document. */
+		ref = pdf_add_object(ctx, dst, page_dict);
+
+		/* Insert it into the page tree. */
+		pdf_insert_page(ctx, dst, page_to, ref);
+	}
+	fz_always(ctx)
+	{
+		pdf_drop_obj(ctx, page_dict);
+		pdf_drop_obj(ctx, ref);
+	}
+	fz_catch(ctx)
+	{
+		fz_rethrow(ctx);
+	}
+}
+
+void pdf_graft_page(fz_context *ctx, pdf_document *dst, int page_to, pdf_document *src, int page_from)
+{
+	pdf_graft_map *map = pdf_new_graft_map(ctx, dst);
+	fz_try(ctx)
+		pdf_graft_mapped_page(ctx, map, page_to, src, page_from);
+	fz_always(ctx)
+		pdf_drop_graft_map(ctx, map);
+	fz_catch(ctx)
+		fz_rethrow(ctx);
+}