--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/fitz/jmemcust.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2001-2017 Artifex Software, Inc.
+ * All Rights Reserved.
+ *
+ * This software is provided AS-IS with no warranty, either express or
+ * implied.
+ *
+ * This software is distributed under license and may not be copied,
+ * modified or distributed except as expressly authorized under the terms
+ * of the license contained in the file LICENSE in this distribution.
+ *
+ * Refer to licensing information at http://www.artifex.com or contact
+ * Artifex Software, Inc., 7 Mt. Lassen Drive - Suite A-134, San Rafael,
+ * CA 94903, U.S.A., +1(415)492-9861, for further information.
+ */
+
+#if !defined(SHARE_JPEG) || SHARE_JPEG==0
+
+#include "jinclude.h"
+#include "jpeglib.h"
+#include "jmemsys.h"
+#include "jerror.h"
+#include "jmemcust.h"
+
+GLOBAL(void *)
+jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+
+	return (void *) (cmem->j_mem_get_small)(cinfo, sizeofobject);
+}
+
+GLOBAL(void)
+jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+
+	(cmem->j_mem_free_small)(cinfo, object, sizeofobject);
+}
+
+/*
+ * "Large" objects are treated the same as "small" ones.
+ * NB: although we include FAR keywords in the routine declarations,
+ * this file won't actually work in 80x86 small/medium model; at least,
+ * you probably won't be able to process useful-size images in only 64KB.
+ */
+
+GLOBAL(void FAR *)
+jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+
+	return (void *) (cmem->j_mem_get_large)(cinfo, sizeofobject);
+}
+
+GLOBAL(void)
+jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+
+	(cmem->j_mem_free_large)(cinfo, object, sizeofobject);
+}
+
+/*
+ * This routine computes the total memory space available for allocation.
+ * Here we always say, "we got all you want bud!"
+ */
+
+GLOBAL(long)
+jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed,
+		long max_bytes_needed, long already_allocated)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+	long ret = max_bytes_needed;
+
+	if (cmem->j_mem_avail)
+		ret = (cmem->j_mem_avail)(cinfo);
+
+	return ret;
+}
+
+/*
+ * Backing store (temporary file) management.
+ * Since jpeg_mem_available always promised the moon,
+ * this should never be called and we can just error out.
+ */
+
+GLOBAL(void)
+jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
+		long total_bytes_needed)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+
+	if (cmem->j_mem_open_backing_store) {
+		(cmem->j_mem_open_backing_store)(cinfo, info, total_bytes_needed);
+	}
+	else
+		ERREXIT(cinfo, JERR_NO_BACKING_STORE);
+}
+
+/*
+ * These routines take care of any system-dependent initialization and
+ * cleanup required. Here, there isn't any.
+ */
+
+GLOBAL(long)
+jpeg_mem_init (j_common_ptr cinfo)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+	long ret = 0;
+
+	if (cmem->j_mem_init)
+		ret = (cmem->j_mem_init)(cinfo);
+
+	return ret;
+}
+
+GLOBAL(void)
+jpeg_mem_term (j_common_ptr cinfo)
+{
+	jpeg_cust_mem_data *cmem = GET_CUST_MEM_DATA(cinfo);
+
+	if (cmem->j_mem_term)
+		(cmem->j_mem_term)(cinfo);
+}
+
+GLOBAL(jpeg_cust_mem_data *)
+jpeg_cust_mem_init(jpeg_cust_mem_data *custm, void *priv,
+		j_custmem_init_ptr init,
+		j_custmem_term_ptr term,
+		j_custmem_avail_ptr avail,
+		j_custmem_get_small_ptr get_small,
+		j_custmem_free_small_ptr free_small,
+		j_cust_mem_get_large_ptr get_large,
+		j_custmem_free_large_ptr free_large,
+		j_custmem_open_backing_store_ptr open_backing_store)
+{
+	jpeg_cust_mem_data *lcustm = NULL;
+
+	/* We need at least the following for a viable memory manager */
+	if (get_small && free_small && get_large && free_large)
+	{
+		lcustm = custm;
+
+		lcustm->priv = priv;
+		lcustm->j_mem_init = init;
+		lcustm->j_mem_term = term;
+		lcustm->j_mem_avail = avail;
+		lcustm->j_mem_get_small = get_small;
+		lcustm->j_mem_free_small = free_small;
+		lcustm->j_mem_get_large = get_large;
+		lcustm->j_mem_free_large = free_large;
+		lcustm->j_mem_open_backing_store = open_backing_store;
+	}
+	return lcustm;
+}
+
+#endif /* !defined(SHARE_JPEG) || SHARE_JPEG==0 */