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/*@ s-bsdipa-lib: port of Colin Percival's BSDiff(/bspatch) to a library.
 *@ BSDiff: create or apply binary difference patch.
 *@
 *@ Remarks:
 *@ - If s_BSDIPA_32 is defined, 31-bit instead of 63-bit limits.
 *@ - Note: the real limit is maximally
 *@   MIN(s_BSDIPA_OFF_MAX, SIZE_MAX) / sizeof(s_bsdipa_off_t)
 *@   (with 32-bit size_t this can be restrictive)!
 *@ - Algorithm requires a lot of memory, multiple times the input size!
 *@   With s_BSDIPA_32 the overhead can almost be halved.
 *@ - If s_BSDIPA_SMALL is defined, libdivsufsort is not actually used,
 *@   but only the original BSDiff algorithm of Colin Percival.
 *@ - If s_BSDIPA_TEXT is defined, alternatively selectable text (linewise)
 *@   differential approach (nothing special, but produces same patch format.)
 *@ - Code requires an ISO STD C99 environment.
 *@
 *@ Changes to original bsdiff / libdivsufsort:
 *@ - Optional (s_BSDIPA_32) 31-bit limits, thus smaller header/control data,
 *@   as well as smaller (about halved) memory overhead.
 *@ - The s_BSDIPA_MAGIC_WINDOW is configurable: the original is bound to
 *@   (32- and) 64-bit binary diffs (8), but eg 16 or 32 are better (for text).
 *@ - Data serialization is in big endian/network byte order.
 *@ - No file I/O, everything is stored on the heap.
 *@ - No bzip2 compression: callee should compress result.
 *@   NOTE: compression is necessary since data is stored in full, meaning
 *@   that identical bytes are stored as NUL.
 *@ -- The s-bsdipa-io.h header is a readily available I/O layer.
 *@    NOTE: I/O layers may impose further size limit restrictions!
 *@ - Internally diff- and extra data share heap to reduce memory overhead.
 *@ -- As a result diff data is stored in reverse order, last byte first.
 *@ - Memory allocation is solely done via user provided allocator.
 *@ - The header includes the extra data length, so that all information
 *@   is available through it.
 *@ - "Data-less" control blocks cannot occur (but for the first):
 *@   BSDiff may generate control blocks which contain no data, but only seek.
 *@   Such fragments are instead collapsed to the former control block,
 *@   tightening testable constraints on the header and control chunks.
 *@
 *@ Informational: original bsdiff file format:
 *@	0	8	"BSDIFF40"
 *@	8	8	X
 *@	16	8	Y
 *@	24	8	sizeof(result[file])
 *@	32	X	bzip2(control block)
 *@	32+X	Y	bzip2(diff block)
 *@	32+X+Y	???	bzip2(extra block)
 *@ With control block being a set of triples (x,y,z) meaning "read x bytes of
 *@ diff data into NEW, then add x bytes from OLD to these x bytes in NEW;
 *@ copy y bytes from the extra block onto NEW; seek forwards in OLD by z".
 */
#define s_BSDIPA_COPYRIGHT \
	"S-bsdipa is\n" \
	"	Copyright (c) 2024 - 2026 Steffen Nurpmeso\n" \
	"	SPDX-License-Identifier: ISC\n" \
	"The used BSDiff algorithm is\n" \
	"	Copyright 2003-2005 Colin Percival\n" \
	"	SPDX-License-Identifier: BSD-2-Clause\n" \
	"and it optionally (!s_BSDIPA_SMALL) uses libdivsufsort that is\n" \
	"	Copyright (c) 2003 Yuta Mori All rights reserved.\n" \
	"	SPDX-License-Identifier: MIT\n"
/* L5E> */
/*@ S-bsdipa copyright:
 *
 * Copyright (c) 2024 - 2026 Steffen Nurpmeso <steffen@sdaoden.eu>.
 * SPDX-License-Identifier: ISC
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
/*@ The algorithm as is used inside the library (s-bsdiff.c) is:
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2003-2005 Colin Percival
 * All rights reserved
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted providing that the following conditions 
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED