1/* Copyright (c) 2013-2014 Jeffrey Pfau
 2 *
 3 * This Source Code Form is subject to the terms of the Mozilla Public
 4 * License, v. 2.0. If a copy of the MPL was not distributed with this
 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 6#include "util/patch-ips.h"
 7
 8#include "util/patch.h"
 9#include "util/vfs.h"
10
11static size_t _IPSOutputSize(struct Patch* patch, size_t inSize);
12static bool _IPSApplyPatch(struct Patch* patch, void* out, size_t outSize);
13
14bool loadPatchIPS(struct Patch* patch) {
15	patch->vf->seek(patch->vf, 0, SEEK_SET);
16
17	char buffer[5];
18	if (patch->vf->read(patch->vf, buffer, 5) != 5) {
19		return false;
20	}
21
22	if (memcmp(buffer, "PATCH", 5) != 0) {
23		return false;
24	}
25
26	patch->vf->seek(patch->vf, -3, SEEK_END);
27	if (patch->vf->read(patch->vf, buffer, 3) != 3) {
28		return false;
29	}
30
31	if (memcmp(buffer, "EOF", 3) != 0) {
32		return false;
33	}
34
35	patch->outputSize = _IPSOutputSize;
36	patch->applyPatch = _IPSApplyPatch;
37	return true;
38}
39
40size_t _IPSOutputSize(struct Patch* patch, size_t inSize) {
41	UNUSED(patch);
42	return inSize;
43}
44
45bool _IPSApplyPatch(struct Patch* patch, void* out, size_t outSize) {
46	if (patch->vf->seek(patch->vf, 5, SEEK_SET) != 5) {
47		return false;
48	}
49	uint8_t* buf = out;
50
51	while (true) {
52		uint32_t offset = 0;
53		uint16_t size = 0;
54
55		if (patch->vf->read(patch->vf, &offset, 3) != 3) {
56			return false;
57		}
58
59		if (offset == 0x464F45) {
60			return true;
61		}
62
63		offset = (offset >> 16) | (offset & 0xFF00) | ((offset << 16) & 0xFF0000);
64		if (patch->vf->read(patch->vf, &size, 2) != 2) {
65			return false;
66		}
67		if (!size) {
68			// RLE chunk
69			if (patch->vf->read(patch->vf, &size, 2) != 2) {
70				return false;
71			}
72			size = (size >> 8) | (size << 8);
73			uint8_t byte;
74			if (patch->vf->read(patch->vf, &byte, 1) != 1) {
75				return false;
76			}
77			if (offset + size > outSize) {
78				return false;
79			}
80			memset(&buf[offset], byte, size);
81		} else {
82			size = (size >> 8) | (size << 8);
83			if (offset + size > outSize) {
84				return false;
85			}
86			if (patch->vf->read(patch->vf, &buf[offset], size) != size) {
87				return false;
88			}
89		}
90	}
91}