summaryrefslogtreecommitdiffstats
path: root/lib/lz4_wrapper.c
blob: 6dc8b764b3f59ecb4bd9fedf46d72832a57e2488 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
/*
 * Copyright 2015 Google Inc.
 *
 * SPDX-License-Identifier: GPL 2.0+ BSD-3-Clause
 */

#include <common.h>
#include <compiler.h>
#include <linux/kernel.h>
#include <linux/types.h>

static u16 LZ4_readLE16(const void *src) { return le16_to_cpu(*(u16 *)src); }
static void LZ4_copy4(void *dst, const void *src) { *(u32 *)dst = *(u32 *)src; }
static void LZ4_copy8(void *dst, const void *src) { *(u64 *)dst = *(u64 *)src; }

typedef  uint8_t BYTE;
typedef uint16_t U16;
typedef uint32_t U32;
typedef  int32_t S32;
typedef uint64_t U64;

#define FORCE_INLINE static inline __attribute__((always_inline))

/* Unaltered (except removing unrelated code) from github.com/Cyan4973/lz4. */
#include "lz4.c"	/* #include for inlining, do not link! */

#define LZ4F_MAGIC 0x184D2204

struct lz4_frame_header {
	u32 magic;
	union {
		u8 flags;
		struct {
			u8 reserved0:2;
			u8 has_content_checksum:1;
			u8 has_content_size:1;
			u8 has_block_checksum:1;
			u8 independent_blocks:1;
			u8 version:2;
		};
	};
	union {
		u8 block_descriptor;
		struct {
			u8 reserved1:4;
			u8 max_block_size:3;
			u8 reserved2:1;
		};
	};
	/* + u64 content_size iff has_content_size is set */
	/* + u8 header_checksum */
} __packed;

struct lz4_block_header {
	union {
		u32 raw;
		struct {
			u32 size:31;
			u32 not_compressed:1;
		};
	};
	/* + size bytes of data */
	/* + u32 block_checksum iff has_block_checksum is set */
} __packed;

int ulz4fn(const void *src, size_t srcn, void *dst, size_t *dstn)
{
	const void *end = dst + *dstn;
	const void *in = src;
	void *out = dst;
	int has_block_checksum;
	int ret;
	*dstn = 0;

	{ /* With in-place decompression the header may become invalid later. */
		const struct lz4_frame_header *h = in;

		if (srcn < sizeof(*h) + sizeof(u64) + sizeof(u8))
			return -EINVAL;	/* input overrun */

		/* We assume there's always only a single, standard frame. */
		if (le32_to_cpu(h->magic) != LZ4F_MAGIC || h->version != 1)
			return -EPROTONOSUPPORT;	/* unknown format */
		if (h->reserved0 || h->reserved1 || h->reserved2)
			return -EINVAL;	/* reserved must be zero */
		if (!h->independent_blocks)
			return -EPROTONOSUPPORT; /* we can't support this yet */
		has_block_checksum = h->has_block_checksum;

		in += sizeof(*h);
		if (h->has_content_size)
			in += sizeof(u64);
		in += sizeof(u8);
	}

	while (1) {
		struct lz4_block_header b;

		b.raw = le32_to_cpu(*(u32 *)in);
		in += sizeof(struct lz4_block_header);

		if (in - src + b.size > srcn) {
			ret = -EINVAL;		/* input overrun */
			break;
		}

		if (!b.size) {
			ret = 0;	/* decompression successful */
			break;
		}

		if (b.not_compressed) {
			size_t size = min((ptrdiff_t)b.size, end - out);
			memcpy(out, in, size);
			out += size;
			if (size < b.size) {
				ret = -ENOBUFS;	/* output overrun */
				break;
			}
		} else {
			/* constant folding essential, do not touch params! */
			ret = LZ4_decompress_generic(in, out, b.size,
					end - out, endOnInputSize,
					full, 0, noDict, out, NULL, 0);
			if (ret < 0) {
				ret = -EPROTO;	/* decompression error */
				break;
			}
			out += ret;
		}

		in += b.size;
		if (has_block_checksum)
			in += sizeof(u32);
	}

	*dstn = out - dst;
	return ret;
}