1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file       alone_encoder.c
4 /// \brief      Encoder for LZMA_Alone files
5 //
6 //  Author:     Lasse Collin
7 //
8 //  This file has been put into the public domain.
9 //  You can do whatever you want with this file.
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12 
13 #include "common.h"
14 #include "lzma_encoder.h"
15 
16 
17 #define ALONE_HEADER_SIZE (1 + 4 + 8)
18 
19 
20 typedef struct {
21 	lzma_next_coder next;
22 
23 	enum {
24 		SEQ_HEADER,
25 		SEQ_CODE,
26 	} sequence;
27 
28 	size_t header_pos;
29 	uint8_t header[ALONE_HEADER_SIZE];
30 } lzma_alone_coder;
31 
32 
33 static lzma_ret
34 alone_encode(void *coder_ptr, const lzma_allocator *allocator,
35 		const uint8_t *restrict in, size_t *restrict in_pos,
36 		size_t in_size, uint8_t *restrict out,
37 		size_t *restrict out_pos, size_t out_size,
38 		lzma_action action)
39 {
40 	lzma_alone_coder *coder = coder_ptr;
41 
42 	while (*out_pos < out_size)
43 	switch (coder->sequence) {
44 	case SEQ_HEADER:
45 		lzma_bufcpy(coder->header, &coder->header_pos,
46 				ALONE_HEADER_SIZE,
47 				out, out_pos, out_size);
48 		if (coder->header_pos < ALONE_HEADER_SIZE)
49 			return LZMA_OK;
50 
51 		coder->sequence = SEQ_CODE;
52 		break;
53 
54 	case SEQ_CODE:
55 		return coder->next.code(coder->next.coder,
56 				allocator, in, in_pos, in_size,
57 				out, out_pos, out_size, action);
58 
59 	default:
60 		assert(0);
61 		return LZMA_PROG_ERROR;
62 	}
63 
64 	return LZMA_OK;
65 }
66 
67 
68 static void
69 alone_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
70 {
71 	lzma_alone_coder *coder = coder_ptr;
72 	lzma_next_end(&coder->next, allocator);
73 	lzma_free(coder, allocator);
74 	return;
75 }
76 
77 
78 static lzma_ret
79 alone_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
80 		const lzma_options_lzma *options)
81 {
82 	lzma_next_coder_init(&alone_encoder_init, next, allocator);
83 
84 	lzma_alone_coder *coder = next->coder;
85 
86 	if (coder == NULL) {
87 		coder = lzma_alloc(sizeof(lzma_alone_coder), allocator);
88 		if (coder == NULL)
89 			return LZMA_MEM_ERROR;
90 
91 		next->coder = coder;
92 		next->code = &alone_encode;
93 		next->end = &alone_encoder_end;
94 		coder->next = LZMA_NEXT_CODER_INIT;
95 	}
96 
97 	// Basic initializations
98 	coder->sequence = SEQ_HEADER;
99 	coder->header_pos = 0;
100 
101 	// Encode the header:
102 	// - Properties (1 byte)
103 	if (lzma_lzma_lclppb_encode(options, coder->header))
104 		return LZMA_OPTIONS_ERROR;
105 
106 	// - Dictionary size (4 bytes)
107 	if (options->dict_size < LZMA_DICT_SIZE_MIN)
108 		return LZMA_OPTIONS_ERROR;
109 
110 	// Round up to the next 2^n or 2^n + 2^(n - 1) depending on which
111 	// one is the next unless it is UINT32_MAX. While the header would
112 	// allow any 32-bit integer, we do this to keep the decoder of liblzma
113 	// accepting the resulting files.
114 	uint32_t d = options->dict_size - 1;
115 	d |= d >> 2;
116 	d |= d >> 3;
117 	d |= d >> 4;
118 	d |= d >> 8;
119 	d |= d >> 16;
120 	if (d != UINT32_MAX)
121 		++d;
122 
123 	write32le(coder->header + 1, d);
124 
125 	// - Uncompressed size (always unknown and using EOPM)
126 	memset(coder->header + 1 + 4, 0xFF, 8);
127 
128 	// Initialize the LZMA encoder.
129 	const lzma_filter_info filters[2] = {
130 		{
131 			.id = LZMA_FILTER_LZMA1,
132 			.init = &lzma_lzma_encoder_init,
133 			.options = (void *)(options),
134 		}, {
135 			.init = NULL,
136 		}
137 	};
138 
139 	return lzma_next_filter_init(&coder->next, allocator, filters);
140 }
141 
142 
143 extern LZMA_API(lzma_ret)
144 lzma_alone_encoder(lzma_stream *strm, const lzma_options_lzma *options)
145 {
146 	lzma_next_strm_init(alone_encoder_init, strm, options);
147 
148 	strm->internal->supported_actions[LZMA_RUN] = true;
149 	strm->internal->supported_actions[LZMA_FINISH] = true;
150 
151 	return LZMA_OK;
152 }
153