liblzma/common/index_encoder.c

///////////////////////////////////////////////////////////////////////////////
//
/// \file       index_encoder.c
/// \brief      Encodes the Index field
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////

#include "index_encoder.h"
#include "index.h"
#include "check.h"


struct lzma_coder_s {
        enum {
                SEQ_INDICATOR,
                SEQ_COUNT,
                SEQ_UNPADDED,
                SEQ_UNCOMPRESSED,
                SEQ_NEXT,
                SEQ_PADDING,
                SEQ_CRC32,
        } sequence;

        /// Index being encoded
        const lzma_index *index;

        /// Iterator for the Index being encoded
        lzma_index_iter iter;

        /// Position in integers
        size_t pos;

        /// CRC32 of the List of Records field
        uint32_t crc32;
};


static lzma_ret
index_encode(lzma_coder *coder,
                const lzma_allocator *allocator lzma_attribute((__unused__)),
                const uint8_t *restrict in lzma_attribute((__unused__)),
                size_t *restrict in_pos lzma_attribute((__unused__)),
                size_t in_size lzma_attribute((__unused__)),
                uint8_t *restrict out, size_t *restrict out_pos,
                size_t out_size,
                lzma_action action lzma_attribute((__unused__)))
{
        // Position where to start calculating CRC32. The idea is that we
        // need to call lzma_crc32() only once per call to index_encode().
        const size_t out_start = *out_pos;

        // Return value to use if we return at the end of this function.
        // We use "goto out" to jump out of the while-switch construct
        // instead of returning directly, because that way we don't need
        // to copypaste the lzma_crc32() call to many places.
        lzma_ret ret = LZMA_OK;

        while (*out_pos < out_size)
        switch (coder->sequence) {
        case SEQ_INDICATOR:
                out[*out_pos] = 0x00;
                ++*out_pos;
                coder->sequence = SEQ_COUNT;
                break;

        case SEQ_COUNT: {
                const lzma_vli count = lzma_index_block_count(coder->index);
                ret = lzma_vli_encode(count, &coder->pos,
                                out, out_pos, out_size);
                if (ret != LZMA_STREAM_END)
                        goto out;

                ret = LZMA_OK;
                coder->pos = 0;
                coder->sequence = SEQ_NEXT;
                break;
        }

        case SEQ_NEXT:
                if (lzma_index_iter_next(
                                &coder->iter, LZMA_INDEX_ITER_BLOCK)) {
                        // Get the size of the Index Padding field.
                        coder->pos = lzma_index_padding_size(coder->index);
                        assert(coder->pos <= 3);
                        coder->sequence = SEQ_PADDING;
                        break;
                }

                coder->sequence = SEQ_UNPADDED;

        // Fall through

        case SEQ_UNPADDED:
        case SEQ_UNCOMPRESSED: {
                const lzma_vli size = coder->sequence == SEQ_UNPADDED
                                ? coder->iter.block.unpadded_size
                                : coder->iter.block.uncompressed_size;

                ret = lzma_vli_encode(size, &coder->pos,
                                out, out_pos, out_size);
                if (ret != LZMA_STREAM_END)
                        goto out;

                ret = LZMA_OK;
                coder->pos = 0;

                // Advance to SEQ_UNCOMPRESSED or SEQ_NEXT.
                ++coder->sequence;
                break;
        }

        case SEQ_PADDING:
                if (coder->pos > 0) {
                        --coder->pos;
                        out[(*out_pos)++] = 0x00;
                        break;
                }

                // Finish the CRC32 calculation.
                coder->crc32 = lzma_crc32(out + out_start,
                                *out_pos - out_start, coder->crc32);

                coder->sequence = SEQ_CRC32;

        // Fall through

        case SEQ_CRC32:
                // We don't use the main loop, because we don't want
                // coder->crc32 to be touched anymore.
                do {
                        if (*out_pos == out_size)
                                return LZMA_OK;

                        out[*out_pos] = (coder->crc32 >> (coder->pos * 8))
                                        & 0xFF;
                        ++*out_pos;

                } while (++coder->pos < 4);

                return LZMA_STREAM_END;

        default:
                assert(0);
                return LZMA_PROG_ERROR;
        }

out:
        // Update the CRC32.
        coder->crc32 = lzma_crc32(out + out_start,
                        *out_pos - out_start, coder->crc32);

        return ret;
}


static void
index_encoder_end(lzma_coder *coder, const lzma_allocator *allocator)
{
        lzma_free(coder, allocator);
        return;
}


static void
index_encoder_reset(lzma_coder *coder, const lzma_index *i)
{
        lzma_index_iter_init(&coder->iter, i);

        coder->sequence = SEQ_INDICATOR;
        coder->index = i;
        coder->pos = 0;
        coder->crc32 = 0;

        return;
}


extern lzma_ret
lzma_index_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
                const lzma_index *i)
{
        lzma_next_coder_init(&lzma_index_encoder_init, next, allocator);

        if (i == NULL)
                return LZMA_PROG_ERROR;

        if (next->coder == NULL) {
                next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
                if (next->coder == NULL)
                        return LZMA_MEM_ERROR;

                next->code = &index_encode;
                next->end = &index_encoder_end;
        }

        index_encoder_reset(next->coder, i);

        return LZMA_OK;
}


extern LZMA_API(lzma_ret)
lzma_index_encoder(lzma_stream *strm, const lzma_index *i)
{
        lzma_next_strm_init(lzma_index_encoder_init, strm, i);

        strm->internal->supported_actions[LZMA_RUN] = true;
        strm->internal->supported_actions[LZMA_FINISH] = true;

        return LZMA_OK;
}


extern LZMA_API(lzma_ret)
lzma_index_buffer_encode(const lzma_index *i,
                uint8_t *out, size_t *out_pos, size_t out_size)
{
        // Validate the arguments.
        if (i == NULL || out == NULL || out_pos == NULL || *out_pos > out_size)
                return LZMA_PROG_ERROR;

        // Don't try to encode if there's not enough output space.
        if (out_size - *out_pos < lzma_index_size(i))
                return LZMA_BUF_ERROR;

        // The Index encoder needs just one small data structure so we can
        // allocate it on stack.
        lzma_coder coder;
        index_encoder_reset(&coder, i);

        // Do the actual encoding. This should never fail, but store
        // the original *out_pos just in case.
        const size_t out_start = *out_pos;
        lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0,
                        out, out_pos, out_size, LZMA_RUN);

        if (ret == LZMA_STREAM_END) {
                ret = LZMA_OK;
        } else {
                // We should never get here, but just in case, restore the
                // output position and set the error accordingly if something
                // goes wrong and debugging isn't enabled.
                assert(0);
                *out_pos = out_start;
                ret = LZMA_PROG_ERROR;
        }

        return ret;
}
Revision:	9176
Committed:	Sat Oct 15 16:14:07 2016 UTC (7 years, 6 months ago) by laffer1
Content type:	text/plain
File size:	5792 byte(s)
Log Message:	5.2.2 from git
#	Content
1	///////////////////////////////////////////////////////////////////////////////
2	//
3	/// \file index_encoder.c
4	/// \brief Encodes the Index field
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 "index_encoder.h"
14	#include "index.h"
15	#include "check.h"
16
17
18	struct lzma_coder_s {
19	enum {
20	SEQ_INDICATOR,
21	SEQ_COUNT,
22	SEQ_UNPADDED,
23	SEQ_UNCOMPRESSED,
24	SEQ_NEXT,
25	SEQ_PADDING,
26	SEQ_CRC32,
27	} sequence;
28
29	/// Index being encoded
30	const lzma_index *index;
31
32	/// Iterator for the Index being encoded
33	lzma_index_iter iter;
34
35	/// Position in integers
36	size_t pos;
37
38	/// CRC32 of the List of Records field
39	uint32_t crc32;
40	};
41
42
43	static lzma_ret
44	index_encode(lzma_coder *coder,
45	const lzma_allocator *allocator lzma_attribute((__unused__)),
46	const uint8_t *restrict in lzma_attribute((__unused__)),
47	size_t *restrict in_pos lzma_attribute((__unused__)),
48	size_t in_size lzma_attribute((__unused__)),
49	uint8_t restrict out, size_t restrict out_pos,
50	size_t out_size,
51	lzma_action action lzma_attribute((__unused__)))
52	{
53	// Position where to start calculating CRC32. The idea is that we
54	// need to call lzma_crc32() only once per call to index_encode().
55	const size_t out_start = *out_pos;
56
57	// Return value to use if we return at the end of this function.
58	// We use "goto out" to jump out of the while-switch construct
59	// instead of returning directly, because that way we don't need
60	// to copypaste the lzma_crc32() call to many places.
61	lzma_ret ret = LZMA_OK;
62
63	while (*out_pos < out_size)
64	switch (coder->sequence) {
65	case SEQ_INDICATOR:
66	out[*out_pos] = 0x00;
67	++*out_pos;
68	coder->sequence = SEQ_COUNT;
69	break;
70
71	case SEQ_COUNT: {
72	const lzma_vli count = lzma_index_block_count(coder->index);
73	ret = lzma_vli_encode(count, &coder->pos,
74	out, out_pos, out_size);
75	if (ret != LZMA_STREAM_END)
76	goto out;
77
78	ret = LZMA_OK;
79	coder->pos = 0;
80	coder->sequence = SEQ_NEXT;
81	break;
82	}
83
84	case SEQ_NEXT:
85	if (lzma_index_iter_next(
86	&coder->iter, LZMA_INDEX_ITER_BLOCK)) {
87	// Get the size of the Index Padding field.
88	coder->pos = lzma_index_padding_size(coder->index);
89	assert(coder->pos <= 3);
90	coder->sequence = SEQ_PADDING;
91	break;
92	}
93
94	coder->sequence = SEQ_UNPADDED;
95
96	// Fall through
97
98	case SEQ_UNPADDED:
99	case SEQ_UNCOMPRESSED: {
100	const lzma_vli size = coder->sequence == SEQ_UNPADDED
101	? coder->iter.block.unpadded_size
102	: coder->iter.block.uncompressed_size;
103
104	ret = lzma_vli_encode(size, &coder->pos,
105	out, out_pos, out_size);
106	if (ret != LZMA_STREAM_END)
107	goto out;
108
109	ret = LZMA_OK;
110	coder->pos = 0;
111
112	// Advance to SEQ_UNCOMPRESSED or SEQ_NEXT.
113	++coder->sequence;
114	break;
115	}
116
117	case SEQ_PADDING:
118	if (coder->pos > 0) {
119	--coder->pos;
120	out[(*out_pos)++] = 0x00;
121	break;
122	}
123
124	// Finish the CRC32 calculation.
125	coder->crc32 = lzma_crc32(out + out_start,
126	*out_pos - out_start, coder->crc32);
127
128	coder->sequence = SEQ_CRC32;
129
130	// Fall through
131
132	case SEQ_CRC32:
133	// We don't use the main loop, because we don't want
134	// coder->crc32 to be touched anymore.
135	do {
136	if (*out_pos == out_size)
137	return LZMA_OK;
138
139	out[out_pos] = (coder->crc32 >> (coder->pos 8))
140	& 0xFF;
141	++*out_pos;
142
143	} while (++coder->pos < 4);
144
145	return LZMA_STREAM_END;
146
147	default:
148	assert(0);
149	return LZMA_PROG_ERROR;
150	}
151
152	out:
153	// Update the CRC32.
154	coder->crc32 = lzma_crc32(out + out_start,
155	*out_pos - out_start, coder->crc32);
156
157	return ret;
158	}
159
160
161	static void
162	index_encoder_end(lzma_coder coder, const lzma_allocator allocator)
163	{
164	lzma_free(coder, allocator);
165	return;
166	}
167
168
169	static void
170	index_encoder_reset(lzma_coder coder, const lzma_index i)
171	{
172	lzma_index_iter_init(&coder->iter, i);
173
174	coder->sequence = SEQ_INDICATOR;
175	coder->index = i;
176	coder->pos = 0;
177	coder->crc32 = 0;
178
179	return;
180	}
181
182
183	extern lzma_ret
184	lzma_index_encoder_init(lzma_next_coder next, const lzma_allocator allocator,
185	const lzma_index *i)
186	{
187	lzma_next_coder_init(&lzma_index_encoder_init, next, allocator);
188
189	if (i == NULL)
190	return LZMA_PROG_ERROR;
191
192	if (next->coder == NULL) {
193	next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
194	if (next->coder == NULL)
195	return LZMA_MEM_ERROR;
196
197	next->code = &index_encode;
198	next->end = &index_encoder_end;
199	}
200
201	index_encoder_reset(next->coder, i);
202
203	return LZMA_OK;
204	}
205
206
207	extern LZMA_API(lzma_ret)
208	lzma_index_encoder(lzma_stream strm, const lzma_index i)
209	{
210	lzma_next_strm_init(lzma_index_encoder_init, strm, i);
211
212	strm->internal->supported_actions[LZMA_RUN] = true;
213	strm->internal->supported_actions[LZMA_FINISH] = true;
214
215	return LZMA_OK;
216	}
217
218
219	extern LZMA_API(lzma_ret)
220	lzma_index_buffer_encode(const lzma_index *i,
221	uint8_t out, size_t out_pos, size_t out_size)
222	{
223	// Validate the arguments.
224	if (i == NULL \|\| out == NULL \|\| out_pos == NULL \|\| *out_pos > out_size)
225	return LZMA_PROG_ERROR;
226
227	// Don't try to encode if there's not enough output space.
228	if (out_size - *out_pos < lzma_index_size(i))
229	return LZMA_BUF_ERROR;
230
231	// The Index encoder needs just one small data structure so we can
232	// allocate it on stack.
233	lzma_coder coder;
234	index_encoder_reset(&coder, i);
235
236	// Do the actual encoding. This should never fail, but store
237	// the original *out_pos just in case.
238	const size_t out_start = *out_pos;
239	lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0,
240	out, out_pos, out_size, LZMA_RUN);
241
242	if (ret == LZMA_STREAM_END) {
243	ret = LZMA_OK;
244	} else {
245	// We should never get here, but just in case, restore the
246	// output position and set the error accordingly if something
247	// goes wrong and debugging isn't enabled.
248	assert(0);
249	*out_pos = out_start;
250	ret = LZMA_PROG_ERROR;
251	}
252
253	return ret;
254	}