1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file simple_coder.c
4 /// \brief Wrapper for simple filters
5 ///
6 /// Simple filters don't change the size of the data i.e. number of bytes
7 /// in equals the number of bytes out.
8 //
9 // Author: Lasse Collin
10 //
11 // This file has been put into the public domain.
12 // You can do whatever you want with this file.
13 //
14 ///////////////////////////////////////////////////////////////////////////////
15
16 #include "simple_private.h"
17
18
19 /// Copied or encodes/decodes more data to out[].
20 static lzma_ret
copy_or_code(lzma_simple_coder * coder,const lzma_allocator * allocator,const uint8_t * restrict in,size_t * restrict in_pos,size_t in_size,uint8_t * restrict out,size_t * restrict out_pos,size_t out_size,lzma_action action)21 copy_or_code(lzma_simple_coder *coder, const lzma_allocator *allocator,
22 const uint8_t *restrict in, size_t *restrict in_pos,
23 size_t in_size, uint8_t *restrict out,
24 size_t *restrict out_pos, size_t out_size, lzma_action action)
25 {
26 assert(!coder->end_was_reached);
27
28 if (coder->next.code == NULL) {
29 lzma_bufcpy(in, in_pos, in_size, out, out_pos, out_size);
30
31 // Check if end of stream was reached.
32 if (coder->is_encoder && action == LZMA_FINISH
33 && *in_pos == in_size)
34 coder->end_was_reached = true;
35
36 } else {
37 // Call the next coder in the chain to provide us some data.
38 const lzma_ret ret = coder->next.code(
39 coder->next.coder, allocator,
40 in, in_pos, in_size,
41 out, out_pos, out_size, action);
42
43 if (ret == LZMA_STREAM_END) {
44 assert(!coder->is_encoder
45 || action == LZMA_FINISH);
46 coder->end_was_reached = true;
47
48 } else if (ret != LZMA_OK) {
49 return ret;
50 }
51 }
52
53 return LZMA_OK;
54 }
55
56
57 static size_t
call_filter(lzma_simple_coder * coder,uint8_t * buffer,size_t size)58 call_filter(lzma_simple_coder *coder, uint8_t *buffer, size_t size)
59 {
60 const size_t filtered = coder->filter(coder->simple,
61 coder->now_pos, coder->is_encoder,
62 buffer, size);
63 coder->now_pos += filtered;
64 return filtered;
65 }
66
67
68 static lzma_ret
simple_code(void * coder_ptr,const lzma_allocator * allocator,const uint8_t * restrict in,size_t * restrict in_pos,size_t in_size,uint8_t * restrict out,size_t * restrict out_pos,size_t out_size,lzma_action action)69 simple_code(void *coder_ptr, const lzma_allocator *allocator,
70 const uint8_t *restrict in, size_t *restrict in_pos,
71 size_t in_size, uint8_t *restrict out,
72 size_t *restrict out_pos, size_t out_size, lzma_action action)
73 {
74 lzma_simple_coder *coder = coder_ptr;
75
76 // TODO: Add partial support for LZMA_SYNC_FLUSH. We can support it
77 // in cases when the filter is able to filter everything. With most
78 // simple filters it can be done at offset that is a multiple of 2,
79 // 4, or 16. With x86 filter, it needs good luck, and thus cannot
80 // be made to work predictably.
81 if (action == LZMA_SYNC_FLUSH)
82 return LZMA_OPTIONS_ERROR;
83
84 // Flush already filtered data from coder->buffer[] to out[].
85 if (coder->pos < coder->filtered) {
86 lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered,
87 out, out_pos, out_size);
88
89 // If we couldn't flush all the filtered data, return to
90 // application immediately.
91 if (coder->pos < coder->filtered)
92 return LZMA_OK;
93
94 if (coder->end_was_reached) {
95 assert(coder->filtered == coder->size);
96 return LZMA_STREAM_END;
97 }
98 }
99
100 // If we get here, there is no filtered data left in the buffer.
101 coder->filtered = 0;
102
103 assert(!coder->end_was_reached);
104
105 // If there is more output space left than there is unfiltered data
106 // in coder->buffer[], flush coder->buffer[] to out[], and copy/code
107 // more data to out[] hopefully filling it completely. Then filter
108 // the data in out[]. This step is where most of the data gets
109 // filtered if the buffer sizes used by the application are reasonable.
110 const size_t out_avail = out_size - *out_pos;
111 const size_t buf_avail = coder->size - coder->pos;
112 if (out_avail > buf_avail || buf_avail == 0) {
113 // Store the old position so that we know from which byte
114 // to start filtering.
115 const size_t out_start = *out_pos;
116
117 // Flush data from coder->buffer[] to out[], but don't reset
118 // coder->pos and coder->size yet. This way the coder can be
119 // restarted if the next filter in the chain returns e.g.
120 // LZMA_MEM_ERROR.
121 memcpy(out + *out_pos, coder->buffer + coder->pos, buf_avail);
122 *out_pos += buf_avail;
123
124 // Copy/Encode/Decode more data to out[].
125 {
126 const lzma_ret ret = copy_or_code(coder, allocator,
127 in, in_pos, in_size,
128 out, out_pos, out_size, action);
129 assert(ret != LZMA_STREAM_END);
130 if (ret != LZMA_OK)
131 return ret;
132 }
133
134 // Filter out[].
135 const size_t size = *out_pos - out_start;
136 const size_t filtered = call_filter(
137 coder, out + out_start, size);
138
139 const size_t unfiltered = size - filtered;
140 assert(unfiltered <= coder->allocated / 2);
141
142 // Now we can update coder->pos and coder->size, because
143 // the next coder in the chain (if any) was successful.
144 coder->pos = 0;
145 coder->size = unfiltered;
146
147 if (coder->end_was_reached) {
148 // The last byte has been copied to out[] already.
149 // They are left as is.
150 coder->size = 0;
151
152 } else if (unfiltered > 0) {
153 // There is unfiltered data left in out[]. Copy it to
154 // coder->buffer[] and rewind *out_pos appropriately.
155 *out_pos -= unfiltered;
156 memcpy(coder->buffer, out + *out_pos, unfiltered);
157 }
158 } else if (coder->pos > 0) {
159 memmove(coder->buffer, coder->buffer + coder->pos, buf_avail);
160 coder->size -= coder->pos;
161 coder->pos = 0;
162 }
163
164 assert(coder->pos == 0);
165
166 // If coder->buffer[] isn't empty, try to fill it by copying/decoding
167 // more data. Then filter coder->buffer[] and copy the successfully
168 // filtered data to out[]. It is probable, that some filtered and
169 // unfiltered data will be left to coder->buffer[].
170 if (coder->size > 0) {
171 {
172 const lzma_ret ret = copy_or_code(coder, allocator,
173 in, in_pos, in_size,
174 coder->buffer, &coder->size,
175 coder->allocated, action);
176 assert(ret != LZMA_STREAM_END);
177 if (ret != LZMA_OK)
178 return ret;
179 }
180
181 coder->filtered = call_filter(
182 coder, coder->buffer, coder->size);
183
184 // Everything is considered to be filtered if coder->buffer[]
185 // contains the last bytes of the data.
186 if (coder->end_was_reached)
187 coder->filtered = coder->size;
188
189 // Flush as much as possible.
190 lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered,
191 out, out_pos, out_size);
192 }
193
194 // Check if we got everything done.
195 if (coder->end_was_reached && coder->pos == coder->size)
196 return LZMA_STREAM_END;
197
198 return LZMA_OK;
199 }
200
201
202 static void
simple_coder_end(void * coder_ptr,const lzma_allocator * allocator)203 simple_coder_end(void *coder_ptr, const lzma_allocator *allocator)
204 {
205 lzma_simple_coder *coder = coder_ptr;
206 lzma_next_end(&coder->next, allocator);
207 lzma_free(coder->simple, allocator);
208 lzma_free(coder, allocator);
209 return;
210 }
211
212
213 static lzma_ret
simple_coder_update(void * coder_ptr,const lzma_allocator * allocator,const lzma_filter * filters_null lzma_attribute ((__unused__)),const lzma_filter * reversed_filters)214 simple_coder_update(void *coder_ptr, const lzma_allocator *allocator,
215 const lzma_filter *filters_null lzma_attribute((__unused__)),
216 const lzma_filter *reversed_filters)
217 {
218 lzma_simple_coder *coder = coder_ptr;
219
220 // No update support, just call the next filter in the chain.
221 return lzma_next_filter_update(
222 &coder->next, allocator, reversed_filters + 1);
223 }
224
225
226 extern lzma_ret
lzma_simple_coder_init(lzma_next_coder * next,const lzma_allocator * allocator,const lzma_filter_info * filters,size_t (* filter)(void * simple,uint32_t now_pos,bool is_encoder,uint8_t * buffer,size_t size),size_t simple_size,size_t unfiltered_max,uint32_t alignment,bool is_encoder)227 lzma_simple_coder_init(lzma_next_coder *next, const lzma_allocator *allocator,
228 const lzma_filter_info *filters,
229 size_t (*filter)(void *simple, uint32_t now_pos,
230 bool is_encoder, uint8_t *buffer, size_t size),
231 size_t simple_size, size_t unfiltered_max,
232 uint32_t alignment, bool is_encoder)
233 {
234 // Allocate memory for the lzma_simple_coder structure if needed.
235 lzma_simple_coder *coder = next->coder;
236 if (coder == NULL) {
237 // Here we allocate space also for the temporary buffer. We
238 // need twice the size of unfiltered_max, because then it
239 // is always possible to filter at least unfiltered_max bytes
240 // more data in coder->buffer[] if it can be filled completely.
241 coder = lzma_alloc(sizeof(lzma_simple_coder)
242 + 2 * unfiltered_max, allocator);
243 if (coder == NULL)
244 return LZMA_MEM_ERROR;
245
246 next->coder = coder;
247 next->code = &simple_code;
248 next->end = &simple_coder_end;
249 next->update = &simple_coder_update;
250
251 coder->next = LZMA_NEXT_CODER_INIT;
252 coder->filter = filter;
253 coder->allocated = 2 * unfiltered_max;
254
255 // Allocate memory for filter-specific data structure.
256 if (simple_size > 0) {
257 coder->simple = lzma_alloc(simple_size, allocator);
258 if (coder->simple == NULL)
259 return LZMA_MEM_ERROR;
260 } else {
261 coder->simple = NULL;
262 }
263 }
264
265 if (filters[0].options != NULL) {
266 const lzma_options_bcj *simple = filters[0].options;
267 coder->now_pos = simple->start_offset;
268 if (coder->now_pos & (alignment - 1))
269 return LZMA_OPTIONS_ERROR;
270 } else {
271 coder->now_pos = 0;
272 }
273
274 // Reset variables.
275 coder->is_encoder = is_encoder;
276 coder->end_was_reached = false;
277 coder->pos = 0;
278 coder->filtered = 0;
279 coder->size = 0;
280
281 return lzma_next_filter_init(&coder->next, allocator, filters + 1);
282 }
283