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