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, 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 58 call_filter(lzma_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 69 simple_code(lzma_coder *coder, 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 // TODO: Add partial support for LZMA_SYNC_FLUSH. We can support it 75 // in cases when the filter is able to filter everything. With most 76 // simple filters it can be done at offset that is a multiple of 2, 77 // 4, or 16. With x86 filter, it needs good luck, and thus cannot 78 // be made to work predictably. 79 if (action == LZMA_SYNC_FLUSH) 80 return LZMA_OPTIONS_ERROR; 81 82 // Flush already filtered data from coder->buffer[] to out[]. 83 if (coder->pos < coder->filtered) { 84 lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered, 85 out, out_pos, out_size); 86 87 // If we couldn't flush all the filtered data, return to 88 // application immediately. 89 if (coder->pos < coder->filtered) 90 return LZMA_OK; 91 92 if (coder->end_was_reached) { 93 assert(coder->filtered == coder->size); 94 return LZMA_STREAM_END; 95 } 96 } 97 98 // If we get here, there is no filtered data left in the buffer. 99 coder->filtered = 0; 100 101 assert(!coder->end_was_reached); 102 103 // If there is more output space left than there is unfiltered data 104 // in coder->buffer[], flush coder->buffer[] to out[], and copy/code 105 // more data to out[] hopefully filling it completely. Then filter 106 // the data in out[]. This step is where most of the data gets 107 // filtered if the buffer sizes used by the application are reasonable. 108 const size_t out_avail = out_size - *out_pos; 109 const size_t buf_avail = coder->size - coder->pos; 110 if (out_avail > buf_avail || buf_avail == 0) { 111 // Store the old position so that we know from which byte 112 // to start filtering. 113 const size_t out_start = *out_pos; 114 115 // Flush data from coder->buffer[] to out[], but don't reset 116 // coder->pos and coder->size yet. This way the coder can be 117 // restarted if the next filter in the chain returns e.g. 118 // LZMA_MEM_ERROR. 119 memcpy(out + *out_pos, coder->buffer + coder->pos, buf_avail); 120 *out_pos += buf_avail; 121 122 // Copy/Encode/Decode more data to out[]. 123 { 124 const lzma_ret ret = copy_or_code(coder, allocator, 125 in, in_pos, in_size, 126 out, out_pos, out_size, action); 127 assert(ret != LZMA_STREAM_END); 128 if (ret != LZMA_OK) 129 return ret; 130 } 131 132 // Filter out[]. 133 const size_t size = *out_pos - out_start; 134 const size_t filtered = call_filter( 135 coder, out + out_start, size); 136 137 const size_t unfiltered = size - filtered; 138 assert(unfiltered <= coder->allocated / 2); 139 140 // Now we can update coder->pos and coder->size, because 141 // the next coder in the chain (if any) was successful. 142 coder->pos = 0; 143 coder->size = unfiltered; 144 145 if (coder->end_was_reached) { 146 // The last byte has been copied to out[] already. 147 // They are left as is. 148 coder->size = 0; 149 150 } else if (unfiltered > 0) { 151 // There is unfiltered data left in out[]. Copy it to 152 // coder->buffer[] and rewind *out_pos appropriately. 153 *out_pos -= unfiltered; 154 memcpy(coder->buffer, out + *out_pos, unfiltered); 155 } 156 } else if (coder->pos > 0) { 157 memmove(coder->buffer, coder->buffer + coder->pos, buf_avail); 158 coder->size -= coder->pos; 159 coder->pos = 0; 160 } 161 162 assert(coder->pos == 0); 163 164 // If coder->buffer[] isn't empty, try to fill it by copying/decoding 165 // more data. Then filter coder->buffer[] and copy the successfully 166 // filtered data to out[]. It is probable, that some filtered and 167 // unfiltered data will be left to coder->buffer[]. 168 if (coder->size > 0) { 169 { 170 const lzma_ret ret = copy_or_code(coder, allocator, 171 in, in_pos, in_size, 172 coder->buffer, &coder->size, 173 coder->allocated, action); 174 assert(ret != LZMA_STREAM_END); 175 if (ret != LZMA_OK) 176 return ret; 177 } 178 179 coder->filtered = call_filter( 180 coder, coder->buffer, coder->size); 181 182 // Everything is considered to be filtered if coder->buffer[] 183 // contains the last bytes of the data. 184 if (coder->end_was_reached) 185 coder->filtered = coder->size; 186 187 // Flush as much as possible. 188 lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered, 189 out, out_pos, out_size); 190 } 191 192 // Check if we got everything done. 193 if (coder->end_was_reached && coder->pos == coder->size) 194 return LZMA_STREAM_END; 195 196 return LZMA_OK; 197 } 198 199 200 static void 201 simple_coder_end(lzma_coder *coder, const lzma_allocator *allocator) 202 { 203 lzma_next_end(&coder->next, allocator); 204 lzma_free(coder->simple, allocator); 205 lzma_free(coder, allocator); 206 return; 207 } 208 209 210 static lzma_ret 211 simple_coder_update(lzma_coder *coder, const lzma_allocator *allocator, 212 const lzma_filter *filters_null lzma_attribute((__unused__)), 213 const lzma_filter *reversed_filters) 214 { 215 // No update support, just call the next filter in the chain. 216 return lzma_next_filter_update( 217 &coder->next, allocator, reversed_filters + 1); 218 } 219 220 221 extern lzma_ret 222 lzma_simple_coder_init(lzma_next_coder *next, const lzma_allocator *allocator, 223 const lzma_filter_info *filters, 224 size_t (*filter)(lzma_simple *simple, uint32_t now_pos, 225 bool is_encoder, uint8_t *buffer, size_t size), 226 size_t simple_size, size_t unfiltered_max, 227 uint32_t alignment, bool is_encoder) 228 { 229 // Allocate memory for the lzma_coder structure if needed. 230 if (next->coder == NULL) { 231 // Here we allocate space also for the temporary buffer. We 232 // need twice the size of unfiltered_max, because then it 233 // is always possible to filter at least unfiltered_max bytes 234 // more data in coder->buffer[] if it can be filled completely. 235 next->coder = lzma_alloc(sizeof(lzma_coder) 236 + 2 * unfiltered_max, allocator); 237 if (next->coder == NULL) 238 return LZMA_MEM_ERROR; 239 240 next->code = &simple_code; 241 next->end = &simple_coder_end; 242 next->update = &simple_coder_update; 243 244 next->coder->next = LZMA_NEXT_CODER_INIT; 245 next->coder->filter = filter; 246 next->coder->allocated = 2 * unfiltered_max; 247 248 // Allocate memory for filter-specific data structure. 249 if (simple_size > 0) { 250 next->coder->simple = lzma_alloc( 251 simple_size, allocator); 252 if (next->coder->simple == NULL) 253 return LZMA_MEM_ERROR; 254 } else { 255 next->coder->simple = NULL; 256 } 257 } 258 259 if (filters[0].options != NULL) { 260 const lzma_options_bcj *simple = filters[0].options; 261 next->coder->now_pos = simple->start_offset; 262 if (next->coder->now_pos & (alignment - 1)) 263 return LZMA_OPTIONS_ERROR; 264 } else { 265 next->coder->now_pos = 0; 266 } 267 268 // Reset variables. 269 next->coder->is_encoder = is_encoder; 270 next->coder->end_was_reached = false; 271 next->coder->pos = 0; 272 next->coder->filtered = 0; 273 next->coder->size = 0; 274 275 return lzma_next_filter_init( 276 &next->coder->next, allocator, filters + 1); 277 } 278