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_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 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 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 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 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 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