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 // 122 // Do the memcpy() conditionally because out can be NULL 123 // (in which case buf_avail is always 0). Calling memcpy() 124 // with a null-pointer is undefined even if the third 125 // argument is 0. 126 if (buf_avail > 0) 127 memcpy(out + *out_pos, coder->buffer + coder->pos, 128 buf_avail); 129 130 *out_pos += buf_avail; 131 132 // Copy/Encode/Decode more data to out[]. 133 { 134 const lzma_ret ret = copy_or_code(coder, allocator, 135 in, in_pos, in_size, 136 out, out_pos, out_size, action); 137 assert(ret != LZMA_STREAM_END); 138 if (ret != LZMA_OK) 139 return ret; 140 } 141 142 // Filter out[] unless there is nothing to filter. 143 // This way we avoid null pointer + 0 (undefined behavior) 144 // when out == NULL. 145 const size_t size = *out_pos - out_start; 146 const size_t filtered = size == 0 ? 0 : call_filter( 147 coder, out + out_start, size); 148 149 const size_t unfiltered = size - filtered; 150 assert(unfiltered <= coder->allocated / 2); 151 152 // Now we can update coder->pos and coder->size, because 153 // the next coder in the chain (if any) was successful. 154 coder->pos = 0; 155 coder->size = unfiltered; 156 157 if (coder->end_was_reached) { 158 // The last byte has been copied to out[] already. 159 // They are left as is. 160 coder->size = 0; 161 162 } else if (unfiltered > 0) { 163 // There is unfiltered data left in out[]. Copy it to 164 // coder->buffer[] and rewind *out_pos appropriately. 165 *out_pos -= unfiltered; 166 memcpy(coder->buffer, out + *out_pos, unfiltered); 167 } 168 } else if (coder->pos > 0) { 169 memmove(coder->buffer, coder->buffer + coder->pos, buf_avail); 170 coder->size -= coder->pos; 171 coder->pos = 0; 172 } 173 174 assert(coder->pos == 0); 175 176 // If coder->buffer[] isn't empty, try to fill it by copying/decoding 177 // more data. Then filter coder->buffer[] and copy the successfully 178 // filtered data to out[]. It is probable, that some filtered and 179 // unfiltered data will be left to coder->buffer[]. 180 if (coder->size > 0) { 181 { 182 const lzma_ret ret = copy_or_code(coder, allocator, 183 in, in_pos, in_size, 184 coder->buffer, &coder->size, 185 coder->allocated, action); 186 assert(ret != LZMA_STREAM_END); 187 if (ret != LZMA_OK) 188 return ret; 189 } 190 191 coder->filtered = call_filter( 192 coder, coder->buffer, coder->size); 193 194 // Everything is considered to be filtered if coder->buffer[] 195 // contains the last bytes of the data. 196 if (coder->end_was_reached) 197 coder->filtered = coder->size; 198 199 // Flush as much as possible. 200 lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered, 201 out, out_pos, out_size); 202 } 203 204 // Check if we got everything done. 205 if (coder->end_was_reached && coder->pos == coder->size) 206 return LZMA_STREAM_END; 207 208 return LZMA_OK; 209 } 210 211 212 static void 213 simple_coder_end(void *coder_ptr, const lzma_allocator *allocator) 214 { 215 lzma_simple_coder *coder = coder_ptr; 216 lzma_next_end(&coder->next, allocator); 217 lzma_free(coder->simple, allocator); 218 lzma_free(coder, allocator); 219 return; 220 } 221 222 223 static lzma_ret 224 simple_coder_update(void *coder_ptr, const lzma_allocator *allocator, 225 const lzma_filter *filters_null lzma_attribute((__unused__)), 226 const lzma_filter *reversed_filters) 227 { 228 lzma_simple_coder *coder = coder_ptr; 229 230 // No update support, just call the next filter in the chain. 231 return lzma_next_filter_update( 232 &coder->next, allocator, reversed_filters + 1); 233 } 234 235 236 extern lzma_ret 237 lzma_simple_coder_init(lzma_next_coder *next, const lzma_allocator *allocator, 238 const lzma_filter_info *filters, 239 size_t (*filter)(void *simple, uint32_t now_pos, 240 bool is_encoder, uint8_t *buffer, size_t size), 241 size_t simple_size, size_t unfiltered_max, 242 uint32_t alignment, bool is_encoder) 243 { 244 // Allocate memory for the lzma_simple_coder structure if needed. 245 lzma_simple_coder *coder = next->coder; 246 if (coder == NULL) { 247 // Here we allocate space also for the temporary buffer. We 248 // need twice the size of unfiltered_max, because then it 249 // is always possible to filter at least unfiltered_max bytes 250 // more data in coder->buffer[] if it can be filled completely. 251 coder = lzma_alloc(sizeof(lzma_simple_coder) 252 + 2 * unfiltered_max, allocator); 253 if (coder == NULL) 254 return LZMA_MEM_ERROR; 255 256 next->coder = coder; 257 next->code = &simple_code; 258 next->end = &simple_coder_end; 259 next->update = &simple_coder_update; 260 261 coder->next = LZMA_NEXT_CODER_INIT; 262 coder->filter = filter; 263 coder->allocated = 2 * unfiltered_max; 264 265 // Allocate memory for filter-specific data structure. 266 if (simple_size > 0) { 267 coder->simple = lzma_alloc(simple_size, allocator); 268 if (coder->simple == NULL) 269 return LZMA_MEM_ERROR; 270 } else { 271 coder->simple = NULL; 272 } 273 } 274 275 if (filters[0].options != NULL) { 276 const lzma_options_bcj *simple = filters[0].options; 277 coder->now_pos = simple->start_offset; 278 if (coder->now_pos & (alignment - 1)) 279 return LZMA_OPTIONS_ERROR; 280 } else { 281 coder->now_pos = 0; 282 } 283 284 // Reset variables. 285 coder->is_encoder = is_encoder; 286 coder->end_was_reached = false; 287 coder->pos = 0; 288 coder->filtered = 0; 289 coder->size = 0; 290 291 return lzma_next_filter_init(&coder->next, allocator, filters + 1); 292 } 293