1207753Smm/////////////////////////////////////////////////////////////////////////////// 2207753Smm// 3207753Smm/// \file alone_decoder.c 4207753Smm/// \brief Decoder for LZMA_Alone files 5207753Smm// 6207753Smm// Author: Lasse Collin 7207753Smm// 8207753Smm// This file has been put into the public domain. 9207753Smm// You can do whatever you want with this file. 10207753Smm// 11207753Smm/////////////////////////////////////////////////////////////////////////////// 12207753Smm 13207753Smm#include "alone_decoder.h" 14207753Smm#include "lzma_decoder.h" 15207753Smm#include "lz_decoder.h" 16207753Smm 17207753Smm 18312518Sdelphijtypedef struct { 19207753Smm lzma_next_coder next; 20207753Smm 21207753Smm enum { 22207753Smm SEQ_PROPERTIES, 23207753Smm SEQ_DICTIONARY_SIZE, 24207753Smm SEQ_UNCOMPRESSED_SIZE, 25207753Smm SEQ_CODER_INIT, 26207753Smm SEQ_CODE, 27207753Smm } sequence; 28207753Smm 29263285Sdelphij /// If true, reject files that are unlikely to be .lzma files. 30263285Sdelphij /// If false, more non-.lzma files get accepted and will give 31263285Sdelphij /// LZMA_DATA_ERROR either immediately or after a few output bytes. 32263285Sdelphij bool picky; 33263285Sdelphij 34207753Smm /// Position in the header fields 35207753Smm size_t pos; 36207753Smm 37207753Smm /// Uncompressed size decoded from the header 38207753Smm lzma_vli uncompressed_size; 39207753Smm 40207753Smm /// Memory usage limit 41207753Smm uint64_t memlimit; 42207753Smm 43207753Smm /// Amount of memory actually needed (only an estimate) 44207753Smm uint64_t memusage; 45207753Smm 46207753Smm /// Options decoded from the header needed to initialize 47207753Smm /// the LZMA decoder 48207753Smm lzma_options_lzma options; 49312518Sdelphij} lzma_alone_coder; 50207753Smm 51207753Smm 52207753Smmstatic lzma_ret 53312518Sdelphijalone_decode(void *coder_ptr, 54292588Sdelphij const lzma_allocator *allocator lzma_attribute((__unused__)), 55207753Smm const uint8_t *restrict in, size_t *restrict in_pos, 56207753Smm size_t in_size, uint8_t *restrict out, 57207753Smm size_t *restrict out_pos, size_t out_size, 58207753Smm lzma_action action) 59207753Smm{ 60312518Sdelphij lzma_alone_coder *coder = coder_ptr; 61312518Sdelphij 62207753Smm while (*out_pos < out_size 63207753Smm && (coder->sequence == SEQ_CODE || *in_pos < in_size)) 64207753Smm switch (coder->sequence) { 65207753Smm case SEQ_PROPERTIES: 66207753Smm if (lzma_lzma_lclppb_decode(&coder->options, in[*in_pos])) 67207753Smm return LZMA_FORMAT_ERROR; 68207753Smm 69207753Smm coder->sequence = SEQ_DICTIONARY_SIZE; 70207753Smm ++*in_pos; 71207753Smm break; 72207753Smm 73207753Smm case SEQ_DICTIONARY_SIZE: 74207753Smm coder->options.dict_size 75207753Smm |= (size_t)(in[*in_pos]) << (coder->pos * 8); 76207753Smm 77207753Smm if (++coder->pos == 4) { 78263285Sdelphij if (coder->picky && coder->options.dict_size 79263285Sdelphij != UINT32_MAX) { 80207753Smm // A hack to ditch tons of false positives: 81207753Smm // We allow only dictionary sizes that are 82207753Smm // 2^n or 2^n + 2^(n-1). LZMA_Alone created 83207753Smm // only files with 2^n, but accepts any 84263285Sdelphij // dictionary size. 85207753Smm uint32_t d = coder->options.dict_size - 1; 86207753Smm d |= d >> 2; 87207753Smm d |= d >> 3; 88207753Smm d |= d >> 4; 89207753Smm d |= d >> 8; 90207753Smm d |= d >> 16; 91207753Smm ++d; 92207753Smm 93207753Smm if (d != coder->options.dict_size) 94207753Smm return LZMA_FORMAT_ERROR; 95207753Smm } 96207753Smm 97207753Smm coder->pos = 0; 98207753Smm coder->sequence = SEQ_UNCOMPRESSED_SIZE; 99207753Smm } 100207753Smm 101207753Smm ++*in_pos; 102207753Smm break; 103207753Smm 104207753Smm case SEQ_UNCOMPRESSED_SIZE: 105207753Smm coder->uncompressed_size 106207753Smm |= (lzma_vli)(in[*in_pos]) << (coder->pos * 8); 107207753Smm ++*in_pos; 108207753Smm if (++coder->pos < 8) 109207753Smm break; 110207753Smm 111207753Smm // Another hack to ditch false positives: Assume that 112207753Smm // if the uncompressed size is known, it must be less 113263285Sdelphij // than 256 GiB. 114263285Sdelphij if (coder->picky 115263285Sdelphij && coder->uncompressed_size != LZMA_VLI_UNKNOWN 116207753Smm && coder->uncompressed_size 117207753Smm >= (LZMA_VLI_C(1) << 38)) 118207753Smm return LZMA_FORMAT_ERROR; 119207753Smm 120207753Smm // Calculate the memory usage so that it is ready 121207753Smm // for SEQ_CODER_INIT. 122207753Smm coder->memusage = lzma_lzma_decoder_memusage(&coder->options) 123207753Smm + LZMA_MEMUSAGE_BASE; 124207753Smm 125207753Smm coder->pos = 0; 126207753Smm coder->sequence = SEQ_CODER_INIT; 127207753Smm 128207753Smm // Fall through 129207753Smm 130207753Smm case SEQ_CODER_INIT: { 131207753Smm if (coder->memusage > coder->memlimit) 132207753Smm return LZMA_MEMLIMIT_ERROR; 133207753Smm 134207753Smm lzma_filter_info filters[2] = { 135207753Smm { 136207753Smm .init = &lzma_lzma_decoder_init, 137207753Smm .options = &coder->options, 138207753Smm }, { 139207753Smm .init = NULL, 140207753Smm } 141207753Smm }; 142207753Smm 143207753Smm const lzma_ret ret = lzma_next_filter_init(&coder->next, 144207753Smm allocator, filters); 145207753Smm if (ret != LZMA_OK) 146207753Smm return ret; 147207753Smm 148207753Smm // Use a hack to set the uncompressed size. 149207753Smm lzma_lz_decoder_uncompressed(coder->next.coder, 150207753Smm coder->uncompressed_size); 151207753Smm 152207753Smm coder->sequence = SEQ_CODE; 153207753Smm break; 154207753Smm } 155207753Smm 156207753Smm case SEQ_CODE: { 157207753Smm return coder->next.code(coder->next.coder, 158207753Smm allocator, in, in_pos, in_size, 159207753Smm out, out_pos, out_size, action); 160207753Smm } 161207753Smm 162207753Smm default: 163207753Smm return LZMA_PROG_ERROR; 164207753Smm } 165207753Smm 166207753Smm return LZMA_OK; 167207753Smm} 168207753Smm 169207753Smm 170207753Smmstatic void 171312518Sdelphijalone_decoder_end(void *coder_ptr, const lzma_allocator *allocator) 172207753Smm{ 173312518Sdelphij lzma_alone_coder *coder = coder_ptr; 174207753Smm lzma_next_end(&coder->next, allocator); 175207753Smm lzma_free(coder, allocator); 176207753Smm return; 177207753Smm} 178207753Smm 179207753Smm 180207753Smmstatic lzma_ret 181312518Sdelphijalone_decoder_memconfig(void *coder_ptr, uint64_t *memusage, 182207753Smm uint64_t *old_memlimit, uint64_t new_memlimit) 183207753Smm{ 184312518Sdelphij lzma_alone_coder *coder = coder_ptr; 185312518Sdelphij 186207753Smm *memusage = coder->memusage; 187207753Smm *old_memlimit = coder->memlimit; 188207753Smm 189207753Smm if (new_memlimit != 0) { 190207753Smm if (new_memlimit < coder->memusage) 191207753Smm return LZMA_MEMLIMIT_ERROR; 192207753Smm 193207753Smm coder->memlimit = new_memlimit; 194207753Smm } 195207753Smm 196207753Smm return LZMA_OK; 197207753Smm} 198207753Smm 199207753Smm 200207753Smmextern lzma_ret 201292588Sdelphijlzma_alone_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, 202263285Sdelphij uint64_t memlimit, bool picky) 203207753Smm{ 204207753Smm lzma_next_coder_init(&lzma_alone_decoder_init, next, allocator); 205207753Smm 206207753Smm if (memlimit == 0) 207207753Smm return LZMA_PROG_ERROR; 208207753Smm 209312518Sdelphij lzma_alone_coder *coder = next->coder; 210312518Sdelphij 211312518Sdelphij if (coder == NULL) { 212312518Sdelphij coder = lzma_alloc(sizeof(lzma_alone_coder), allocator); 213312518Sdelphij if (coder == NULL) 214207753Smm return LZMA_MEM_ERROR; 215207753Smm 216312518Sdelphij next->coder = coder; 217207753Smm next->code = &alone_decode; 218207753Smm next->end = &alone_decoder_end; 219207753Smm next->memconfig = &alone_decoder_memconfig; 220312518Sdelphij coder->next = LZMA_NEXT_CODER_INIT; 221207753Smm } 222207753Smm 223312518Sdelphij coder->sequence = SEQ_PROPERTIES; 224312518Sdelphij coder->picky = picky; 225312518Sdelphij coder->pos = 0; 226312518Sdelphij coder->options.dict_size = 0; 227312518Sdelphij coder->options.preset_dict = NULL; 228312518Sdelphij coder->options.preset_dict_size = 0; 229312518Sdelphij coder->uncompressed_size = 0; 230312518Sdelphij coder->memlimit = memlimit; 231312518Sdelphij coder->memusage = LZMA_MEMUSAGE_BASE; 232207753Smm 233207753Smm return LZMA_OK; 234207753Smm} 235207753Smm 236207753Smm 237207753Smmextern LZMA_API(lzma_ret) 238207753Smmlzma_alone_decoder(lzma_stream *strm, uint64_t memlimit) 239207753Smm{ 240263285Sdelphij lzma_next_strm_init(lzma_alone_decoder_init, strm, memlimit, false); 241207753Smm 242207753Smm strm->internal->supported_actions[LZMA_RUN] = true; 243207753Smm strm->internal->supported_actions[LZMA_FINISH] = true; 244207753Smm 245207753Smm return LZMA_OK; 246207753Smm} 247