1 ///////////////////////////////////////////////////////////////////////////////
3 /// \file alone_decoder.c
4 /// \brief Decoder for LZMA_Alone files
6 // Author: Lasse Collin
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
11 ///////////////////////////////////////////////////////////////////////////////
13 #include "alone_decoder.h"
14 #include "lzma_decoder.h"
15 #include "lz_decoder.h"
24 SEQ_UNCOMPRESSED_SIZE,
29 /// If true, reject files that are unlikely to be .lzma files.
30 /// If false, more non-.lzma files get accepted and will give
31 /// LZMA_DATA_ERROR either immediately or after a few output bytes.
34 /// Position in the header fields
37 /// Uncompressed size decoded from the header
38 lzma_vli uncompressed_size;
40 /// Memory usage limit
43 /// Amount of memory actually needed (only an estimate)
46 /// Options decoded from the header needed to initialize
48 lzma_options_lzma options;
53 alone_decode(lzma_coder *coder,
54 lzma_allocator *allocator lzma_attribute((__unused__)),
55 const uint8_t *restrict in, size_t *restrict in_pos,
56 size_t in_size, uint8_t *restrict out,
57 size_t *restrict out_pos, size_t out_size,
60 while (*out_pos < out_size
61 && (coder->sequence == SEQ_CODE || *in_pos < in_size))
62 switch (coder->sequence) {
64 if (lzma_lzma_lclppb_decode(&coder->options, in[*in_pos]))
65 return LZMA_FORMAT_ERROR;
67 coder->sequence = SEQ_DICTIONARY_SIZE;
71 case SEQ_DICTIONARY_SIZE:
72 coder->options.dict_size
73 |= (size_t)(in[*in_pos]) << (coder->pos * 8);
75 if (++coder->pos == 4) {
76 if (coder->picky && coder->options.dict_size
78 // A hack to ditch tons of false positives:
79 // We allow only dictionary sizes that are
80 // 2^n or 2^n + 2^(n-1). LZMA_Alone created
81 // only files with 2^n, but accepts any
83 uint32_t d = coder->options.dict_size - 1;
91 if (d != coder->options.dict_size)
92 return LZMA_FORMAT_ERROR;
96 coder->sequence = SEQ_UNCOMPRESSED_SIZE;
102 case SEQ_UNCOMPRESSED_SIZE:
103 coder->uncompressed_size
104 |= (lzma_vli)(in[*in_pos]) << (coder->pos * 8);
106 if (++coder->pos < 8)
109 // Another hack to ditch false positives: Assume that
110 // if the uncompressed size is known, it must be less
113 && coder->uncompressed_size != LZMA_VLI_UNKNOWN
114 && coder->uncompressed_size
115 >= (LZMA_VLI_C(1) << 38))
116 return LZMA_FORMAT_ERROR;
118 // Calculate the memory usage so that it is ready
119 // for SEQ_CODER_INIT.
120 coder->memusage = lzma_lzma_decoder_memusage(&coder->options)
121 + LZMA_MEMUSAGE_BASE;
124 coder->sequence = SEQ_CODER_INIT;
128 case SEQ_CODER_INIT: {
129 if (coder->memusage > coder->memlimit)
130 return LZMA_MEMLIMIT_ERROR;
132 lzma_filter_info filters[2] = {
134 .init = &lzma_lzma_decoder_init,
135 .options = &coder->options,
141 const lzma_ret ret = lzma_next_filter_init(&coder->next,
146 // Use a hack to set the uncompressed size.
147 lzma_lz_decoder_uncompressed(coder->next.coder,
148 coder->uncompressed_size);
150 coder->sequence = SEQ_CODE;
155 return coder->next.code(coder->next.coder,
156 allocator, in, in_pos, in_size,
157 out, out_pos, out_size, action);
161 return LZMA_PROG_ERROR;
169 alone_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
171 lzma_next_end(&coder->next, allocator);
172 lzma_free(coder, allocator);
178 alone_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
179 uint64_t *old_memlimit, uint64_t new_memlimit)
181 *memusage = coder->memusage;
182 *old_memlimit = coder->memlimit;
184 if (new_memlimit != 0) {
185 if (new_memlimit < coder->memusage)
186 return LZMA_MEMLIMIT_ERROR;
188 coder->memlimit = new_memlimit;
196 lzma_alone_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
197 uint64_t memlimit, bool picky)
199 lzma_next_coder_init(&lzma_alone_decoder_init, next, allocator);
202 return LZMA_PROG_ERROR;
204 if (next->coder == NULL) {
205 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
206 if (next->coder == NULL)
207 return LZMA_MEM_ERROR;
209 next->code = &alone_decode;
210 next->end = &alone_decoder_end;
211 next->memconfig = &alone_decoder_memconfig;
212 next->coder->next = LZMA_NEXT_CODER_INIT;
215 next->coder->sequence = SEQ_PROPERTIES;
216 next->coder->picky = picky;
217 next->coder->pos = 0;
218 next->coder->options.dict_size = 0;
219 next->coder->options.preset_dict = NULL;
220 next->coder->options.preset_dict_size = 0;
221 next->coder->uncompressed_size = 0;
222 next->coder->memlimit = memlimit;
223 next->coder->memusage = LZMA_MEMUSAGE_BASE;
229 extern LZMA_API(lzma_ret)
230 lzma_alone_decoder(lzma_stream *strm, uint64_t memlimit)
232 lzma_next_strm_init(lzma_alone_decoder_init, strm, memlimit, false);
234 strm->internal->supported_actions[LZMA_RUN] = true;
235 strm->internal->supported_actions[LZMA_FINISH] = true;