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 #define _POSIX_C_SOURCE 199309L
15 #include "alone_decoder.h"
16 #include "lzma_decoder.h"
17 #include "lz_decoder.h"
26 SEQ_UNCOMPRESSED_SIZE,
31 /// If true, reject files that are unlikely to be .lzma files.
32 /// If false, more non-.lzma files get accepted and will give
33 /// LZMA_DATA_ERROR either immediately or after a few output bytes.
36 /// Position in the header fields
39 /// Uncompressed size decoded from the header
40 lzma_vli uncompressed_size;
42 /// Memory usage limit
45 /// Amount of memory actually needed (only an estimate)
48 /// Options decoded from the header needed to initialize
50 lzma_options_lzma options;
55 alone_decode(lzma_coder *coder,
56 const lzma_allocator *allocator lzma_attribute((__unused__)),
57 const uint8_t *restrict in, size_t *restrict in_pos,
58 size_t in_size, uint8_t *restrict out,
59 size_t *restrict out_pos, size_t out_size,
62 while (*out_pos < out_size
63 && (coder->sequence == SEQ_CODE || *in_pos < in_size))
64 switch (coder->sequence) {
66 if (lzma_lzma_lclppb_decode(&coder->options, in[*in_pos]))
67 return LZMA_FORMAT_ERROR;
69 coder->sequence = SEQ_DICTIONARY_SIZE;
73 case SEQ_DICTIONARY_SIZE:
74 coder->options.dict_size
75 |= (size_t)(in[*in_pos]) << (coder->pos * 8);
77 if (++coder->pos == 4) {
78 if (coder->picky && coder->options.dict_size
80 // A hack to ditch tons of false positives:
81 // We allow only dictionary sizes that are
82 // 2^n or 2^n + 2^(n-1). LZMA_Alone created
83 // only files with 2^n, but accepts any
85 uint32_t d = coder->options.dict_size - 1;
93 if (d != coder->options.dict_size)
94 return LZMA_FORMAT_ERROR;
98 coder->sequence = SEQ_UNCOMPRESSED_SIZE;
104 case SEQ_UNCOMPRESSED_SIZE:
105 coder->uncompressed_size
106 |= (lzma_vli)(in[*in_pos]) << (coder->pos * 8);
108 if (++coder->pos < 8)
111 // Another hack to ditch false positives: Assume that
112 // if the uncompressed size is known, it must be less
115 && coder->uncompressed_size != LZMA_VLI_UNKNOWN
116 && coder->uncompressed_size
117 >= (LZMA_VLI_C(1) << 38))
118 return LZMA_FORMAT_ERROR;
120 // Calculate the memory usage so that it is ready
121 // for SEQ_CODER_INIT.
122 coder->memusage = lzma_lzma_decoder_memusage(&coder->options)
123 + LZMA_MEMUSAGE_BASE;
126 coder->sequence = SEQ_CODER_INIT;
130 case SEQ_CODER_INIT: {
131 if (coder->memusage > coder->memlimit)
132 return LZMA_MEMLIMIT_ERROR;
134 lzma_filter_info filters[2] = {
136 .init = &lzma_lzma_decoder_init,
137 .options = &coder->options,
143 const lzma_ret ret = lzma_next_filter_init(&coder->next,
148 // Use a hack to set the uncompressed size.
149 lzma_lz_decoder_uncompressed(coder->next.coder,
150 coder->uncompressed_size);
152 coder->sequence = SEQ_CODE;
157 return coder->next.code(coder->next.coder,
158 allocator, in, in_pos, in_size,
159 out, out_pos, out_size, action);
163 return LZMA_PROG_ERROR;
171 alone_decoder_end(lzma_coder *coder, const lzma_allocator *allocator)
173 lzma_next_end(&coder->next, allocator);
174 lzma_free(coder, allocator);
180 alone_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
181 uint64_t *old_memlimit, uint64_t new_memlimit)
183 *memusage = coder->memusage;
184 *old_memlimit = coder->memlimit;
186 if (new_memlimit != 0) {
187 if (new_memlimit < coder->memusage)
188 return LZMA_MEMLIMIT_ERROR;
190 coder->memlimit = new_memlimit;
198 lzma_alone_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
199 uint64_t memlimit, bool picky)
201 lzma_next_coder_init(&lzma_alone_decoder_init, next, allocator);
204 return LZMA_PROG_ERROR;
206 if (next->coder == NULL) {
207 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
208 if (next->coder == NULL)
209 return LZMA_MEM_ERROR;
211 next->code = &alone_decode;
212 next->end = &alone_decoder_end;
213 next->memconfig = &alone_decoder_memconfig;
214 next->coder->next = LZMA_NEXT_CODER_INIT;
217 next->coder->sequence = SEQ_PROPERTIES;
218 next->coder->picky = picky;
219 next->coder->pos = 0;
220 next->coder->options.dict_size = 0;
221 next->coder->options.preset_dict = NULL;
222 next->coder->options.preset_dict_size = 0;
223 next->coder->uncompressed_size = 0;
224 next->coder->memlimit = memlimit;
225 next->coder->memusage = LZMA_MEMUSAGE_BASE;
231 extern LZMA_API(lzma_ret)
232 lzma_alone_decoder(lzma_stream *strm, uint64_t memlimit)
234 lzma_next_strm_init(lzma_alone_decoder_init, strm, memlimit, false);
236 strm->internal->supported_actions[LZMA_RUN] = true;
237 strm->internal->supported_actions[LZMA_FINISH] = true;