1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file auto_decoder.c
4 /// \brief Autodetect between .xz Stream and .lzma (LZMA_Alone) formats
5 //
6 // Author: Lasse Collin
7 //
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12
13 #include "stream_decoder.h"
14 #include "alone_decoder.h"
15
16
17 struct lzma_coder_s {
18 /// Stream decoder or LZMA_Alone decoder
19 lzma_next_coder next;
20
21 uint64_t memlimit;
22 uint32_t flags;
23
24 enum {
25 SEQ_INIT,
26 SEQ_CODE,
27 SEQ_FINISH,
28 } sequence;
29 };
30
31
32 static lzma_ret
auto_decode(lzma_coder * coder,const lzma_allocator * allocator,const uint8_t * restrict in,size_t * restrict in_pos,size_t in_size,uint8_t * restrict out,size_t * restrict out_pos,size_t out_size,lzma_action action)33 auto_decode(lzma_coder *coder, const lzma_allocator *allocator,
34 const uint8_t *restrict in, size_t *restrict in_pos,
35 size_t in_size, uint8_t *restrict out,
36 size_t *restrict out_pos, size_t out_size, lzma_action action)
37 {
38 switch (coder->sequence) {
39 case SEQ_INIT:
40 if (*in_pos >= in_size)
41 return LZMA_OK;
42
43 // Update the sequence now, because we want to continue from
44 // SEQ_CODE even if we return some LZMA_*_CHECK.
45 coder->sequence = SEQ_CODE;
46
47 // Detect the file format. For now this is simple, since if
48 // it doesn't start with 0xFD (the first magic byte of the
49 // new format), it has to be LZMA_Alone, or something that
50 // we don't support at all.
51 if (in[*in_pos] == 0xFD) {
52 return_if_error(lzma_stream_decoder_init(
53 &coder->next, allocator,
54 coder->memlimit, coder->flags));
55 } else {
56 return_if_error(lzma_alone_decoder_init(&coder->next,
57 allocator, coder->memlimit, true));
58
59 // If the application wants to know about missing
60 // integrity check or about the check in general, we
61 // need to handle it here, because LZMA_Alone decoder
62 // doesn't accept any flags.
63 if (coder->flags & LZMA_TELL_NO_CHECK)
64 return LZMA_NO_CHECK;
65
66 if (coder->flags & LZMA_TELL_ANY_CHECK)
67 return LZMA_GET_CHECK;
68 }
69
70 // Fall through
71
72 case SEQ_CODE: {
73 const lzma_ret ret = coder->next.code(
74 coder->next.coder, allocator,
75 in, in_pos, in_size,
76 out, out_pos, out_size, action);
77 if (ret != LZMA_STREAM_END
78 || (coder->flags & LZMA_CONCATENATED) == 0)
79 return ret;
80
81 coder->sequence = SEQ_FINISH;
82 }
83
84 // Fall through
85
86 case SEQ_FINISH:
87 // When LZMA_DECODE_CONCATENATED was used and we were decoding
88 // LZMA_Alone file, we need to check check that there is no
89 // trailing garbage and wait for LZMA_FINISH.
90 if (*in_pos < in_size)
91 return LZMA_DATA_ERROR;
92
93 return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;
94
95 default:
96 assert(0);
97 return LZMA_PROG_ERROR;
98 }
99 }
100
101
102 static void
auto_decoder_end(lzma_coder * coder,const lzma_allocator * allocator)103 auto_decoder_end(lzma_coder *coder, const lzma_allocator *allocator)
104 {
105 lzma_next_end(&coder->next, allocator);
106 lzma_free(coder, allocator);
107 return;
108 }
109
110
111 static lzma_check
auto_decoder_get_check(const lzma_coder * coder)112 auto_decoder_get_check(const lzma_coder *coder)
113 {
114 // It is LZMA_Alone if get_check is NULL.
115 return coder->next.get_check == NULL ? LZMA_CHECK_NONE
116 : coder->next.get_check(coder->next.coder);
117 }
118
119
120 static lzma_ret
auto_decoder_memconfig(lzma_coder * coder,uint64_t * memusage,uint64_t * old_memlimit,uint64_t new_memlimit)121 auto_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
122 uint64_t *old_memlimit, uint64_t new_memlimit)
123 {
124 lzma_ret ret;
125
126 if (coder->next.memconfig != NULL) {
127 ret = coder->next.memconfig(coder->next.coder,
128 memusage, old_memlimit, new_memlimit);
129 assert(*old_memlimit == coder->memlimit);
130 } else {
131 // No coder is configured yet. Use the base value as
132 // the current memory usage.
133 *memusage = LZMA_MEMUSAGE_BASE;
134 *old_memlimit = coder->memlimit;
135 ret = LZMA_OK;
136 }
137
138 if (ret == LZMA_OK && new_memlimit != 0)
139 coder->memlimit = new_memlimit;
140
141 return ret;
142 }
143
144
145 static lzma_ret
auto_decoder_init(lzma_next_coder * next,const lzma_allocator * allocator,uint64_t memlimit,uint32_t flags)146 auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
147 uint64_t memlimit, uint32_t flags)
148 {
149 lzma_next_coder_init(&auto_decoder_init, next, allocator);
150
151 if (memlimit == 0)
152 return LZMA_PROG_ERROR;
153
154 if (flags & ~LZMA_SUPPORTED_FLAGS)
155 return LZMA_OPTIONS_ERROR;
156
157 if (next->coder == NULL) {
158 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
159 if (next->coder == NULL)
160 return LZMA_MEM_ERROR;
161
162 next->code = &auto_decode;
163 next->end = &auto_decoder_end;
164 next->get_check = &auto_decoder_get_check;
165 next->memconfig = &auto_decoder_memconfig;
166 next->coder->next = LZMA_NEXT_CODER_INIT;
167 }
168
169 next->coder->memlimit = memlimit;
170 next->coder->flags = flags;
171 next->coder->sequence = SEQ_INIT;
172
173 return LZMA_OK;
174 }
175
176
177 extern LZMA_API(lzma_ret)
lzma_auto_decoder(lzma_stream * strm,uint64_t memlimit,uint32_t flags)178 lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
179 {
180 lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);
181
182 strm->internal->supported_actions[LZMA_RUN] = true;
183 strm->internal->supported_actions[LZMA_FINISH] = true;
184
185 return LZMA_OK;
186 }
187