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 typedef struct {
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 } lzma_auto_coder;
30
31
32 static lzma_ret
auto_decode(void * coder_ptr,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(void *coder_ptr, 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 lzma_auto_coder *coder = coder_ptr;
39
40 switch (coder->sequence) {
41 case SEQ_INIT:
42 if (*in_pos >= in_size)
43 return LZMA_OK;
44
45 // Update the sequence now, because we want to continue from
46 // SEQ_CODE even if we return some LZMA_*_CHECK.
47 coder->sequence = SEQ_CODE;
48
49 // Detect the file format. For now this is simple, since if
50 // it doesn't start with 0xFD (the first magic byte of the
51 // new format), it has to be LZMA_Alone, or something that
52 // we don't support at all.
53 if (in[*in_pos] == 0xFD) {
54 return_if_error(lzma_stream_decoder_init(
55 &coder->next, allocator,
56 coder->memlimit, coder->flags));
57 } else {
58 return_if_error(lzma_alone_decoder_init(&coder->next,
59 allocator, coder->memlimit, true));
60
61 // If the application wants to know about missing
62 // integrity check or about the check in general, we
63 // need to handle it here, because LZMA_Alone decoder
64 // doesn't accept any flags.
65 if (coder->flags & LZMA_TELL_NO_CHECK)
66 return LZMA_NO_CHECK;
67
68 if (coder->flags & LZMA_TELL_ANY_CHECK)
69 return LZMA_GET_CHECK;
70 }
71
72 // Fall through
73
74 case SEQ_CODE: {
75 const lzma_ret ret = coder->next.code(
76 coder->next.coder, allocator,
77 in, in_pos, in_size,
78 out, out_pos, out_size, action);
79 if (ret != LZMA_STREAM_END
80 || (coder->flags & LZMA_CONCATENATED) == 0)
81 return ret;
82
83 coder->sequence = SEQ_FINISH;
84 }
85
86 // Fall through
87
88 case SEQ_FINISH:
89 // When LZMA_DECODE_CONCATENATED was used and we were decoding
90 // LZMA_Alone file, we need to check check that there is no
91 // trailing garbage and wait for LZMA_FINISH.
92 if (*in_pos < in_size)
93 return LZMA_DATA_ERROR;
94
95 return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;
96
97 default:
98 assert(0);
99 return LZMA_PROG_ERROR;
100 }
101 }
102
103
104 static void
auto_decoder_end(void * coder_ptr,const lzma_allocator * allocator)105 auto_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
106 {
107 lzma_auto_coder *coder = coder_ptr;
108 lzma_next_end(&coder->next, allocator);
109 lzma_free(coder, allocator);
110 return;
111 }
112
113
114 static lzma_check
auto_decoder_get_check(const void * coder_ptr)115 auto_decoder_get_check(const void *coder_ptr)
116 {
117 const lzma_auto_coder *coder = coder_ptr;
118
119 // It is LZMA_Alone if get_check is NULL.
120 return coder->next.get_check == NULL ? LZMA_CHECK_NONE
121 : coder->next.get_check(coder->next.coder);
122 }
123
124
125 static lzma_ret
auto_decoder_memconfig(void * coder_ptr,uint64_t * memusage,uint64_t * old_memlimit,uint64_t new_memlimit)126 auto_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
127 uint64_t *old_memlimit, uint64_t new_memlimit)
128 {
129 lzma_auto_coder *coder = coder_ptr;
130
131 lzma_ret ret;
132
133 if (coder->next.memconfig != NULL) {
134 ret = coder->next.memconfig(coder->next.coder,
135 memusage, old_memlimit, new_memlimit);
136 assert(*old_memlimit == coder->memlimit);
137 } else {
138 // No coder is configured yet. Use the base value as
139 // the current memory usage.
140 *memusage = LZMA_MEMUSAGE_BASE;
141 *old_memlimit = coder->memlimit;
142
143 ret = LZMA_OK;
144 if (new_memlimit != 0 && new_memlimit < *memusage)
145 ret = LZMA_MEMLIMIT_ERROR;
146 }
147
148 if (ret == LZMA_OK && new_memlimit != 0)
149 coder->memlimit = new_memlimit;
150
151 return ret;
152 }
153
154
155 static lzma_ret
auto_decoder_init(lzma_next_coder * next,const lzma_allocator * allocator,uint64_t memlimit,uint32_t flags)156 auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
157 uint64_t memlimit, uint32_t flags)
158 {
159 lzma_next_coder_init(&auto_decoder_init, next, allocator);
160
161 if (flags & ~LZMA_SUPPORTED_FLAGS)
162 return LZMA_OPTIONS_ERROR;
163
164 lzma_auto_coder *coder = next->coder;
165 if (coder == NULL) {
166 coder = lzma_alloc(sizeof(lzma_auto_coder), allocator);
167 if (coder == NULL)
168 return LZMA_MEM_ERROR;
169
170 next->coder = coder;
171 next->code = &auto_decode;
172 next->end = &auto_decoder_end;
173 next->get_check = &auto_decoder_get_check;
174 next->memconfig = &auto_decoder_memconfig;
175 coder->next = LZMA_NEXT_CODER_INIT;
176 }
177
178 coder->memlimit = my_max(1, memlimit);
179 coder->flags = flags;
180 coder->sequence = SEQ_INIT;
181
182 return LZMA_OK;
183 }
184
185
186 extern LZMA_API(lzma_ret)
lzma_auto_decoder(lzma_stream * strm,uint64_t memlimit,uint32_t flags)187 lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
188 {
189 lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);
190
191 strm->internal->supported_actions[LZMA_RUN] = true;
192 strm->internal->supported_actions[LZMA_FINISH] = true;
193
194 return LZMA_OK;
195 }
196