Contents of /trunk/mkinitrd-magellan/busybox/archival/libunarchive/unxz/xz.h
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Wed Aug 18 21:56:57 2010 UTC (13 years, 9 months ago) by niro
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Wed Aug 18 21:56:57 2010 UTC (13 years, 9 months ago) by niro
File MIME type: text/plain
File size: 11597 byte(s)
-updated to busybox-1.17.1
1 | /* |
2 | * XZ decompressor |
3 | * |
4 | * Authors: Lasse Collin <lasse.collin@tukaani.org> |
5 | * Igor Pavlov <http://7-zip.org/> |
6 | * |
7 | * This file has been put into the public domain. |
8 | * You can do whatever you want with this file. |
9 | */ |
10 | |
11 | #ifndef XZ_H |
12 | #define XZ_H |
13 | |
14 | #ifdef __KERNEL__ |
15 | # include <linux/stddef.h> |
16 | # include <linux/types.h> |
17 | #else |
18 | # include <stddef.h> |
19 | # include <stdint.h> |
20 | #endif |
21 | |
22 | /* In Linux, this is used to make extern functions static when needed. */ |
23 | #ifndef XZ_EXTERN |
24 | # define XZ_EXTERN extern |
25 | #endif |
26 | |
27 | /* In Linux, this is used to mark the functions with __init when needed. */ |
28 | #ifndef XZ_FUNC |
29 | # define XZ_FUNC |
30 | #endif |
31 | |
32 | /** |
33 | * enum xz_mode - Operation mode |
34 | * |
35 | * @XZ_SINGLE: Single-call mode. This uses less RAM than |
36 | * than multi-call modes, because the LZMA2 |
37 | * dictionary doesn't need to be allocated as |
38 | * part of the decoder state. All required data |
39 | * structures are allocated at initialization, |
40 | * so xz_dec_run() cannot return XZ_MEM_ERROR. |
41 | * @XZ_PREALLOC: Multi-call mode with preallocated LZMA2 |
42 | * dictionary buffer. All data structures are |
43 | * allocated at initialization, so xz_dec_run() |
44 | * cannot return XZ_MEM_ERROR. |
45 | * @XZ_DYNALLOC: Multi-call mode. The LZMA2 dictionary is |
46 | * allocated once the required size has been |
47 | * parsed from the stream headers. If the |
48 | * allocation fails, xz_dec_run() will return |
49 | * XZ_MEM_ERROR. |
50 | * |
51 | * It is possible to enable support only for a subset of the above |
52 | * modes at compile time by defining XZ_DEC_SINGLE, XZ_DEC_PREALLOC, |
53 | * or XZ_DEC_DYNALLOC. The xz_dec kernel module is always compiled |
54 | * with support for all operation modes, but the preboot code may |
55 | * be built with fewer features to minimize code size. |
56 | */ |
57 | enum xz_mode { |
58 | XZ_SINGLE, |
59 | XZ_PREALLOC, |
60 | XZ_DYNALLOC |
61 | }; |
62 | |
63 | /** |
64 | * enum xz_ret - Return codes |
65 | * @XZ_OK: Everything is OK so far. More input or more |
66 | * output space is required to continue. This |
67 | * return code is possible only in multi-call mode |
68 | * (XZ_PREALLOC or XZ_DYNALLOC). |
69 | * @XZ_STREAM_END: Operation finished successfully. |
70 | * @XZ_UNSUPPORTED_CHECK: Integrity check type is not supported. Decoding |
71 | * is still possible in multi-call mode by simply |
72 | * calling xz_dec_run() again. |
73 | * NOTE: This return value is used only if |
74 | * XZ_DEC_ANY_CHECK was defined at build time, |
75 | * which is not used in the kernel. Unsupported |
76 | * check types return XZ_OPTIONS_ERROR if |
77 | * XZ_DEC_ANY_CHECK was not defined at build time. |
78 | * @XZ_MEM_ERROR: Allocating memory failed. This return code is |
79 | * possible only if the decoder was initialized |
80 | * with XZ_DYNALLOC. The amount of memory that was |
81 | * tried to be allocated was no more than the |
82 | * dict_max argument given to xz_dec_init(). |
83 | * @XZ_MEMLIMIT_ERROR: A bigger LZMA2 dictionary would be needed than |
84 | * allowed by the dict_max argument given to |
85 | * xz_dec_init(). This return value is possible |
86 | * only in multi-call mode (XZ_PREALLOC or |
87 | * XZ_DYNALLOC); the single-call mode (XZ_SINGLE) |
88 | * ignores the dict_max argument. |
89 | * @XZ_FORMAT_ERROR: File format was not recognized (wrong magic |
90 | * bytes). |
91 | * @XZ_OPTIONS_ERROR: This implementation doesn't support the requested |
92 | * compression options. In the decoder this means |
93 | * that the header CRC32 matches, but the header |
94 | * itself specifies something that we don't support. |
95 | * @XZ_DATA_ERROR: Compressed data is corrupt. |
96 | * @XZ_BUF_ERROR: Cannot make any progress. Details are slightly |
97 | * different between multi-call and single-call |
98 | * mode; more information below. |
99 | * |
100 | * In multi-call mode, XZ_BUF_ERROR is returned when two consecutive calls |
101 | * to XZ code cannot consume any input and cannot produce any new output. |
102 | * This happens when there is no new input available, or the output buffer |
103 | * is full while at least one output byte is still pending. Assuming your |
104 | * code is not buggy, you can get this error only when decoding a compressed |
105 | * stream that is truncated or otherwise corrupt. |
106 | * |
107 | * In single-call mode, XZ_BUF_ERROR is returned only when the output buffer |
108 | * is too small, or the compressed input is corrupt in a way that makes the |
109 | * decoder produce more output than the caller expected. When it is |
110 | * (relatively) clear that the compressed input is truncated, XZ_DATA_ERROR |
111 | * is used instead of XZ_BUF_ERROR. |
112 | */ |
113 | enum xz_ret { |
114 | XZ_OK, |
115 | XZ_STREAM_END, |
116 | XZ_UNSUPPORTED_CHECK, |
117 | XZ_MEM_ERROR, |
118 | XZ_MEMLIMIT_ERROR, |
119 | XZ_FORMAT_ERROR, |
120 | XZ_OPTIONS_ERROR, |
121 | XZ_DATA_ERROR, |
122 | XZ_BUF_ERROR |
123 | }; |
124 | |
125 | /** |
126 | * struct xz_buf - Passing input and output buffers to XZ code |
127 | * @in: Beginning of the input buffer. This may be NULL if and only |
128 | * if in_pos is equal to in_size. |
129 | * @in_pos: Current position in the input buffer. This must not exceed |
130 | * in_size. |
131 | * @in_size: Size of the input buffer |
132 | * @out: Beginning of the output buffer. This may be NULL if and only |
133 | * if out_pos is equal to out_size. |
134 | * @out_pos: Current position in the output buffer. This must not exceed |
135 | * out_size. |
136 | * @out_size: Size of the output buffer |
137 | * |
138 | * Only the contents of the output buffer from out[out_pos] onward, and |
139 | * the variables in_pos and out_pos are modified by the XZ code. |
140 | */ |
141 | struct xz_buf { |
142 | const uint8_t *in; |
143 | size_t in_pos; |
144 | size_t in_size; |
145 | |
146 | uint8_t *out; |
147 | size_t out_pos; |
148 | size_t out_size; |
149 | }; |
150 | |
151 | /** |
152 | * struct xz_dec - Opaque type to hold the XZ decoder state |
153 | */ |
154 | struct xz_dec; |
155 | |
156 | /** |
157 | * xz_dec_init() - Allocate and initialize a XZ decoder state |
158 | * @mode: Operation mode |
159 | * @dict_max: Maximum size of the LZMA2 dictionary (history buffer) for |
160 | * multi-call decoding. This is ignored in single-call mode |
161 | * (mode == XZ_SINGLE). LZMA2 dictionary is always 2^n bytes |
162 | * or 2^n + 2^(n-1) bytes (the latter sizes are less common |
163 | * in practice), so other values for dict_max don't make sense. |
164 | * In the kernel, dictionary sizes of 64 KiB, 128 KiB, 256 KiB, |
165 | * 512 KiB, and 1 MiB are probably the only reasonable values, |
166 | * except for kernel and initramfs images where a bigger |
167 | * dictionary can be fine and useful. |
168 | * |
169 | * Single-call mode (XZ_SINGLE): xz_dec_run() decodes the whole stream at |
170 | * once. The caller must provide enough output space or the decoding will |
171 | * fail. The output space is used as the dictionary buffer, which is why |
172 | * there is no need to allocate the dictionary as part of the decoder's |
173 | * internal state. |
174 | * |
175 | * Because the output buffer is used as the workspace, streams encoded using |
176 | * a big dictionary are not a problem in single-call mode. It is enough that |
177 | * the output buffer is big enough to hold the actual uncompressed data; it |
178 | * can be smaller than the dictionary size stored in the stream headers. |
179 | * |
180 | * Multi-call mode with preallocated dictionary (XZ_PREALLOC): dict_max bytes |
181 | * of memory is preallocated for the LZMA2 dictionary. This way there is no |
182 | * risk that xz_dec_run() could run out of memory, since xz_dec_run() will |
183 | * never allocate any memory. Instead, if the preallocated dictionary is too |
184 | * small for decoding the given input stream, xz_dec_run() will return |
185 | * XZ_MEMLIMIT_ERROR. Thus, it is important to know what kind of data will be |
186 | * decoded to avoid allocating excessive amount of memory for the dictionary. |
187 | * |
188 | * Multi-call mode with dynamically allocated dictionary (XZ_DYNALLOC): |
189 | * dict_max specifies the maximum allowed dictionary size that xz_dec_run() |
190 | * may allocate once it has parsed the dictionary size from the stream |
191 | * headers. This way excessive allocations can be avoided while still |
192 | * limiting the maximum memory usage to a sane value to prevent running the |
193 | * system out of memory when decompressing streams from untrusted sources. |
194 | * |
195 | * On success, xz_dec_init() returns a pointer to struct xz_dec, which is |
196 | * ready to be used with xz_dec_run(). If memory allocation fails, |
197 | * xz_dec_init() returns NULL. |
198 | */ |
199 | XZ_EXTERN struct xz_dec * XZ_FUNC xz_dec_init( |
200 | enum xz_mode mode, uint32_t dict_max); |
201 | |
202 | /** |
203 | * xz_dec_run() - Run the XZ decoder |
204 | * @s: Decoder state allocated using xz_dec_init() |
205 | * @b: Input and output buffers |
206 | * |
207 | * The possible return values depend on build options and operation mode. |
208 | * See enum xz_ret for details. |
209 | * |
210 | * NOTE: If an error occurs in single-call mode (return value is not |
211 | * XZ_STREAM_END), b->in_pos and b->out_pos are not modified, and the |
212 | * contents of the output buffer from b->out[b->out_pos] onward are |
213 | * undefined. This is true even after XZ_BUF_ERROR, because with some filter |
214 | * chains, there may be a second pass over the output buffer, and this pass |
215 | * cannot be properly done if the output buffer is truncated. Thus, you |
216 | * cannot give the single-call decoder a too small buffer and then expect to |
217 | * get that amount valid data from the beginning of the stream. You must use |
218 | * the multi-call decoder if you don't want to uncompress the whole stream. |
219 | */ |
220 | XZ_EXTERN enum xz_ret XZ_FUNC xz_dec_run(struct xz_dec *s, struct xz_buf *b); |
221 | |
222 | /** |
223 | * xz_dec_reset() - Reset an already allocated decoder state |
224 | * @s: Decoder state allocated using xz_dec_init() |
225 | * |
226 | * This function can be used to reset the multi-call decoder state without |
227 | * freeing and reallocating memory with xz_dec_end() and xz_dec_init(). |
228 | * |
229 | * In single-call mode, xz_dec_reset() is always called in the beginning of |
230 | * xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in |
231 | * multi-call mode. |
232 | */ |
233 | XZ_EXTERN void XZ_FUNC xz_dec_reset(struct xz_dec *s); |
234 | |
235 | /** |
236 | * xz_dec_end() - Free the memory allocated for the decoder state |
237 | * @s: Decoder state allocated using xz_dec_init(). If s is NULL, |
238 | * this function does nothing. |
239 | */ |
240 | XZ_EXTERN void XZ_FUNC xz_dec_end(struct xz_dec *s); |
241 | |
242 | /* |
243 | * Standalone build (userspace build or in-kernel build for boot time use) |
244 | * needs a CRC32 implementation. For normal in-kernel use, kernel's own |
245 | * CRC32 module is used instead, and users of this module don't need to |
246 | * care about the functions below. |
247 | */ |
248 | #ifndef XZ_INTERNAL_CRC32 |
249 | # ifdef __KERNEL__ |
250 | # define XZ_INTERNAL_CRC32 0 |
251 | # else |
252 | # define XZ_INTERNAL_CRC32 1 |
253 | # endif |
254 | #endif |
255 | |
256 | #if XZ_INTERNAL_CRC32 |
257 | /* |
258 | * This must be called before any other xz_* function to initialize |
259 | * the CRC32 lookup table. |
260 | */ |
261 | XZ_EXTERN void XZ_FUNC xz_crc32_init(void); |
262 | |
263 | /* |
264 | * Update CRC32 value using the polynomial from IEEE-802.3. To start a new |
265 | * calculation, the third argument must be zero. To continue the calculation, |
266 | * the previously returned value is passed as the third argument. |
267 | */ |
268 | XZ_EXTERN uint32_t XZ_FUNC xz_crc32( |
269 | const uint8_t *buf, size_t size, uint32_t crc); |
270 | #endif |
271 | #endif |