arch/all-pc/boot/grub2-aros/grub-core/lib/xzembed/xz.h

   1 /* xz.h - XZ decompressor */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2010  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19 /*
  20  * This file is based on code from XZ embedded project
  21  * http://tukaani.org/xz/embedded.html
  22  */
  23
  24 #ifndef XZ_H
  25 #define XZ_H
  26
  27 #include <stdint.h>
  28 #include <unistd.h>
  29 #include <string.h>
  30 #include <grub/misc.h>
  31
  32 #ifndef GRUB_POSIX_BOOL_DEFINED
  33 typedef enum { false = 0, true = 1 } bool;
  34 #endif
  35
  36 /**
  37  * enum xz_ret - Return codes
  38  * @XZ_OK:              Everything is OK so far. More input or more output
  39  *                      space is required to continue.
  40  * @XZ_STREAM_END:      Operation finished successfully.
  41  * @XZ_MEMLIMIT_ERROR:  Not enough memory was preallocated at decoder
  42  *                      initialization time.
  43  * @XZ_FORMAT_ERROR:    File format was not recognized (wrong magic bytes).
  44  * @XZ_OPTIONS_ERROR:   This implementation doesn't support the requested
  45  *                      compression options. In the decoder this means that
  46  *                      the header CRC32 matches, but the header itself
  47  *                      specifies something that we don't support.
  48  * @XZ_DATA_ERROR:      Compressed data is corrupt.
  49  * @XZ_BUF_ERROR:       Cannot make any progress. Details are slightly
  50  *                      different between multi-call and single-call mode;
  51  *                      more information below.
  52  *
  53  * In multi-call mode, XZ_BUF_ERROR is returned when two consecutive calls
  54  * to XZ code cannot consume any input and cannot produce any new output.
  55  * This happens when there is no new input available, or the output buffer
  56  * is full while at least one output byte is still pending. Assuming your
  57  * code is not buggy, you can get this error only when decoding a compressed
  58  * stream that is truncated or otherwise corrupt.
  59  *
  60  * In single-call mode, XZ_BUF_ERROR is returned only when the output buffer
  61  * is too small, or the compressed input is corrupt in a way that makes the
  62  * decoder produce more output than the caller expected. When it is
  63  * (relatively) clear that the compressed input is truncated, XZ_DATA_ERROR
  64  * is used instead of XZ_BUF_ERROR.
  65  */
  66 enum xz_ret {
  67         XZ_OK,
  68         XZ_STREAM_END,
  69         XZ_MEMLIMIT_ERROR,
  70         XZ_FORMAT_ERROR,
  71         XZ_OPTIONS_ERROR,
  72         XZ_DATA_ERROR,
  73         XZ_BUF_ERROR
  74 };
  75
  76 /**
  77  * struct xz_buf - Passing input and output buffers to XZ code
  78  * @in:         Beginning of the input buffer. This may be NULL if and only
  79  *              if in_pos is equal to in_size.
  80  * @in_pos:     Current position in the input buffer. This must not exceed
  81  *              in_size.
  82  * @in_size:    Size of the input buffer
  83  * @out:        Beginning of the output buffer. This may be NULL if and only
  84  *              if out_pos is equal to out_size.
  85  * @out_pos:    Current position in the output buffer. This must not exceed
  86  *              out_size.
  87  * @out_size:   Size of the output buffer
  88  *
  89  * Only the contents of the output buffer from out[out_pos] onward, and
  90  * the variables in_pos and out_pos are modified by the XZ code.
  91  */
  92 struct xz_buf {
  93         const uint8_t *in;
  94         size_t in_pos;
  95         size_t in_size;
  96
  97         uint8_t *out;
  98         size_t out_pos;
  99         size_t out_size;
 100 };
 101
 102 /**
 103  * struct xz_dec - Opaque type to hold the XZ decoder state
 104  */
 105 struct xz_dec;
 106
 107 /**
 108  * xz_dec_init() - Allocate and initialize a XZ decoder state
 109  * @dict_max:   Maximum size of the LZMA2 dictionary (history buffer) for
 110  *              multi-call decoding, or special value of zero to indicate
 111  *              single-call decoding mode.
 112  *
 113  * If dict_max > 0, the decoder is initialized to work in multi-call mode.
 114  * dict_max number of bytes of memory is preallocated for the LZMA2
 115  * dictionary. This way there is no risk that xz_dec_run() could run out
 116  * of memory, since xz_dec_run() will never allocate any memory. Instead,
 117  * if the preallocated dictionary is too small for decoding the given input
 118  * stream, xz_dec_run() will return XZ_MEMLIMIT_ERROR. Thus, it is important
 119  * to know what kind of data will be decoded to avoid allocating excessive
 120  * amount of memory for the dictionary.
 121  *
 122  * LZMA2 dictionary is always 2^n bytes or 2^n + 2^(n-1) bytes (the latter
 123  * sizes are less common in practice). In the kernel, dictionary sizes of
 124  * 64 KiB, 128 KiB, 256 KiB, 512 KiB, and 1 MiB are probably the only
 125  * reasonable values.
 126  *
 127  * If dict_max == 0, the decoder is initialized to work in single-call mode.
 128  * In single-call mode, xz_dec_run() decodes the whole stream at once. The
 129  * caller must provide enough output space or the decoding will fail. The
 130  * output space is used as the dictionary buffer, which is why there is
 131  * no need to allocate the dictionary as part of the decoder's internal
 132  * state.
 133  *
 134  * Because the output buffer is used as the workspace, streams encoded using
 135  * a big dictionary are not a problem in single-call. It is enough that the
 136  * output buffer is is big enough to hold the actual uncompressed data; it
 137  * can be smaller than the dictionary size stored in the stream headers.
 138  *
 139  * On success, xz_dec_init() returns a pointer to struct xz_dec, which is
 140  * ready to be used with xz_dec_run(). On error, xz_dec_init() returns NULL.
 141  */
 142 struct xz_dec * xz_dec_init(uint32_t dict_max);
 143
 144 /**
 145  * xz_dec_run() - Run the XZ decoder
 146  * @s:          Decoder state allocated using xz_dec_init()
 147  * @b:          Input and output buffers
 148  *
 149  * In multi-call mode, this function may return any of the values listed in
 150  * enum xz_ret.
 151  *
 152  * In single-call mode, this function never returns XZ_OK. If an error occurs
 153  * in single-call mode (return value is not XZ_STREAM_END), b->in_pos and
 154  * b->out_pos are not modified, and the contents of the output buffer from
 155  * b->out[b->out_pos] onward are undefined.
 156  *
 157  * NOTE: In single-call mode, the contents of the output buffer are undefined
 158  * also after XZ_BUF_ERROR. This is because with some filter chains, there
 159  * may be a second pass over the output buffer, and this pass cannot be
 160  * properly done if the output buffer is truncated. Thus, you cannot give
 161  * the single-call decoder a too small buffer and then expect to get that
 162  * amount valid data from the beginning of the stream. You must use the
 163  * multi-call decoder if you don't want to uncompress the whole stream.
 164  */
 165 enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
 166
 167 /**
 168  * xz_dec_reset() - Reset an already allocated decoder state
 169  * @s:          Decoder state allocated using xz_dec_init()
 170  *
 171  * This function can be used to reset the multi-call decoder state without
 172  * freeing and reallocating memory with xz_dec_end() and xz_dec_init().
 173  *
 174  * In single-call mode, xz_dec_reset() is always called in the beginning of
 175  * xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in
 176  * multi-call mode.
 177  */
 178 void xz_dec_reset(struct xz_dec *s);
 179
 180 /**
 181  * xz_dec_end() - Free the memory allocated for the decoder state
 182  * @s:          Decoder state allocated using xz_dec_init(). If s is NULL,
 183  *              this function does nothing.
 184  */
 185 void xz_dec_end(struct xz_dec *s);
 186
 187 #endif