OSCL-LXR linux-6.0.1/​include/​linux/​xz.h	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * XZ decompressor
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
  *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
  */
 
 #ifndef XZ_H
 #define XZ_H
 
 #ifdef __KERNEL__
 #   include <linux/stddef.h>
 #   include <linux/types.h>
 #else
 #   include <stddef.h>
 #   include <stdint.h>
 #endif
 
 /* In Linux, this is used to make extern functions static when needed. */
 #ifndef XZ_EXTERN
 #   define XZ_EXTERN extern
 #endif
 
 /**
  * enum xz_mode - Operation mode
  *
  * @XZ_SINGLE:              Single-call mode. This uses less RAM than
  *                          multi-call modes, because the LZMA2
  *                          dictionary doesn't need to be allocated as
  *                          part of the decoder state. All required data
  *                          structures are allocated at initialization,
  *                          so xz_dec_run() cannot return XZ_MEM_ERROR.
  * @XZ_PREALLOC:            Multi-call mode with preallocated LZMA2
  *                          dictionary buffer. All data structures are
  *                          allocated at initialization, so xz_dec_run()
  *                          cannot return XZ_MEM_ERROR.
  * @XZ_DYNALLOC:            Multi-call mode. The LZMA2 dictionary is
  *                          allocated once the required size has been
  *                          parsed from the stream headers. If the
  *                          allocation fails, xz_dec_run() will return
  *                          XZ_MEM_ERROR.
  *
  * It is possible to enable support only for a subset of the above
  * modes at compile time by defining XZ_DEC_SINGLE, XZ_DEC_PREALLOC,
  * or XZ_DEC_DYNALLOC. The xz_dec kernel module is always compiled
  * with support for all operation modes, but the preboot code may
  * be built with fewer features to minimize code size.
  */
 enum xz_mode {
     XZ_SINGLE,
     XZ_PREALLOC,
     XZ_DYNALLOC
 };
 
 /**
  * enum xz_ret - Return codes
  * @XZ_OK:                  Everything is OK so far. More input or more
  *                          output space is required to continue. This
  *                          return code is possible only in multi-call mode
  *                          (XZ_PREALLOC or XZ_DYNALLOC).
  * @XZ_STREAM_END:          Operation finished successfully.
  * @XZ_UNSUPPORTED_CHECK:   Integrity check type is not supported. Decoding
  *                          is still possible in multi-call mode by simply
  *                          calling xz_dec_run() again.
  *                          Note that this return value is used only if
  *                          XZ_DEC_ANY_CHECK was defined at build time,
  *                          which is not used in the kernel. Unsupported
  *                          check types return XZ_OPTIONS_ERROR if
  *                          XZ_DEC_ANY_CHECK was not defined at build time.
  * @XZ_MEM_ERROR:           Allocating memory failed. This return code is
  *                          possible only if the decoder was initialized
  *                          with XZ_DYNALLOC. The amount of memory that was
  *                          tried to be allocated was no more than the
  *                          dict_max argument given to xz_dec_init().
  * @XZ_MEMLIMIT_ERROR:      A bigger LZMA2 dictionary would be needed than
  *                          allowed by the dict_max argument given to
  *                          xz_dec_init(). This return value is possible
  *                          only in multi-call mode (XZ_PREALLOC or
  *                          XZ_DYNALLOC); the single-call mode (XZ_SINGLE)
  *                          ignores the dict_max argument.
  * @XZ_FORMAT_ERROR:        File format was not recognized (wrong magic
  *                          bytes).
  * @XZ_OPTIONS_ERROR:       This implementation doesn't support the requested
  *                          compression options. In the decoder this means
  *                          that the header CRC32 matches, but the header
  *                          itself specifies something that we don't support.
  * @XZ_DATA_ERROR:          Compressed data is corrupt.
  * @XZ_BUF_ERROR:           Cannot make any progress. Details are slightly
  *                          different between multi-call and single-call
  *                          mode; more information below.
  *
  * In multi-call mode, XZ_BUF_ERROR is returned when two consecutive calls
  * to XZ code cannot consume any input and cannot produce any new output.
  * This happens when there is no new input available, or the output buffer
  * is full while at least one output byte is still pending. Assuming your
  * code is not buggy, you can get this error only when decoding a compressed
  * stream that is truncated or otherwise corrupt.
  *
  * In single-call mode, XZ_BUF_ERROR is returned only when the output buffer
  * is too small or the compressed input is corrupt in a way that makes the
  * decoder produce more output than the caller expected. When it is
  * (relatively) clear that the compressed input is truncated, XZ_DATA_ERROR
  * is used instead of XZ_BUF_ERROR.
  */
 enum xz_ret {
     XZ_OK,
     XZ_STREAM_END,
     XZ_UNSUPPORTED_CHECK,
     XZ_MEM_ERROR,
     XZ_MEMLIMIT_ERROR,
     XZ_FORMAT_ERROR,
     XZ_OPTIONS_ERROR,
     XZ_DATA_ERROR,
     XZ_BUF_ERROR
 };
 
 /**
  * struct xz_buf - Passing input and output buffers to XZ code
  * @in:         Beginning of the input buffer. This may be NULL if and only
  *              if in_pos is equal to in_size.
  * @in_pos:     Current position in the input buffer. This must not exceed
  *              in_size.
  * @in_size:    Size of the input buffer
  * @out:        Beginning of the output buffer. This may be NULL if and only
  *              if out_pos is equal to out_size.
  * @out_pos:    Current position in the output buffer. This must not exceed
  *              out_size.
  * @out_size:   Size of the output buffer
  *
  * Only the contents of the output buffer from out[out_pos] onward, and
  * the variables in_pos and out_pos are modified by the XZ code.
  */
 struct xz_buf {
     const uint8_t *in;
     size_t in_pos;
     size_t in_size;
 
     uint8_t *out;
     size_t out_pos;
     size_t out_size;
 };
 
 /**
  * struct xz_dec - Opaque type to hold the XZ decoder state
  */
 struct xz_dec;
 
 /**
  * xz_dec_init() - Allocate and initialize a XZ decoder state
  * @mode:       Operation mode
  * @dict_max:   Maximum size of the LZMA2 dictionary (history buffer) for
  *              multi-call decoding. This is ignored in single-call mode
  *              (mode == XZ_SINGLE). LZMA2 dictionary is always 2^n bytes
  *              or 2^n + 2^(n-1) bytes (the latter sizes are less common
  *              in practice), so other values for dict_max don't make sense.
  *              In the kernel, dictionary sizes of 64 KiB, 128 KiB, 256 KiB,
  *              512 KiB, and 1 MiB are probably the only reasonable values,
  *              except for kernel and initramfs images where a bigger
  *              dictionary can be fine and useful.
  *
  * Single-call mode (XZ_SINGLE): xz_dec_run() decodes the whole stream at
  * once. The caller must provide enough output space or the decoding will
  * fail. The output space is used as the dictionary buffer, which is why
  * there is no need to allocate the dictionary as part of the decoder's
  * internal state.
  *
  * Because the output buffer is used as the workspace, streams encoded using
  * a big dictionary are not a problem in single-call mode. It is enough that
  * the output buffer is big enough to hold the actual uncompressed data; it
  * can be smaller than the dictionary size stored in the stream headers.
  *
  * Multi-call mode with preallocated dictionary (XZ_PREALLOC): dict_max bytes
  * of memory is preallocated for the LZMA2 dictionary. This way there is no
  * risk that xz_dec_run() could run out of memory, since xz_dec_run() will
  * never allocate any memory. Instead, if the preallocated dictionary is too
  * small for decoding the given input stream, xz_dec_run() will return
  * XZ_MEMLIMIT_ERROR. Thus, it is important to know what kind of data will be
  * decoded to avoid allocating excessive amount of memory for the dictionary.
  *
  * Multi-call mode with dynamically allocated dictionary (XZ_DYNALLOC):
  * dict_max specifies the maximum allowed dictionary size that xz_dec_run()
  * may allocate once it has parsed the dictionary size from the stream
  * headers. This way excessive allocations can be avoided while still
  * limiting the maximum memory usage to a sane value to prevent running the
  * system out of memory when decompressing streams from untrusted sources.
  *
  * On success, xz_dec_init() returns a pointer to struct xz_dec, which is
  * ready to be used with xz_dec_run(). If memory allocation fails,
  * xz_dec_init() returns NULL.
  */
 XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max);
 
 /**
  * xz_dec_run() - Run the XZ decoder
  * @s:          Decoder state allocated using xz_dec_init()
  * @b:          Input and output buffers
  *
  * The possible return values depend on build options and operation mode.
  * See enum xz_ret for details.
  *
  * Note that if an error occurs in single-call mode (return value is not
  * XZ_STREAM_END), b->in_pos and b->out_pos are not modified and the
  * contents of the output buffer from b->out[b->out_pos] onward are
  * undefined. This is true even after XZ_BUF_ERROR, because with some filter
  * chains, there may be a second pass over the output buffer, and this pass
  * cannot be properly done if the output buffer is truncated. Thus, you
  * cannot give the single-call decoder a too small buffer and then expect to
  * get that amount valid data from the beginning of the stream. You must use
  * the multi-call decoder if you don't want to uncompress the whole stream.
  */
 XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
 
 /**
  * xz_dec_reset() - Reset an already allocated decoder state
  * @s:          Decoder state allocated using xz_dec_init()
  *
  * This function can be used to reset the multi-call decoder state without
  * freeing and reallocating memory with xz_dec_end() and xz_dec_init().
  *
  * In single-call mode, xz_dec_reset() is always called in the beginning of
  * xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in
  * multi-call mode.
  */
 XZ_EXTERN void xz_dec_reset(struct xz_dec *s);
 
 /**
  * xz_dec_end() - Free the memory allocated for the decoder state
  * @s:          Decoder state allocated using xz_dec_init(). If s is NULL,
  *              this function does nothing.
  */
 XZ_EXTERN void xz_dec_end(struct xz_dec *s);
 
 /*
  * Decompressor for MicroLZMA, an LZMA variant with a very minimal header.
  * See xz_dec_microlzma_alloc() below for details.
  *
  * These functions aren't used or available in preboot code and thus aren't
  * marked with XZ_EXTERN. This avoids warnings about static functions that
  * are never defined.
  */
 /**
  * struct xz_dec_microlzma - Opaque type to hold the MicroLZMA decoder state
  */
 struct xz_dec_microlzma;
 
 /**
  * xz_dec_microlzma_alloc() - Allocate memory for the MicroLZMA decoder
  * @mode        XZ_SINGLE or XZ_PREALLOC
  * @dict_size   LZMA dictionary size. This must be at least 4 KiB and
  *              at most 3 GiB.
  *
  * In contrast to xz_dec_init(), this function only allocates the memory
  * and remembers the dictionary size. xz_dec_microlzma_reset() must be used
  * before calling xz_dec_microlzma_run().
  *
  * The amount of allocated memory is a little less than 30 KiB with XZ_SINGLE.
  * With XZ_PREALLOC also a dictionary buffer of dict_size bytes is allocated.
  *
  * On success, xz_dec_microlzma_alloc() returns a pointer to
  * struct xz_dec_microlzma. If memory allocation fails or
  * dict_size is invalid, NULL is returned.
  *
  * The compressed format supported by this decoder is a raw LZMA stream
  * whose first byte (always 0x00) has been replaced with bitwise-negation
  * of the LZMA properties (lc/lp/pb) byte. For example, if lc/lp/pb is
  * 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00.
  * Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream
  * marker must not be used. The unused values are reserved for future use.
  * This MicroLZMA header format was created for use in EROFS but may be used
  * by others too.
  */
 extern struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
                                uint32_t dict_size);
 
 /**
  * xz_dec_microlzma_reset() - Reset the MicroLZMA decoder state
  * @s           Decoder state allocated using xz_dec_microlzma_alloc()
  * @comp_size   Compressed size of the input stream
  * @uncomp_size Uncompressed size of the input stream. A value smaller
  *              than the real uncompressed size of the input stream can
  *              be specified if uncomp_size_is_exact is set to false.
  *              uncomp_size can never be set to a value larger than the
  *              expected real uncompressed size because it would eventually
  *              result in XZ_DATA_ERROR.
  * @uncomp_size_is_exact  This is an int instead of bool to avoid
  *              requiring stdbool.h. This should normally be set to true.
  *              When this is set to false, error detection is weaker.
  */
 extern void xz_dec_microlzma_reset(struct xz_dec_microlzma *s,
                    uint32_t comp_size, uint32_t uncomp_size,
                    int uncomp_size_is_exact);
 
 /**
  * xz_dec_microlzma_run() - Run the MicroLZMA decoder
  * @s           Decoder state initialized using xz_dec_microlzma_reset()
  * @b:          Input and output buffers
  *
  * This works similarly to xz_dec_run() with a few important differences.
  * Only the differences are documented here.
  *
  * The only possible return values are XZ_OK, XZ_STREAM_END, and
  * XZ_DATA_ERROR. This function cannot return XZ_BUF_ERROR: if no progress
  * is possible due to lack of input data or output space, this function will
  * keep returning XZ_OK. Thus, the calling code must be written so that it
  * will eventually provide input and output space matching (or exceeding)
  * comp_size and uncomp_size arguments given to xz_dec_microlzma_reset().
  * If the caller cannot do this (for example, if the input file is truncated
  * or otherwise corrupt), the caller must detect this error by itself to
  * avoid an infinite loop.
  *
  * If the compressed data seems to be corrupt, XZ_DATA_ERROR is returned.
  * This can happen also when incorrect dictionary, uncompressed, or
  * compressed sizes have been specified.
  *
  * With XZ_PREALLOC only: As an extra feature, b->out may be NULL to skip over
  * uncompressed data. This way the caller doesn't need to provide a temporary
  * output buffer for the bytes that will be ignored.
  *
  * With XZ_SINGLE only: In contrast to xz_dec_run(), the return value XZ_OK
  * is also possible and thus XZ_SINGLE is actually a limited multi-call mode.
  * After XZ_OK the bytes decoded so far may be read from the output buffer.
  * It is possible to continue decoding but the variables b->out and b->out_pos
  * MUST NOT be changed by the caller. Increasing the value of b->out_size is
  * allowed to make more output space available; one doesn't need to provide
  * space for the whole uncompressed data on the first call. The input buffer
  * may be changed normally like with XZ_PREALLOC. This way input data can be
  * provided from non-contiguous memory.
  */
 extern enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s,
                     struct xz_buf *b);
 
 /**
  * xz_dec_microlzma_end() - Free the memory allocated for the decoder state
  * @s:          Decoder state allocated using xz_dec_microlzma_alloc().
  *              If s is NULL, this function does nothing.
  */
 extern void xz_dec_microlzma_end(struct xz_dec_microlzma *s);
 
 /*
  * Standalone build (userspace build or in-kernel build for boot time use)
  * needs a CRC32 implementation. For normal in-kernel use, kernel's own
  * CRC32 module is used instead, and users of this module don't need to
  * care about the functions below.
  */
 #ifndef XZ_INTERNAL_CRC32
 #   ifdef __KERNEL__
 #       define XZ_INTERNAL_CRC32 0
 #   else
 #       define XZ_INTERNAL_CRC32 1
 #   endif
 #endif
 
 #if XZ_INTERNAL_CRC32
 /*
  * This must be called before any other xz_* function to initialize
  * the CRC32 lookup table.
  */
 XZ_EXTERN void xz_crc32_init(void);
 
 /*
  * Update CRC32 value using the polynomial from IEEE-802.3. To start a new
  * calculation, the third argument must be zero. To continue the calculation,
  * the previously returned value is passed as the third argument.
  */
 XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc);
 #endif
 #endif

This page was automatically generated by the 2.1.0 LXR engine. The LXR team