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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:54:16 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:54:16 +0000
commit485f6ecd453d8a2fd8b9b9fadea03159d8b50797 (patch)
tree32451fa3cdd9321fb2591fada9891b2cb70a9cd1 /grub-core/lib/xzembed/xz.h
parentInitial commit. (diff)
downloadgrub2-485f6ecd453d8a2fd8b9b9fadea03159d8b50797.tar.xz
grub2-485f6ecd453d8a2fd8b9b9fadea03159d8b50797.zip
Adding upstream version 2.06.upstream/2.06upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'grub-core/lib/xzembed/xz.h')
-rw-r--r--grub-core/lib/xzembed/xz.h188
1 files changed, 188 insertions, 0 deletions
diff --git a/grub-core/lib/xzembed/xz.h b/grub-core/lib/xzembed/xz.h
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+/* xz.h - XZ decompressor */
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2010 Free Software Foundation, Inc.
+ *
+ * GRUB is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GRUB is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
+ */
+/*
+ * This file is based on code from XZ embedded project
+ * http://tukaani.org/xz/embedded.html
+ */
+
+#ifndef XZ_H
+#define XZ_H
+
+#include <config.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+#include <grub/misc.h>
+
+#ifndef GRUB_POSIX_BOOL_DEFINED
+typedef enum { false = 0, true = 1 } bool;
+#endif
+
+/**
+ * enum xz_ret - Return codes
+ * @XZ_OK: Everything is OK so far. More input or more output
+ * space is required to continue.
+ * @XZ_STREAM_END: Operation finished successfully.
+ * @XZ_MEMLIMIT_ERROR: Not enough memory was preallocated at decoder
+ * initialization time.
+ * @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_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
+ * @dict_max: Maximum size of the LZMA2 dictionary (history buffer) for
+ * multi-call decoding, or special value of zero to indicate
+ * single-call decoding mode.
+ *
+ * If dict_max > 0, the decoder is initialized to work in multi-call mode.
+ * dict_max number of 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.
+ *
+ * LZMA2 dictionary is always 2^n bytes or 2^n + 2^(n-1) bytes (the latter
+ * sizes are less common in practice). In the kernel, dictionary sizes of
+ * 64 KiB, 128 KiB, 256 KiB, 512 KiB, and 1 MiB are probably the only
+ * reasonable values.
+ *
+ * If dict_max == 0, the decoder is initialized to work in single-call mode.
+ * In single-call mode, 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. It is enough that the
+ * output buffer is is big enough to hold the actual uncompressed data; it
+ * can be smaller than the dictionary size stored in the stream headers.
+ *
+ * On success, xz_dec_init() returns a pointer to struct xz_dec, which is
+ * ready to be used with xz_dec_run(). On error, xz_dec_init() returns NULL.
+ */
+struct xz_dec * xz_dec_init(uint32_t dict_max);
+
+/**
+ * xz_dec_run() - Run the XZ decoder
+ * @s: Decoder state allocated using xz_dec_init()
+ * @b: Input and output buffers
+ *
+ * In multi-call mode, this function may return any of the values listed in
+ * enum xz_ret.
+ *
+ * In single-call mode, this function never returns XZ_OK. 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.
+ *
+ * NOTE: In single-call mode, the contents of the output buffer are undefined
+ * also after XZ_BUF_ERROR. This is 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.
+ */
+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.
+ */
+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.
+ */
+void xz_dec_end(struct xz_dec *s);
+
+#endif