cregit-Linux how code gets into the kernel

Release 4.15 lib/decompress_unlzo.c

Directory: lib
/*
 * LZO decompressor for the Linux kernel. Code borrowed from the lzo
 * implementation by Markus Franz Xaver Johannes Oberhumer.
 *
 * Linux kernel adaptation:
 * Copyright (C) 2009
 * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
 *
 * Original code:
 * Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
 * All Rights Reserved.
 *
 * lzop and the LZO library are free software; you can redistribute them
 * and/or modify them under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program 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 this program; see the file COPYING.
 * If not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Markus F.X.J. Oberhumer
 * <markus@oberhumer.com>
 * http://www.oberhumer.com/opensource/lzop/
 */

#ifdef STATIC

#define PREBOOT
#include "lzo/lzo1x_decompress_safe.c"
#else
#include <linux/decompress/unlzo.h>
#endif

#include <linux/types.h>
#include <linux/lzo.h>
#include <linux/decompress/mm.h>

#include <linux/compiler.h>
#include <asm/unaligned.h>


static const unsigned char lzop_magic[] = {
	0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };


#define LZO_BLOCK_SIZE        (256*1024l)

#define HEADER_HAS_FILTER      0x00000800L

#define HEADER_SIZE_MIN       (9 + 7     + 4 + 8     + 1       + 4)

#define HEADER_SIZE_MAX       (9 + 7 + 1 + 8 + 8 + 4 + 1 + 255 + 4)


STATIC inline long INIT parse_header(u8 *input, long *skip, long in_len) { int l; u8 *parse = input; u8 *end = input + in_len; u8 level = 0; u16 version; /* * Check that there's enough input to possibly have a valid header. * Then it is possible to parse several fields until the minimum * size may have been used. */ if (in_len < HEADER_SIZE_MIN) return 0; /* read magic: 9 first bits */ for (l = 0; l < 9; l++) { if (*parse++ != lzop_magic[l]) return 0; } /* get version (2bytes), skip library version (2), * 'need to be extracted' version (2) and * method (1) */ version = get_unaligned_be16(parse); parse += 7; if (version >= 0x0940) level = *parse++; if (get_unaligned_be32(parse) & HEADER_HAS_FILTER) parse += 8; /* flags + filter info */ else parse += 4; /* flags */ /* * At least mode, mtime_low, filename length, and checksum must * be left to be parsed. If also mtime_high is present, it's OK * because the next input buffer check is after reading the * filename length. */ if (end - parse < 8 + 1 + 4) return 0; /* skip mode and mtime_low */ parse += 8; if (version >= 0x0940) parse += 4; /* skip mtime_high */ l = *parse++; /* don't care about the file name, and skip checksum */ if (end - parse < l + 4) return 0; parse += l + 4; *skip = parse - input; return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Albin Tonnerre14473.47%133.33%
Lasse Collin4925.00%133.33%
Yinghai Lu31.53%133.33%
Total196100.00%3100.00%


STATIC int INIT unlzo(u8 *input, long in_len, long (*fill)(void *, unsigned long), long (*flush)(void *, unsigned long), u8 *output, long *posp, void (*error) (char *x)) { u8 r = 0; long skip = 0; u32 src_len, dst_len; size_t tmp; u8 *in_buf, *in_buf_save, *out_buf; int ret = -1; if (output) { out_buf = output; } else if (!flush) { error("NULL output pointer and no flush function provided"); goto exit; } else { out_buf = malloc(LZO_BLOCK_SIZE); if (!out_buf) { error("Could not allocate output buffer"); goto exit; } } if (input && fill) { error("Both input pointer and fill function provided, don't know what to do"); goto exit_1; } else if (input) { in_buf = input; } else if (!fill) { error("NULL input pointer and missing fill function"); goto exit_1; } else { in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE)); if (!in_buf) { error("Could not allocate input buffer"); goto exit_1; } } in_buf_save = in_buf; if (posp) *posp = 0; if (fill) { /* * Start from in_buf + HEADER_SIZE_MAX to make it possible * to use memcpy() to copy the unused data to the beginning * of the buffer. This way memmove() isn't needed which * is missing from pre-boot environments of most archs. */ in_buf += HEADER_SIZE_MAX; in_len = fill(in_buf, HEADER_SIZE_MAX); } if (!parse_header(in_buf, &skip, in_len)) { error("invalid header"); goto exit_2; } in_buf += skip; in_len -= skip; if (fill) { /* Move the unused data to the beginning of the buffer. */ memcpy(in_buf_save, in_buf, in_len); in_buf = in_buf_save; } if (posp) *posp = skip; for (;;) { /* read uncompressed block size */ if (fill && in_len < 4) { skip = fill(in_buf + in_len, 4 - in_len); if (skip > 0) in_len += skip; } if (in_len < 4) { error("file corrupted"); goto exit_2; } dst_len = get_unaligned_be32(in_buf); in_buf += 4; in_len -= 4; /* exit if last block */ if (dst_len == 0) { if (posp) *posp += 4; break; } if (dst_len > LZO_BLOCK_SIZE) { error("dest len longer than block size"); goto exit_2; } /* read compressed block size, and skip block checksum info */ if (fill && in_len < 8) { skip = fill(in_buf + in_len, 8 - in_len); if (skip > 0) in_len += skip; } if (in_len < 8) { error("file corrupted"); goto exit_2; } src_len = get_unaligned_be32(in_buf); in_buf += 8; in_len -= 8; if (src_len <= 0 || src_len > dst_len) { error("file corrupted"); goto exit_2; } /* decompress */ if (fill && in_len < src_len) { skip = fill(in_buf + in_len, src_len - in_len); if (skip > 0) in_len += skip; } if (in_len < src_len) { error("file corrupted"); goto exit_2; } tmp = dst_len; /* When the input data is not compressed at all, * lzo1x_decompress_safe will fail, so call memcpy() * instead */ if (unlikely(dst_len == src_len)) memcpy(out_buf, in_buf, src_len); else { r = lzo1x_decompress_safe((u8 *) in_buf, src_len, out_buf, &tmp); if (r != LZO_E_OK || dst_len != tmp) { error("Compressed data violation"); goto exit_2; } } if (flush && flush(out_buf, dst_len) != dst_len) goto exit_2; if (output) out_buf += dst_len; if (posp) *posp += src_len + 12; in_buf += src_len; in_len -= src_len; if (fill) { /* * If there happens to still be unused data left in * in_buf, move it to the beginning of the buffer. * Use a loop to avoid memmove() dependency. */ if (in_len > 0) for (skip = 0; skip < in_len; ++skip) in_buf_save[skip] = in_buf[skip]; in_buf = in_buf_save; } } ret = 0; exit_2: if (!input) free(in_buf_save); exit_1: if (!output) free(out_buf); exit: return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Albin Tonnerre47965.62%225.00%
Lasse Collin24333.29%450.00%
Yinghai Lu70.96%112.50%
Sascha Hauer10.14%112.50%
Total730100.00%8100.00%

#ifdef PREBOOT
STATIC int INIT __decompress(unsigned char *buf, long len, long (*fill)(void*, unsigned long), long (*flush)(void*, unsigned long), unsigned char *out_buf, long olen, long *pos, void (*error)(char *x)) { return unlzo(buf, len, fill, flush, out_buf, pos, error); }

Contributors

PersonTokensPropCommitsCommitProp
Yinghai Lu82100.00%1100.00%
Total82100.00%1100.00%

#endif

Overall Contributors

PersonTokensPropCommitsCommitProp
Albin Tonnerre68663.05%220.00%
Lasse Collin30027.57%440.00%
Yinghai Lu1009.19%220.00%
Markus F.X.J. Oberhumer10.09%110.00%
Sascha Hauer10.09%110.00%
Total1088100.00%10100.00%
Directory: lib
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