162 lines
3.1 KiB
C
162 lines
3.1 KiB
C
/* $NetBSD: unzip.c,v 1.1 1998/09/01 20:03:47 itohy Exp $ */
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/*
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* Extract gzip'ed data on the memory
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*
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* Written by Yasha (ITOH Yasufumi)
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* This code is in the public domain.
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*/
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#include <string.h>
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#include "gzip.h"
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const uch *csrc; /* compressed data */
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uch *udst; /* uncompressed data */
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long udst_cnt; /* output byte counter */
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unsigned outcnt; /* data length to be flushed */
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void
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flush_window()
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{
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#if defined(__GNUC__) && defined(__m68k__)
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asm("lea _outcnt,a0\n\
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movel a0@,d0\n\
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addl d0,_udst_cnt\n\
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movel d0,sp@-\n\
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pea _window\n\
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lea _udst,a1\n\
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movel a1@,sp@-\n\
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addl d0,a1@\n\
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clrl a0@\n\
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jbsr _memcpy\n\
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lea sp@(12),sp");
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#else
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register unsigned cnt = outcnt;
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udst_cnt += cnt;
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memcpy(udst, window, cnt);
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udst += cnt;
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outcnt = 0;
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#endif
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}
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#ifndef TEST
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#include "inflate.c"
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#endif
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/*
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* decompress gzip'ed data
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*
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* src: compressed data area for input
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* dst: decompressed data area for output
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*/
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long
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unzip(src, dst)
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const uch *src;
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uch *dst;
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{
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uch flags;
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udst_cnt = 0;
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udst = dst;
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/* skip magic (must be checked before) */
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src += 2;
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/* check compression method */
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if (*src++ != GZIP_METHOD_DEFLATED) {
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error("unknown compression method");
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/* NOTREACHED */
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}
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/* check flags */
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flags = *src++;
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if (flags &
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(GZIP_FLAG_MULTIPART | GZIP_FLAG_ENCRYPTED | GZIP_FLAGS_RESERVED)) {
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error("unsupported compression flag");
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/* NOTREACHED */
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}
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/* skip mod time (4bytes), extra flags, operating system */
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src += (4 + 1 + 1);
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/* part number (2bytes) may exist here but not supported */
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/* skip extra field if present */
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if (flags & GZIP_FLAG_EXTRA) {
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/* its length (LSB first) */
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unsigned extralen;
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#if defined(__GNUC__) && defined(__m68k__)
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/*
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* This doesn't work on 68000/010 since it does an unaligned access.
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*/
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asm("movew %1@+,%0\n\
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rolw #8,%0" : "=d" (extralen), "=a" (src) : "0" (0), "1" (src));
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#else
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extralen = *src++;
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extralen += (*src++ << 8);
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#endif
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src += extralen;
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}
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/* skip original file name if present */
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if (flags & GZIP_FLAG_FILE_NAME)
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while (*src++)
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;
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/* skip file comment if present */
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if (flags & GZIP_FLAG_COMMENT)
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while (*src++)
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;
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/* encryption header (12bytes) may exist here but not supported */
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/*
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* Here must exist compressed data...
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*/
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csrc = src;
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switch (inflate()) {
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case 0:
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/* no error */
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break;
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case 3:
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error("out of memory");
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/* NOTREACHED */
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default:
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invdata:
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error("invalid compressed data");
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/* NOTREACHED */
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}
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src = csrc;
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/* 32bit CRC is not checked --- skip */
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src += 4;
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/* check uncompressed input size (LSB first) */
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{
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uint32 len;
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#if defined(__GNUC__) && defined(__m68k__)
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/*
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* I think this is the smallest for MC68020 and later
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* This doesn't work on 68000/010 since it does an unaligned access.
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*/
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asm("rolw #8,%0\n\
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swap %0\n\
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rolw #8,%0" : "=d" (len) : "0" (*(uint32 *)src));
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#else
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len = *src++;
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len += *src++ << 8;
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len += *src++ << 16;
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len += *src << 24;
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#endif
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if (len != (uint32) udst_cnt)
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goto invdata;
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}
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return udst_cnt;
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}
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