98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
/*
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* Copyright (c) 2018 rajkosto
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* Copyright (c) 2018 SciresM
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include "blz.h"
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const blz_footer *blz_get_footer(const unsigned char *compData, unsigned int compDataLen, blz_footer *outFooter)
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{
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if (compDataLen < sizeof(blz_footer))
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return NULL;
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const blz_footer *srcFooter = (const blz_footer*)&compData[compDataLen - sizeof(blz_footer)];
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if (outFooter != NULL)
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memcpy(outFooter, srcFooter, sizeof(blz_footer)); // Must be a memcpy because no umaligned accesses on ARMv4.
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return srcFooter;
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}
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// From https://github.com/SciresM/hactool/blob/master/kip.c which is exactly how kernel does it, thanks SciresM!
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int blz_uncompress_inplace(unsigned char *dataBuf, unsigned int compSize, const blz_footer *footer)
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{
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u32 addl_size = footer->addl_size;
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u32 header_size = footer->header_size;
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u32 cmp_and_hdr_size = footer->cmp_and_hdr_size;
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unsigned char* cmp_start = &dataBuf[compSize] - cmp_and_hdr_size;
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u32 cmp_ofs = cmp_and_hdr_size - header_size;
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u32 out_ofs = cmp_and_hdr_size + addl_size;
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while (out_ofs)
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{
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unsigned char control = cmp_start[--cmp_ofs];
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for (unsigned int i=0; i<8; i++)
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{
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if (control & 0x80)
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{
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if (cmp_ofs < 2)
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return 0; // Out of bounds.
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cmp_ofs -= 2;
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u16 seg_val = ((unsigned int)(cmp_start[cmp_ofs + 1]) << 8) | cmp_start[cmp_ofs];
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u32 seg_size = ((seg_val >> 12) & 0xF) + 3;
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u32 seg_ofs = (seg_val & 0x0FFF) + 3;
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if (out_ofs < seg_size) // Kernel restricts segment copy to stay in bounds.
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seg_size = out_ofs;
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out_ofs -= seg_size;
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for (unsigned int j = 0; j < seg_size; j++)
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cmp_start[out_ofs + j] = cmp_start[out_ofs + j + seg_ofs];
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}
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else
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{
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// Copy directly.
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if (cmp_ofs < 1)
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return 0; //out of bounds
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cmp_start[--out_ofs] = cmp_start[--cmp_ofs];
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}
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control <<= 1;
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if (out_ofs == 0) // Blz works backwards, so if it reaches byte 0, it's done.
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return 1;
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}
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}
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return 1;
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}
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int blz_uncompress_srcdest(const unsigned char *compData, unsigned int compDataLen, unsigned char *dstData, unsigned int dstSize)
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{
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blz_footer footer;
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const blz_footer *compFooterPtr = blz_get_footer(compData, compDataLen, &footer);
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if (compFooterPtr == NULL)
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return 0;
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// Decompression must be done in-place, so need to copy the relevant compressed data first.
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unsigned int numCompBytes = (const unsigned char*)(compFooterPtr)-compData;
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memcpy(dstData, compData, numCompBytes);
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memset(&dstData[numCompBytes], 0, dstSize - numCompBytes);
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return blz_uncompress_inplace(dstData, compDataLen, &footer);
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}
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