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AIO-switch-updater/rcm/bdk/libs/compr/blz.c

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/*
* Copyright (c) 2018 rajkosto
* Copyright (c) 2018 SciresM
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <string.h>
#include "blz.h"
const blz_footer *blz_get_footer(const unsigned char *compData, unsigned int compDataLen, blz_footer *outFooter)
{
if (compDataLen < sizeof(blz_footer))
return NULL;
const blz_footer *srcFooter = (const blz_footer*)&compData[compDataLen - sizeof(blz_footer)];
if (outFooter != NULL)
memcpy(outFooter, srcFooter, sizeof(blz_footer)); // Must be a memcpy because no umaligned accesses on ARMv4.
return srcFooter;
}
// From https://github.com/SciresM/hactool/blob/master/kip.c which is exactly how kernel does it, thanks SciresM!
int blz_uncompress_inplace(unsigned char *dataBuf, unsigned int compSize, const blz_footer *footer)
{
u32 addl_size = footer->addl_size;
u32 header_size = footer->header_size;
u32 cmp_and_hdr_size = footer->cmp_and_hdr_size;
unsigned char* cmp_start = &dataBuf[compSize] - cmp_and_hdr_size;
u32 cmp_ofs = cmp_and_hdr_size - header_size;
u32 out_ofs = cmp_and_hdr_size + addl_size;
while (out_ofs)
{
unsigned char control = cmp_start[--cmp_ofs];
for (unsigned int i=0; i<8; i++)
{
if (control & 0x80)
{
if (cmp_ofs < 2)
return 0; // Out of bounds.
cmp_ofs -= 2;
u16 seg_val = ((unsigned int)(cmp_start[cmp_ofs + 1]) << 8) | cmp_start[cmp_ofs];
u32 seg_size = ((seg_val >> 12) & 0xF) + 3;
u32 seg_ofs = (seg_val & 0x0FFF) + 3;
if (out_ofs < seg_size) // Kernel restricts segment copy to stay in bounds.
seg_size = out_ofs;
out_ofs -= seg_size;
for (unsigned int j = 0; j < seg_size; j++)
cmp_start[out_ofs + j] = cmp_start[out_ofs + j + seg_ofs];
}
else
{
// Copy directly.
if (cmp_ofs < 1)
return 0; //out of bounds
cmp_start[--out_ofs] = cmp_start[--cmp_ofs];
}
control <<= 1;
if (out_ofs == 0) // Blz works backwards, so if it reaches byte 0, it's done.
return 1;
}
}
return 1;
}
int blz_uncompress_srcdest(const unsigned char *compData, unsigned int compDataLen, unsigned char *dstData, unsigned int dstSize)
{
blz_footer footer;
const blz_footer *compFooterPtr = blz_get_footer(compData, compDataLen, &footer);
if (compFooterPtr == NULL)
return 0;
// Decompression must be done in-place, so need to copy the relevant compressed data first.
unsigned int numCompBytes = (const unsigned char*)(compFooterPtr)-compData;
memcpy(dstData, compData, numCompBytes);
memset(&dstData[numCompBytes], 0, dstSize - numCompBytes);
return blz_uncompress_inplace(dstData, compDataLen, &footer);
}