Markus F.X.J. Oberhumer
179 lines
4.7 KiB
C
179 lines
4.7 KiB
C
/* ctok.h -- filter CTO implementation
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This file is part of the UPX executable compressor.
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Copyright (C) 1996-2009 Markus Franz Xaver Johannes Oberhumer
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Copyright (C) 1996-2009 Laszlo Molnar
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Copyright (C) 2000-2009 John F. Reiser
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All Rights Reserved.
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UPX and the UCL library are free software; you can redistribute them
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and/or modify them under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING.
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If not, write to the Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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Markus F.X.J. Oberhumer Laszlo Molnar
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<markus@oberhumer.com> <ml1050@users.sourceforge.net>
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John F. Reiser
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<jreiser@users.sourceforge.net>
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*/
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/*************************************************************************
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// filter / scan
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**************************************************************************/
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static int F(Filter *f)
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{
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#ifdef U
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// filter
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upx_byte *b = f->buf;
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#else
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// scan
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const upx_byte *b = f->buf;
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#endif
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const unsigned addvalue = f->addvalue;
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const unsigned size = f->buf_len;
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unsigned const id = f->id;
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unsigned ic, jc, kc;
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unsigned calls = 0, noncalls = 0, noncalls2 = 0;
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unsigned lastnoncall = size, lastcall = 0;
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// find a 16 MiB large empty address space
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{
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unsigned char buf[256];
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memset(buf,0,256);
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for (ic = 0; ic < size - 5; ic++)
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{
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if (!COND(b,ic,lastcall,id))
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continue;
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jc = get_le32(b+ic+1)+ic+1;
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if (jc < size)
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{
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if (jc + addvalue >= (1u << 24)) // hi 8 bits won't be cto8
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return -1;
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}
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else
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buf[b[ic+1]] |= 1;
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}
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if (getcto(f, buf) < 0)
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return -1;
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}
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const unsigned char cto8 = f->cto;
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#ifdef U
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const unsigned cto = (unsigned)f->cto << 24;
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#endif
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for (ic = 0; ic < size - 5; ic++)
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{
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if (!COND(b,ic,lastcall,id))
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continue;
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jc = get_le32(b+ic+1)+ic+1;
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// try to detect 'real' calls only
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if (jc < size)
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{
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assert(jc + addvalue < (1u << 24)); // hi 8 bits won't be cto8
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#ifdef U
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set_be32(b+ic+1,jc+addvalue+cto);
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#endif
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if (ic - lastnoncall < 5)
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{
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// check the last 4 bytes before this call
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for (kc = 4; kc; kc--)
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if (COND(b,ic-kc,lastcall,id) && b[ic-kc+1] == cto8)
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break;
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if (kc)
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{
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#ifdef U
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// restore original
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set_le32(b+ic+1,jc-ic-1);
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#endif
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if (b[ic+1] == cto8)
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return 1; // fail - buffer not restored
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lastnoncall = ic;
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noncalls2++;
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continue;
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}
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}
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calls++;
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ic += 4;
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lastcall = ic+1;
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}
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else
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{
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assert(b[ic+1] != cto8); // this should not happen
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lastnoncall = ic;
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noncalls++;
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}
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}
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f->calls = calls;
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f->noncalls = noncalls;
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f->lastcall = lastcall;
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#if 0 || defined(TESTING)
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printf("\ncalls=%d noncalls=%d noncalls2=%d text_size=%x calltrickoffset=%x\n",calls,noncalls,noncalls2,size,cto);
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#endif
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return 0;
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}
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/*************************************************************************
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// unfilter
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**************************************************************************/
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#ifdef U
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static int U(Filter *f)
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{
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upx_byte *b = f->buf;
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const unsigned size5 = f->buf_len - 5;
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const unsigned addvalue = f->addvalue;
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const unsigned cto = (unsigned)f->cto << 24;
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unsigned const id = f->id;
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unsigned lastcall = 0;
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unsigned ic, jc;
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for (ic = 0; ic < size5; ic++)
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if (COND(b,ic,lastcall,id))
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{
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jc = get_be32(b+ic+1);
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if (b[ic+1] == f->cto)
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{
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set_le32(b+ic+1,jc-ic-1-addvalue-cto);
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f->calls++;
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ic += 4;
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f->lastcall = lastcall = ic+1;
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}
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else
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f->noncalls++;
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}
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return 0;
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}
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#endif
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#undef F
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#undef U
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/*
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vi:ts=4:et:nowrap
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*/
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