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mateuszvis |
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/* This file is part of the SvarCOM project and is published under the terms
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* of the MIT license.
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*
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* Copyright (C) 2021 Mateusz Viste
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#include <i86.h>
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#include "rmodinit.h"
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#include "sayonara.h"
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/* rewires my parent pointer, uninstalls rmod let DOS terminate me, UNLESS
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* my parent is unknown */
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mateuszvis |
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void sayonara(struct rmod_props far *rmod) {
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unsigned short rmodseg = rmod->rmodseg;
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mateuszvis |
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unsigned long *myparent = (void *)0x0A;
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unsigned short far *rmodenv_ptr = MK_FP(rmodseg, RMOD_OFFSET_ENVSEG);
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unsigned short rmodenv = *rmodenv_ptr;
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mateuszvis |
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/* detect "I am the origin shell" situations */
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mateuszvis |
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if (rmod->flags & FLAG_PERMANENT) return; /* COMMAND.COM /P */
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mateuszvis |
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if ((rmod->origparent >> 16) == 0xffff) return; /* original parent seg set to 0xffff (DOS-C / FreeDOS) */
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mateuszvis |
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if (rmod->origenvseg == 0) return; /* no original environment (MSDOS 5/6) */
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mateuszvis |
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/* set my parent back to original value */
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mateuszvis |
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*myparent = rmod->origparent;
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mateuszvis |
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_asm {
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/* free RMOD's code segment and env segment */
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mov ah, 0x49 /* DOS 2+ -- Free Memory Block */
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mov es, [rmodseg]
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int 0x21
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/* free RMOD's env segment */
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mov ah, 0x49 /* DOS 2+ -- Free Memory Block */
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mov es, [rmodenv]
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int 0x21
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/* gameover */
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mov ax, 0x4C00 /* DOS 2+ -- Terminate with exit code 0 */
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int 0x21
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}
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}
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