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care for stack wrapping when setting up exec block (ripsaw, fixes gp/gp cycles)

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3522
This commit is contained in:
Sebastian Strohhäcker 2010-01-06 19:34:23 +00:00
parent 8021ebdb6c
commit 1d7e48c0dc
1 changed files with 10 additions and 15 deletions
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25
src/dos/dos_execute.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (C) 2002-2009 The DOSBox Team
* Copyright (C) 2002-2010 The DOSBox Team
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -57,11 +57,6 @@ struct EXE_Header {
#define MAGIC2 0x4d5a
#define MAXENV 32768u
#define ENV_KEEPFREE 83 /* keep unallocated by environment variables */
/* The '65' added to nEnvSize does not cover the additional stuff:
+ 2 bytes: number of strings
+ 80 bytes: maximum absolute filename
+ 1 byte: '\0'
-- 1999/04/21 ska */
#define LOADNGO 0
#define LOAD 1
#define OVERLAY 3
@ -107,7 +102,7 @@ void DOS_UpdatePSPName(void) {
void DOS_Terminate(Bit16u pspseg,bool tsr,Bit8u exitcode) {
dos.return_code=exitcode;
dos.return_mode=(tsr)?RETURN_TSR:RETURN_EXIT;
dos.return_mode=(tsr)?(Bit8u)RETURN_TSR:(Bit8u)RETURN_EXIT;
DOS_PSP curpsp(pspseg);
if (pspseg==curpsp.GetParent()) return;
@ -361,7 +356,7 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
if (!iscom) {
/* Check if requested to load program into upper part of allocated memory */
if ((head.minmemory == 0) && (head.maxmemory == 0))
loadseg = ((pspseg+memsize)*0x10-imagesize)/0x10;
loadseg = (Bit16u)(((pspseg+memsize)*0x10-imagesize)/0x10);
}
} else loadseg=block.overlay.loadseg;
/* Load the executable */
@ -416,6 +411,7 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
} else {
csip=RealMake(loadseg+head.initCS,head.initIP);
sssp=RealMake(loadseg+head.initSS,head.initSP);
if (head.initSP<4) E_Exit("stack underflow/wrap at EXEC");
}
if (flags==LOAD) {
@ -437,6 +433,7 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
}
if (flags==LOADNGO) {
if ((reg_sp>0xfffe) || (reg_sp<18)) E_Exit("stack underflow/wrap at EXEC");
/* Get Caller's program CS:IP of the stack and set termination address to that */
RealSetVec(0x22,RealMake(mem_readw(SegPhys(ss)+reg_sp+2),mem_readw(SegPhys(ss)+reg_sp)));
SaveRegisters();
@ -455,12 +452,10 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
/* Set the stack for new program */
SegSet16(ss,RealSeg(sssp));reg_sp=RealOff(sssp);
/* Add some flags and CS:IP on the stack for the IRET */
reg_sp-=4;
mem_writew(SegPhys(ss)+reg_sp+0,RealOff(csip));
mem_writew(SegPhys(ss)+reg_sp+2,RealSeg(csip));
/* Old info, we now jump to a RETF:
* DOS starts programs with a RETF, so our IRET
* should not modify critical flags (IOPL in v86 mode);
CPU_Push16(RealSeg(csip));
CPU_Push16(RealOff(csip));
/* DOS starts programs with a RETF, so critical flags
* should not be modified (IOPL in v86 mode);
* interrupt flag is set explicitly, test flags cleared */
reg_flags=(reg_flags&(~FMASK_TEST))|FLAG_IF;
//Jump to retf so that we only need to store cs:ip on the stack
@ -481,7 +476,7 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
while (char chr=*name++) {
switch (chr) {
case ':':case '\\':case '/':index=0;break;
default:if (index<8) stripname[index++]=toupper(chr);
default:if (index<8) stripname[index++]=(char)toupper(chr);
}
}
index=0;