351 lines
9.8 KiB
C
351 lines
9.8 KiB
C
/*
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* Debugger break-points handling
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*
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* Copyright 1994 Martin von Loewis
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* Copyright 1995 Alexandre Julliard
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include "windows.h"
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#include "debugger.h"
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#define INT3 0xcc /* int 3 opcode */
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#define STEP_FLAG 0x100 /* single-step flag */
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#define MAX_BREAKPOINTS 25
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typedef struct
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{
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DBG_ADDR addr;
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BYTE addrlen;
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BYTE opcode;
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BOOL enabled;
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BOOL in_use;
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} BREAKPOINT;
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static BREAKPOINT breakpoints[MAX_BREAKPOINTS];
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static int next_bp = 1; /* breakpoint 0 is reserved for step-over */
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/***********************************************************************
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* DEBUG_ChangeOpcode
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*
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* Change the opcode at segment:addr.
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*/
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static void DEBUG_SetOpcode( const DBG_ADDR *addr, BYTE op )
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{
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if (addr->seg)
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{
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*(BYTE *)PTR_SEG_OFF_TO_LIN( addr->seg, addr->off ) = op;
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}
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else /* 32-bit code, so we have to change the protection first */
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{
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/* There are a couple of problems with this. On Linux prior to
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1.1.62, this call fails (ENOACCESS) due to a bug in fs/exec.c.
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This code is currently not tested at all on BSD.
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How do I determine the page size in a more symbolic manner?
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And why does mprotect need that start address of the page
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in the first place?
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Not that portability matters, this code is i386 only anyways...
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How do I get the old protection in order to restore it later on?
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*/
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if (mprotect((caddr_t)(addr->off & (~4095)), 4096,
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PROT_READ | PROT_WRITE | PROT_EXEC) == -1)
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{
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perror( "Can't set break point" );
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return;
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}
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*(BYTE *)addr->off = op;
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mprotect((caddr_t)(addr->off & ~4095), 4096,
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PROT_READ | PROT_EXEC );
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}
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}
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/***********************************************************************
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* DEBUG_IsStepOverInstr
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*
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* Determine if the instruction at CS:EIP is an instruction that
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* we need to step over (like a call or a repetitive string move).
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*/
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static BOOL DEBUG_IsStepOverInstr( struct sigcontext_struct *context )
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{
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BYTE *instr = (BYTE *)PTR_SEG_OFF_TO_LIN(CS_reg(context),EIP_reg(context));
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for (;;)
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{
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switch(*instr)
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{
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/* Skip all prefixes */
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case 0x2e: /* cs: */
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case 0x36: /* ss: */
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case 0x3e: /* ds: */
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case 0x26: /* es: */
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case 0x64: /* fs: */
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case 0x65: /* gs: */
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case 0x66: /* opcode size prefix */
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case 0x67: /* addr size prefix */
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case 0xf0: /* lock */
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case 0xf2: /* repne */
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case 0xf3: /* repe */
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instr++;
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continue;
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/* Handle call instructions */
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case 0xe8: /* call <offset> */
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case 0x9a: /* lcall <seg>:<off> */
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return TRUE;
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case 0xff: /* call <regmodrm> */
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return (((instr[1] & 0x38) == 0x10) ||
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((instr[1] & 0x38) == 0x18));
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/* Handle string instructions */
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case 0x6c: /* insb */
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case 0x6d: /* insw */
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case 0x6e: /* outsb */
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case 0x6f: /* outsw */
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case 0xa4: /* movsb */
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case 0xa5: /* movsw */
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case 0xa6: /* cmpsb */
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case 0xa7: /* cmpsw */
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case 0xaa: /* stosb */
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case 0xab: /* stosw */
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case 0xac: /* lodsb */
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case 0xad: /* lodsw */
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case 0xae: /* scasb */
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case 0xaf: /* scasw */
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return TRUE;
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default:
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return FALSE;
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}
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}
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}
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/***********************************************************************
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* DEBUG_SetBreakpoints
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*
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* Set or remove all the breakpoints.
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*/
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void DEBUG_SetBreakpoints( BOOL set )
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{
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int i;
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for (i = 0; i < MAX_BREAKPOINTS; i++)
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{
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if (breakpoints[i].in_use && breakpoints[i].enabled)
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{
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if (DEBUG_IsBadWritePtr( &breakpoints[i].addr, 1 ))
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{
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fprintf( stderr, "Invalid address for breakpoint %d, disabling it\n", i );
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breakpoints[i].enabled = FALSE;
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}
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else DEBUG_SetOpcode( &breakpoints[i].addr,
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set ? INT3 : breakpoints[i].opcode );
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}
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}
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}
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/***********************************************************************
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* DEBUG_FindBreakpoint
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*
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* Find the breakpoint for a given address. Return the breakpoint
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* number or -1 if none.
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*/
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int DEBUG_FindBreakpoint( const DBG_ADDR *addr )
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{
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int i;
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for (i = 0; i < MAX_BREAKPOINTS; i++)
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{
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if (breakpoints[i].in_use && breakpoints[i].enabled &&
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breakpoints[i].addr.seg == addr->seg &&
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breakpoints[i].addr.off == addr->off) return i;
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}
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return -1;
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}
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/***********************************************************************
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* DEBUG_AddBreakpoint
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*
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* Add a breakpoint.
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*/
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void DEBUG_AddBreakpoint( const DBG_ADDR *address )
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{
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DBG_ADDR addr = *address;
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int num;
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BYTE *p;
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DBG_FIX_ADDR_SEG( &addr, CS_reg(DEBUG_context) );
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if (next_bp < MAX_BREAKPOINTS)
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num = next_bp++;
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else /* try to find an empty slot */
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{
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for (num = 1; num < MAX_BREAKPOINTS; num++)
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if (!breakpoints[num].in_use) break;
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if (num >= MAX_BREAKPOINTS)
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{
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fprintf( stderr, "Too many breakpoints. Please delete some.\n" );
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return;
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}
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}
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if (!DBG_CHECK_READ_PTR( &addr, 1 )) return;
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p = DBG_ADDR_TO_LIN( &addr );
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breakpoints[num].addr = addr;
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breakpoints[num].addrlen = !addr.seg ? 32 :
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(GET_SEL_FLAGS(addr.seg) & LDT_FLAGS_32BIT) ? 32 : 16;
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breakpoints[num].opcode = *p;
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breakpoints[num].enabled = TRUE;
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breakpoints[num].in_use = TRUE;
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fprintf( stderr, "Breakpoint %d at ", num );
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DEBUG_PrintAddress( &breakpoints[num].addr, breakpoints[num].addrlen );
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fprintf( stderr, "\n" );
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}
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/***********************************************************************
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* DEBUG_DelBreakpoint
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*
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* Delete a breakpoint.
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*/
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void DEBUG_DelBreakpoint( int num )
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{
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if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
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{
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fprintf( stderr, "Invalid breakpoint number %d\n", num );
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return;
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}
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breakpoints[num].enabled = FALSE;
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breakpoints[num].in_use = FALSE;
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}
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/***********************************************************************
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* DEBUG_EnableBreakpoint
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*
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* Enable or disable a break point.
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*/
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void DEBUG_EnableBreakpoint( int num, BOOL enable )
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{
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if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
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{
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fprintf( stderr, "Invalid breakpoint number %d\n", num );
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return;
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}
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breakpoints[num].enabled = enable;
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}
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/***********************************************************************
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* DEBUG_InfoBreakpoints
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*
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* Display break points information.
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*/
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void DEBUG_InfoBreakpoints(void)
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{
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int i;
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fprintf( stderr, "Breakpoints:\n" );
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for (i = 1; i < next_bp; i++)
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{
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if (breakpoints[i].in_use)
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{
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fprintf( stderr, "%d: %c ", i, breakpoints[i].enabled ? 'y' : 'n');
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DEBUG_PrintAddress( &breakpoints[i].addr, breakpoints[i].addrlen );
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fprintf( stderr, "\n" );
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}
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}
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}
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/***********************************************************************
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* DEBUG_ShouldContinue
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*
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* Determine if we should continue execution after a SIGTRAP signal when
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* executing in the given mode.
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*/
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BOOL DEBUG_ShouldContinue( struct sigcontext_struct *context,
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enum exec_mode mode )
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{
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DBG_ADDR addr;
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int bpnum;
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/* If not single-stepping, back up over the int3 instruction */
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if (!(EFL_reg(DEBUG_context) & STEP_FLAG)) EIP_reg(DEBUG_context)--;
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addr.seg = (CS_reg(DEBUG_context) == WINE_CODE_SELECTOR) ?
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0 : CS_reg(DEBUG_context);
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addr.off = EIP_reg(DEBUG_context);
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bpnum = DEBUG_FindBreakpoint( &addr );
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breakpoints[0].enabled = 0; /* disable the step-over breakpoint */
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if ((bpnum != 0) && (bpnum != -1))
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{
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fprintf( stderr, "Stopped on breakpoint %d at ", bpnum );
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DEBUG_PrintAddress( &breakpoints[bpnum].addr,
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breakpoints[bpnum].addrlen );
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fprintf( stderr, "\n" );
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return FALSE;
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}
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/* no breakpoint, continue if in continuous mode */
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return (mode == EXEC_CONT);
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}
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/***********************************************************************
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* DEBUG_RestartExecution
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*
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* Set the breakpoints to the correct state to restart execution
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* in the given mode.
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*/
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void DEBUG_RestartExecution( struct sigcontext_struct *context,
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enum exec_mode mode, int instr_len )
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{
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DBG_ADDR addr;
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addr.seg = (CS_reg(DEBUG_context) == WINE_CODE_SELECTOR) ?
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0 : CS_reg(DEBUG_context);
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addr.off = EIP_reg(DEBUG_context);
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if (DEBUG_FindBreakpoint( &addr ) != -1)
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mode = EXEC_STEP_INSTR; /* If there's a breakpoint, skip it */
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switch(mode)
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{
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case EXEC_CONT: /* Continuous execution */
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EFL_reg(DEBUG_context) &= ~STEP_FLAG;
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DEBUG_SetBreakpoints( TRUE );
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break;
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case EXEC_STEP_OVER: /* Stepping over a call */
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if (DEBUG_IsStepOverInstr(DEBUG_context))
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{
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EFL_reg(DEBUG_context) &= ~STEP_FLAG;
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addr.off += instr_len;
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breakpoints[0].addr = addr;
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breakpoints[0].enabled = TRUE;
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breakpoints[0].in_use = TRUE;
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breakpoints[0].opcode = *(BYTE *)DBG_ADDR_TO_LIN( &addr );
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DEBUG_SetBreakpoints( TRUE );
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break;
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}
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/* else fall through to single-stepping */
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case EXEC_STEP_INSTR: /* Single-stepping an instruction */
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EFL_reg(DEBUG_context) |= STEP_FLAG;
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break;
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}
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}
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