debugger/break.c

   1 /*
   2  * Debugger break-points handling
   3  *
   4  * Copyright 1994 Martin von Loewis
   5  * Copyright 1995 Alexandre Julliard
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <sys/types.h>
  11 #include <sys/mman.h>
  12 #include "module.h"
  13 #include "process.h"
  14 #include "task.h"
  15 #include "miscemu.h"
  16 #include "toolhelp.h"
  17 #include "windows.h"
  18 #include "debugger.h"
  19 #include "dosexe.h"
  20
  21 #define INT3          0xcc   /* int 3 opcode */
  22
  23 #define MAX_BREAKPOINTS 100
  24
  25 typedef struct
  26 {
  27     DBG_ADDR      addr;
  28     BYTE          addrlen;
  29     BYTE          opcode;
  30     BOOL16        enabled;
  31     WORD          skipcount;
  32     BOOL16        in_use;
  33     struct expr * condition;
  34 } BREAKPOINT;
  35
  36 static BREAKPOINT breakpoints[MAX_BREAKPOINTS];
  37
  38 static int next_bp = 1;  /* breakpoint 0 is reserved for step-over */
  39
  40
  41 /***********************************************************************
  42  *           DEBUG_ChangeOpcode
  43  *
  44  * Change the opcode at segment:addr.
  45  */
  46 static void DEBUG_SetOpcode( const DBG_ADDR *addr, BYTE op )
  47 {
  48     BYTE *ptr = DBG_ADDR_TO_LIN(addr);
  49
  50     /* There are a couple of problems with this. On Linux prior to
  51        1.1.62, this call fails (ENOACCESS) due to a bug in fs/exec.c.
  52        This code is currently not tested at all on BSD.
  53        How do I get the old protection in order to restore it later on?
  54        */
  55     if (mprotect((caddr_t)((int)ptr & (~4095)), 4096,
  56                  PROT_READ | PROT_WRITE | PROT_EXEC) == -1)
  57     {
  58         perror( "Can't set break point" );
  59         return;
  60     }
  61     *ptr = op;
  62     /* mprotect((caddr_t)(addr->off & ~4095), 4096,
  63        PROT_READ | PROT_EXEC ); */
  64 }
  65
  66
  67 /***********************************************************************
  68  *           DEBUG_IsStepOverInstr
  69  *
  70  * Determine if the instruction at CS:EIP is an instruction that
  71  * we need to step over (like a call or a repetitive string move).
  72  */
  73 static BOOL32 DEBUG_IsStepOverInstr()
  74 {
  75     BYTE *instr = (BYTE *)CTX_SEG_OFF_TO_LIN( &DEBUG_context,
  76                                               CS_reg(&DEBUG_context),
  77                                               EIP_reg(&DEBUG_context) );
  78
  79     for (;;)
  80     {
  81         switch(*instr)
  82         {
  83           /* Skip all prefixes */
  84
  85         case 0x2e:  /* cs: */
  86         case 0x36:  /* ss: */
  87         case 0x3e:  /* ds: */
  88         case 0x26:  /* es: */
  89         case 0x64:  /* fs: */
  90         case 0x65:  /* gs: */
  91         case 0x66:  /* opcode size prefix */
  92         case 0x67:  /* addr size prefix */
  93         case 0xf0:  /* lock */
  94         case 0xf2:  /* repne */
  95         case 0xf3:  /* repe */
  96             instr++;
  97             continue;
  98
  99           /* Handle call instructions */
 100
 101         case 0xcd:  /* int <intno> */
 102         case 0xe8:  /* call <offset> */
 103         case 0x9a:  /* lcall <seg>:<off> */
 104             return TRUE;
 105
 106         case 0xff:  /* call <regmodrm> */
 107             return (((instr[1] & 0x38) == 0x10) ||
 108                     ((instr[1] & 0x38) == 0x18));
 109
 110           /* Handle string instructions */
 111
 112         case 0x6c:  /* insb */
 113         case 0x6d:  /* insw */
 114         case 0x6e:  /* outsb */
 115         case 0x6f:  /* outsw */
 116         case 0xa4:  /* movsb */
 117         case 0xa5:  /* movsw */
 118         case 0xa6:  /* cmpsb */
 119         case 0xa7:  /* cmpsw */
 120         case 0xaa:  /* stosb */
 121         case 0xab:  /* stosw */
 122         case 0xac:  /* lodsb */
 123         case 0xad:  /* lodsw */
 124         case 0xae:  /* scasb */
 125         case 0xaf:  /* scasw */
 126             return TRUE;
 127
 128         default:
 129             return FALSE;
 130         }
 131     }
 132 }
 133
 134
 135 /***********************************************************************
 136  *           DEBUG_IsFctReturn
 137  *
 138  * Determine if the instruction at CS:EIP is an instruction that
 139  * is a function return.
 140  */
 141 BOOL32 DEBUG_IsFctReturn(void)
 142 {
 143     BYTE *instr = (BYTE *)CTX_SEG_OFF_TO_LIN( &DEBUG_context,
 144                                               CS_reg(&DEBUG_context),
 145                                               EIP_reg(&DEBUG_context) );
 146
 147     for (;;)
 148     {
 149         switch(*instr)
 150         {
 151         case 0xc2:
 152         case 0xc3:
 153           return TRUE;
 154         default:
 155             return FALSE;
 156         }
 157     }
 158 }
 159
 160
 161 /***********************************************************************
 162  *           DEBUG_SetBreakpoints
 163  *
 164  * Set or remove all the breakpoints.
 165  */
 166 void DEBUG_SetBreakpoints( BOOL32 set )
 167 {
 168     int i;
 169
 170     for (i = 0; i < MAX_BREAKPOINTS; i++)
 171     {
 172         if (breakpoints[i].in_use && breakpoints[i].enabled)
 173         {
 174             /* Note: we check for read here, because if reading is allowed */
 175             /*       writing permission will be forced in DEBUG_SetOpcode. */
 176             if (DEBUG_IsBadReadPtr( &breakpoints[i].addr, 1 ))
 177             {
 178                 fprintf( stderr, "Invalid address for breakpoint %d, disabling it\n", i );
 179                 breakpoints[i].enabled = FALSE;
 180             }
 181             else DEBUG_SetOpcode( &breakpoints[i].addr,
 182                                   set ? INT3 : breakpoints[i].opcode );
 183         }
 184     }
 185 }
 186
 187
 188 /***********************************************************************
 189  *           DEBUG_FindBreakpoint
 190  *
 191  * Find the breakpoint for a given address. Return the breakpoint
 192  * number or -1 if none.
 193  */
 194 int DEBUG_FindBreakpoint( const DBG_ADDR *addr )
 195 {
 196     int i;
 197
 198     for (i = 0; i < MAX_BREAKPOINTS; i++)
 199     {
 200         if (breakpoints[i].in_use && breakpoints[i].enabled &&
 201             breakpoints[i].addr.seg == addr->seg &&
 202             breakpoints[i].addr.off == addr->off) return i;
 203     }
 204     return -1;
 205 }
 206
 207
 208 /***********************************************************************
 209  *           DEBUG_AddBreakpoint
 210  *
 211  * Add a breakpoint.
 212  */
 213 void DEBUG_AddBreakpoint( const DBG_ADDR *address )
 214 {
 215     DBG_ADDR addr = *address;
 216     int num;
 217     unsigned int seg2;
 218     BYTE *p;
 219
 220     DBG_FIX_ADDR_SEG( &addr, CS_reg(&DEBUG_context) );
 221
 222     if( addr.type != NULL && addr.type == DEBUG_TypeIntConst )
 223       {
 224         /*
 225          * We know that we have the actual offset stored somewhere
 226          * else in 32-bit space.  Grab it, and we
 227          * should be all set.
 228          */
 229         seg2 = addr.seg;
 230         addr.seg = 0;
 231         addr.off = DEBUG_GetExprValue(&addr, NULL);
 232         addr.seg = seg2;
 233       }
 234     if (!DBG_CHECK_READ_PTR( &addr, 1 )) return;
 235
 236     if (next_bp < MAX_BREAKPOINTS)
 237         num = next_bp++;
 238     else  /* try to find an empty slot */
 239     {
 240         for (num = 1; num < MAX_BREAKPOINTS; num++)
 241             if (!breakpoints[num].in_use) break;
 242         if (num >= MAX_BREAKPOINTS)
 243         {
 244             fprintf( stderr, "Too many breakpoints. Please delete some.\n" );
 245             return;
 246         }
 247     }
 248     p = DBG_ADDR_TO_LIN( &addr );
 249     breakpoints[num].addr    = addr;
 250     breakpoints[num].addrlen = !addr.seg ? 32 :
 251                          (GET_SEL_FLAGS(addr.seg) & LDT_FLAGS_32BIT) ? 32 : 16;
 252     breakpoints[num].opcode  = *p;
 253     breakpoints[num].enabled = TRUE;
 254     breakpoints[num].in_use  = TRUE;
 255     breakpoints[num].skipcount = 0;
 256     fprintf( stderr, "Breakpoint %d at ", num );
 257     DEBUG_PrintAddress( &breakpoints[num].addr, breakpoints[num].addrlen,
 258                         TRUE );
 259     fprintf( stderr, "\n" );
 260 }
 261
 262
 263 /***********************************************************************
 264  *           DEBUG_DelBreakpoint
 265  *
 266  * Delete a breakpoint.
 267  */
 268 void DEBUG_DelBreakpoint( int num )
 269 {
 270     if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
 271     {
 272         fprintf( stderr, "Invalid breakpoint number %d\n", num );
 273         return;
 274     }
 275
 276     if( breakpoints[num].condition != NULL )
 277       {
 278         DEBUG_FreeExpr(breakpoints[num].condition);
 279         breakpoints[num].condition = NULL;
 280       }
 281
 282     breakpoints[num].enabled = FALSE;
 283     breakpoints[num].in_use  = FALSE;
 284     breakpoints[num].skipcount = 0;
 285 }
 286
 287
 288 /***********************************************************************
 289  *           DEBUG_EnableBreakpoint
 290  *
 291  * Enable or disable a break point.
 292  */
 293 void DEBUG_EnableBreakpoint( int num, BOOL32 enable )
 294 {
 295     if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
 296     {
 297         fprintf( stderr, "Invalid breakpoint number %d\n", num );
 298         return;
 299     }
 300     breakpoints[num].enabled = enable;
 301     breakpoints[num].skipcount = 0;
 302 }
 303
 304
 305 /***********************************************************************
 306  *           DEBUG_InfoBreakpoints
 307  *
 308  * Display break points information.
 309  */
 310 void DEBUG_InfoBreakpoints(void)
 311 {
 312     int i;
 313
 314     fprintf( stderr, "Breakpoints:\n" );
 315     for (i = 1; i < next_bp; i++)
 316     {
 317         if (breakpoints[i].in_use)
 318         {
 319             fprintf( stderr, "%d: %c ", i, breakpoints[i].enabled ? 'y' : 'n');
 320             DEBUG_PrintAddress( &breakpoints[i].addr, breakpoints[i].addrlen,
 321                                 TRUE);
 322             fprintf( stderr, "\n" );
 323             if( breakpoints[i].condition != NULL )
 324               {
 325                 fprintf(stderr, "\t\tstop when  ");
 326                 DEBUG_DisplayExpr(breakpoints[i].condition);
 327                 fprintf(stderr, "\n");
 328               }
 329         }
 330     }
 331 }
 332
 333
 334 /***********************************************************************
 335  *           DEBUG_AddTaskEntryBreakpoint
 336  *
 337  * Add a breakpoint at the entry point of the given task
 338  */
 339 void DEBUG_AddTaskEntryBreakpoint( HTASK16 hTask )
 340 {
 341     TDB *pTask = (TDB *)GlobalLock16( hTask );
 342     NE_MODULE *pModule;
 343     DBG_ADDR addr = { NULL, 0, 0 };
 344
 345     if ( pTask )
 346     {
 347         if (!(pModule = NE_GetPtr( pTask->hModule ))) return;
 348         if (pModule->flags & NE_FFLAGS_LIBMODULE) return;  /* Library */
 349
 350         if (pModule->lpDosTask) { /* DOS module */
 351             addr.seg = pModule->lpDosTask->init_cs | ((DWORD)pModule->self << 16);
 352             addr.off = pModule->lpDosTask->init_ip;
 353             fprintf( stderr, "DOS task '%s': ", NE_MODULE_NAME( pModule ) );
 354             DEBUG_AddBreakpoint( &addr );
 355         } else
 356         if (!(pModule->flags & NE_FFLAGS_WIN32))  /* NE module */
 357         {
 358             addr.seg =
 359                 GlobalHandleToSel(NE_SEG_TABLE(pModule)[pModule->cs-1].hSeg);
 360             addr.off = pModule->ip;
 361             fprintf( stderr, "Win16 task '%s': ", NE_MODULE_NAME( pModule ) );
 362             DEBUG_AddBreakpoint( &addr );
 363         }
 364         else /* PE module */
 365         {
 366             addr.seg = 0;
 367             addr.off = (DWORD)RVA_PTR( pModule->module32,
 368                            OptionalHeader.AddressOfEntryPoint);
 369             fprintf( stderr, "Win32 task '%s': ", NE_MODULE_NAME( pModule ) );
 370             DEBUG_AddBreakpoint( &addr );
 371         }
 372     }
 373
 374     DEBUG_SetBreakpoints( TRUE );  /* Setup breakpoints */
 375 }
 376
 377
 378 /***********************************************************************
 379  *           DEBUG_ShouldContinue
 380  *
 381  * Determine if we should continue execution after a SIGTRAP signal when
 382  * executing in the given mode.
 383  */
 384 BOOL32 DEBUG_ShouldContinue( enum exec_mode mode, int * count )
 385 {
 386     DBG_ADDR addr;
 387     DBG_ADDR cond_addr;
 388     int bpnum;
 389     struct list_id list;
 390     TDB *pTask = (TDB*)GlobalLock16( GetCurrentTask() );
 391
 392       /* If not single-stepping, back up over the int3 instruction */
 393     if (!(EFL_reg(&DEBUG_context) & STEP_FLAG)) EIP_reg(&DEBUG_context)--;
 394
 395     addr.seg = CS_reg(&DEBUG_context);
 396     addr.off = EIP_reg(&DEBUG_context);
 397     if (ISV86(&DEBUG_context)) addr.seg |= (DWORD)(pTask?(pTask->hModule):0)<<16; else
 398     if (IS_SELECTOR_SYSTEM(addr.seg)) addr.seg = 0;
 399
 400     GlobalUnlock16( GetCurrentTask() );
 401
 402     bpnum = DEBUG_FindBreakpoint( &addr );
 403     breakpoints[0].enabled = 0;  /* disable the step-over breakpoint */
 404
 405     if ((bpnum != 0) && (bpnum != -1))
 406     {
 407         if( breakpoints[bpnum].condition != NULL )
 408           {
 409             cond_addr = DEBUG_EvalExpr(breakpoints[bpnum].condition);
 410             if( cond_addr.type == NULL )
 411               {
 412                 /*
 413                  * Something wrong - unable to evaluate this expression.
 414                  */
 415                 fprintf(stderr, "Unable to evaluate expression ");
 416                 DEBUG_DisplayExpr(breakpoints[bpnum].condition);
 417                 fprintf(stderr, "\nTurning off condition\n");
 418                 DEBUG_AddBPCondition(bpnum, NULL);
 419               }
 420             else if( ! DEBUG_GetExprValue( &cond_addr, NULL) )
 421               {
 422                 return TRUE;
 423               }
 424           }
 425
 426         if( breakpoints[bpnum].skipcount > 0 )
 427           {
 428             breakpoints[bpnum].skipcount--;
 429             if( breakpoints[bpnum].skipcount > 0 )
 430               {
 431                 return TRUE;
 432               }
 433           }
 434         fprintf( stderr, "Stopped on breakpoint %d at ", bpnum );
 435         DEBUG_PrintAddress( &breakpoints[bpnum].addr,
 436                             breakpoints[bpnum].addrlen, TRUE );
 437         fprintf( stderr, "\n" );
 438
 439         /*
 440          * See if there is a source file for this bp.  If so,
 441          * then dig it out and display one line.
 442          */
 443         DEBUG_FindNearestSymbol( &addr, TRUE, NULL, 0, &list);
 444         if( list.sourcefile != NULL )
 445           {
 446             DEBUG_List(&list, NULL, 0);
 447           }
 448         return FALSE;
 449     }
 450
 451     /*
 452      * If our mode indicates that we are stepping line numbers,
 453      * get the current function, and figure out if we are exactly
 454      * on a line number or not.
 455      */
 456     if( mode == EXEC_STEP_OVER
 457         || mode == EXEC_STEP_INSTR )
 458       {
 459         if( DEBUG_CheckLinenoStatus(&addr) == AT_LINENUMBER )
 460           {
 461             (*count)--;
 462           }
 463       }
 464     else if( mode == EXEC_STEPI_OVER
 465         || mode == EXEC_STEPI_INSTR )
 466
 467       {
 468         (*count)--;
 469       }
 470
 471     if( *count > 0 || mode == EXEC_FINISH )
 472       {
 473         /*
 474          * We still need to execute more instructions.
 475          */
 476         return TRUE;
 477       }
 478
 479     /*
 480      * If we are about to stop, then print out the source line if we
 481      * have it.
 482      */
 483     if( (mode != EXEC_CONT && mode != EXEC_FINISH) )
 484       {
 485         DEBUG_FindNearestSymbol( &addr, TRUE, NULL, 0, &list);
 486         if( list.sourcefile != NULL )
 487           {
 488             DEBUG_List(&list, NULL, 0);
 489           }
 490       }
 491
 492     /* If there's no breakpoint and we are not single-stepping, then we     */
 493     /* must have encountered an int3 in the Windows program; let's skip it. */
 494     if ((bpnum == -1) && !(EFL_reg(&DEBUG_context) & STEP_FLAG))
 495         EIP_reg(&DEBUG_context)++;
 496
 497       /* no breakpoint, continue if in continuous mode */
 498     return (mode == EXEC_CONT || mode == EXEC_FINISH);
 499 }
 500
 501
 502 /***********************************************************************
 503  *           DEBUG_RestartExecution
 504  *
 505  * Set the breakpoints to the correct state to restart execution
 506  * in the given mode.
 507  */
 508 enum exec_mode DEBUG_RestartExecution( enum exec_mode mode, int count )
 509 {
 510     DBG_ADDR addr;
 511     DBG_ADDR addr2;
 512     int bp;
 513     int delta;
 514     int status;
 515     unsigned int * value;
 516     enum exec_mode ret_mode;
 517     BYTE *instr;
 518     TDB *pTask = (TDB*)GlobalLock16( GetCurrentTask() );
 519
 520     addr.seg = CS_reg(&DEBUG_context);
 521     addr.off = EIP_reg(&DEBUG_context);
 522     if (ISV86(&DEBUG_context)) addr.seg |= (DWORD)(pTask?(pTask->hModule):0)<<16; else
 523     if (IS_SELECTOR_SYSTEM(addr.seg)) addr.seg = 0;
 524
 525     GlobalUnlock16( GetCurrentTask() );
 526
 527     /*
 528      * This is the mode we will be running in after we finish.  We would like
 529      * to be able to modify this in certain cases.
 530      */
 531     ret_mode = mode;
 532
 533     bp = DEBUG_FindBreakpoint( &addr );
 534     if ( bp != -1 && bp != 0)
 535       {
 536         /*
 537          * If we have set a new value, then save it in the BP number.
 538          */
 539         if( count != 0 && mode == EXEC_CONT )
 540           {
 541             breakpoints[bp].skipcount = count;
 542           }
 543         mode = EXEC_STEPI_INSTR;  /* If there's a breakpoint, skip it */
 544       }
 545     else
 546       {
 547         if( mode == EXEC_CONT && count > 1 )
 548           {
 549             fprintf(stderr,"Not stopped at any breakpoint; argument ignored.\n");
 550           }
 551       }
 552
 553     if( mode == EXEC_FINISH && DEBUG_IsFctReturn() )
 554       {
 555         mode = ret_mode = EXEC_STEPI_INSTR;
 556       }
 557
 558     instr = (BYTE *)CTX_SEG_OFF_TO_LIN( &DEBUG_context,
 559                                         CS_reg(&DEBUG_context),
 560                                         EIP_reg(&DEBUG_context) );
 561     /*
 562      * See if the function we are stepping into has debug info
 563      * and line numbers.  If not, then we step over it instead.
 564      * FIXME - we need to check for things like thunks or trampolines,
 565      * as the actual function may in fact have debug info.
 566      */
 567     if( *instr == 0xe8 )
 568       {
 569         delta = *(unsigned int*) (instr + 1);
 570         addr2 = addr;
 571         DEBUG_Disasm(&addr2, FALSE);
 572         addr2.off += delta;
 573
 574         status = DEBUG_CheckLinenoStatus(&addr2);
 575         /*
 576          * Anytime we have a trampoline, step over it.
 577          */
 578         if( ((mode == EXEC_STEP_OVER) || (mode == EXEC_STEPI_OVER))
 579             && status == FUNC_IS_TRAMPOLINE )
 580           {
 581 #if 0
 582             fprintf(stderr, "Not stepping into trampoline at %x (no lines)\n",
 583                     addr2.off);
 584 #endif
 585             mode = EXEC_STEP_OVER_TRAMPOLINE;
 586           }
 587
 588         if( mode == EXEC_STEP_INSTR && status == FUNC_HAS_NO_LINES )
 589           {
 590 #if 0
 591             fprintf(stderr, "Not stepping into function at %x (no lines)\n",
 592                     addr2.off);
 593 #endif
 594             mode = EXEC_STEP_OVER;
 595           }
 596       }
 597
 598
 599     if( mode == EXEC_STEP_INSTR )
 600       {
 601         if( DEBUG_CheckLinenoStatus(&addr) == FUNC_HAS_NO_LINES )
 602           {
 603             fprintf(stderr, "Single stepping until exit from function, \n");
 604             fprintf(stderr, "which has no line number information.\n");
 605
 606             ret_mode = mode = EXEC_FINISH;
 607           }
 608       }
 609
 610     switch(mode)
 611     {
 612     case EXEC_CONT: /* Continuous execution */
 613         EFL_reg(&DEBUG_context) &= ~STEP_FLAG;
 614         DEBUG_SetBreakpoints( TRUE );
 615         break;
 616
 617     case EXEC_STEP_OVER_TRAMPOLINE:
 618       /*
 619        * This is the means by which we step over our conversion stubs
 620        * in callfrom*.s and callto*.s.  We dig the appropriate address
 621        * off the stack, and we set the breakpoint there instead of the
 622        * address just after the call.
 623        */
 624       value = (unsigned int *) ESP_reg(&DEBUG_context) + 2;
 625       addr.off = *value;
 626       EFL_reg(&DEBUG_context) &= ~STEP_FLAG;
 627       breakpoints[0].addr    = addr;
 628       breakpoints[0].enabled = TRUE;
 629       breakpoints[0].in_use  = TRUE;
 630       breakpoints[0].skipcount = 0;
 631       breakpoints[0].opcode  = *(BYTE *)DBG_ADDR_TO_LIN( &addr );
 632       DEBUG_SetBreakpoints( TRUE );
 633       break;
 634
 635     case EXEC_FINISH:
 636     case EXEC_STEPI_OVER:  /* Stepping over a call */
 637     case EXEC_STEP_OVER:  /* Stepping over a call */
 638         if (DEBUG_IsStepOverInstr())
 639         {
 640             EFL_reg(&DEBUG_context) &= ~STEP_FLAG;
 641             DEBUG_Disasm(&addr, FALSE);
 642             breakpoints[0].addr    = addr;
 643             breakpoints[0].enabled = TRUE;
 644             breakpoints[0].in_use  = TRUE;
 645             breakpoints[0].skipcount = 0;
 646             breakpoints[0].opcode  = *(BYTE *)DBG_ADDR_TO_LIN( &addr );
 647             DEBUG_SetBreakpoints( TRUE );
 648             break;
 649         }
 650         /* else fall through to single-stepping */
 651
 652     case EXEC_STEP_INSTR: /* Single-stepping an instruction */
 653     case EXEC_STEPI_INSTR: /* Single-stepping an instruction */
 654         EFL_reg(&DEBUG_context) |= STEP_FLAG;
 655         break;
 656     }
 657     return ret_mode;
 658 }
 659
 660 int
 661 DEBUG_AddBPCondition(int num, struct expr * exp)
 662 {
 663     if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
 664     {
 665         fprintf( stderr, "Invalid breakpoint number %d\n", num );
 666         return FALSE;
 667     }
 668
 669     if( breakpoints[num].condition != NULL )
 670       {
 671         DEBUG_FreeExpr(breakpoints[num].condition);
 672         breakpoints[num].condition = NULL;
 673       }
 674
 675     if( exp != NULL )
 676       {
 677         breakpoints[num].condition = DEBUG_CloneExpr(exp);
 678       }
 679
 680    return TRUE;
 681 }