WinDBG conditional breakpoints on member of a class pointer value - windbg

Question

Trying to set breakpoint to class member, but I get syntax error or error saying "could not resolve".
Target variable is abc of class pointer xyz.
0:000> ??##c++(xyz->abc)
short 0n812
0:000> dt xyz
Local var # rbx Type Prop*
+0x000 __VFN_table : 0x00007ffd`b9229510
+0x058 abc : 0n0147
Attempts:
0:000> bu ***!***::function+0x56 ".if (##c++(xyz->abc))==147) {.echo 'hit'} .else {gc}"
^ Syntax error in '.if ....'
I want to set breakpoint when pProp->ydu value is equal to 147.

Answer 1

source
#include <iostream>
using namespace std;
class Rectangle {
int width, height;
public:
Rectangle (int x ,int y) : width(x) , height(y) {}
int area (void) {return (width*height);}
};
void CalcArea(int i,int j,Rectangle *rect) {
cout << "Area for Rect("<<i<<","<<j<<") = "<<rect->area()<< endl;
}
int main () {
int i,j;
for(i=10,j=10; (i<100 && j<100); i+=5,j+=10){
Rectangle rect (i,j);
CalcArea(i,j,&rect);
}
return 0;
}
compiled with vs 2017 community cmd prompt
cl /EHsc /W4 /analyze /Zi /Od classy.cpp /link /release
executed
classy.exe
Area for Rect(10,10) = 100
Area for Rect(15,20) = 300
Area for Rect(20,30) = 600
Area for Rect(25,40) = 1000
Area for Rect(30,50) = 1500
Area for Rect(35,60) = 2100
Area for Rect(40,70) = 2800
Area for Rect(45,80) = 3600
Area for Rect(50,90) = 4500
loaded in windbg and set a conditional break point and run
:\>cdb classy.exe
Microsoft (R) Windows Debugger Version 10.0.16299.15 X86
0:000> bu classy!CalcArea ".if(((##c++(rect->width))==0n40)){ .echo \"hit\" } .else{gc}"
0:000> bl
0 e 00841100 0001 (0001) 0:****
classy!CalcArea ".if( ((##c++(rect->width))==0n40) ) { .echo \"hit\" } .else {gc}"
0:000> g
Area for Rect(10,10) = 100
Area for Rect(15,20) = 300
Area for Rect(20,30) = 600
Area for Rect(25,40) = 1000
Area for Rect(30,50) = 1500
Area for Rect(35,60) = 2100
hit <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
eax=00000028 ebx=7ffdf000 ecx=002dff08 edx=00000046 esi=008c9bf0 edi=000d8b28
eip=00841100 esp=002dfef8 ebp=002dff18 iopl=0 nv up ei ng nz na pe cy
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00000287
classy!CalcArea:
00841100 55 push ebp
0:000> ?? rect
class Rectangle * 0x002dff08
+0x000 width : 0n40 <<<<<<<<<<<<<<<
+0x004 height : 0n70
0:000>