[Bug 28089] New: exception handling code touches stack for exceptions handled by the debugger

http://bugs.winehq.org/show_bug.cgi?id=28089

Summary: exception handling code touches stack for exceptions
                    handled by the debugger
           Product: Wine
           Version: unspecified
          Platform: x86
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ntdll
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

Created an attachment (id=35971)
 --> (http://bugs.winehq.org/attachment.cgi?id=35971)
a hack to work around the problem

Wine places the CONTEXT and EXCEPTION_RECORD structures onto the stack past ESP
during the unix signal handler and continues with most of the exception
handling code outside of the signal handler. Unfortunately and contrary to
windows behavior the debugger gets notified only after this happens. Windows
doesn't touch the stack at all, if the exception is handled by the debugger.
This makes it very hard to single step trough code which keeps useful data past
ESP (securom 8 for example).

it's easy to show with this small test:

void foo()
{
    char *x = 0, *y = 0, *from = 0, *to = 0;
    char c;

x = &c;
    y = &c - 500;

while (y != x)
        *y++ = 0x55;

c = 0x77;  /* single step a few times here */
    y = &c - 500;

while (y != x)
    {
        if (*y != 0x55)
            if (from)
                to = y;
            else
                from = y;
        y++;
    }
    /* to and from shoudl be NULL */
}