Re: [HACKERS] Win32 WEXITSTATUS too

Takayuki Tsunakawa wrote:
> From: "Bruce Momjian" <bruce(at)momjian(dot)us>
> > OK, I have tested on MinGW and found I can use FormatMessage() to
> print
> > a description for all ERROR* system() failures, rather than print a
> hex
> > value. This removes the need for a URL or lookup of hex values.
> > Attached and applied.
>
> Excuse me if I'm misunderstanding, but I'm afraid you are mixing up
> Win32 error codes and exception codes. I saw the following fragment
> in your patch:
>
> ! * On MinGW, system() returns STATUS_* values. MSVC might be
> ! * different. To test, create a binary that does *(NULL), and
> ! * then create a second binary that calls it via system(),
> ! * and check the return value of system(). On MinGW, it is
> ! * 0xC0000005 == STATUS_ACCESS_VIOLATION, and 0x5 is a value
> ! * FormatMessage() can look up. GetLastError() does not work;
> ! * always zero.
>
> Exception codes and error codes are different and not related. In the
> above test, 0xC0000005 is an "exception code". On the other hand, what
> FormatMessage() accepts is an error code. Error codes can't derived
> from exception codes. Stripping off 0xC bit from an exception code
> does not convert it to an error code.
> I suspect the reason why you misunderstood is that the descriptions
> are similar:
> the description for exception 0xC0000005 (STATUS_ACCESS_VIOLATION) is
> "access violation" (though the text can't be obtained). This is
> caused by an illegal memory access. This is a program bug.
> The description for 0x5 (ERROR_ACCESS_DENIED) is "Access is denied."
> This is caused by permission checks. This is not a bug, and can
> happen normally.
>
> Try "1.0 / 0.0" (devide by zero) instead of (*NULL). What would your
> patch display? The exception would be 0xC000008E
> (STATUS_FLOAT_DIVIDE_BY_ZERO), I think. 0x8E is ERROR_BUSY_DRIVE.

Yes, you are 100% correct that I had exceptions and errors confused. I
have backed out the patch that used FormatMessage(), and instead of
using a URL, the message is now:

child process was terminated by exception %X
See /include/ntstatus.h for a description of the hex value.

When I search for /include/ntstatus.h, I get the Wine page first, so
hopefully we can mark this item as completed.

--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com

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