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From: linyanmi on 14 Nov 2008 09:50
Hi,
My application tries to call function PostMessage(...) to the windows
message queue, but it fails. GetLastError() return error code 183.
According to the system code table 183 means:
ERROR_ALREADY_EXISTS (0xB7): Cannot create a file when that file
already exists.
What can cause such kind of failure?
Thanks in advance for any suggestion...
From: Igor Tandetnik on 14 Nov 2008 15:11
linyanmi(a)gmail.com wrote:
> My application tries to call function PostMessage(...) to the windows
> message queue, but it fails. GetLastError() return error code 183.

How do you know it fails? Do you check its return value, or do you call
GetLastError right away?

Most API functions set last error on failure, but _don't_ reset it on
success. The result of GetLastError is only meaningful if the most
recent call has indeed failed (usually indicated by its return value).
You can't rely on GetLastError returning NOERROR after a successful
call.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925


From: linyanmi on 17 Nov 2008 12:55
Hi Igor Tandetnik,
Thanks for your reply.
The failure actually occurred when it called SendMessageTimeout
function:

if (!SendMessageTimeout(hwndSubscibed, ulSubscribedMsg,
ulNotification,lQueueElement, SMTO_ABORTIFHUNG, 10, &dwResult))
{
Trace("PostNotifications( ) : OP_FAIL:PostMessage:[%d]",
GetLastError());
}

GetLastError() is called right away, the trace shows error code 183
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