Ivan,
although I essentially grok what you are saying, please follow the
guidelines at http://apr.apache.org/patches.html so there is absolutely
no ambiguity in the fix that needs to be applied. If you get to it right
away, this might make in into the next release, since I'm eager to close
this race condition.
Yours,
Bill
Ivan Leung wrote:
Hi,
I found that there is race condition in apr_file_read on Windows.
In read_with_timeout(), ReadFile() is an overlapped I/O operation
which is waited by WaitForSingleObject() afterwards. If the
message comes to the file handle just after
WaitForSingleObject. (with timeout) and before CancelIo(). The message
will be ignored and hence lost. My workaround is to check if
there is event on file handle after CancelIo. Adds following piece
of code just after CancelIo.
if (rv != APR_SUCCESS) {
if (apr_os_level >= APR_WIN_98)
CancelIo(file->filehand);
GetOverlappedResult(file->filehand, file->pOverlapped,
(LPDWORD)nbytes, FALSE);
if (*nbytes > 0)
rv = APR_SUCCESS;
}
