[PATCH] Cygwin: pipe: Handle STATUS_PENDING even for nonblocking mode.
Takashi Yano
takashi.yano@nifty.ne.jp
Tue Nov 16 08:10:56 GMT 2021
On Tue, 16 Nov 2021 12:18:47 +0900
Takashi Yano wrote:
> - NtReadFile() and NtWriteFile() seems to return STATUS_PENDING
> occasionally even in nonblocking mode. This patch adds handling
> for STATUS_PENDING in nonblocking mode.
>
> Addresses:
> https://cygwin.com/pipermail/cygwin/2021-November/249910.html
> ---
> winsup/cygwin/fhandler_pipe.cc | 10 ++++++----
> winsup/cygwin/release/3.3.3 | 5 +++++
> 2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
> index 1ebf4de10..f70ff56fe 100644
> --- a/winsup/cygwin/fhandler_pipe.cc
> +++ b/winsup/cygwin/fhandler_pipe.cc
> @@ -336,9 +336,10 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
> break;
> status = NtReadFile (get_handle (), evt, NULL, NULL, &io, ptr,
> len1, NULL, NULL);
> - if (evt && status == STATUS_PENDING)
> + if (status == STATUS_PENDING)
> {
> - waitret = cygwait (evt, INFINITE, cw_cancel | cw_sig);
> + HANDLE w = evt ?: get_handle ();
> + waitret = cygwait (w, INFINITE, cw_cancel | cw_sig);
> /* If io.Status is STATUS_CANCELLED after CancelIo, IO has actually
> been cancelled and io.Information contains the number of bytes
> processed so far.
> @@ -507,10 +508,11 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
> break;
> len1 >>= 1;
> }
> - if (evt && status == STATUS_PENDING)
> + if (status == STATUS_PENDING)
> {
> + HANDLE w = evt ?: get_handle ();
> while (WAIT_TIMEOUT ==
> - (waitret = cygwait (evt, (DWORD) 0, cw_cancel | cw_sig)))
> + (waitret = cygwait (w, (DWORD) 0, cw_cancel | cw_sig)))
> {
> if (reader_closed ())
> {
> diff --git a/winsup/cygwin/release/3.3.3 b/winsup/cygwin/release/3.3.3
> index 1eb25e2fc..49c1bcdc3 100644
> --- a/winsup/cygwin/release/3.3.3
> +++ b/winsup/cygwin/release/3.3.3
> @@ -16,3 +16,8 @@ Bug Fixes
> - Fix long-standing problem that new files don't get created with the
> FILE_ATTRIBUTE_ARCHIVE DOS attribute set.
> Addresses: https://cygwin.com/pipermail/cygwin/2021-November/249909.html
> +
> +- Fix issue that pipe read()/write() occationally returns a garnage
> + length when NtReadFile/NtWriteFile returns STATUS_PENDING in non-
> + blocking mode.
> + Addresses: https://cygwin.com/pipermail/cygwin/2021-November/249910.html
> --
> 2.33.0
I noticed that this patch sometimes does not work as expected.
cygwaint(get_handle(), ...) may sometimes return WAIT_OBJECT_0
even when the operation is not completed.
I will submit a patch according to Corinna's way. (Use event
even in nonblocking mode.)
--
Takashi Yano <takashi.yano@nifty.ne.jp>
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