Re: [PATCH v3] Cygwin: pipe: Handle STATUS_PENDING even for nonblocking mode.

2021-11-16 Thread Ken Brown

On 11/16/2021 9:33 AM, 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.


I haven't tested (I assume you have), but LGTM except for two typos below.


+- Fix issue that pipe read()/write() occationally returns a garnage

   occasionally   garbage

Ken


[PATCH v3] Cygwin: pipe: Handle STATUS_PENDING even for nonblocking mode.

2021-11-16 Thread Takashi Yano
- 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 | 81 --
 winsup/cygwin/release/3.3.3|  5 +++
 2 files changed, 43 insertions(+), 43 deletions(-)

diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
index 9392a28c1..3cbd434b7 100644
--- a/winsup/cygwin/fhandler_pipe.cc
+++ b/winsup/cygwin/fhandler_pipe.cc
@@ -279,13 +279,12 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
   size_t nbytes = 0;
   NTSTATUS status = STATUS_SUCCESS;
   IO_STATUS_BLOCK io;
-  HANDLE evt = NULL;
+  HANDLE evt;
 
   if (!len)
 return;
 
-  /* Create a wait event if we're in blocking mode. */
-  if (!is_nonblocking () && !(evt = CreateEvent (NULL, false, false, NULL)))
+  if (!(evt = CreateEvent (NULL, false, false, NULL)))
 {
   __seterrno ();
   len = (size_t) -1;
@@ -321,8 +320,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
   ULONG len1 = (ULONG) (len - nbytes);
   waitret = WAIT_OBJECT_0;
 
-  if (evt)
-   ResetEvent (evt);
+  ResetEvent (evt);
   FILE_PIPE_LOCAL_INFORMATION fpli;
   status = NtQueryInformationFile (get_handle (), ,
   , sizeof (fpli),
@@ -336,7 +334,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
break;
   status = NtReadFile (get_handle (), evt, NULL, NULL, , ptr,
   len1, NULL, NULL);
-  if (evt && status == STATUS_PENDING)
+  if (status == STATUS_PENDING)
{
  waitret = cygwait (evt, INFINITE, cw_cancel | cw_sig);
  /* If io.Status is STATUS_CANCELLED after CancelIo, IO has actually
@@ -406,8 +404,7 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
break;
 }
   ReleaseMutex (read_mtx);
-  if (evt)
-CloseHandle (evt);
+  CloseHandle (evt);
   if (status == STATUS_THREAD_SIGNALED && nbytes == 0)
 {
   set_errno (EINTR);
@@ -437,7 +434,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
   ULONG chunk;
   NTSTATUS status = STATUS_SUCCESS;
   IO_STATUS_BLOCK io;
-  HANDLE evt = NULL;
+  HANDLE evt;
 
   if (!len)
 return 0;
@@ -456,8 +453,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
   else
 chunk = pipe_buf_size;
 
-  /* Create a wait event if the pipe or fifo is in blocking mode. */
-  if (!is_nonblocking () && !(evt = CreateEvent (NULL, false, false, NULL)))
+  if (!(evt = CreateEvent (NULL, false, false, NULL)))
 {
   __seterrno ();
   return -1;
@@ -502,41 +498,41 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t 
len)
{
  status = NtWriteFile (get_handle (), evt, NULL, NULL, ,
(PVOID) ptr, len1, NULL, NULL);
- if (evt || !NT_SUCCESS (status) || io.Information > 0
- || len <= PIPE_BUF)
-   break;
- len1 >>= 1;
-   }
-  if (evt && status == STATUS_PENDING)
-   {
- while (WAIT_TIMEOUT ==
-(waitret = cygwait (evt, (DWORD) 0, cw_cancel | cw_sig)))
+ if (status == STATUS_PENDING)
{
- if (reader_closed ())
+ while (WAIT_TIMEOUT ==
+(waitret = cygwait (evt, (DWORD) 0, cw_cancel | cw_sig)))
{
- CancelIo (get_handle ());
- set_errno (EPIPE);
- raise (SIGPIPE);
- goto out;
+ if (reader_closed ())
+   {
+ CancelIo (get_handle ());
+ set_errno (EPIPE);
+ raise (SIGPIPE);
+ goto out;
+   }
+ else
+   cygwait (select_sem, 10);
}
+ /* If io.Status is STATUS_CANCELLED after CancelIo, IO has
+actually been cancelled and io.Information contains the
+number of bytes processed so far.
+Otherwise IO has been finished regulary and io.Status
+contains valid success or error information. */
+ CancelIo (get_handle ());
+ if (waitret == WAIT_SIGNALED && io.Status != STATUS_CANCELLED)
+   waitret = WAIT_OBJECT_0;
+
+ if (waitret == WAIT_CANCELED)
+   status = STATUS_THREAD_CANCELED;
+ else if (waitret == WAIT_SIGNALED)
+   status = STATUS_THREAD_SIGNALED;
  else
-   cygwait (select_sem, 10);
+   status = io.Status;
}
- /* If io.Status is STATUS_CANCELLED after CancelIo, IO has actually
-been cancelled and io.Information contains the number of bytes
-processed so far.
-Otherwise IO has been finished regulary and