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authorCorinna Vinschen <corinna@vinschen.de>2020-03-25 21:01:29 +0100
committerCorinna Vinschen <corinna@vinschen.de>2020-03-25 21:01:29 +0100
commit009c7a0553b6d59f0d5ed79210069a9c7c336184 (patch)
tree97612749ad5da2006cff88b6bcc1fae5fa238e94
parent8ffe12b394e4ed593b38c991da6d094100c3b78d (diff)
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Revert "Cygwin: serial: read: if VMIN > 0, wait for VMIN chars in inbound queue"github/topic/serial_iotopic/serial_io
This reverts commit 082f2513c721e942d0fd563c4dc9117eee3513ab. Turns out, Linux as well as BSD really only wait for the smaller number, MIN or # of requested bytes. Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
-rw-r--r--winsup/cygwin/fhandler_serial.cc38
1 files changed, 12 insertions, 26 deletions
diff --git a/winsup/cygwin/fhandler_serial.cc b/winsup/cygwin/fhandler_serial.cc
index 3fd8a97..9446315 100644
--- a/winsup/cygwin/fhandler_serial.cc
+++ b/winsup/cygwin/fhandler_serial.cc
@@ -34,20 +34,19 @@ void __reg3
fhandler_serial::raw_read (void *ptr, size_t& ulen)
{
OVERLAPPED ov = { 0 };
- DWORD io_err, event;
+ DWORD io_err;
COMSTAT st;
DWORD bytes_to_read, read_bytes;
ssize_t tot = 0;
- bool wait_for_vmin, ret;
if (ulen > SSIZE_MAX)
ulen = SSIZE_MAX;
if (ulen == 0)
return;
- /* If MIN > 0 in blocking mode, we have to wait for at least MIN chars.
- Otherwise we're in polling mode and there's no minimum chars. */
- ssize_t minchars = is_nonblocking () ? 0 : vmin_;
+ /* If MIN > 0 in blocking mode, we have to read at least VMIN chars,
+ otherwise we're in polling mode and there's no minimum chars. */
+ ssize_t minchars = (!is_nonblocking () && vmin_) ? MIN (vmin_, ulen) : 0;
debug_printf ("ulen %ld, vmin_ %u, vtime_ %u", ulen, vmin_, vtime_);
@@ -55,8 +54,6 @@ fhandler_serial::raw_read (void *ptr, size_t& ulen)
do
{
- wait_for_vmin = false;
-
/* First check if chars are already in the inbound queue. */
if (!ClearCommError (get_handle (), &io_err, &st))
goto err;
@@ -85,22 +82,14 @@ fhandler_serial::raw_read (void *ptr, size_t& ulen)
and don't wait. */
if (st.cbInQue && st.cbInQue >= minchars)
bytes_to_read = MIN (st.cbInQue, bytes_to_read);
- /* Otherwise, if MIN > 0, TIME == 0, we have to wait until
- MIN bytes are available in the inbound queue. */
- else if (minchars && !vtime_)
- wait_for_vmin = true;
}
ResetEvent (ov.hEvent);
- if (wait_for_vmin)
- ret = WaitCommEvent (get_handle (), &event, &ov);
- else
- ret = ReadFile (get_handle (), ptr, bytes_to_read, &read_bytes, &ov);
- if (!ret)
+ if (!ReadFile (get_handle (), ptr, bytes_to_read, &read_bytes, &ov))
{
if (GetLastError () != ERROR_IO_PENDING)
goto err;
- if (!wait_for_vmin && is_nonblocking ())
+ if (is_nonblocking ())
{
CancelIo (get_handle ());
if (!GetOverlappedResult (get_handle (), &ov, &read_bytes,
@@ -145,15 +134,12 @@ fhandler_serial::raw_read (void *ptr, size_t& ulen)
}
}
}
- if (!wait_for_vmin)
- {
- tot += read_bytes;
- ptr = (void *) ((caddr_t) ptr + read_bytes);
- ulen -= read_bytes;
- minchars -= read_bytes;
- debug_printf ("vtime_ %u, vmin_ %u, read_bytes %u, tot %D",
- vtime_, vmin_, read_bytes, tot);
- }
+ tot += read_bytes;
+ ptr = (void *) ((caddr_t) ptr + read_bytes);
+ ulen -= read_bytes;
+ minchars -= read_bytes;
+ debug_printf ("vtime_ %u, vmin_ %u, read_bytes %u, tot %D",
+ vtime_, vmin_, read_bytes, tot);
continue;
err: