[newlib-cygwin] Cygwin: ioctl: TIOCINQ: always return number of chars in the inbound queue

[newlib-cygwin] Cygwin: ioctl: TIOCINQ: always return number of chars in the inbound queue

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=1b7fcf22bea529fba920310dcd2db144bb24ccc6

commit 1b7fcf22bea529fba920310dcd2db144bb24ccc6
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Mon Mar 2 17:02:51 2020 +0100

    Cygwin: ioctl: TIOCINQ: always return number of chars in the inbound queue
    
    So far ioctl(TIOCINQ) could end up returning -1 with errno set to EINVAL
    if a non-zero device error mask has been returned by ClearCommError.
    This doesn't reflect Linux behaviour, which always returns the number of
    chars in the inbound queue, independent of any I/O error condition.
    EINVAL was a pretty weird error code to use in this scenario, too.
    
    Fix this by dropping all checking for device errors in the TIOCINQ
    case.  Just return the number of chars in the inbound queue.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/fhandler_serial.cc | 9 +--------
 winsup/cygwin/release/3.1.5      | 3 +++
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/winsup/cygwin/fhandler_serial.cc b/winsup/cygwin/fhandler_serial.cc
index 615b251..69e5768 100644
--- a/winsup/cygwin/fhandler_serial.cc
+++ b/winsup/cygwin/fhandler_serial.cc
@@ -519,14 +519,7 @@ fhandler_serial::ioctl (unsigned int cmd, void *buf)
 	  }
 	break;
      case TIOCINQ:
-       if (ev & CE_FRAME || ev & CE_IOE || ev & CE_OVERRUN || ev & CE_RXOVER
-	   || ev & CE_RXPARITY)
-	 {
-	   set_errno (EINVAL);	/* FIXME: Use correct errno */
-	   res = -1;
-	 }
-       else
-	 ipbuf = st.cbInQue;
+       ipbuf = st.cbInQue;
        break;
      case TIOCGWINSZ:
        ((struct winsize *) buf)->ws_row = 0;
diff --git a/winsup/cygwin/release/3.1.5 b/winsup/cygwin/release/3.1.5
index e34fdb8..e567ecb 100644
--- a/winsup/cygwin/release/3.1.5
+++ b/winsup/cygwin/release/3.1.5
@@ -9,3 +9,6 @@ Bug Fixes:
 - Fix a segfault when starting, e.g., mintty from a bash in a console
   running xterm emulation.
   Addresses: https://cygwin.com/ml/cygwin/2020-02/msg00197.html
+
+- Fix TIOCINQ to always return number of inbound chars if available.
+  Addresses: https://cygwin.com/ml/cygwin/2020-02/msg00258.html