[PATCH v2 0/2] Make terminal read() thread-safe.

[PATCH v2 0/2] Make terminal read() thread-safe.

[Takashi Yano]

Currently read() for console and pty slave are somehow
not thread-safe. These patches fix the issue.

Takashi Yano (2):
  Cygwin: console: Make read() thread-safe.
  Cygwin: pty: Make slave read() thread-safe.

 winsup/cygwin/fhandler_console.cc | 10 +++++-----
 winsup/cygwin/fhandler_tty.cc     |  6 ++++++
 2 files changed, 11 insertions(+), 5 deletions(-)

-- 
2.30.0

[PATCH v2 1/2] Cygwin: console: Make read() thread-safe.

[Takashi Yano]

- Currently read() is somehow not thread-safe. This patch fixes the
  issue.
---
 winsup/cygwin/fhandler_console.cc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/winsup/cygwin/fhandler_console.cc b/winsup/cygwin/fhandler_console.cc
index 02d0ac052..d0e5bb33a 100644
--- a/winsup/cygwin/fhandler_console.cc
+++ b/winsup/cygwin/fhandler_console.cc
@@ -530,12 +530,14 @@ fhandler_console::read (void *pv, size_t& buflen)
   if (wincap.has_con_24bit_colors ())
     request_xterm_mode_input (true, &handle_set);
 
+  acquire_input_mutex (INFINITE);
   while (!input_ready && !get_cons_readahead_valid ())
     {
       int bgres;
       if ((bgres = bg_check (SIGTTIN)) <= bg_eof)
 	{
 	  buflen = bgres;
+	  release_input_mutex ();
 	  return;
 	}
 
@@ -552,6 +554,7 @@ wait_retry:
 	  pthread::static_cancel_self ();
 	  /*NOTREACHED*/
 	case WAIT_TIMEOUT:
+	  release_input_mutex ();
 	  set_sig_errno (EAGAIN);
 	  buflen = (size_t) -1;
 	  return;
@@ -572,9 +575,7 @@ wait_retry:
 
       int ret;
       acquire_attach_mutex (INFINITE);
-      acquire_input_mutex (INFINITE);
       ret = process_input_message ();
-      release_input_mutex ();
       release_attach_mutex ();
       switch (ret)
 	{
@@ -595,7 +596,6 @@ wait_retry:
     }
 
   /* Check console read-ahead buffer filled from terminal requests */
-  acquire_input_mutex (INFINITE);
   while (con.cons_rapoi && *con.cons_rapoi && buflen)
     {
       buf[copied_chars++] = *con.cons_rapoi++;
@@ -615,11 +615,13 @@ wait_retry:
   return;
 
 err:
+  release_input_mutex ();
   __seterrno ();
   buflen = (size_t) -1;
   return;
 
 sig_exit:
+  release_input_mutex ();
   set_sig_errno (EINTR);
   buflen = (size_t) -1;
 }
@@ -984,9 +986,7 @@ fhandler_console::process_input_message (void)
       if (toadd)
 	{
 	  ssize_t ret;
-	  release_input_mutex ();
 	  line_edit_status res = line_edit (toadd, nread, *ti, &ret);
-	  acquire_input_mutex (INFINITE);
 	  if (res == line_edit_signalled)
 	    {
 	      stat = input_signalled;
-- 
2.30.0

[PATCH v2 2/2] Cygwin: pty: Make slave read() thread-safe.

[Takashi Yano]

- Currently slave read() is somehow not thread-safe. This patch
  fixes the issue.
---
 winsup/cygwin/fhandler_tty.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 06fc19ac2..48b89ae77 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -1241,6 +1241,7 @@ fhandler_pty_slave::read (void *ptr, size_t& len)
 	time_to_wait = !vtime ? INFINITE : 100 * vtime;
     }
 
+wait_retry:
   while (len)
     {
       switch (cygwait (input_available_event, time_to_wait))
@@ -1319,6 +1320,11 @@ fhandler_pty_slave::read (void *ptr, size_t& len)
 	    }
 	  goto out;
 	}
+      if (!IsEventSignalled (input_available_event))
+	{ /* Maybe another thread has processed input. */
+	  ReleaseMutex (input_mutex);
+	  goto wait_retry;
+	}
 
       if (!bytes_available (bytes_in_pipe))
 	{
-- 
2.30.0

Re: [PATCH v2 1/2] Cygwin: console: Make read() thread-safe.

[Takashi Yano]

On Thu, 28 Jan 2021 21:20:09 +0900
Takashi Yano wrote:
> - Currently read() is somehow not thread-safe. This patch fixes the
>   issue.
> ---
>  winsup/cygwin/fhandler_console.cc | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

Sorry again. This also has a problem......

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>