Previously, though readahead buffer handling in pty master was not
fully thread-safe, accept_input() was called from peek_pipe() thread
in select.cc. This caused the problem reported in:
https://cygwin.com/pipermail/cygwin/2023-July/253984.html
The mechanism of the problem is:
1) accept_input() which is called from peek_pipe() thread calls
eat_readahead(-1) before reading readahead buffer. This allows
writing to the readahead buffer from another (main) thread.
2) The main thread calls fhandler_pty_master::write() just after
eat_readahead(-1) was called and before reading the readahead
buffer by accept_input() called from peek_pipe() thread. This
overwrites the readahead buffer.
3) The read result from readahead buffer which was overwritten is
sent to the slave.
This patch makes readahead buffer handling fully thread-safe using
input_mutex to resolve this issue.
Fixes: 7b03b0d8ce ("select.cc (peek_pipe): Call flush_to_slave whenever we're checking for a pty master.")
Reported-by: Thomas Wolff <towo@towo.net>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
While st_rdev returned by fstat() for /dev/tty should be FH_TTY,
the current cygwin1.dll returns FH_PTYS+minor or FH_CONS+minor.
Similarly, fstat() does not return correct value for /dev/console,
/dev/conout, /dev/conin or /dev/ptmx.
This patch fixes the issue by:
1) Introduce dev_referred_via in fhandler_termios.
2) Add new argument, which has dev_t value referred by open(),
for constructors of fhandler_pty_slave and fhandler_pty_master to
set the value of dev_referred_via.
3) Set st_rdev using dev_referred_via in fhandler_termios::fstat()
if it is available.
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
This patch replaces ctty constants with more descriptive macros
(CTTY_UNINITIALIZED and CTTY_RELEASED) rather than -1 and -2 as
well as checking sign with CTTY_IS_VALID().
Fixes: 3b7df69aaa (Cygwin: ctty: Add comments for the special values: -1 and -2.)
Suggested-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Previously, SNDCTL_DSP_SETFRAGMENT was just a fake. In this patch,
it has been implemented to allow latency control in some apps.
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
fhandler_dev_dsp (OSS) has a problem that waitforallsent(), which is
called from close(), falls into infinite loop if another thread calls
write() accidentally after close(). This patch fixes the issue.
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Previously, fhandler_dev_dsp (OSS) has a problem that fcntl() does
not take effect at all. This patch fixes the issue.
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Previously, the console device could not be accessed from other terminals.
Due to this limitation, GNU screen and tmux cannot be opened in console.
With this patch, console device can be accessed from other TTYs, such as
other consoles or ptys. Thanks to this patch, screen and tmux get working
in console.
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
Only required for Windows 7.
This in turn allows to drop the helper_pid and related
methods from fhandler_pty_common.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Only required for Windows 7.
This allows to remove fhandler_pipe::get_query_hdl_per_system(),
too.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
- The codes related to pty and console in spawn.cc have been moved
into the new class fhandler_termios::spawn_worker, and make spawn.cc
call them. The functionality has not been changed at all.
According to POSIX and the Linux man page, select(2) is supposed to
report read ready if a file is at EOF. In the case of a FIFO, this
means that the pipe is empty and there are no writers. But there
seems to be an undocumented exception, observed on Linux and other
platforms: If no writer has ever been opened, then select(2) does not
report read ready. This can happen if a reader is opened with
O_NONBLOCK before any writers have opened.
This commit makes Cygwin consistent with those other platforms by
introducing a special EOF test, fhandler_fifo::select_hit_eof, which
returns false if there's never been a writer opened.
To implement this we use a new variable '_writer_opened' in the FIFO's
shared memory, which is set to 1 the first time a writer opens. New
methods writer_opened() and set_writer_opened() are used to test and
set this variable.
Addresses: https://cygwin.com/pipermail/cygwin/2022-September/252223.html
Takashi Yano
Corinna Vinschen
Ken Brown