- As mentioned in commit message of the commit b531d6b0, if multiple
writers including non-cygwin app exist, the non-cygwin app cannot
detect pipe closure on the read side when the pipe is created by
system account or the the pipe creator is running as service.
This is because query_hdl which is held in write side also is a
read end of the pipe, so the pipe is still alive for the non-cygwin
app even after the reader is closed.
To avoid this problem, this patch lets all processes in the same
process group close query_hdl using newly introduced internal signal
__SIGNONCYGCHLD when non-cygwin app is started.
Addresses: https://cygwin.com/pipermail/cygwin/2022-March/251097.html
- After the commit "Cygwin: pty, console: Fix handle leak which
occurs on exec() error.", startxwin cannot start X due to the
error "Failed to activate virtual core keyboard: 2". The problem
is access violation in the code retrieving the pgid of the ctty.
This patch fixes the issue.
Addresses: https://cygwin.com/pipermail/cygwin/2022-March/251013.html
- The recent commit "Cygwin: pinfo: Fix exit code when non-cygwin app
exits by Ctrl-C." did not fix enough the issue. If a non-cygwin app
is reading the console, it will not return STATUS_CONTROL_C_EXIT
even if it is terminated by Ctrl-C. As a result, the previous patch
does not take effect.
This patch solves this issue by setting sigExeced to SIGINT in
ctrl_c_handler(). In addition, sigExeced will be cleared if the app
does not terminated within predetermined time period. The reason is
that the app does not seem to be terminated by the signal sigExeced.
- This patch fixes the handle leak which occurs when exec() fails
with an error. The duplicated handles will be closed when the
exec'ed process is terminated. However, if exec() fails, the code
path does not reach to the code closing the duplicated handles.
To implement this fix more appropriately, the setup, cleanup and
closing pty codes which was previously located in spawn.cc are
encapsulated into the fhandler_pty_slave class functions.
- With this patch, all set_(in|out)put_mode() calls are rearranged
as follows.
1) Setup for cygwin apps, started from non-cygwin app, is done
in fhandler_console::post_open_setup(), which overrides
fhandler_base::post_open_setup() called from dtable.cc.
2) Cleanup for cygwin app is done in fhandler_console::close().
3) Setup for cygwin apps is also in fhandler_console::bg_check(),
which overrides fhandler_termios::bg_check(). This is called
on read(), write() and select() for console. It is necessary
if cygwin and non-cygwin apps are started simultaneously in
the same process group.
4) Setup for non-cygwin apps is done in spawn.cc via
fhandler_console::setup_console_for_non_cygwin_app().
5) Cleanup for non-cygwin app is done in spawn.cc vid
fhandler_console::cleanup_console_for_non_cygwin_app().
6) Setup for non-cygwin app started by GDB is done in
fhandler_console::set_console_mode_to_native().
7) No explicit cleanup for non-cygwin app started by GDB, because
console mode is automatically reset to tty::cygwin on read()/
write() in GDB thanks to 3).
- When non-cygwin app is started in console, console mode is set to
tty::native. However, if stdin is redirected, current code does not
set the input mode of the console. In this case, if the app opens
"CONIN$", the console mode will not be appropriate for non-cygwin
app. This patch fixes the issue.
Addresses:
https://github.com/GitCredentialManager/git-credential-manager/issues/576
- GDB inferior may be suspended while the inferior grabs mutex.
This causes deadlock in terminal I/O. With this patch, timeout
for waiting mutex is set to 0 for the debugger process when the
process calls CreateProcess() with DEBUG_PROCESS flag to avoid
deadlock. This may cause the race issue in GDB, however, there
is no other way than that.
Addresses:
https://cygwin.com/pipermail/cygwin-developers/2021-December/012542.html
- The recent commit: "Cygwin: pty: Fix Ctrl-C handling for non-cygwin
apps in background." causes the problem that cmd.exe is terminated
by Ctrl-C even if it is running in pseudo console. This patch fixes
the issue.
- Usually WriteQuotaAvailable retrieved by NtQueryInformationFile()
on the write side reflects the space available in the inbound buffer
on the read side. However, if a pipe read is currently pending,
WriteQuotaAvailable on the write side is decremented by the number
of bytes the read side is requesting. So it's possible (even likely)
that WriteQuotaAvailable is 0, even if the inbound buffer on the
read side is not full. This can lead to a deadlock situation:
The reader is waiting for data, but select on the writer side
assumes that no space is available in the read side inbound buffer.
Currently, to avoid this stuation, read() does not request larger
block than pipe size - 1. However, this mechanism does not take
effect if the reader side is non-cygwin app.
The only reliable information is available on the read side, so
fetch info from the read side via the pipe-specific query handle
(query_hdl) introduced.
If the query_hdl (read handle) is kept in write side, writer can
not detect closure of read pipe. Therefore, raw_write() counts
write handle and query_hdl. If they are equal, only the pairs of
write handle and query_hdl are alive. In this case, raw_write()
returns EPIPE and raises SIGPIPE.
- Nonblocking pipes (PIPE_NOWAIT) are not well handled by non-Cygwin
tools, so convert pipe handles to PIPE_WAIT handles when spawning
a non-Cygwin process.
- Currently, functions/variables regarding the handles for cygwin
apps are with "_cyg", and those of handles for non-cygwin apps
are without "_cyg", such as get_handle_cyg() and get_handle().
This patch renames these to the names without "_nat" and with
"_nat" respectively, such as get_handle() and get_handle_nat().
The Windows Store version of Python (and apparently other Windows Store
applications) install a special reparse point called "app execution
alias" into the user's `PATH`.
These applications can be executed without any problem, but they cannot
be read as if they were files. This trips up Cygwin's beautiful logic that
tries to determine whether we're about to execute a Cygwin executable or
not: instead of executing the application, it will fail, saying
"Permission denied".
Let's detect this situation (`NtOpenFile()` helpfully says that this
operation is not supported on this reparse point type), and simply skip
the logic: Windows Store apps are not Cygwin executables (and even if
they were, it is unlikely that they would come with a compatible
`cygwin1.dll` or `msys-2.0.dll`).
This fixes https://github.com/msys2/MSYS2-packages/issues/1943
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
- If ENABLE_LINE_INPUT is set, Ctrl-S is handled by Windows if the
OS is Windows 7. This conflicts with Ctrl-S handling in cygwin
console code. This patch unsets ENABLE_LINE_INPUT flag in cygwin
and set it when native app is executed.
- Currently, input transfer is performed every time one line is read(),
if the non-cygwin app is running in the background. With this patch,
transfer is triggered by setpgid() rather than read() so that the
unnecessary input transfer can be reduced much in that situation.
- After commit bb428520, there has been the disadvantage:
7) Pseudo console cannot be activated if it is already activated for
another process on same pty.
This patch clears this disadvantage.
- After commit bb428520, there has been the disadvantage:
2) The apps which use console API cannot be debugged with gdb. This
is because pseudo console is not activated since gdb uses
CreateProcess() rather than exec(). Even with this limitation,
attaching gdb to native app, in which pseudo console is already
activated, works.
This patch clears this disadvantage.
- PTY has a problem that the key input, which is typed during windows
native app is running, disappears when it returns to shell. This is
beacuse pty has two input pipes, one is for cygwin apps and the other
one is for native windows apps. The key input during windows native
program is running is sent to the second input pipe while cygwin
shell reads input from the first input pipe. This issue had been
fixed once by commit 29431fcb, however, the new implementation of
pseudo console support by commit bb428520 could not inherit this
feature. This patch realize transfering input data between these
two pipes bidirectionally by utilizing cygwin-console-helper process.
The helper process is launched prior to starting the non-cygwin app,
however, exits immediately unlike previous implementation.
- After commit 232fde0e, pty changes console code page when the first
non-cygwin app is executed. If pty is started in real console device,
pty changes the code page of root console. This causes very annoying
result because changing code page changes the font of command prompt
if console is in legacy mode. This patch avoids this by creating a
new invisible console for the first pty started in console device.
- The function close_pseudoconsole() should be static so that it
can be safely called in spawn.cc even after the fhandler_pty_slave
instance has been deleted. That is, there is a problem with the
current code. This patch fixes the issue.
- If application changes the console mode, mode management introduced
by commit 10d8c278 will be corrupted. For example, stdout of jansi
v2.0.1 or later is piped to less, jansi resets the xterm mode flag
ENABLE_VIRTUAL_TERMINA_PROCESSING when jansi is terminated. This
causes garbled output in less because less needs this flag enabled.
This patch fixes the issue.
- Pseudo console internally sends escape sequence CSI6n (query cursor
position) on startup of non-cygwin apps. If the terminal does not
support CSI6n, CreateProcess() hangs waiting for response. To prevent
hang, this patch disables pseudo console if the terminal does not
have CSI6n. This is checked on the first execution of non-cygwin
app using the following steps.
1) Check if the terminal support ANSI escape sequences by looking
into terminfo database. If terminfo has cursor_home (ESC [H),
the terminal is supposed to support ANSI escape sequences.
2) If the terminal supports ANSI escape sequneces, send CSI6n for
a test and wait for a responce for 40ms.
3) If there is a responce within 40ms, CSI6n is supposed to be
supported.
Also set-title capability is checked, and removes escape sequence
for setting window title if the terminal does not have the set-
title capability.
pinfo::remember with the detach parameter set to true is
the only way to call proc_subproc with PROC_DETACHED_CHILD.
This call is exclusively used in spawn to set up a pinfo for
a detached child, and that pinfo goes out of scope right
afterwards without any further action.
Drop the flag and drop the detach parameter from pinfo::remember.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
After patch 23a779bf3d
"Cygwin: pinfo: stop remember doing reattach",
PROC_ADDCHILD actually just sets up a new child, mirroring
PROC_DETACHED_CHILD. The actual attaching of the child is
performed by action PROC_REATTACH_CHILD or pinfo::reattach
respectively.
To better reflect what's going on, rename PROC_REATTACH_CHILD
to PROC_ATTACH_CHILD and rename pinfo::reattach to pinfo::attach.
For better readability change PROC_ADDCHILD to PROC_ADD_CHILD.
Fix comments accordingly.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
- In this implementation, pseudo console is created for each native
console app. Advantages and disadvantages of this implementation
over the previous implementation are as follows.
Advantages:
1) No performance degradation in pty output for cygwin process.
https://cygwin.com/pipermail/cygwin/2020-February/243858.html
2) Free from the problem caused by difference of behaviour of control
sequences between real terminal and pseudo console.
https://cygwin.com/pipermail/cygwin/2019-December/243281.htmlhttps://cygwin.com/pipermail/cygwin/2020-February/243855.html
3) Free from the problem in cgdb and emacs gud.
https://cygwin.com/pipermail/cygwin/2020-January/243601.htmlhttps://cygwin.com/pipermail/cygwin/2020-March/244146.html
4) Redrawing screen on executing native console apps is not necessary.
5) cygwin-console-helper is not necessary for the pseudo console
support.
6) The codes for pseudo console support are much simpler than that
of the previous one.
Disadvantages:
1) The cygwin program which calls console API directly does not work.
2) The apps which use console API cannot be debugged with gdb. This
is because pseudo console is not activated since gdb uses
CreateProcess() rather than exec(). Even with this limitation,
attaching gdb to native apps, in which pseudo console is already
activated, works.
3) Typeahead key inputs are discarded while native console app is
executed. Simirally, typeahead key inputs while cygwin app is
executed are not inherited to native console app.
4) Code page cannot be changed by chcp.com. Acctually, chcp works
itself and changes code page of its own pseudo console. However,
since pseudo console is recreated for another process, it cannot
inherit the code page.
5) system_printf() does not work after stderr is closed. (Same with
cygwin 3.0.7)
6) Startup time of native console apps is about 3 times slower than
previous implemenation.
7) Pseudo console cannot be activated if it is already activated for
another process on same pty.
- After commit 095972ce5b, charset
conversion in mintty is broken if charset is set to other than
UTF-8. This seems to be caused because mintty does not set locale
yet at fork() call. This patch changes the timing of set_locale()
call again to avoid this issue.
- If a lot of mintty are started in a short time from a mintty, some
of them hang with empty screen, crash immediately or hang on exiting
mintty. The following report seems to be related to this issue.
https://cygwin.com/pipermail/cygwin/2020-August/245751.html
The cause is not clear at all, but this patch seems to solve the
issue.
Newlib's posix_spawn has been taken from FreeBSD. The code relies on
BSD-specific behaviour of vfork, namely the fact that vfork blocks
the parent until the child exits or calls execve as well as the fact
that the child shares parent memory in non-COW mode.
This behaviour can't be emulated by Cygwin. Cygwin's vfork is
equivalent to fork. This is POSIX-compliant, but it's lacking BSD's
vfork ingrained synchronization of the parent to wait for the child
calling execve, or the chance to just write a variable and the parent
will see the result.
So this requires a Cygwin-specific solution. The core function of
posix_spawn, called do_posix_spawn is now implemented twice, once using
the BSD method, and once for Cygwin using Windows synchronization under
the hood waiting for the child to call execve and signalling errors
upstream. The Windows specifics are hidden inside Cygwin, so newlib
only calls internal Cygwin functions.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
- If two cygwin programs are executed simultaneousley with pipes
in cmd.exe, xterm compatible mode is accidentally disabled by
the process which ends first. After that, escape sequences are
not handled correctly in the other app. This is the problem 2
reported in https://cygwin.com/ml/cygwin/2020-02/msg00116.html.
This patch fixes the issue. This patch also fixes the problem 3.
For these issues, the timing of setting and unsetting xterm
compatible mode is changed. For read, xterm compatible mode is
enabled only within read() or select() functions. For write, it
is enabled every time write() is called, and restored on close().
- In octave gui, sometimes state mismatch between real pty state
and state variable occurs. For example, this occurs when 'ls'
command is executed in octave gui. This patch fixes the issue.
- After commit e1a0775dc0, the problem
reported in https://www.cygwin.com/ml/cygwin/2020-01/msg00093.html
occurs. For Gnu scren and tmux, calling FreeConsole() on pty close
is necessary. However, if FreeConsole() is called, cygwin setup
with '-h' option does not work. Therefore, the commit
e1a0775dc0 delayed closing pty.
This is the cause of the problem above. Now, instead of delaying
pty close, FreeConsole() is not called if the process is non cygwin
processes such as cygwin setup.
- Special function keys such as arrow keys or function keys do not
work in ConEmu with cygwin-connector after commit
6a06c6bc8f. This patch fixes the
issue.
Call find_exec with the FE_NNF flag to enforce a NULL return when the
executable isn't found in $PATH. Convert NULL to "". This aligns
spawnvp and spawnvpe with execvp and execvpe.
- Previously, input and output pipes were switched together between
the traditional pty and the pseudo console. However, for example,
if stdin is redirected to another device, it is better to leave
input pipe traditional pty side even for non-cygwin program. This
patch realizes such behaviour.
- When the I/O pipe is switched to the pseudo console side, the
behaviour of Ctrl-C was unstable. This rarely happens, however,
for example, shell sometimes crashes by Ctrl-C in that situation.
Furthermore, Ctrl-C was ignored if output of non-cygwin program
is redirected to pipe. This patch fixes these issues.
- Pseudo console support introduced by commit
169d65a577 sometimes cause random
crash or freeze by pressing ^C while cygwin and non-cygwin
processes are executed simultaneously in the same pty. This
patch is a workaround for this issue.
- Pseudo console support introduced by commit
169d65a577 has some bugs which
cause mismatch between state variables and real pseudo console
state regarding console attaching and r/w pipe switching. This
patch fixes this issue by redesigning the state management.
- Support pseudo console in PTY. Pseudo console is a new feature
in Windows 10 1809, which provides console APIs on virtual
terminal. With this patch, native console applications can work
in PTYs such as mintty, ssh, gnu screen or tmux.
When the exec family of functions is called for a script-like
file, the av::setup function handles the exec[vl]p case as
well. The execve case for files not starting with a she-bang
is handled first by returning ENOEXEC. Only after that, the
file's executability is checked.
This leads to the problem that ENOEXEC is returned for non-executable
files as well. A calling shell interprets this as a file it should try
to run as script. This is not desired for non-executable files.
Fix this problem by checking the file for executability first. Only
after that, follow the other potential code paths.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
During fork, the child process requires the process table to be
initialized for fixup_shms_after_fork, while still allowing subsequent
dlls.load_after_fork to fail silently (for when the "forkable" hardlinks
are not created yet).
pinfo::remember not performing reattach anymore requires explicit
pinfo::reattach now where appropriate.
Prepares to improve "Cygwin: fork: Remember child not before success."
commit f03ea8e1c5, which leads to fork
problems if cygserver is running:
https://cygwin.com/ml/cygwin-patches/2019-q2/msg00155.html
Takashi Yano
Johannes Schindelin
Takashi Yano via Cygwin-patches
Corinna Vinschen
Ken Brown
Michael Haubenwallner