- Previously, the command "cmd /c script -c cmd" in console of Win7
crashes. This seems to be due to a bug (?) of AttachConsole().
This patch adds workaround for this issue.
Currently, pty reattaches to the console of the process which is
predetermined by ConsoleProcessList() after temporarily attaching
to another console. After that, the console output handle opened
with the name "CONOUT$" may not be accessible in Win7.
This seems to happen when the attached process does not have the
same handle even if the console attached is the same. With this
patch, cygwin-console-helper which is started when pty master is
opened in console, is utilized to be a target process to which
pty reattaches if the OS is Win7.
- 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
- Previously, reset_switch_to_nat_pipe() is called from many places
in pty code. This patch reorganizes that. With this patch, it is
called only from bg_check() and setpgid_aux(). The calls which
does not have enough reason have been omitted.
- This patch communalizes the code for attaching another console
temporarily and resuming to the original attach state, because
there were a plurality of similar codes throughout.
- This patch revises the acquiring/releasing timing for attach_mutex
to make the period in which it is being acquired shorter. Further,
acquiring/releasing are added to where they are missing but needed.
- With this patch, some pty functions/variables have been renamed
so that the name *pcon* is not used for those that are called
even when the pseudo console is not active.
- When Ctrl-C terminates a non-cygwin process on a pseudo console,
pty master attaches to the pseudo console first, and send
CTRL_C_EVENT. If the non-cygwin process closes the pseudo console
before the pty master calls FreeConsole(), the pty master process
will crash. With this patch, pty master process takes over the
ownership of the pseudo console, and closes it by myself.
- The commit "Cygwin: console: Redesign handling of special keys."
removes special treatment for pty in with pseudo console activated,
however, it is necessary on second thought. This is because sending
CTRL_C_EVENT to non-cygwin apps will be done in pseudo console,
therefore, sending it in fhandler_pty_master::write() duplicates
that event for non-cygwin apps.
- After some recent changes for special keys handling break the
apps which open pty (such as script command). If the app which
opens pty is executed in console, the following issues occur.
1) If the script command was started from non-cygwin shell
(such as cmd.exe), another cygwin app started in pty slave
cannot receive Ctrl-C.
2) If non-cygwin app is executed in pty slave, the app which
opened the pty (e.g. script command) crashes by Ctrl-C.
This patch fixes these issues.
- The inferior of the GDB cannot be continued after SIGINT even
though nopass option is set. This seems because cygwin GDB does
not support hooking cygwin signal. Therefore, a workaround for
GDB is added. With this patch, only CTRL_C_EVENT is sent to the
GDB inferior by Ctrl-C and sending SIGINT is omitted. Note that
"handle SIGINT (no)pass" command does not take effect even with
or without this patch.
- This patch rearranges the cooperation between cons_master_thread,
line_edit, and ctrl_c_handler so that only one of them operates
at the same time. Since these handle Ctrl-C individually, so the
signal may be sent multiple times to the process. This patch fixes
the issue.
Bash has a very convenient feature that is called process substitution
(e.g. `diff -u <(seq 0 10) <(seq 1 11)`). To make this work, Bash
requires the `/dev/fd` symlink to exist, and Cygwin therefore creates
this symlink (together with the `stdin`, `stdout` and `stderr` ones)
upon start-up.
This strategy is incompatible with the idea of providing a subset of
Cygwin in a `.zip` file (because there is no standard way to represent
symlinks in `.zip` files, and besides, older Windows versions would
potentially lack support for them anyway).
That type of `.zip` file is what Git for Windows wants to use, though,
bundling a minimal subset for third-party applications in MinGit (see
https://github.com/git-for-windows/git/wiki/MinGit for details).
Let's side-step this problem completely by creating those symlinks
implicitly, similar to the way `/dev/` is populated with special
devices.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
- 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).
- This patch commonize the code which processes special keys in pty
and console to improve maintanancibility. As a result, some small
bugs have been fixed.
- Currently, there is no chance to change console mode for non-cygwin
inferior of GDB. With this patch, the console mode is changed to
tty::native in CreateProcess() and ContinueDebugEvent() hooked in
fhandler_console.
- Closing attach_mutex and recreating it causes the race issue
between pty and console codes. With this patch, attach_mutex
is created only once in a process which opens pty, and never
closed in order to avoid this issue.
Addresses:
https://cygwin.com/pipermail/cygwin-developers/2021-December/012548.html
- The recent commit "Cygwin: pty: Add missing input transfer when
switch_to_pcon_in state." causes regression that rlwrap cannot
work with cmd.exe. This patch fixes the issue.
i. e., Vista/2008.
AllocConsole appears to allow creating a console only on the currently
visible desktop since Windows 7, which broke the simple code opening
the console on an invisible desktop in an invisible window station.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
- The commit b531d6b0 introduced temporary_query_hdl() which uses
SystemHandleInformation. With this patch, ProcessHandleInformation
rather than SystemHandleInformation is used if it is available.
This request is faster, however, is only available since Windows 8,
therefore, SystemHandleInformation is used for Windows Vista and 7
as before.
- The commit f79a4611 introduced query_hdl, which is the read pipe
handle kept in the write pipe instance in order to determine if
the pipe is ready to write in select(). This implementation has
a potential risk that the write side fails to detect the closure
of the read side if more than one writer exists and one of them
is a non-cygwin process.
With this patch, the strategy of commit f79a4611 is used only if
the process is running as a service. For a normal process,
instead of keeping query_hdl in the write pipe instance, it is
retrieved temporarily when select() is called. Actually, we
want to use tenporary query_hdl for all processes, however, it
does not work for service processes due to OpenProcess()
failure.
- query_hdl and hdl_cnt_mtx are moved from fhandler_pipe_fifo to
fhandler_pipe. Then reader_closed() is changed to virtual and
overridden in fhandler_pipe.
- This patch fixes the race issue in the handle counting to detect
closure of read pipe, which is introduced by commit f79a4611.
A mutex hdl_cnt_mtx is introduced for this issue.
- Currently, raw_read(), raw_write() and close() release select_sem
unconditionally even if no waiter for select_sem exists. With this
patch, only the minimum number of semaphores required is released.
- 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.
Rename fhandler_pipe_and_fifo::max_atomic_write to pipe_buf_size.
This reflect its actual meaning better. The fhandler_pipe_and_fifo
constructor initializes it to DEFAULT_PIPEBUFSIZE (== 64K), which is
the buffer size for the windows pipes created by fhandler_pipe and
fhandler_fifo. But if we inherit a stdio pipe handle from a
non-Cygwin process, the buffer size could be different.
To remedy this, add a method fhandler_pipe::set_pipe_buf_size that
queries the OS for the pipe buffer size, and use it in
dtable::init_std_file_from_handle.
This is a parent of fhandler_pipe and fhandler_fifo for code that is
common between the two classes. Currently it just contains
max_atomic_write and raw_write(). The latter is identical to what
used to be fhandler_pipe::raw_write().
FILE_PIPE_LOCAL_INFORMATION::WriteQuotaAvailable is unreliable.
Usually WriteQuotaAvailable 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.
This patch implements a workaround by never trying to read more than
half the buffer size blocking if the read buffer is empty. This first
cut tries to take the number of open readers into account by reducing
the amount of requested bytes accordingly.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
The read handles of pipes created by CreateNamedPipe don't have
FILE_WRITE_ATTRIBUTES access unless the pipe is created with
PIPE_ACCESS_DUPLEX. This causes set_pipe_non_blocking to fail on such
handles. To fix this, add a helper function nt_create, which uses
NtCreateNamedPipeFile instead of CreateNamedPipe and gives us more
flexibility in setting access rights.
Use this helper function in fhandler_pipe::create (fhandler_pipe *[2],
unsigned, int), which is the version of fhandler_pipe::create used by
the pipe and pipe2 system calls.
For convenience, also add a static member function
fhandler_pipe::npfs_handle similar to those used by fhandler_fifo and
fhandler_socket_unix.
Add methods 'set_pipe_non_blocking' and 'fcntl' to keep the blocking
mode of the Windows pipe in sync with that of the fhandler_pipe
object. This applies to pipes created with the 'pipe' and 'pipe2'
system calls.
Previously fhandler_pipe was derived from fhandler_base_overlapped,
which we are going to remove in a future commit. Make minimal changes
so that the build still succeeds.
Ken Brown
Takashi Yano
Johannes Schindelin
Corinna Vinschen