As Gareth McMullin <gareth@blacksphere.co.nz> reports at
<https://sourceware.org/ml/gdb-patches/2017-02/msg00560.html>, the
timeout mechanism in ser-unix.c was broken by commit 048094acc
("target remote: Don't rely on immediate_quit (introduce quit
handlers)").
Instead of applying a local fix, and since we now finally always use
interrupt_select [1], let's get rid of hardwire_readchar entirely, and
use ser_base_readchar instead, which has similar timeout handling,
except for the bug.
Smoke tested with:
$ socat -d -d pty,raw,echo=0 pty,raw,echo=0
2017/03/14 14:08:13 socat[4994] N PTY is /dev/pts/14
2017/03/14 14:08:13 socat[4994] N PTY is /dev/pts/15
2017/03/14 14:08:13 socat[4994] N starting data transfer loop with FDs [3,3] and [5,5]
$ gdbserver /dev/pts/14 PROG
$ gdb PROG -ex "tar rem /dev/pts/15"
and then a few continues/ctrl-c's, plus killing gdbserver and socat.
[1] - See FIXME comments being removed.
gdb/ChangeLog:
2017-03-17 Pedro Alves <palves@redhat.com>
PR remote/21188
* ser-base.c (ser_base_wait_for): Add comment.
(do_ser_base_readchar): Improve comment based on the ser-unix.c's
version.
* ser-unix.c (hardwire_raw): Remove reference to
scb->current_timeout.
(wait_for, do_hardwire_readchar, hardwire_readchar): Delete.
(hardwire_ops): Install ser_base_readchar instead of
hardwire_readchar.
* serial.h (struct serial) <current_timeout, timeout_remaining>:
Remove fields.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This patch adds a new "event" struct serial type, that is an
abstraction specifically for waking up blocking waits/selects,
implemented on top of a pipe on POSIX, and on top of a native Windows
event (CreateEvent, etc.) on Windows.
This will be used to plug signal handler / mainline code races.
For example, GDB can indefinitely delay handling a quit request if the
user presses Ctrl-C between the last QUIT call and the next (blocking)
gdb_select call in the event loop:
QUIT;
<<< press ctrl-c here and end up blocked in gdb_select
indefinitely.
gdb_select (...); // whoops, SIGINT was already handled, no EINTR.
A global alone (either the quit flag, or the "ready" flag of the async
signal handlers in the event loop) is not sufficient.
To plug races such as these on POSIX systems, we have to register some
waitable file descriptor in the set of files gdb_select waits on, and
write to it from the signal handler. This is classically a pipe, and
the pattern called the self-pipe trick. On Linux, it could be a more
efficient eventfd instead, but I'm sticking with a pipe for
simplifity, as we need it for portability anyway.
(Alternatively, we could use pselect/ppoll, and block signals until
the pselect. The latter is not a design I think GDB could use,
because we want the QUIT macro to be super cheap, as it is used in
loops. Plus, Windows.)
This is a "struct serial" because Windows's gdb_select relies on that.
Windows's gdb_select, our "select" replacement, knows how to wait on
all kinds of handles (regular files, pipes, sockets, console, etc.)
unlike the native Windows "select" function, which can only wait on
sockets. Each file descriptor for a "serial" type that is not
normally waitable with WaitForMultipleObjects must have a
corresponding struct serial instance. gdb_select then internally
looks up the struct serial instance that wraps each file descriptor,
and asks it for the corresponding Windows waitable handle.
We could use serial_pipe() to create a "struct serial"-wrapped pipe
that is usable everywhere, including Windows. That's what currently
python/python.c uses for cross-thread posting of events.
However, serial_write and serial_readchar are not designed to be
async-signal-safe on POSIX hosts. It's easier to bypass those when
setting/clearing the event source.
And writing and a serial pipe is a bit heavy weight on Windows.
gdb_select requires an extra thread to wait on the pipe and several
Windows events, when a single manual-reset Windows event, with no
extra thread is sufficient.
The intended usage is simply:
- Call make_serial_event to create a serial event object.
- From the signal handler call serial_event_set to set the event.
- From mainline code, have select/poll wait for serial_event_fd(), in
addition to whatever other files you're about to wait for.
gdb/ChangeLog:
2016-04-12 Pedro Alves <palves@redhat.com>
* Makefile.in (SFILES): Add ser-event.c.
(HFILES_NO_SRCDIR): Add ser-event.h.
(COMMON_OBS): Add ser-event.o.
* ser-event.c, ser-event.h: New files.
* serial.c (new_serial): New function, factored out from
(serial_fdopen_ops): ... this.
(serial_open_ops_1): New function, factored out from
(serial_open): ... this.
(serial_open_ops): New function.
* serial.h (struct serial): Forware declare.
(serial_open_ops): New declaration.
Not used by anything.
gdb/ChangeLog:
2016-04-12 Pedro Alves <palves@redhat.com>
* serial.c (serial_open, serial_fdopen_ops, do_serial_close):
Remove references to name.
* serial.h (struct serial) <name>: Delete.
The "set serial parity" command allows the user to control which
parity to use when communicating over a serial connection, rather
than having the parity hardcoded to none.
gdb/ChangeLog:
* NEWS: Mention set/show serial parity command.
* monitor.c (monitor_open): Call serial_setparity.
* remote.c (remote_open_1): Likewise.
* ser-base.c (ser_base_serparity): New function.
* ser-base.h (ser_base_setparity): Add declaration.
* ser-go32.c (dos_ops): Set "setparity" field.
* ser-mingw.c (ser_windows_raw): Do not set state.fParity and
state.Parity.
(ser_windows_setparity): New function.
(hardwire_ops): Add ser_windows_setparity.
(tty_ops): Add NULL for setparity field.
(pipe_ops): Add ser_base_setparity.
(tcp_ops): Likewise.
* ser-pipe.c (pipe_ops): Likewise.
* ser-tcp.c (tcp_ops): Likewise.
* ser-unix.c (hardwire_setparity): Add declaration.
(hardwire_raw): Don't reset PARENB flag.
(hardwire_setparity): New function.
(hardwire_ops): Add hardwire_setparity.
* serial.c (serial_setparity): New function.
(serial_parity): New global.
(parity_none, parity_odd, parity_even, parity_enums, parity):
New static globals.
(set_parity): New function.
(_initialize_serial): Add set/show serial parity commands.
* serial.h (GDBPARITY_NONE): Define.
(GDBPARITY_ODD): Define.
(GDBPARITY_EVEN): Define.
(serial_setparity) Add declaration.
(struct serial_ops): Add setparity field.
* target.h (serial_parity): Add declaration.
gdb/doc/ChangeLog:
* gdb.texinfo (Remote configuration): Document "set/show
serial parity" command.
I noticed that the serial_ops vtable is not const, but really it ought
to be.
This patch constifies it, removing the only mutable field in the
process.
Tested by rebuilding on x86-64 Fedora 18, both natively and using the
mingw cross tools.
2013-12-19 Tom Tromey <tromey@redhat.com>
* serial.c (serial_ops_p): New typedef.
(serial_ops_list): Now a VEC.
(serial_interface_lookup): Return const. Use VEC_iterate.
(serial_add_interface): Make parameter const.
(serial_open): Update.
(serial_fdopen_ops): Make 'ops' const.
(serial_pipe): Update.
* ser-tcp.c (_initialize_ser_tcp): Update.
* ser-pipe.c (_initialize_ser_pipe): Update.
* ser-unix.c (_initialize_ser_hardwire): Update.
* ser-mingw.c (_initialize_ser_windows): Update.
* ser-go32.c (dos_ops): Now const. Update.
* serial.h (struct serial) <ops>: Now const.
(struct serial_ops) <next>: Remove.
(serial_add_interface): Make parameter const.
While remote.c works with "char *" buffers most of the time, other
remote targets have binary-ish-er protocols, and choose to use
"unsigned char" throughout, like e.g., remote-mips.c or
remote-m32r-sdi.c. That results in -Wpointer-sign warnings in those
targets, unless we add casts in calls to serial_write. Since
serial_write is only concerned about sending raw host bytes out, and
serial_ops->write_prim already works with "void *"/"size_t", a similar
interface to the "write" or "send" system calls, I find it natural to
change serial_write's prototype accordingly, avoiding the need for
casts.
Tested on x86_64 Fedora 17, and also by building x86_64-mingw32
and DJGPP/go32 -hosted gdbs.
gdb/
2013-04-19 Pedro Alves <palves@redhat.com>
* ser-base.c (ser_base_write): Change prototype -- take 'void *'
buffer and size_t size. Adjust.
* ser-base.h (ser_base_write): Adjust.
* ser-go32.c (cnts): Change type to size_t.
(dos_write): Change prototype -- take 'void *'
buffer and size_t size. Adjust.
(dos_info): Print elements of 'cnts' as unsigned long.
* serial.c (serial_write): Likewise.
* serial.h (serial_write): Adjust.
(struct serial_ops) <write>: Change prototype -- take 'void *'
buffer and size_t size. Adjust.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
Partial revert of previous change.
* serial.c (scb_base): New global.
(serial_for_fd): New.
(serial_open, serial_fdopen_ops): Link new serial in open serials
chain.
(do_serial_close): Unlink serial from the open serials chain.
* ser-base.c (run_async_handler_and_reschedule): New.
(fd_event, push_event): Use it.
* serial.c (serial_open, serial_fdopen_ops): Set the initial
reference count to 1.
(do_serial_close): Set the bufp field to NULL. Use serial_unref
instead of xfree.
(serial_is_open, serial_ref, serial_unref): New.
* serial.h (serial_open): Adjust comment.
(serial_is_open): Declare.
(serial_close): Adjust comment.
(serial_ref, serial_unref) Declare.
(struct serial): New field 'refcnt'.
* serial.c (serial_interface_lookup): Take a const char pointer.
(serial_fdopen): Rename to ...
(serial_fdopen_ops): ... this. Add an OPS parameter and use it.
Call the OPS' fdopen function if there is one.
(serial_fdopen): Rewrite as wrapper to serial_fdopen_ops.
(serial_pipe): New.
(struct serial_ops) <fdopen>: New field.
* ser-mingw.c (free_pipe_state):
(free_pipe_state): Close output on non-pex pipes.
(pipe_windows_fdopen): New.
(gdb_pipe): New.
(_initialize_ser_windows): Register pipe_windows_fdopen.
* ser-go32.c (gdb_pipe): New.
* ser-pipe.c (pipe_close): Close file descriptor even if there's
no state pointer.
(pipe_ops): Delete.
(gdb_pipe): New.
via gdb_stderr.
* serial.c (serial_open): Set error_fd to -1.
* serial.h (struct serial): New field error_fd.
(struct serial_opts): New field avail.
* ser-pipe.c (pipe_open): Create another pair
of sockets. Pass stderr to gdb.
* ser-mingw.c (pipe_windows_open): Pass
PEX_STDERR_TO_PIPE to pex_run. Initialize
sd->error_fd.
(pipe_avail): New.
(_initialize_ser_windows): Hook pipe_avail.
* ser-base.c (generic_readchar): Check if there's
anything in stderr channel and route that to gdb_stderr.
(struct ser_console_state, struct net_windows_state): Add exit_select,
have_stopped, thread.
(pipe_select_thread, console_select_thread)
(net_windows_select_thread): Don't create a local state copy or
close stop_select. Exit on exit_select instead of stop_select. Set
have_stopped.
(console_select_thread): Don't report control keypresses as pending
input.
(pipe_select_thread): Allow stop_select to interrupt sleeping.
(set_console_wait_handle): Create exit_select and have_stopped.
Save the thread handle. Check _kbhit before starting a thread.
(ser_console_done_wait_handle): New.
(ser_console_close): Close new handles. Wait for the thread to
exit.
(new_windows_select_thread): Assert that an event occurred.
(net_windows_wait_handle): Check for pending input before starting
a thread.
(net_windows_done_wait_handle): New.
(net_windows_open): Create exit_select and have_stopped.
Save the thread handle.
(net_windows_close): Close new handles. Wait for the thread to
exit.
(_intiialize_ser_windows): Register done_wait_handle methods.
* serial.c [USE_WIN32API] (serial_done_wait_handle): New.
* serial.h [USE_WIN32API] (struct serial_ops): Add done_wait_handle.
[USE_WIN32API] (serial_done_wait_handle): New prototype.
* mingw-hdep.c (gdb_select): Use serial_done_wait_handle.
* Makefile.in (gdb_select_h, ser_tcp_h): New.
(ALLDEPFILES): Add ser-mingw.c.
(event-loop.o, inflow.o, mingw-hdep.o, posix-hdep.o, ser-base.o)
(ser-tcp.o, ser-unix.o): Update.
(ser-mingw.o): New rule.
* configure: Regenerated.
* configure.ac: Add ser-mingw.o for mingw32.
* ser-mingw.c: New file.
* event-loop.c: Include "gdb_select.h".
(gdb_select): Remove, moved to mingw-hdep.c and posix-hdep.c.
* ser-base.c: Include "gdb_select.h".
(ser_base_wait_for): Use gdb_select.
* serial.c (serial_for_fd): New function.
(serial_fdopen): Try "terminal" before "hardwire". Initialize
the allocated struct serial.
(serial_wait_handle): New function.
* serial.h (serial_for_fd, serial_wait_handle): New prototypes.
(struct serial_ops) [USE_WIN32API]: Add wait_handle.
* gdb_select.h: New file.
* ser-tcp.c: Include "ser-tcp.h". Remove unused "ser-unix.h" include.
(net_close, net_read_prim, net_write_prim): Make global.
(net_open): Likewise. Pass an exception set to select. Whitespace fix.
Document why we can not use gdb_select.
(_initialize_ser_tcp) [USE_WIN32API]: Do not register TCP support here.
* ser-tcp.h: New file.
* inflow.c (gdb_has_a_terminal): Don't initialize stdin_serial here.
(handle_sigio): Use gdb_select.
(initialize_stdin_serial): New function.
* terminal.h (initialize_stdin_serial): New prototype.
* top.c (gdb_init): Call initialize_stdin_serial.
* mingw-hdep.c (gdb_select): New function, moved from gdb_select in
event-loop.c. Add exception condition support. Use serial_for_fd
and serial_wait_handle. Fix timeout handling.
* posix-hdep.c: Include "gdb_select.h".
(gdb_select): New function.
* remote-st.c (connect_command): Use gdb_select.
* ser-unix.c: Include "gdb_select.h".
(hardwire_send_break, wait_for): Use gdb_select.
-lws2_32.
* ser-tcp.c (<winsock2.h>): Include, for Windows.
(ETIMEDOUT): Define, for Windows.
(ioctl): Likewise.
(closesocket): Define, for POSIX.
(net_open): Adjust for differences in socket functions between
Windows and UNIX.
(net_close): Likweise.
(net_read_prim): New function.
(net_write_prim): Likewise.
(_initialize_ser_tcp): Initialize winsock. Fill in read_prim and
write_prim.
* ser-unix.h (ser_unix_readcchar): Remove.
(ser_unix_read_prim): Declare.
(ser_unix_write_prim): Likewise.
* ser-unix.c (generic_readchar): Move to ser-base.c.
(ser_unix_wait_for): Likewise.
(do_unix_readchar): Likewise.
(ser_unix_readchar): Likewise.
(_initialize_ser_hardwire): Initialize read_prim and write_prim.
(ser_unix_read_prim): New function.
(ser_unix_write_prim): Likewise.
* ser-base.h (generic_readchar): Declare.
(ser_base_readchar): Likewise.
* ser-base.c (<winsock2.h>): Include, for windows.
(fd_event): Use the read primitive specified by the serial
interface.
(ser_base_wait_for): Moved from ser-unix.c
(do_ser_base_read_char): Likewise.
(generic_readchar): Likewise.
(ser_base_readchar): Likewise.
(ser_base_write): Use the write primitive specified by the serial
interface.
* ser-pipe.c (_initialize_ser_pipe): Use ser_base_readchar, not
ser_unix_readchar. Initialize read_prim and write_prim.
* serial.c (struct serial_ops): Add read_prim and write_prim.
* configure: Regenerate.
Pedro Alves