Go to file
Simon Marchi 26a06916b6 Do not send queries on secondary UIs
This is a follow-up to

  https://sourceware.org/ml/gdb-patches/2017-02/msg00261.html

This patch restricts queries to the main UI, which allows to avoid two
different problems.

The first one is that GDB is issuing queries on secondary MI channels
for which a TTY is allocated.  The second one is that GDB is not able to
handle queries on two (CLI) UIs simultaneously.  Restricting queries to
the main UI allows to bypass these two problems.

More details on how/why these two problems happen:

1. Queries on secondary MI UI

  The current criterion to decide if we should query the user is whether
  the input stream is a TTY.  The original way to start GDB in MI mode
  from a front-end was to create a subprocess with pipes to its
  stdin/stdout.  In this case, the input was considered non-interactive
  and queries were auto-answered.  Now that front-ends can create the MI
  channel as a separate UI connected to a dedicated TTY, GDB now
  considers this input stream as interactive and sends queries to it.
  By restricting queries to the main UI, we make sure we never query on
  the secondary MI UI.

2. Simultaneous queries

  As Pedro stated it, when you have two queries on two different CLI UIs
  at the same time, you end up with the following pseudo stack:

  #0 gdb_readline_wrapper
  #1 defaulted_query                 // for UI #2
  #2 handle_command
  #3 execute_command ("handle SIGTRAP" ....
  #4 stdin_event_handler             // input on UI #2
  #5 gdb_do_one_event
  #7 gdb_readline_wrapper
  #8 defaulted_query                 // for UI #1
  #9 handle_command
  #10 execute_command ("handle SIGINT" ....
  #11 stdin_event_handler            // input on UI #1
  #12 gdb_do_one_event
  #13 gdb_readline_wrapper

  trying to answer the query on UI #1 will therefore answer for UI #2.

  By restricting the queries to the main UI, we ensure that there will
  never be more than one pending query, since you can't have two queries
  on a UI at the same time.

I added a snippet to gdb.base/new-ui.exp to verify that we get a query
on the main UI, but that we don't on the secondary one (or, more
precisely, that it gets auto-answered).

gdb/ChangeLog:

	* utils.c (defaulted_query): Don't query on secondary UIs.

gdb/testsuite/ChangeLog:

	* gdb.base/new-ui.exp (do_test): Test queries behavior on main
	and extra UIs.
2017-02-10 16:29:50 -05:00
bfd Automatic date update in version.in 2017-02-10 00:00:16 +00:00
binutils
config
cpu
elfcpp
etc
gas POWER9 add scv/rfscv instruction support 2017-02-10 19:04:26 +10:30
gdb Do not send queries on secondary UIs 2017-02-10 16:29:50 -05:00
gold [GOLD] PowerPC64 TOC indirect to TOC relative segfault 2017-02-03 20:06:53 +10:30
gprof
include [ARC] Provide an interface to decode ARC instructions. 2017-02-06 11:26:13 +01:00
intl
ld ld/arc: Change default linker emulation for nps400 2017-02-08 23:47:43 +00:00
libdecnumber
libiberty
opcodes POWER9 add scv/rfscv instruction support 2017-02-10 19:04:26 +10:30
readline
sim
texinfo
zlib
.cvsignore
.gitattributes
.gitignore
ChangeLog
compile
config-ml.in
config.guess
config.rpath
config.sub
configure
configure.ac
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
depcomp
djunpack.bat
install-sh
libtool.m4
lt~obsolete.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS
Makefile.def
Makefile.in
Makefile.tpl
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
README
README-maintainer-mode
setup.com
src-release.sh
symlink-tree
ylwrap

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.