Fix "attach" command vs user input race
On async targets, a synchronous attach is done like this:
#1 - target_attach is called (PTRACE_ATTACH is issued)
#2 - a continuation is installed
#3 - we go back to the event loop
#4 - target reports stop (SIGSTOP), event loop wakes up, and
attach continuation is called
#5 - among other things, the continuation calls
target_terminal_inferior, which removes stdin from the event
loop
Note that in #3, GDB is still processing user input. If the user is
fast enough, e.g., with something like:
echo -e "attach PID\nset xxx=1" | gdb
... then the "set" command is processed before the attach completes.
We get worse behavior even, if input is a tty and therefore
readline/editing is enabled, with e.g.,:
(gdb) attach PID\nset xxx=1
we then crash readline/gdb, with:
Attaching to program: attach-wait-input, process 14537
readline: readline_callback_read_char() called with no handler!
Aborted
$
Fix this by calling target_terminal_inferior before #3 above.
The test covers both scenarios by running with editing/readline forced
to both on and off.
gdb/
2014-07-09 Pedro Alves <palves@redhat.com>
* infcmd.c (attach_command_post_wait): Don't call
target_terminal_inferior here.
(attach_command): Call it here instead.
gdb/testsuite/
2014-07-09 Pedro Alves <palves@redhat.com>
* gdb.base/attach-wait-input.exp: New file.
* gdb.base/attach-wait-input.c: New file.
2014-07-09 16:59:02 +02:00
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/* This testcase is part of GDB, the GNU debugger.
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2018-01-01 05:43:02 +01:00
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Copyright 2014-2018 Free Software Foundation, Inc.
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Fix "attach" command vs user input race
On async targets, a synchronous attach is done like this:
#1 - target_attach is called (PTRACE_ATTACH is issued)
#2 - a continuation is installed
#3 - we go back to the event loop
#4 - target reports stop (SIGSTOP), event loop wakes up, and
attach continuation is called
#5 - among other things, the continuation calls
target_terminal_inferior, which removes stdin from the event
loop
Note that in #3, GDB is still processing user input. If the user is
fast enough, e.g., with something like:
echo -e "attach PID\nset xxx=1" | gdb
... then the "set" command is processed before the attach completes.
We get worse behavior even, if input is a tty and therefore
readline/editing is enabled, with e.g.,:
(gdb) attach PID\nset xxx=1
we then crash readline/gdb, with:
Attaching to program: attach-wait-input, process 14537
readline: readline_callback_read_char() called with no handler!
Aborted
$
Fix this by calling target_terminal_inferior before #3 above.
The test covers both scenarios by running with editing/readline forced
to both on and off.
gdb/
2014-07-09 Pedro Alves <palves@redhat.com>
* infcmd.c (attach_command_post_wait): Don't call
target_terminal_inferior here.
(attach_command): Call it here instead.
gdb/testsuite/
2014-07-09 Pedro Alves <palves@redhat.com>
* gdb.base/attach-wait-input.exp: New file.
* gdb.base/attach-wait-input.c: New file.
2014-07-09 16:59:02 +02:00
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <sys/types.h>
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#include <unistd.h>
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volatile int should_exit = 0;
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int mypid;
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static void
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setup_done (void)
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{
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}
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int
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main (void)
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{
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unsigned int counter = 1;
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mypid = getpid ();
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setup_done ();
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for (counter = 0; !should_exit && counter < 100; counter++)
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sleep (1);
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return 0;
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}
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