Always switch fork child to the main UI
The following scenario: - gdb started in normal CLI mode. - separate MI channel created with new-ui - inferior output redirected with the "set inferior-tty" command. - use -exec-run in the MI channel to run the inferior is presently mishandled. When we create the inferior, in fork-child.c, right after vfork, we'll close all the file descriptors in the vfork child, and then dup the tty to file descriptors 0/1/2, create a session, etc. Note that when we close all descriptors, we close the file descriptors behind gdb_stdin/gdb_stdout/gdb_stderr of all secondary UIs... So if anything goes wrong in the child and it calls warning/error, it'll end up writting to the current UI's stdout/stderr streams, which are backed by file descriptors that have since been closed. Because this happens in a vfork region, the corresponding stdin/stdout/stderr in the parent/gdb end up corrupted. The fix is to switch to the main UI right after the vfork, so that gdb_stdin/gdb_stdout/gdb_stderr are correctly mapped to stdin/stdout/stderr (and thus to file descriptors 0/1/2), so this code works as it has always worked. (Technically, we're doing a lot of stuff we shouldn't be doing after a vfork, while we should only be calling async-signal-safe functions.) gdb/ChangeLog: 2016-06-21 Pedro Alves <palves@redhat.com> * fork-child.c (fork_inferior): Switch the child to the main UI right after vfork. Save/restore the current UI in the parent. Flush outputs of the main UI instead of the current UI. gdb/testsuite/ChangeLog: 2016-06-21 Pedro Alves <palves@redhat.com> * gdb.mi/mi-exec-run.exp: New file.
This commit is contained in:
parent
ef274d26b5
commit
49940788ab
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@ -1,3 +1,9 @@
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2016-06-21 Pedro Alves <palves@redhat.com>
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* fork-child.c (fork_inferior): Switch the child to the main UI
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right after vfork. Save/restore the current UI in the parent.
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Flush outputs of the main UI instead of the current UI.
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2016-06-21 Pedro Alves <palves@redhat.com>
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2016-06-21 Pedro Alves <palves@redhat.com>
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* breakpoint.c (watchpoint_check): Send watchpoint-deleted output
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* breakpoint.c (watchpoint_check): Send watchpoint-deleted output
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@ -31,6 +31,7 @@
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#include "gdbcmd.h"
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#include "gdbcmd.h"
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#include "solib.h"
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#include "solib.h"
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#include "filestuff.h"
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#include "filestuff.h"
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#include "top.h"
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#include <signal.h>
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#include <signal.h>
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@ -141,6 +142,7 @@ fork_inferior (char *exec_file_arg, char *allargs, char **env,
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struct inferior *inf;
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struct inferior *inf;
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int i;
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int i;
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int save_errno;
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int save_errno;
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struct ui *save_ui;
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/* If no exec file handed to us, get it from the exec-file command
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/* If no exec file handed to us, get it from the exec-file command
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-- with a good, common error message if none is specified. */
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-- with a good, common error message if none is specified. */
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@ -275,6 +277,9 @@ fork_inferior (char *exec_file_arg, char *allargs, char **env,
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restore it. */
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restore it. */
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save_our_env = environ;
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save_our_env = environ;
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/* Likewise the current UI. */
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save_ui = current_ui;
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/* Tell the terminal handling subsystem what tty we plan to run on;
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/* Tell the terminal handling subsystem what tty we plan to run on;
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it will just record the information for later. */
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it will just record the information for later. */
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new_tty_prefork (inferior_io_terminal);
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new_tty_prefork (inferior_io_terminal);
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@ -282,8 +287,8 @@ fork_inferior (char *exec_file_arg, char *allargs, char **env,
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/* It is generally good practice to flush any possible pending stdio
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/* It is generally good practice to flush any possible pending stdio
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output prior to doing a fork, to avoid the possibility of both
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output prior to doing a fork, to avoid the possibility of both
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the parent and child flushing the same data after the fork. */
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the parent and child flushing the same data after the fork. */
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gdb_flush (gdb_stdout);
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gdb_flush (main_ui->m_gdb_stdout);
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gdb_flush (gdb_stderr);
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gdb_flush (main_ui->m_gdb_stderr);
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/* If there's any initialization of the target layers that must
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/* If there's any initialization of the target layers that must
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happen to prepare to handle the child we're about fork, do it
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happen to prepare to handle the child we're about fork, do it
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@ -312,6 +317,16 @@ fork_inferior (char *exec_file_arg, char *allargs, char **env,
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if (pid == 0)
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if (pid == 0)
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{
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{
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/* Switch to the main UI, so that gdb_std{in/out/err} in the
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child are mapped to std{in/out/err}. This makes it possible
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to use fprintf_unfiltered/warning/error/etc. in the child
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from here on. */
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current_ui = main_ui;
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/* Close all file descriptors except those that gdb inherited
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(usually 0/1/2), so they don't leak to the inferior. Note
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that this closes the file descriptors of all secondary
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UIs. */
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close_most_fds ();
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close_most_fds ();
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if (debug_fork)
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if (debug_fork)
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@ -378,6 +393,9 @@ fork_inferior (char *exec_file_arg, char *allargs, char **env,
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/* Restore our environment in case a vforked child clob'd it. */
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/* Restore our environment in case a vforked child clob'd it. */
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environ = save_our_env;
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environ = save_our_env;
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/* Likewise the current UI. */
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current_ui = save_ui;
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if (!have_inferiors ())
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if (!have_inferiors ())
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init_thread_list ();
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init_thread_list ();
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@ -1,3 +1,7 @@
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2016-06-21 Pedro Alves <palves@redhat.com>
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* gdb.mi/mi-exec-run.exp: New file.
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2016-06-21 Pedro Alves <palves@redhat.com>
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2016-06-21 Pedro Alves <palves@redhat.com>
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* gdb.mi/mi-break.exp (test_breakpoint_commands): Always expect
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* gdb.mi/mi-break.exp (test_breakpoint_commands): Always expect
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@ -0,0 +1,158 @@
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# Copyright 2016 Free Software Foundation, Inc.
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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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#
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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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#
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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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# Test that -exec-run works as expected. Exercises various testing
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# axes:
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#
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# - MI running on main UI vs separate UI.
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#
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# - inferior tty set to main tty vs separate tty.
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#
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# - forking the child failing and sending output to the right inferior
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# terminal, vs the child not failing to start.
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load_lib mi-support.exp
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set MIFLAGS "-i=mi"
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# The purpose of this testcase is to test the -exec-run command. If we
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# cannot use it, then there is no point in running this testcase.
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if [target_info exists use_gdb_stub] {
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untested "cannot use -exec-run command"
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return -1
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}
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standard_testfile mi-start.c
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if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
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untested "could not build mi-exec-run"
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return -1
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}
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# The test proper. INFTTY_MODE determines whether "set inferior-tty"
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# is in effect. MI_MODE determines whether MI is run on the main UI,
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# or as a separate UI. FORCE_FAIL is true when we want -exec-run to
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# fail and cause inferior output be sent to the inferior tty.
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proc test {inftty_mode mi_mode force_fail} {
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global srcdir subdir binfile srcfile
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global gdb_spawn_id gdb_main_spawn_id mi_spawn_id inferior_spawn_id
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global decimal
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mi_gdb_exit
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set start_ops {}
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if {$inftty_mode == "separate"} {
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lappend start_ops "separate-inferior-tty"
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}
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if {$mi_mode == "separate"} {
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lappend start_ops "separate-mi-tty"
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}
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if [eval mi_gdb_start $start_ops] {
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return
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}
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if {$force_fail} {
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# Disable the shell so that its the first exec that fails,
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# instead of the shell starting and then failing with some
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# unspecified output.
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mi_gdb_test "-gdb-set startup-with-shell off" ".*"
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set bin $binfile.nox
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} else {
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set bin $binfile
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}
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mi_delete_breakpoints
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mi_gdb_reinitialize_dir $srcdir/$subdir
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mi_gdb_reinitialize_dir $srcdir/$subdir
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mi_gdb_load ${bin}
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# Useful for debugging:
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verbose -log "Channels:"
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verbose -log " inferior_spawn_id=$inferior_spawn_id"
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verbose -log " gdb_spawn_id=$gdb_spawn_id"
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verbose -log " gdb_main_spawn_id=$gdb_main_spawn_id"
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verbose -log " mi_spawn_id=$mi_spawn_id"
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if {$force_fail} {
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set saw_perm_error 0
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set saw_mi_error 0
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set test "run failure detected"
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send_gdb "-exec-run --start\n"
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while {1} {
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gdb_expect {
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-i "$inferior_spawn_id"
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-re ".*Cannot exec.*Permission denied" {
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set saw_perm_error 1
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verbose -log "saw mi error"
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}
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-i "$gdb_spawn_id"
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-re "\\^error,msg=\"During startup program exited with code 127" {
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set saw_mi_error 1
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verbose -log "saw mi error"
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}
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timeout {
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fail "$test (timeout)"
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break
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}
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-i "$gdb_main_spawn_id"
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eof {
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fail "$test (eof)"
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break
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}
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}
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if {$saw_perm_error && $saw_mi_error} {
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pass $test
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break
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}
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}
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} else {
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mi_run_cmd "--start"
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mi_expect_stop "breakpoint-hit" "main" "" ".*$srcfile" "$decimal" \
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{ "" "disp=\"del\"" } "breakpoint hit reported on mi"
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if {$mi_mode == "separate"} {
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# Check that the breakpoint hit is reported on the main
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# UI/CLI. Note no prompt is expected.
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switch_gdb_spawn_id $gdb_main_spawn_id
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set test "breakpoint hit reported on console"
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gdb_test_multiple "" $test {
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-re "Temporary breakpoint .*, main \\(\\) at .*$srcfile:$decimal.*return 0;" {
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pass $test
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}
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}
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# Switch back to the MI UI.
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global mi_spawn_id
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switch_gdb_spawn_id $mi_spawn_id
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}
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}
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}
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# Create a not-executable copy of the program, in order to exercise
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# vfork->exec failing.
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gdb_remote_download host $binfile $binfile.nox
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remote_spawn target "chmod \"a-x\" $binfile.nox"
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foreach_with_prefix inferior-tty {"main" "separate"} {
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foreach_with_prefix mi {"main" "separate"} {
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foreach_with_prefix force-fail {0 1} {
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test ${inferior-tty} ${mi} ${force-fail}
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}
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}
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}
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