old-cross-binutils/gdb/testsuite/lib/gdb-utils.exp
Pedro Alves c3f814a143 Fix paginate-*.exp races
Jan pointed out in
<https://sourceware.org/ml/gdb-patches/2014-07/msg00553.html> that
these testcases have racy results:

  gdb.base/double-prompt-target-event-error.exp
  gdb.base/paginate-after-ctrl-c-running.exp
  gdb.base/paginate-bg-execution.exp
  gdb.base/paginate-execution-startup.exp
  gdb.base/paginate-inferior-exit.exp

This is easily reproducible with "read1" from:

  [reproducer for races of expect incomplete reads]
  http://sourceware.org/bugzilla/show_bug.cgi?id=12649

The '-notransfer -re "<return>" { exp_continue }' trick in the current
tests doesn't actually work.

The issue that led to the -notransfer trick was that

  "---Type <return> to continue, or q <return> to quit---"

has two "<return>"s.  If one wants gdb_test_multiple to not hit the
built-in "<return>" match that results in FAIL, one has to expect the
pagination prompt in chunks, first up to the first "<return>", then
again, up to the second.  Something around these lines:

  gdb_test_multiple "" $test {
      -re "<return>" {
	  exp_continue
      }
      -re "to quit ---" {
	  pass $test
      }
  }

The intent was for -notransfer+exp_continue to make expect fetch more
input, and rerun the matches against the now potentially fuller
buffer, and then eventually the -re that includes the full pagination
prompt regex would match instead (because it's listed higher up, it
would match first).  But, once that "<return>" -notransfer -re
matches, it keeps re-matching forever.  It seems like with
exp_continue, expect immediately retries matching, instead of first
reading in more data into the buffer, if available.

Fix this like I should have done in the first place.  There's actually
no good reason for gdb_test_multiple to only match "<return>".  We can
make gdb_test_multiple expect the whole pagination prompt text
instead, which is store in the 'pagination_prompt' global (similar to
'gdb_prompt').  Then a gdb_test_multiple caller that doesn't want the
default match to trigger, because it wants to see one pagination
prompt, does simply:

  gdb_test_multiple "" $test {
      -re "$pagination_prompt$" {
	  pass $test
      }
  }

which is just like when we don't want the default $gdb_prompt match
within gdb_test_multiple to trigger, like:

  gdb_test_multiple "" $test {
      -re "$gdb_prompt $" {
	  pass $test
      }
  }

Tested on x86_64 Fedora 20.  In addition, I've let the racy tests run
all in parallel in a loop for 30 minutes, and they never failed.

gdb/testsuite/
2014-07-25  Pedro Alves  <palves@redhat.com>

	* gdb.base/double-prompt-target-event-error.exp
	(cancel_pagination_in_target_event): Remove '-notransfer <return>'
	match.
	(cancel_pagination_in_target_event): Rework double prompt
	detection.
	* gdb.base/paginate-after-ctrl-c-running.exp
	(test_ctrlc_while_target_running_paginates): Remove '-notransfer
	<return>' match.
	* gdb.base/paginate-bg-execution.exp
	(test_bg_execution_pagination_return)
	(test_bg_execution_pagination_cancel): Remove '-notransfer
	<return>' matches.
	* gdb.base/paginate-execution-startup.exp
	(test_fg_execution_pagination_return)
	(test_fg_execution_pagination_cancel): Remove '-notransfer
	<return>' matches.
	* gdb.base/paginate-inferior-exit.exp
	(test_paginate_inferior_exited): Remove '-notransfer <return>'
	match.
	* lib/gdb-utils.exp (string_to_regexp): Move here from lib/gdb.exp.
	* lib/gdb.exp (pagination_prompt): Run text through
	string_to_regexp.
	(gdb_test_multiple): Match $pagination_prompt instead of
	"<return>".
	(string_to_regexp): Move to lib/gdb-utils.exp.
2014-07-25 10:07:38 +01:00

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# Copyright 2014 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# Utility procedures, shared between test suite domains.
# A helper procedure to retrieve commands to send to GDB before a program
# is started.
proc gdb_init_commands {} {
set commands ""
if [target_info exists gdb_init_command] {
lappend commands [target_info gdb_init_command]
}
if [target_info exists gdb_init_commands] {
set commands [concat $commands [target_info gdb_init_commands]]
}
return $commands
}
# Given an input string, adds backslashes as needed to create a
# regexp that will match the string.
proc string_to_regexp {str} {
set result $str
regsub -all {[]*+.|()^$\[\\]} $str {\\&} result
return $result
}