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.
This commit is contained in:
Pedro Alves 2014-07-25 10:07:38 +01:00
parent a3673aac3c
commit c3f814a143
8 changed files with 56 additions and 46 deletions

View File

@ -1,3 +1,31 @@
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.
2014-07-22 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.arch/amd64-entry-value-paramref.S: New file.

View File

@ -75,10 +75,6 @@ proc cancel_pagination_in_target_event { command } {
set saw_continuing 1
exp_continue
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
}
# We're now stopped in a pagination query while handling a
@ -87,18 +83,28 @@ proc cancel_pagination_in_target_event { command } {
# output.
send_gdb "\003p 1\n"
# Note gdb_test_multiple has a default match for the prompt,
# which issues a FAIL. Consume the first prompt.
set test "first prompt"
gdb_test_multiple "" $test {
-re "$gdb_prompt" {
pass "first prompt"
}
}
# We should only see one prompt more, and it should be
# preceeded by print's output.
set test "no double prompt"
gdb_test_multiple "" $test {
-re "$gdb_prompt.*$gdb_prompt.*$gdb_prompt $" {
-re "$gdb_prompt.*$gdb_prompt $" {
# The bug is present, and expect managed to read
# enough characters into the buffer to fill it with
# both prompts.
fail $test
}
-re "$gdb_prompt .* = 1\r\n$gdb_prompt $" {
-re " = 1\r\n$gdb_prompt $" {
pass $test
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
}
# In case the board file wants to send further commands.

View File

@ -70,10 +70,6 @@ proc test_ctrlc_while_target_running_paginates {} {
-re "$gdb_prompt $" {
gdb_assert $saw_pagination_prompt $test
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
}
# Confirm GDB can still process input.

View File

@ -51,11 +51,6 @@ proc test_bg_execution_pagination_return {} {
send_gdb "\n"
exp_continue
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an
# error.
exp_continue
}
-re "after sleep\[^\r\n\]+\r\n$" {
gdb_assert $saw_pagination_prompt $test
}
@ -96,10 +91,6 @@ proc test_bg_execution_pagination_cancel { how } {
-re "$pagination_prompt$" {
pass $test
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
}
set test "cancel pagination"

View File

@ -111,10 +111,6 @@ proc test_fg_execution_pagination_return {} {
send_gdb "\n"
exp_continue
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
-re "$gdb_prompt $" {
gdb_assert $saw_pagination_prompt $test
}
@ -154,10 +150,6 @@ proc test_fg_execution_pagination_cancel { how } {
-re "$pagination_prompt$" {
pass $test
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
}
set test "cancel pagination"

View File

@ -58,10 +58,6 @@ proc test_paginate_inferior_exited {} {
set saw_starting 1
exp_continue
}
-notransfer -re "<return>" {
# Otherwise gdb_test_multiple considers this an error.
exp_continue
}
}
# We're now stopped in a pagination output while handling a

View File

@ -28,3 +28,12 @@ proc 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
}

View File

@ -71,7 +71,7 @@ if ![info exists gdb_prompt] then {
}
# A regexp that matches the pagination prompt.
set pagination_prompt "---Type <return> to continue, or q <return> to quit---"
set pagination_prompt [string_to_regexp "---Type <return> to continue, or q <return> to quit---"]
# The variable fullname_syntax_POSIX is a regexp which matches a POSIX
# absolute path ie. /foo/
@ -649,7 +649,7 @@ proc gdb_internal_error_resync {} {
#
proc gdb_test_multiple { command message user_code } {
global verbose use_gdb_stub
global gdb_prompt
global gdb_prompt pagination_prompt
global GDB
global inferior_exited_re
upvar timeout timeout
@ -873,7 +873,7 @@ proc gdb_test_multiple { command message user_code } {
}
set result 1
}
"<return>" {
-re "$pagination_prompt" {
send_gdb "\n"
perror "Window too small."
fail "$message"
@ -1109,14 +1109,6 @@ proc test_print_reject { args } {
}
}
# 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
}
# Same as gdb_test, but the second parameter is not a regexp,
# but a string that must match exactly.