416 lines
14 KiB
Diff
416 lines
14 KiB
Diff
http://sourceware.org/ml/gdb-patches/2014-07/msg00593.html
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Subject: Re: [testsuite patch] Fix paginate-*.exp race for "read1"
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Hi Jan,
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Thanks for noticing this. It'd be very nice IMO to put that read1
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trick in the sources somewhere, to make it easy (easier) to use. Ideally
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we'd have a simple Makefile flag to activate it, like 'make check READ1="1"'
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or some such, but really just putting the files as attached to the PR, as
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is, with absolutely no other glue at all, not even a Makefile, under
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gdb/contrib/read1 or some such would already be great. We can always
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improve and integrate things more incrementally. WDYT?
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On 07/22/2014 06:36 PM, Jan Kratochvil wrote:
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> + global saw_continuing
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> set saw_continuing 0
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> set test "continue to pagination"
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> - gdb_test_multiple "$command" $test {
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> - -re "$pagination_prompt$" {
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> - if {$saw_continuing} {
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> - pass $test
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> - } else {
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> - send_gdb "\n"
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> - exp_continue
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> - }
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> + gdb_test_pagination $command $test {
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> + global saw_continuing
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> + if {$saw_continuing} {
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> + pass $test
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> + } else {
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> + send_gdb "\n"
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> + exp_continue
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> }
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> + } {
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> -re "Continuing" {
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> + global saw_continuing
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> set saw_continuing 1
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The need for these "global"s indicates an issue
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with uplevel/upvar in the new procedure.
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> exp_continue
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> }
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> - -notransfer -re "<return>" {
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> - # Otherwise gdb_test_multiple considers this an error.
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> - exp_continue
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> - }
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> }
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>
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> # We're now stopped in a pagination query while handling a
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> +proc gdb_test_pagination { command test { code_prompt3 {} } { code_append {} } } {
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...
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> + append code_append {
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...
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> + -re "${pagination_prompt3}$" {
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> + if { $saw_pagination_prompt != 2 } {
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> + fail "$test (3)"
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> + }
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> + set saw_pagination_prompt 3
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> + eval $code_prompt3
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The issue is that $code_prompt3 and $code_append should really be
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evaluated in this function's caller ...
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> + }
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> + }
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> +
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> + set saw_pagination_prompt 0
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> + gdb_test_multiple $command $test $code_append
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... but gdb_test_multiple evaluates the passed in $code_append
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in the context of "uplevel 1" (and likewise it does a couple
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upvar's with level one. To make that work, you'd need to
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rename gdb_test_multiple to gdb_test_multiple_with_level or
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some such, add a 'level' parameter, and pass that as level to
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the existing uplevel/upvar calls. Then in gdb_test_pagination
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you'd pass in "two levels up", like:
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gdb_test_multiple_with_level 2 $command $test $code_append
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instead, and likewise gdb_test_multiple would be reimplemented in
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terms of gdb_test_multiple_with_level.
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But... We don't really need ...
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> +# Prevent gdb_test_multiple considering an error -re "<return>" match.
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> +# For unknown reason -notransfer -re "<return>" { exp_continue } does not
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> +# prevent it.
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> +
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> +proc gdb_test_pagination { command test { code_prompt3 {} } { code_append {} } } {
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> + global pagination_prompt1 pagination_prompt2 pagination_prompt3
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> + global gdb_prompt
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> +
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> + # A regexp that matches the pagination prompt.
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> + set pagination_prompt1 "---Type <return"
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> + set pagination_prompt2 "> to continue, or q <return"
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> + set pagination_prompt3 "> to quit---"
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> +
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... this, if we instead tackle what IMO is the root of the
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issue, and make gdb_test_multiple match the whole pagination
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prompt, like in the patch below. I should really have done
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this in the first place. :-/
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This fixes the races for me, even when stressing them in
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parallel mode, as mentioned in the commit log.
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Does this fix them for you too?
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----------
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>From 0c6260e734bdb28272119d50b0150fb777a458ab Mon Sep 17 00:00:00 2001
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From: Pedro Alves <palves@redhat.com>
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Date: Wed, 23 Jul 2014 17:00:21 +0100
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Subject: [PATCH] Fix paginate-*.exp races
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Subject: [PATCH] Fix paginate-*.exp races
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These testcases have racy results:
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gdb.base/double-prompt-target-event-error.exp
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gdb.base/paginate-after-ctrl-c-running.exp
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gdb.base/paginate-bg-execution.exp
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gdb.base/paginate-execution-startup.exp
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gdb.base/paginate-inferior-exit.exp
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This is easily reproducible with "read1" from:
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[reproducer for races of expect incomplete reads]
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http://sourceware.org/bugzilla/show_bug.cgi?id=12649
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The '-notransfer -re "<return>" { exp_continue }' trick in the current
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tests doesn't actually work.
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The issue that led to the -notransfer trick was that
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"---Type <return> to continue, or q <return> to quit---"
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has two "<return>"s. If one wants gdb_test_multiple to not hit the
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built-in "<return>" match that results in FAIL, one has to expect the
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pagination prompt in chunks, first up to the first "<return>", then
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again, up to the second. Something around these lines:
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gdb_test_multiple "" $test {
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-re "<return>" {
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exp_continue
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}
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-re "to quit ---" {
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pass $test
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}
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}
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The intent was for -notransfer+exp_continue to make expect fetch more
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input, and rerun the matches against the now potentially fuller
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buffer, and then eventually the -re that includes the full pagination
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prompt regex would match instead (because it's listed higher up, it
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would match first). But, once that "<return>" -notransfer -re
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matches, it keeps re-matching forever. It seems like with
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exp_continue, expect immediately retries matching, instead of first
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reading in more data into the buffer, if available.
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Fix this like I should have done in the first place. There's actually
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no good reason for gdb_test_multiple to only match "<return>". We can
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make gdb_test_multiple expect the whole pagination prompt text
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instead, which is store in the 'pagination_prompt' global (similar to
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'gdb_prompt'). Then a gdb_test_multiple caller that doesn't want the
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default match to trigger, because it wants to see one pagination
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prompt, does simply:
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gdb_test_multiple "" $test {
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-re "$pagination_prompt$" {
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pass $test
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}
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}
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which is just like when we don't want the default $gdb_prompt match
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within gdb_test_multiple to trigger, like:
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gdb_test_multiple "" $test {
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-re "$gdb_prompt $" {
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pass $test
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}
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}
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Tested on x86_64 Fedora 20. In addition, I've let the racy tests run
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all in parallel in a loop for 30 minutes, and they never failed.
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gdb/testsuite/
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2014-07-24 Pedro Alves <palves@redhat.com>
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* gdb.base/double-prompt-target-event-error.exp
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(cancel_pagination_in_target_event): Remove '-notransfer <return>'
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match.
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(cancel_pagination_in_target_event): Rework double prompt
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detection.
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* gdb.base/paginate-after-ctrl-c-running.exp
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(test_ctrlc_while_target_running_paginates): Remove '-notransfer
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<return>' match.
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* gdb.base/paginate-bg-execution.exp
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(test_bg_execution_pagination_return)
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(test_bg_execution_pagination_cancel): Remove '-notransfer
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<return>' matches.
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* gdb.base/paginate-execution-startup.exp
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(test_fg_execution_pagination_return)
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(test_fg_execution_pagination_cancel): Remove '-notransfer
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<return>' matches.
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* gdb.base/paginate-inferior-exit.exp
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(test_paginate_inferior_exited): Remove '-notransfer <return>'
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match.
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* lib/gdb-utils.exp (string_to_regexp): Move here from lib/gdb.exp.
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* lib/gdb.exp (pagination_prompt): Run text through
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string_to_regexp.
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(gdb_test_multiple): Match $pagination_prompt instead of
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"<return>".
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(string_to_regexp): Move to lib/gdb-utils.exp.
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---
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.../gdb.base/double-prompt-target-event-error.exp | 26 +++++++++++++---------
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.../gdb.base/paginate-after-ctrl-c-running.exp | 4 ----
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gdb/testsuite/gdb.base/paginate-bg-execution.exp | 9 --------
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.../gdb.base/paginate-execution-startup.exp | 8 -------
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gdb/testsuite/gdb.base/paginate-inferior-exit.exp | 4 ----
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gdb/testsuite/lib/gdb-utils.exp | 9 ++++++++
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gdb/testsuite/lib/gdb.exp | 14 +++---------
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7 files changed, 28 insertions(+), 46 deletions(-)
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diff --git a/gdb/testsuite/gdb.base/double-prompt-target-event-error.exp b/gdb/testsuite/gdb.base/double-prompt-target-event-error.exp
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index 5571cdf..84c6c45 100644
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--- a/gdb/testsuite/gdb.base/double-prompt-target-event-error.exp
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+++ b/gdb/testsuite/gdb.base/double-prompt-target-event-error.exp
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@@ -75,10 +75,6 @@ proc cancel_pagination_in_target_event { command } {
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set saw_continuing 1
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exp_continue
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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}
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# We're now stopped in a pagination query while handling a
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@@ -87,18 +83,28 @@ proc cancel_pagination_in_target_event { command } {
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# output.
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send_gdb "\003p 1\n"
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+ # Note gdb_test_multiple has a default match for the prompt,
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+ # which issues a FAIL. Consume the first prompt.
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+ set test "first prompt"
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+ gdb_test_multiple "" $test {
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+ -re "$gdb_prompt" {
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+ pass "first prompt"
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+ }
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+ }
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+
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+ # We should only see one prompt more, and it should be
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+ # preceeded by print's output.
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set test "no double prompt"
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gdb_test_multiple "" $test {
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- -re "$gdb_prompt.*$gdb_prompt.*$gdb_prompt $" {
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+ -re "$gdb_prompt.*$gdb_prompt $" {
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+ # The bug is present, and expect managed to read
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+ # enough characters into the buffer to fill it with
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+ # both prompts.
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fail $test
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}
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- -re "$gdb_prompt .* = 1\r\n$gdb_prompt $" {
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+ -re " = 1\r\n$gdb_prompt $" {
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pass $test
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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}
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# In case the board file wants to send further commands.
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diff --git a/gdb/testsuite/gdb.base/paginate-after-ctrl-c-running.exp b/gdb/testsuite/gdb.base/paginate-after-ctrl-c-running.exp
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index 0ed8c92..5898d5b 100644
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--- a/gdb/testsuite/gdb.base/paginate-after-ctrl-c-running.exp
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+++ b/gdb/testsuite/gdb.base/paginate-after-ctrl-c-running.exp
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@@ -70,10 +70,6 @@ proc test_ctrlc_while_target_running_paginates {} {
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-re "$gdb_prompt $" {
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gdb_assert $saw_pagination_prompt $test
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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}
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# Confirm GDB can still process input.
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diff --git a/gdb/testsuite/gdb.base/paginate-bg-execution.exp b/gdb/testsuite/gdb.base/paginate-bg-execution.exp
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index dcff8ad..116cc2b 100644
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--- a/gdb/testsuite/gdb.base/paginate-bg-execution.exp
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+++ b/gdb/testsuite/gdb.base/paginate-bg-execution.exp
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@@ -51,11 +51,6 @@ proc test_bg_execution_pagination_return {} {
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send_gdb "\n"
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exp_continue
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an
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- # error.
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- exp_continue
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- }
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-re "after sleep\[^\r\n\]+\r\n$" {
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gdb_assert $saw_pagination_prompt $test
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}
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@@ -96,10 +91,6 @@ proc test_bg_execution_pagination_cancel { how } {
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-re "$pagination_prompt$" {
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pass $test
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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}
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set test "cancel pagination"
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diff --git a/gdb/testsuite/gdb.base/paginate-execution-startup.exp b/gdb/testsuite/gdb.base/paginate-execution-startup.exp
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index dc713ec..1628a0f 100644
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--- a/gdb/testsuite/gdb.base/paginate-execution-startup.exp
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+++ b/gdb/testsuite/gdb.base/paginate-execution-startup.exp
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@@ -111,10 +111,6 @@ proc test_fg_execution_pagination_return {} {
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send_gdb "\n"
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exp_continue
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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-re "$gdb_prompt $" {
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gdb_assert $saw_pagination_prompt $test
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}
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@@ -154,10 +150,6 @@ proc test_fg_execution_pagination_cancel { how } {
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-re "$pagination_prompt$" {
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pass $test
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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}
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set test "cancel pagination"
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diff --git a/gdb/testsuite/gdb.base/paginate-inferior-exit.exp b/gdb/testsuite/gdb.base/paginate-inferior-exit.exp
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index 0e37be9..7c63289 100644
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--- a/gdb/testsuite/gdb.base/paginate-inferior-exit.exp
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+++ b/gdb/testsuite/gdb.base/paginate-inferior-exit.exp
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@@ -58,10 +58,6 @@ proc test_paginate_inferior_exited {} {
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set saw_starting 1
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exp_continue
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}
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- -notransfer -re "<return>" {
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- # Otherwise gdb_test_multiple considers this an error.
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- exp_continue
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- }
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}
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# We're now stopped in a pagination output while handling a
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diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
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index 7a00efb..8cb98ae 100644
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--- a/gdb/testsuite/lib/gdb.exp
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+++ b/gdb/testsuite/lib/gdb.exp
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@@ -71,7 +71,15 @@ if ![info exists gdb_prompt] then {
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}
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# A regexp that matches the pagination prompt.
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+# Given an input string, adds backslashes as needed to create a
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+# regexp that will match the string.
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+
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+proc string_to_regexp {str} {
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+ set result $str
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+ regsub -all {[]*+.|()^$\[\\]} $str {\\&} result
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+ return $result
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+}
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-set pagination_prompt "---Type <return> to continue, or q <return> to quit---"
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+set pagination_prompt [string_to_regexp "---Type <return> to continue, or q <return> to quit---"]
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# The variable fullname_syntax_POSIX is a regexp which matches a POSIX
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# absolute path ie. /foo/
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@@ -649,7 +649,7 @@ proc gdb_internal_error_resync {} {
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#
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proc gdb_test_multiple { command message user_code } {
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global verbose use_gdb_stub
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- global gdb_prompt
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+ global gdb_prompt pagination_prompt
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global GDB
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global inferior_exited_re
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upvar timeout timeout
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@@ -873,7 +873,7 @@ proc gdb_test_multiple { command message user_code } {
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}
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set result 1
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}
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- "<return>" {
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+ -re "$pagination_prompt" {
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send_gdb "\n"
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perror "Window too small."
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fail "$message"
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@@ -1109,14 +1109,6 @@ proc test_print_reject { args } {
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}
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}
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-# Given an input string, adds backslashes as needed to create a
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-# regexp that will match the string.
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-
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-proc string_to_regexp {str} {
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- set result $str
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- regsub -all {[]*+.|()^$\[\\]} $str {\\&} result
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- return $result
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-}
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# Same as gdb_test, but the second parameter is not a regexp,
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# but a string that must match exactly.
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--
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1.9.3
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