Re: [PATCH v2] New testcase for PR tui/25126 (staled source cache)

[Luis Machado <luis.machado@linaro.org>]

On 2/10/20 5:02 PM, Sergio Durigan Junior wrote:
> I'm dealing with a Fedora GDB bug that is related to PR tui/25126, and
> I thought I'd write a specific testcase for it because I couldn't find
> one.
> 
> The idea is to get the simple reproducer from the bug and tweak the
> testcase around it.  This one was a bit hard because, since we need to
> modify the source file and recompile it, it involved a bit of TCL-foo
> to do things.  Also for this reason, I'm only enabling the test for
> native boards.
> 
> I tested this with an upstream GDB and made sure everything is
> passing.  I also tested with a faulty GDB and made sure the test
> failed.
> 
> gdb/testsuite/ChangeLog:
> 2020-02-10  Sergio Durigan Junior  <sergiodj@redhat.com>
> 
> 	PR tui/25126
> 	* gdb.base/cached-source-file.c: New file.
> 	* gdb.base/cached-source-file.exp: New file.
> 
> Change-Id: Ib1b074342ebe8613c6d1dfde631691ebdf6d81c6
> ---
>   gdb/testsuite/gdb.base/cached-source-file.c   | 43 ++++++++
>   gdb/testsuite/gdb.base/cached-source-file.exp | 99 +++++++++++++++++++
>   2 files changed, 142 insertions(+)
>   create mode 100644 gdb/testsuite/gdb.base/cached-source-file.c
>   create mode 100644 gdb/testsuite/gdb.base/cached-source-file.exp
> 
> diff --git a/gdb/testsuite/gdb.base/cached-source-file.c b/gdb/testsuite/gdb.base/cached-source-file.c
> new file mode 100644
> index 0000000000..6f62c29799
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/cached-source-file.c
> @@ -0,0 +1,43 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2020 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/>.  */
> +
> +/* Test for PR tui/25126.
> +
> +   The bug is about a regression that makes GDB not reload its source
> +   code cache when the inferior's symbols are reloaded, which leads to
> +   wrong backtraces/listings.
> +
> +   This bug is reproducible even without using the TUI.
> +
> +   The .exp testcase depends on the line numbers and contents from
> +   this file  If you change this file, make sure to double-check the
> +   testcase.  */
> +
> +#include <stdio.h>
> +
> +void
> +foo (void)
> +{
> +  printf ("hello\n"); /* break-here */
> +}
> +
> +int
> +main ()
> +{
> +  foo ();
> +  return 0;
> +}
> diff --git a/gdb/testsuite/gdb.base/cached-source-file.exp b/gdb/testsuite/gdb.base/cached-source-file.exp
> new file mode 100644
> index 0000000000..f6e5f081f0
> --- /dev/null
> +++ b/gdb/testsuite/gdb.base/cached-source-file.exp
> @@ -0,0 +1,99 @@
> +# Copyright (C) 2020 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/>.
> +
> +# Test for PR tui/25126.
> +#
> +# The bug is about a regression that makes GDB not reload its source
> +# code cache when the inferior's symbols are reloaded, which leads to
> +# wrong backtraces/listings.
> +#
> +# This bug is reproducible even without using the TUI.
> +
> +standard_testfile
> +
> +# Only run on native boards.
> +if { [use_gdb_stub] || [target_info gdb_protocol] == "extended-remote" } {
> +    return -1
> +}
> +
> +# Because we need to modify the source file later, it's better if we
> +# just copy it to our output directory (instead of messing with the
> +# user's source directory).
> +set newsrc [standard_output_file $testfile].c
> +file copy -force -- $srcdir/$subdir/$srcfile $newsrc
> +set srcfile $newsrc
> +
> +if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
> +    return -1
> +}
> +
> +# Get the line number for the line with the "break-here" marker.
> +set bp_line [gdb_get_line_number "break-here" $srcfile]
> +
> +gdb_assert { [runto "$srcfile:$bp_line"] } \
> +    "run to $srcfile:$bp_line"
> +
> +# Do a "list" and check that the printed line matches the line of the
> +# original source file.
> +gdb_test_no_output "set listsize 1"
> +gdb_test "list" "$bp_line\[ \t\]+printf \\(\"hello\\\\n\"\\); /\\* break-here \\*/" \
> +    "check the first version of the source file"
> +
> +# Modify the original source file, and add an extra line into it.
> +# This only works locally because of the TCL commands.
> +set bkpsrc [standard_output_file $testfile].c.bkp
> +set bkpsrcfd [open $bkpsrc w]
> +set srcfd [open $srcfile r]
> +
> +while { [gets $srcfd line] != -1 } {
> +    if { [string first "break-here" $line] != -1 } {
> +	# Put a "printf" line before the "break-here" line.
> +	puts $bkpsrcfd "  printf (\"foo\\n\"); /* new-marker */"
> +    }
> +    puts $bkpsrcfd $line
> +}
> +
> +close $bkpsrcfd
> +close $srcfd
> +file rename -force -- $bkpsrc $srcfile
> +# Here, we have to wait 1 second because of the way GDB keeps track to
> +# check whether the binary has changed or not.  GDB uses stat(2) and
> +# currently checks 'st_mtime', whose precision is measured in
> +# seconds.  Since the whole file-copying/rename operation can take
> +# less than 1 second, GDB can mistakenly assume that the binary is
> +# still the same if we don't wait here.
> +sleep 1
> +
> +# Recompile the modified source.  We use "gdb_compile" here instead of
> +# "prepare_for_testing" because we don't want to call "clean_restart".
> +if { [gdb_compile "${srcfile}" "${binfile}" executable {debug}] != "" } {
> +    return -1
> +}
> +
> +# Rerun the program.  This should not only force GDB to reload the
> +# source cache, but also to break at BP_LINE again, which now has
> +# different contents.
> +gdb_test_multiple "run" "rerun program" {
> +    -re {The program being debugged has been started already\.\r\nStart it from the beginning\? \(y or n\) $} {
> +	set binregex [string_to_regexp $binfile]
> +	gdb_test "y" "\\`$binregex\\' has changed; re-reading symbols\.\r\nStarting program: ${binregex}.*" \
> +	    "rerun program"
> +    }
> +}
> +
> +# Again, perform the listing and check that the line indeed has
> +# changed for GDB.
> +gdb_test "list" "${bp_line}\[ \t\]+printf \\(\"foo\\\\n\"\\); /\\\* new-marker \\\*/.*" \
> +    "verify that the source code is properly reloaded"
> 

Thanks. I have no further comments on this one.