Fix for 917770: Use of uninitialized value in substitution (s///) at pt-config-diff line 1996

This turned out to be two bugs mangled into one.

First, _parse_varvals can deal with (var, undef), but not with (undef).
This is a problem because two of the trhee spots that call
_parse_varvals can return undef because of this:

      map  { $_ =~ m/^([^=]+)(?:=(.*))?$/ }
      grep { $_ !~ m/^\s*#/ }  # no # comment lines
      split("\n", $mysqld_section)

The problem is twofold. First, we are not skipping empty or
whitespace-only lines. That means that the map will fail,
and pass an undef to _parse_varvals. So this ended up in
a triple fix: Make _parse_varvals deal with a sole undef,
skip empty/whitespace lines, and change that map to

	map  { $_ =~ m/^([^=]+)(?:=(.*))?$/ ? ($1, $2) : () }

so even if the regex fails in the future, no sole undef
will be passed down the chain.

bin/pt-config-diff

@@ -2168,7 +2168,9 @@ sub parse_my_print_defaults {
    my ($output) = @args{@required_args};
 
    my ($config, $dupes) = _parse_varvals(
-      map { $_ =~ m/^--([^=]+)(?:=(.*))?$/ } split("\n", $output)
+      map  { $_ =~ m/^--([^=]+)(?:=(.*))?$/ ? ($1, $2) : () }
+      grep { $_ !~ m/^\s*$/ }  # no empty lines
+      split("\n", $output)
    );
 
    return $config, $dupes;
@@ -2186,7 +2188,8 @@ sub parse_option_file {
    die "Failed to parse the [mysqld] section" unless $mysqld_section;
 
    my ($config, $dupes) = _parse_varvals(
-      map  { $_ =~ m/^([^=]+)(?:=(.*))?$/ }
+      map  { $_ =~ m/^([^=]+)(?:=(.*))?$/ ? ($1, $2) : () }
+      grep { $_ !~ m/^\s*$/ }  # no empty lines
       grep { $_ !~ m/^\s*#/ }  # no # comment lines
       split("\n", $mysqld_section)
    );
@@ -2206,6 +2209,9 @@ sub _parse_varvals {
    my $val;  # value for current variable
    ITEM:
    foreach my $item ( @varvals ) {
+      if ( !defined($item) ) {
+         $item = '';
+      }
       if ( $item ) {
          $item =~ s/^\s+//;
          $item =~ s/\s+$//;

lib/MySQLConfig.pm

@@ -288,7 +288,9 @@ sub parse_my_print_defaults {
 
    # Parse the "--var=val" lines.
    my ($config, $dupes) = _parse_varvals(
-      map { $_ =~ m/^--([^=]+)(?:=(.*))?$/ } split("\n", $output)
+      map  { $_ =~ m/^--([^=]+)(?:=(.*))?$/ ? ($1, $2) : () }
+      grep { $_ !~ m/^\s*$/ }  # no empty lines
+      split("\n", $output)
    );
 
    return $config, $dupes;
@@ -309,7 +311,8 @@ sub parse_option_file {
 
    # Parse the "var=val" lines.
    my ($config, $dupes) = _parse_varvals(
-      map  { $_ =~ m/^([^=]+)(?:=(.*))?$/ }
+      map  { $_ =~ m/^([^=]+)(?:=(.*))?$/ ? ($1, $2) : () }
+      grep { $_ !~ m/^\s*$/ }  # no empty lines
       grep { $_ !~ m/^\s*#/ }  # no # comment lines
       split("\n", $mysqld_section)
    );
@@ -336,6 +339,11 @@ sub _parse_varvals {
    my $val;  # value for current variable
    ITEM:
    foreach my $item ( @varvals ) {
+      # We were passed an undef for the value, or we're dealing with an empty
+      # line
+      if ( !defined($item) ) {
+         $item = '';
+      }
       if ( $item ) {
          # Strip leading and trailing whitespace.
          $item =~ s/^\s+//;

t/lib/MySQLConfig.t

@@ -9,7 +9,7 @@ BEGIN {
 use strict;
 use warnings FATAL => 'all';
 use English qw(-no_match_vars);
-use Test::More tests => 30;
+use Test::More;
 
 use MySQLConfig;
 use DSNParser;
@@ -827,6 +827,30 @@ SKIP: {
    );
 }
 
+# #############################################################################
+# Use of uninitialized value in substitution (s///) at pt-config-diff line 1996
+# https://bugs.launchpad.net/percona-toolkit/+bug/917770
+# #############################################################################
+
+$config = eval {
+   new MySQLConfig(
+      file                => "$trunk/t/pt-config-diff/samples/bug_917770.cnf",
+      TextResultSetParser => $trp,
+   );
+};
+
+is(
+   $EVAL_ERROR,
+   '',
+   "Bug 917770: Lives ok on lines with just spaces"
+);
+
+is(
+   $config->format(),
+   'option_file',
+   "Detect option_file type"
+);
+
 # #############################################################################
 # Done.
 # #############################################################################
@@ -841,4 +865,5 @@ like(
    '_d() works'
 );
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+done_testing;
 exit;

t/pt-config-diff/samples/bug_917770.cnf

@@ -0,0 +1,31 @@
+[client]
+user     = msandbox
+password = msandbox
+port     = PORT
+socket   = /tmp/PORT/mysql_sandboxPORT.sock
+
+[mysqld]
+port                       = PORTa
+socket                     = /tmp/PORT/mysql_sandboxPORT.sock
+pid-file                   = /tmp/PORT/data/mysql_sandboxPORT.pid
+basedir                    = PERCONA_TOOLKIT_SANDBOX
+datadir                    = /tmp/PORT/data
+key_buffer_size            = 16M
+innodb_buffer_pool_size    = 16M
+innodb_data_home_dir       = /tmp/PORT/data
+innodb_log_group_home_dir  = /tmp/PORT/data
+innodb_data_file_path      = ibdata1:10M:autoextend
+innodb_log_file_size       = 5M
+log-bin                    = mysql-bin
+relay_log                  = mysql-relay-bin
+log_slave_updates
+server-id                  = PORT
+report-host                = 127.0.0.1
+report-port                = PORT
+log-error                  = /tmp/PORT/data/mysqld.log
+innodb_lock_wait_timeout   = 3
+general_log
+general_log_file           = genlog
+# These next two lines have a space in them, and trigger the bug
+ 
+