Add check for unix socket path truncation

Don't allow unix socket path to be truncated 

mysql-test/lib/My/Platform.pm

@@ -20,7 +20,8 @@ use strict;
 
 use base qw(Exporter);
 our @EXPORT= qw(IS_CYGWIN IS_WINDOWS IS_WIN32PERL
-		native_path posix_path mixed_path);
+		native_path posix_path mixed_path
+                check_socket_path_length);
 
 BEGIN {
   if ($^O eq "cygwin") {
@@ -50,6 +51,15 @@ BEGIN {
   }
 }
 
+BEGIN {
+  if (eval "use IO::Socket::UNIX; 1") {
+    eval 'sub HAVE_UNIX_SOCKET { 1 }';
+  }
+  else {
+    eval 'sub HAVE_UNIX_SOCKET { 0 }';
+  }
+}
+
 
 #
 # native_path
@@ -91,5 +101,33 @@ sub posix_path {
 }
 
 
+sub check_socket_path_length {
+  my ($path)= @_;
+  my $truncated= 0;
+
+  if (HAVE_UNIX_SOCKET){
+    require IO::Socket::UNIX;
+
+    my $sock = new IO::Socket::UNIX
+    (
+     Local => $path,
+     Listen => 1,
+    ) or die $!;
+    if ($path ne $sock->hostpath()){
+      # Path was truncated
+      $truncated= 1;
+      # Output diagnostic messages
+      print "path: '$path', length: ", length($path) ,"\n";
+      print "hostpath: '", $sock->hostpath(),
+	"', length: ", length($sock->hostpath()), "\n";
+    }
+    $sock= undef;
+    unlink($path);
+    return $truncated;
+  };
+  # All paths OK!
+  return $truncated;
+}
+
 
 1;

mysql-test/mysql-test-run.pl

@@ -606,6 +606,15 @@ sub command_line_setup {
   $opt_tmpdir=       "$opt_vardir/tmp" unless $opt_tmpdir;
   $opt_tmpdir =~ s,/+$,,;       # Remove ending slash if any
 
+  # On some operating systems, there is a limit to the length of a
+  # UNIX domain socket's path far below PATH_MAX.
+  # Don't allow that to happen
+  if (check_socket_path_length("$opt_tmpdir/testsocket.sock")){
+    mtr_error("Socket path '$opt_tmpdir' too long, it would be ",
+	      "truncated and thus not possible to use for connection to ",
+	      "MySQL Server. Set a shorter with --tmpdir=<path> option");
+  }
+
   # --------------------------------------------------------------------------
   # fast option
   # --------------------------------------------------------------------------
@@ -735,17 +744,6 @@ sub command_line_setup {
     $opt_user= "root"; # We want to do FLUSH xxx commands
   }
 
-  # On QNX, /tmp/dir/master.sock and /tmp/dir//master.sock seem to be
-  # considered different, so avoid the extra slash (/) in the socket
-  # paths.
-  my $sockdir = $opt_tmpdir;
-  $sockdir =~ s|/+$||;
-
-  # On some operating systems, there is a limit to the length of a
-  # UNIX domain socket's path far below PATH_MAX, so try to avoid long
-  # socket path names.
-  $sockdir = tempdir(CLEANUP => 0) if ( length($sockdir) >= 70 );
-
   $path_testlog=         "$opt_vardir/log/mysqltest.log";
   $path_current_testlog= "$opt_vardir/log/current_test";
 
@@ -1186,6 +1184,7 @@ sub environment_setup {
   $ENV{'MYSQL_TEST_DIR'}=     $glob_mysql_test_dir;
   $ENV{'MYSQLTEST_VARDIR'}=   $opt_vardir;
   $ENV{'DEFAULT_MASTER_PORT'}= $mysqld_variables{'master-port'} || 3306;
+  $ENV{'MYSQL_TMP_DIR'}=      $opt_tmpdir;
 
   # ----------------------------------------------------
   # Setup env for NDB