Fix TestLib::slurp_file() with offset on windows.

3c5b0685b921 used setFilePointer() to set the position of the filehandle, but
passed the wrong filehandle, always leaving the position at 0. Instead of just
fixing that, remove use of setFilePointer(), we have a perl fd at this point,
so we can just use perl's seek().

Additionally, the perl filehandle wasn't closed, just the windows filehandle.

Reviewed-By: Andrew Dunstan <andrew@dunslane.net>
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20211003173038.64mmhgxctfqn7wl6@alap3.anarazel.de
Backpatch: 9.6-, like 3c5b0685b921

diff --git a/src/test/perl/TestLib.pm b/src/test/perl/TestLib.pm
index 151c7a4cce506198159247a9caaadcd4cafcd24a..f466def1d709dda7975f1b85aac6a23642bbe279 100644 (file)
--- a/src/test/perl/TestLib.pm
+++ b/src/test/perl/TestLib.pm
@@ -82,7 +82,7 @@ BEGIN
    if ($windows_os)
    {
        require Win32API::File;
-       Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle setFilePointer));
+       Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle));
    }
 }
 
@@ -234,33 +234,33 @@ sub slurp_file
    my ($filename, $offset) = @_;
    local $/;
    my $contents;
+   my $fh;
+
+   # On windows open file using win32 APIs, to allow us to set the
+   # FILE_SHARE_DELETE flag ("d" below), otherwise other accesses to the file
+   # may fail.
    if ($Config{osname} ne 'MSWin32')
    {
-       open(my $in, '<', $filename)
+       open($fh, '<', $filename)
          or die "could not read \"$filename\": $!";
-       if (defined($offset))
-       {
-           seek($in, $offset, SEEK_SET)
-             or die "could not seek \"$filename\": $!";
-       }
-       $contents = <$in>;
-       close $in;
    }
    else
    {
        my $fHandle = createFile($filename, "r", "rwd")
          or die "could not open \"$filename\": $^E";
-       OsFHandleOpen(my $fh = IO::Handle->new(), $fHandle, 'r')
+       OsFHandleOpen($fh = IO::Handle->new(), $fHandle, 'r')
          or die "could not read \"$filename\": $^E\n";
-       if (defined($offset))
-       {
-           setFilePointer($fh, $offset, qw(FILE_BEGIN))
-             or die "could not seek \"$filename\": $^E\n";
-       }
-       $contents = <$fh>;
-       CloseHandle($fHandle)
-         or die "could not close \"$filename\": $^E\n";
    }
+
+   if (defined($offset))
+   {
+       seek($fh, $offset, SEEK_SET)
+         or die "could not seek \"$filename\": $!";
+   }
+
+   $contents = <$fh>;
+   close $fh;
+
    $contents =~ s/\r\n/\n/g if $Config{osname} eq 'msys';
    return $contents;
 }