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 71a500564a44526d629de29891f0dbd93488bac0..d609f025d9ca8e7a77b0306d5100d1302b0f2aa8 100644 (file)
--- a/src/test/perl/TestLib.pm
+++ b/src/test/perl/TestLib.pm
@@ -90,7 +90,7 @@ BEGIN
    if ($windows_os)
    {
        require Win32API::File;
-       Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle setFilePointer));
+       Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle));
    }
 }
 
@@ -259,33 +259,33 @@ 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;
 }