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 a5c7ae71495a6c80a5b5006c6befb85b420afab2..1231c10fc3c70b2e35ff0f2169d80ecd6edf2611 100644 (file)
--- a/src/test/perl/TestLib.pm
+++ b/src/test/perl/TestLib.pm
@@ -96,7 +96,7 @@ BEGIN
        if ($windows_os)
        {
                require Win32API::File;
-               Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle setFilePointer));
+               Win32API::File->import(qw(createFile OsFHandleOpen CloseHandle));
        }
 }
 
@@ -272,33 +272,33 @@ 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;
 }