Perl如何知道从IO::Select::->can_read中读取句柄的字节数？

use IO::Select;

my $select = IO::Select->new();
$select->add($handle);

my @ready = $select->can_read(0);  # 设置超时时间为0，立即返回可读句柄列表

foreach my $handle (@ready) {
    my $buffer;
    my $bytes_read = sysread($handle, $buffer, 1024);  # 读取句柄的数据，最多读取1024字节
    if ($bytes_read) {
        print "Read $bytes_read bytes from the handle.\n";
    } elsif (defined $bytes_read) {
        print "End of file reached.\n";
    } else {
        print "Error reading from the handle: $!\n";
    }
}