Method test_splice_offset_out

Lib/test/test_os.py:594–633

(self)

    @unittest.skipUnless(hasattr(os, 'splice'), 'test needs os.splice()')
    @requires_splice_pipe
    def test_splice_offset_out(self):
        TESTFN4 = os_helper.TESTFN + ".4"
        data = b'0123456789'
        bytes_to_copy = 6
        out_seek = 3

        create_file(os_helper.TESTFN, data)
        self.addCleanup(os_helper.unlink, os_helper.TESTFN)

        read_fd, write_fd = os.pipe()
        self.addCleanup(lambda: os.close(read_fd))
        self.addCleanup(lambda: os.close(write_fd))
        os.write(write_fd, data)

        out_file = open(TESTFN4, 'w+b')
        self.addCleanup(os_helper.unlink, TESTFN4)
        self.addCleanup(out_file.close)
        out_fd = out_file.fileno()

        try:
            i = os.splice(read_fd, out_fd, bytes_to_copy, offset_dst=out_seek)
        except OSError as e:
            # Handle the case in which Python was compiled
            # in a system with the syscall but without support
            # in the kernel.
            if e.errno != errno.ENOSYS:
                raise
            self.skipTest(e)
        else:
            # The number of copied bytes can be less than
            # the number of bytes originally requested.
            self.assertIn(i, range(0, bytes_to_copy+1));

            with open(TESTFN4, 'rb') as in_file:
                read = in_file.read()
            # seeked bytes (5) are zero'ed
            self.assertEqual(read[:out_seek], b'\x00'*out_seek)
            # 012 are skipped (in_skip)
            # 345678 are copied in the file (in_skip + bytes_to_copy)
            self.assertEqual(read[out_seek:], data[:i])


# Test attributes on return values from os.*stat* family.