[LTP] [PATCH] syscalls/write06: Add new test

[Cyril Hrubis]

Hi!
> What I want to test is the following description of open(2) man-pages:
> 
> O_APPEND
>  ?????? ?? The file is opened in append mode.?? Before each write(2), the 
> file offset is positioned at the end of the file, as if with lseek(2).?? 
> The modification of the file offset and the write operation are 
> performed as a single atomic step.

Ah, now it makes much more sense.

I think part of the problem is that the code is actually confusing. I do
not like the l_seek() function at all, it's confusing at best because it
does several different things at the same time. So it would be much
better to write the offset check as:

	off = SAFE_LSEEK(fd, 1K, SEEK_SET)
	if (off != 1K)
		tst_brk(TBROK, "Failed to seek to 1K");

	SAFE_WRITE(1, fd, write_buf[1], K1);

	off = SAFE_LSEEK(fd, 0, SEEK_CUR);
	if (off != K3)
		tst_res(TFAIL, "Wrong offset after write %zu expected %u", off, K3)
	else
		tst_res(TPASS, "Offset is correct after write %zu", off);

	SAFE_FSTAT(fd, &statbuf);
	if (statbuf.st_size != K3) {
		tst_res(TFAIL, "Wrong file size after append %zu expected %u",
			statubuf.st_size, K3);
	} else {
		tst_res(TPASS, "Correct file size after append %u", K3);
	}


This makes it much clearer what happens here and the TPASS message
actually says what has passed...

-- 
Cyril Hrubis
chrubis@suse.cz