mount(8): Add libxo(3) support

[me_cameronkatri.com]

Test Plan

• Text output is the same.

[me_cameronkatri.com]

Use no quote modifier on dump and pass.

[me_cameronkatri.com]

Add full context.

[otis]

sbin/mount/mount.c

156

Aren't these lines (151, 152) a suitable candidate for a macro?

[me_cameronkatri.com]

Open the mount container before any calls to xo_errx
Use a macro to close the container, finish and exit.

[imp]

I think the xo_emit() stuff is right, but I'm not sure.
The rest of the stuff seems good, modulo my comments.

sbin/mount/mount.c

69

Minor nit: I'd align all the \ if they aren't already (it's hard to tell with phab sometimes, but I think there's a tab missing)

257

This doesn't make any sense. Negative return values from main are weird.
Better to do a xo_errx(1, "Can't parse arges") (or w/o the xo_ prefix if this isn't allowed). Return '1' if there's already an error message printed so it isn't doubled.

675

this is indented too far. It should just be tab 4-spaces.

[me_cameronkatri.com]

Check argc after xo_parse_args().

[me_cameronkatri.com]

Revert last diff (uploaded to wrong differential)

[me_cameronkatri.com]

Fix some styling.

[me_cameronkatri.com]

sbin/mount/mount.c

69

This looks aligned in vim with freebsd.vim.

[pstef]

sbin/mount/mount.c

711

I'm not sure I understand the purpose of this, as asprintf will allocate the buffer and set fsidbuf to point to it.

714–718

Probably should check the return value of asprintf.

914

Should we update usage()?

[me_cameronkatri.com]

Check the return value of asprintf.

[me_cameronkatri.com]

sbin/mount/mount.c

711

If I don't do this, when using --libxo json the fsid will start with (null), I'm sure there is a better way to stop that but this worked.

914

Should we update usage()?

It doesn't look like any other commands show --libxo in their usage.

[pstef]

sbin/mount/mount.c

711

There are some 32-bit ints in fsid_t and we want to interpret them as unsigned bytes and print using hexadecimal representation. So it's a matter of calculating the needed space once and using that space in a loop, like this:

		if (sfp->f_fsid.val[0] != 0 || sfp->f_fsid.val[1] != 0) {
			xo_emit("{D:, }{Lw:fsid}");
			fsidbuf = malloc(sizeof(sfp->f_fsid) * 2 + 1);
			if (fsidbuf == NULL)
				xo_errx(1, "malloc failed");
			for (i = 0; i < sizeof(sfp->f_fsid); i++)
				sprintf(&fsidbuf[i * 2], "%02x",
				    ((u_char *)&sfp->f_fsid)[i]);
			fsidbuf[i * 2] = '\0';
			xo_emit("{:fsid}", fsidbuf);
			free(fsidbuf);
		}

[pstef]

sbin/mount/mount.c

711

And then it seems the two xo_emit() calls can be folded into xo_emit("{D:, }{Lw:fsid}{:fsid}", fsidbuf);

[me_cameronkatri.com]

Change fsid allocation. Thanks pstef.

[phil]

xo_parse_args gives error messages for invalid arguments; no further error is needed.

https://libxo.readthedocs.io/en/latest/api.html?#parsing-command-line-arguments-xo-parse-args

argc = xo_parse_args(argc, argv);
if (argc < 0)
    exit(EXIT_FAILURE);

Also looks like you've lost the space in "write: sync". Use "{Lwc:writes}{P: }{Lw:sync}".

Could you please give me more details about your comment "If I don't do this, when using --libxo json the fsid will start with (null),", since we don't want that to be happening?

Thanks,
Phil

[phil]

One more thing: Does libxo need an xo_exit() function? It would be just xo_finish + exit, like your EXIT macro, but might help minimize diffs like this.

Thanks,
Phil

[me_cameronkatri.com]

In D30341#727179, @phil wrote:

Also looks like you've lost the space in "write: sync". Use "{Lwc:writes}{P: }{Lw:sync}".

diff -u <(sudo /usr/obj/usr/src/amd64.amd64/sbin/mount/mount -v) <(sudo mount -v) doesn't show any difference between the outputs before and after this commit.

[pstef]

In D30341#727179, @phil wrote:

Could you please give me more details about your comment "If I don't do this, when using --libxo json the fsid will start with (null),", since we don't want that to be happening?

That was about a previous version of this diff and it had more to do with memory management and strings than with libxo.