kern: devctl: add devctl_safe_quote_sb_len

[kevans]

Summary

This will be used momentarily to support quoting strings that aren't
guaranteed to be NUL terminated, but may have a length we can use.

[imp]

sys/kern/subr_bus.c

898

I'd be happier with < len here.

904

How arbitrary? The function you copied this from assumes no newlines in the string either. Is that a possibility with your intended use case?

[kevans]

sys/kern/subr_bus.c

904

Nah, if an ssid contains non-printable characters (< ' ') we typically resort to hex output for the entire ssid -- and we do resort to hex output in the future caller.

[kevans]

<

[kevans]

Wrong review...

[imp]

OK. I'm sold on this one.

[imp]

On second thought, please update devctl_safe_quote_sb.9 for this alternative interface.

[kevans]

Update manpage

[pauamma_gundo.com]

share/man/man9/devctl_safe_quote_sb.9

52

Or maybe "a quoted string".

57–59

My C is very rusty, but the source code, to me, reads like len is applied to the source string, not the buffer, which would have to hold up to 2*len characters, for a string that contains only \ or " characters. Can you clarify which is intended?

[imp]

share/man/man9/devctl_safe_quote_sb.9

52

"protocol requires a quoted string to have these special characters quoted."

is likely better.

57–59

sbuf automatically grows the size of the buffer, so you don't have to manage these things.

[pauamma_gundo.com]

share/man/man9/devctl_safe_quote_sb.9

57–59

sbuf automatically grows the size of the buffer, so you don't have to manage these things.

That bit of the manual page says that len is a limit applied to the buffer. My (admittedly very rusty) C tells me the source code is applying that limit to the source string. You said the buffer doesn't need it, and that's consistent with how I read the source code, but the inconsistency with the manual page still needs to be addressed.

[kevans]

share/man/man9/devctl_safe_quote_sb.9

57–59

This was based in the verbiage of the comment above the function:

* @param src	Original buffer.

[kevans]

share/man/man9/devctl_safe_quote_sb.9

57–59

(arguably, it's not a string anymore if it's not guaranteed to be NUL terminated)

How about I just change it to
.Va src
instead?

[pauamma_gundo.com]

share/man/man9/devctl_safe_quote_sb.9

57–59

That WFM.

[kevans]

share/man/man9/devctl_safe_quote_sb.9

52

I went with roughly this latest version, though I think "[...] escaped." makes more sense to me, since we're not actually further quoting anything but rather escaping existing quotes and escaping previous escapes.

[kevans]

Updates

[pauamma_gundo.com]

Manual page LGTM now. I can't vouch for consistency with the source code beyond the one point I raised.