wireguard-openbsd/lib/libc/stdio, branch master

For the snprintf range check demo, add a (size_t) cast in the right place

2021-04-01T14:27:47Z

which will satisfy the toughest compiler options

article fixes; from eddie youseph

2021-02-02T07:33:29Z

The printf format string component %n is a nearly turning-complete gadget.

2020-10-27T21:06:57Z

Largely considered attack surface nowadays. The benefit provided by %n is completely overshadowed by the risk. New uses of %n don't seem to be entering the C ecosystem, as static tools flag them. And everyone points fingers at those people.... The list of programs (and libraries) which use %n is therefore finite and shrinking. Most of the %n use comes out of the GNU ecosystem. jca@ has convinced gnulib to fix their code (so we need to wait for software including gnulib to make new releases). A few libraries have moved ahead of us and become more strict. Some n longer permit %n (for instance, andriod bionic). Others log the occurance. Some log and abort if the output location is W|X (MacOS). Our base tree is clean. The ports tree contains a handful during build time, and unknown count (more) during runtime. We would like to abort programs on any occurance of %n. Or we could be like MacOS, aborting for W|X pages (but would need a system call which can check that condition, and that introduces addressspace knowledge we don't want attackers to know, and may be a poor tradeoff). For now, we can syslog, to increase awareness, and involve more people in the greater community to remove %n uses. [If %n is at the end, use the *printf return value. If it occurs in the middle, split the printf calls into multiples] Hopefully one day, we can just abort() when %n happens. Help us get there? ok jca, plus naddy for ports team

Spell out n as en for consistency with other parts of the page.

2020-09-13T12:58:08Z

%lln is percent ell ell n (not dee).

2020-09-13T11:55:53Z

OK deraadt@

Fix append mode so it always writes to the end and expand regress.

2020-08-17T16:17:39Z

OK deraadt@ martijn@

Fix handling of "w+" mode, we were only truncating for "w".

2020-08-14T12:00:33Z

OK martijn@ mpi@

adjust %n description to vaguely say "pointer", becuase the following

2020-07-10T17:04:18Z

list of "[size]n" includes "n" on it's own, thereby the "int" case is described correctly. ok schwarze

As suggested by deraadt@, rewrite most of the printf(3) manual page

2020-07-10T14:43:18Z

to properly show the (differing) syntaxes of all the conversion specifications, and reduce the amount of forward references from the list of modifiers to the list of specifiers. While here, properly explain %lc and %ls. Also correct RETURN VALUES, which incorrectly talked about counting characters while actually bytes are counted. Using feedback from millert@, deraadt@, tb@, and Martin Vahlensieck. OK deraadt@, millert@, and tb@ on intermediate versions of this diff and no objections from jmc@.

Minor tweaks in the description of %g:

2020-07-06T17:24:59Z

1. Clarify that %G uses %F, not %f; noticed by millert@. 2. Mention that %g originally meant "general notation", see: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/libc/stdio/doprnt.s Triggered by a somewhat different patch from Ian . Feedback and OK millert@ and jmc@.