[Toybox] [PATCH] macOS: replace local strnstr with strcasestr.

[enh]

On Mon, Dec 3, 2018 at 11:33 AM Rob Landley <rob at landley.net> wrote:
>
> On 12/3/18 12:00 PM, enh wrote:
> > amusingly, the same line causes a (different) compile-time warning
> > with old versions of glibc. glibc 2.15 at least has mktemp marked as
> > warn_unused_result, and AOSP currently uses glibc 2.15 for host
> > builds. i've sent a patch to fix that (and attached the same patch
> > here too, in case the spam filter is still messing with you :-) ).
>
> I enabled the header rewrite whatsis in the list plumbing and that seems to have
> fixed the worst of it.
>
> I was looking at doing my own mktemp with xgetrandom() but the x part says
> "denial of service attack/exploit waiting to happen" when a script calls
> NAME=$(mktemp) and gets an empty string with some discarded stderr output...
>
> If bionic and musl _both_ don't warn about it, it's a glibc bug. Still annoying,
> but I'll leave it for now and check if I still feel like trying to do something
> about it during pre-release cleanup...

well:

* POSIX 1003.1-2008 removed mktemp(3).

* musl has no compile-time deprecation/warn_unused_result warnings for anything.

* bionic _does_ have a compile-time deprecation warning for mktemp
because _most_ callers shouldn't use it (and POSIX did remove it, even
if it seems unlikely that any libc will remove it any time soon).
mktemp(1) -u/--dry-run just happens to be a weird exception where two
wrongs make a right.

* glibc doesn't have a compile-time deprecation warning because it's
guarded behind "are we pre-2008 POSIX?".

* glibc does have a link-time deprecation warning.

* old glibc did have a compile-time warn_unused_result warning, but
apparently they've thought better of that since and removed the
attribute.

so it's all just a big mess, really :-)

(and, yes, i have seen uses that can't actually write to the directory
--- the basic [anti-]pattern seems to be "there's something exposed
via something like /proc, i want a unique name in that namespace, but
there's some other mechanism for creating the thing than mkdir(2)". as
far as i can tell, these are tests rather than production code.)

> > someone's looking at upgrading the host glibc, but 2.15 is just inside
> > the 7-year rule. plus i assume you'll be happy to save a line anyway.
> > i'm not sure why i didn't write it as one line in the first place...
> > even i don't find it obfuscatory in this case.
>
> Applied.

thanks.

> Rob