GNU bug report logs -
#58966
[Trunk] Xcode 14.1+ (and macOS 13.0+) deprecate sprintf()
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Message #56 received at 58966 <at> debbugs.gnu.org (full text, mbox):
On 2022-11-05 09:26, Stefan Kangas wrote:
> snprintf is part of the C99 standard, so I think we can always rely on
> it being there. Switching sounds like a good idea.
sprintf is also part of the C99 (and C17 and C23) standards, so "it's in
the standard" does not mean we need to switch away from sprintf.
While we're on the topic: sprintf and snprintf both have serious design
flaws, in that they cannot generate output longer than INT_MAX bytes,
and this contradicts the GNU design philosophy to avoid arbitrary
limits. Instead, code that needs low level formatting should use Emacs's
own esprintf family of functions, which don't have the INT_MAX limit.
(Often it's better for code to use Fformat etc. and generate a Lisp
string, which doesn't have that limit either.)
Admittedly we haven't always been good about this, as sprintf/snprintf
are standard and are tempting to use. It might be a good idea, though,
for someone to go through the code and see if there are any
INT_MAX-related bugs lurking in Emacs now due to its use of sprintf
and/or snprintf, and replace these calls with something better.
On 2022-11-04 20:12, Richard Stallman wrote:
> We could switch to snprintf, and define snprintf to call sprintf
> in systems where snprintf isn't available.
That wouldn't that easy to do, and would make code more awkward and slow
it down a bit. The current 3-line change to configure.ac is much
simpler. It's pretty implausible that Apple will make sprintf go away
entirely - and if Apple is foolish enough to do so, there are simple
workarounds for that that don't involve messing with our legacy code.
> It is possible to verify
> that sprintf did not overwrite the buffer.
Sorry, I don't know what this comment is trying to say.
In my experience, with a debugging runtime sprintf is better than
snprintf, as sprintf reliably reports bugs whereas snprintf silently
truncates and continues with hard-to-debug behavior occuring later. Of
course with traditional non-debugging runtimes one loses with sprintf,
but in practice it's a tradeoff often worth making.
This bug report was last modified 2 years and 220 days ago.
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