bin/83347: [patch] improper handling of malloc failures within libc's vfprintf

[Bruce Evans]

On Mon, 17 Dec 2007 das at FreeBSD.org wrote:

> State-Changed-Why:
> If malloc fails, the program will SIGBUS on the next line anyway, so
> there's no need to call abort(). This situation can only arise if the
> programmer has asked printf() to handle a very long and bizarre series
> of positional arguments after exhausting all available virtual memory,
> so hopefully this won't be a big deal.

Er, printf() is not permitted to either dump core or call abort() due
to resource shortages.

This is handled correctly in __wcsconv() -- __wcsconv() uses malloc()
only internally and returns NULL on malloc failure; it can fail for
other reasons and all failures become error returns for _vfprintf().

This is handled incorrectly by the horrible arg table extension.  It
aborts on malloc failure in 2 cases (on actually reallocf) and follows
the null pointer in one other case.

I prefer following the NULL pointer to aborting.  It gives core dumps
that aren't messed up by abort()'s frames and doesn't waste space doing
wrong error handling.

Anyway, malloc() never ;-) fails, and when it does misconfigured
MALLOC_OPTIONS (with A) often breaks precisely the programs that
actually handle malloc failure correctly; in vfprintf it just makes
the broken code more unreachable than with malloc "never" failing.

Bruce