[Bug 282576] Memory leak in sysctlbyname FreeBSD 14.1-RELEASE-p5 GENERIC x64

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=282576

Dag-Erling Smørgrav <des@FreeBSD.org> changed:

           What    |Removed                     |Added
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                 CC|                            |des@FreeBSD.org

--- Comment #3 from Dag-Erling Smørgrav <des@FreeBSD.org> ---
The “leak” isn't even in sysctlbyname(), which never allocates memory; it's in
printf().  You get the exact same result from this program:

    int main(void) { printf("Hello, world!\n"); }

Simply put, by default, the first time you try to print to stdout, libc will
allocate a 4 kB buffer which is never freed.  Adding the following line at the
top of your program renders stdout unbuffered and prevents the “leak”:

    setbuf(stdout, NULL);

Valgrind incorrectly reports the allocation as having occurred in vfprintf_l().
 It actually takes place in __smakebuf().  I suspect valgrind gets confused
because large parts of stdio are implemented as macros and inline functions for
performance reasons.

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