On Thu, Feb 05, 2015 at 03:52:24PM -0500, Rich Felker wrote:
> On Thu, Feb 05, 2015 at 09:42:08PM +0100, Denys Vlasenko wrote:
> > struct passwd *getpwent()
> > {
> > static char *line;
> > static struct passwd pw;
> > size_t size=0;
> > if (!f) f = fopen("/etc/passwd", "rbe");
> > if (!f) return 0;
> > return __getpwent_a(f, &pw, &line, &size);
> > }
> >
> > I would prefer that even "struct passwd" is malloced...
>
> I don't think it would make much practical difference. It could be
> changed though.
>
> > But more importantly, bbox can't optimize only for musl.
> > Other libc'es may have static line buffers there.
> >
> > And musl will eventually be forced to implement getpwent_r()
> > if it wants to be usable for more packages... so...
>
> getpwent_r makes no sense; the _r functions are for thread-safe
> versions of their corresponding legacy functions, but getpwent_r has
> inherent global state -- the iterator. Whoever made it just wasn't
> thinking. To make a correct interface like this the caller would need
> to have an iterator object to pass to the function, but I can't see
> much merit in inventing a new interface for this.
Besides having hidden global state, the man page notes:
Other systems use the prototype
struct passwd *getpwent_r(struct passwd *pwd, char *buf, int buflen);
or, better,
int getpwent_r(struct passwd *pwd, char *buf, int buflen, FILE **pw_fp);
In other words, according to the manpage, getpwent_r() is decidedly
unportable.
Per my investigations, Dragonfly/Net/FreeBSD seem to use the same
prototype as glibc; apparently Solaris uses the first alternate prototype;
and the last mentioned seems to be a reference to Tru64, which
uses pw_fp to keep track of its position instead of an iterator.
OpenBSD and MirBSD do not implement getpwent_r, as far as I can tell.
HTH,
Isaac Dunham
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