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Path: utzoo!mnetor!seismo!husc6!cmcl2!phri!roy
From: roy@phri.UUCP (Roy Smith)
Newsgroups: comp.unix.wizards
Subject: trouble with getpwuid(3) on SunOS-3.2
Message-ID: <2761@phri.UUCP>
Date: Tue, 30-Jun-87 15:36:23 EDT
Article-I.D.: phri.2761
Posted: Tue Jun 30 15:36:23 1987
Date-Received: Fri, 3-Jul-87 02:08:46 EDT
Reply-To: roy@phri.UUCP (Roy Smith)
Organization: Public Health Research Institute, NYC, NY
Lines: 84


	I've been having some strange problems with getpwuid(3) on a
Sun-3.2 system.  Here's a little program I wrote to demonstrate the
problem:

----------------
# include <pwd.h>
# include <stdio.h>

main ()
{
	int i;
	struct passwd *pw;
	extern int errno;

	i = getuid();
	printf ("i = %d, errno = %d\n", i, errno);
	perror ("");

	pw = getpwuid (i);
	printf ("pw = %#x, errno = %d\n", pw, errno);
	perror ("");

	if (pw != NULL)
		printf ("name = %s, dir = %s\n", pw->pw_name, pw->pw_dir);
}
----------------

	I've got Sun-3's running both 3.1 and 3.2.  Alanine is a 3.1
machine; inosine runs 3.2.  I can compile this program on either machine
and run it on the same machine with no problem.  If, however, I compile it
on alanine and run in on inosine (3.2 is supposed to run 3.[01] binaries),
I get:

inosine% pw.alanine
i = 101, errno = 0
Error 0
pw = 0, errno = 49
Can't assign requested address

	It correctly gets my uid, then the getpwuid() fails.  The kicker is
that if I login to another 3.2 machine and run the 3.1 binary, it works
fine (sort of; see below):

cytosine% pw.alanine
i = 101, errno = 0
Error 0
pw = 0x215ac, errno = 48
Address already in use		<-- huh?
name = roy, dir = /usr/goober/roy

	So, there is obviously something wrong with the way we have inosine
set up which allows 3.2 binaries using getpwuid to work properly, but not
3.1 binaries.  As far as I can tell, however, both inosine and cytosine are
configured the same.

	As long as the requested passwd entry is in the local /etc/passwd
(i.e. you don't need a yellow pages call), it works fine no matter what
machine I run it on; for example, a version of pw.c which has "getpwuid(7)"
hardwired into it (correctly) gives me back the local entry for ingres:

Error 0
pw = 0x215bc, errno = 0
name = ingres, dir = /usr/ingres

	I'm totally stumped.  What could I possibly have set up wrong on
inosine which would cause this behaviour?  Also, why do I get an "address
already in use" indication in errno when the getpwuid() call works?  I know
errno isn't cleared on non-error calls, but I don't understand where this
is comming from anyway.  It doesn't happen on non-yp calls (such as the
ingres version above).

	BTW, I got onto this because Adobe's "enscript" (a 3.0 binary
copied to the 3.2 server) started dumping core on inosine.  Some dbxing
showed that a getpwuid() call was failing, but enscript doesn't bother to
check for errors (grrrrr...) and later gets a segmentation violation
referencing through the null pointer that getpwuid() returns.

	The obvious and practical thing to do is to just recompile
everything under 3.2, but that's not very satisfying.
-- 
Roy Smith, {allegra,cmcl2,philabs}!phri!roy
System Administrator, Public Health Research Institute
455 First Avenue, New York, NY 10016