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Date:      Sun, 9 Feb 2003 02:47:05 -0500 (EST)
From:      Mikhail Teterin <mi@aldan.algebra.com>
To:        FreeBSD-gnats-submit@FreeBSD.org
Subject:   bin/48114: gethostname(3) can leave the wrong errno
Message-ID:  <200302090747.h197l5k0044333@aldan.algebra.com>

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>Number:         48114
>Category:       bin
>Synopsis:       gethostname(3) can leave the wrong errno
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Feb 09 12:00:24 PST 2003
>Closed-Date:
>Last-Modified:
>Originator:     Mikhail Teterin
>Release:        FreeBSD 5.0-CURRENT i386
>Organization:
Virtual Estates, Inc.
>Environment:
System: FreeBSD aldan.algebra.com 5.0-CURRENT FreeBSD 5.0-CURRENT #2:
Sat Feb 8
18:55:41 EST 2003 root@aldan.algebra.com:/ccd/obj/ccd/src/sys/DEBUG i386

>Description:

	gethostname(3) is known and documented to set errno to the
	special ENAMETOOLONG in case of the insufficient buffer size.
	However, sysctl(3)'s value for this case is ENOMEM. As a result,
	errno after an unsuccessful call to gethostname(3) may have a
	value unexpected by an application. See, for example,

	http://www.FreeBSD.org/cgi/query-pr.cgi?pr=ports/30298

>How-To-Repeat:

>Fix:

        How about the following?

cvs server: Diffing .
Index: gethostname.c
===================================================================
RCS file: /home/ncvs/src/lib/libc/gen/gethostname.c,v
retrieving revision 1.3
diff -U2 -r1.3 gethostname.c
--- gethostname.c	22 Mar 2002 21:52:05 -0000	1.3
+++ gethostname.c	9 Feb 2003 07:43:33 -0000
@@ -52,6 +52,9 @@
 	mib[1] = KERN_HOSTNAME;
 	size = namelen;
-	if (sysctl(mib, 2, name, &size, NULL, 0) == -1)
+	if (sysctl(mib, 2, name, &size, NULL, 0) == -1) {
+		if (errno == ENOMEM)
+			errno = ENAMETOOLONG;
 		return (-1);
+	}
 	return (0);
 }
>Release-Note:
>Audit-Trail:
>Unformatted:

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