Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com X-T2-Posting-ID: dCnToGxhL58ot4EWY8b+QGwMembwLoz1X2yB7MdtIiA= Date: Thu, 25 Aug 2005 23:34:22 +0200 From: Samuel Thibault To: cygwin@cygwin.com Cc: dave@mielke.cc Subject: strerror(), errno and syslog() Message-ID: <20050825213422.GQ7662@bouh.ens-lyon.fr> Mail-Followup-To: Samuel Thibault , cygwin@cygwin.com, dave@mielke.cc Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.9i-nntp Hi, This crashes (yes it's odd code, but it shouldn't crash): #include #include int main(void) { errno = -1; syslog(LOG_ERR,"foo"); } Indeed, one of the first things that vsyslog does is char *errtext = strerror (get_errno ()); int errlen = strlen (errtext); And it happens that the current implementation of strerror() returns NULL on invalid errno. This is not posix compliant: posix says that "strerror() shall map any value of type int to a message". GNU libc uses something like snprintf("Unknown error %d",errnoval); for instance. Furthermore, "Since no return value is reserved to indicate an error, an application wishing to check for error situations should set errno to 0, then call strerror(), then check errno.". So on error, strerror() should just set errno to whatever EFOO is suited, and return a message similar to GNU libc's. Regards, Samuel -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/