On Sun, Feb 25, 2007 at 11:36:34PM +0800, Moore Michael wrote: > Hi there > > I use net-snmp-5.4, and there's a NULL pointer operator in > snmplib/snmp_api.c > > void * > snmp_sess_pointer(netsnmp_session * session) > { > struct session_list *slp; > > snmp_res_lock(MT_LIBRARY_ID, MT_LIB_SESSION); > for (slp = Sessions; slp!=NULL; slp = slp->next) { > if (slp->session == session) { > > /* ^------------------- here for the loop end, slp=NULL > then slp->session illegal, or change the for loop to while loop; such as > while(slp!=NULL) { xxx; slp=slp->next; } */ > > break; > } > }
This code is perfectly valid: for (slp = Sessions; slp; slp = slp->next) { if (slp->session == session) { break; } } is the same as slp = Sessions; /* initialization part */ while ( slp != NULL ) /* test part */ { if ( slp->session == session ) break; slp = slp->next; /* increment part */ } In particular, the increment is not done until after the slp!=NULL test has been performed. Steve --- Stephen J Friedl | Security Consultant | UNIX Wizard | +1 714 544-6561 www.unixwiz.net | Tustin, Calif. USA | Microsoft MVP | [EMAIL PROTECTED] ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Net-snmp-coders mailing list Net-snmp-coders@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/net-snmp-coders