svn commit: r206637 - in head: sbin/ifconfig share/man/man4 sys/net

[Xin LI]

Author: delphij
Date: Wed Apr 14 22:02:19 2010
New Revision: 206637
URL: http://svn.freebsd.org/changeset/base/206637

Log:
  When an underlying ioctl(2) handler returns an error, our ioctl(2)
  interface considers that it hits a fatal error, and will not copyout
  the request structure back for _IOW and _IOWR ioctls, keeping them
  untouched.
  
  The previous implementation of the SIOCGIFDESCR ioctl intends to
  feed the buffer length back to userland.  However, if we return
  an error, the feedback would be defeated and ifconfig(8) would
  trap into an infinite loop.
  
  This commit changes SIOCGIFDESCR to set buffer field to NULL to
  indicate the previous ENAMETOOLONG case.
  
  Reported by:	bschmidt
  MFC after:	2 weeks

Modified:
  head/sbin/ifconfig/ifconfig.c
  head/share/man/man4/netintro.4
  head/sys/net/if.c

Modified: head/sbin/ifconfig/ifconfig.c
==============================================================================
--- head/sbin/ifconfig/ifconfig.c	Wed Apr 14 21:59:22 2010	(r206636)
+++ head/sbin/ifconfig/ifconfig.c	Wed Apr 14 22:02:19 2010	(r206637)
@@ -922,19 +922,20 @@ status(const struct afswtch *afp, const 
 			ifr.ifr_buffer.buffer = descr;
 			ifr.ifr_buffer.length = descrlen;
 			if (ioctl(s, SIOCGIFDESCR, &ifr) == 0) {
-				if (strlen(descr) > 0)
-					printf("\tdescription: %s\n", descr);
-				break;
-			} else if (errno == ENAMETOOLONG)
-				descrlen = ifr.ifr_buffer.length;
-			else
-				break;
-		} else {
+				if (ifr.ifr_buffer.buffer == descr) {
+					if (strlen(descr) > 0)
+						printf("\tdescription: %s\n",
+						    descr);
+				} else if (ifr.ifr_buffer.length > descrlen) {
+					descrlen = ifr.ifr_buffer.length;
+					continue;
+				}
+			}
+		} else
 			warn("unable to allocate memory for interface"
 			    "description");
-			break;
-		}
-	};
+		break;
+	}
 
 	if (ioctl(s, SIOCGIFCAP, (caddr_t)&ifr) == 0) {
 		if (ifr.ifr_curcap != 0) {

Modified: head/share/man/man4/netintro.4
==============================================================================
--- head/share/man/man4/netintro.4	Wed Apr 14 21:59:22 2010	(r206636)
+++ head/share/man/man4/netintro.4	Wed Apr 14 22:02:19 2010	(r206637)
@@ -32,7 +32,7 @@
 .\"     @(#)netintro.4	8.2 (Berkeley) 11/30/93
 .\" $FreeBSD$
 .\"
-.Dd January 26, 2010
+.Dd April 14, 2010
 .Dt NETINTRO 4
 .Os
 .Sh NAME
@@ -292,8 +292,11 @@ field of
 struct passed in as parameter, and the length would include
 the terminating nul character.
 If there is not enough space to hold the interface length,
-no copy would be done and an
-error would be returned.
+no copy would be done and the
+.Va buffer
+field of
+.Va ifru_buffer
+would be set to NULL.
 The kernel will store the buffer length in the
 .Va length
 field upon return, regardless whether the buffer itself is

Modified: head/sys/net/if.c
==============================================================================
--- head/sys/net/if.c	Wed Apr 14 21:59:22 2010	(r206636)
+++ head/sys/net/if.c	Wed Apr 14 22:02:19 2010	(r206637)
@@ -2049,14 +2049,13 @@ ifhwioctl(u_long cmd, struct ifnet *ifp,
 	case SIOCGIFDESCR:
 		error = 0;
 		sx_slock(&ifdescr_sx);
-		if (ifp->if_description == NULL) {
-			ifr->ifr_buffer.length = 0;
+		if (ifp->if_description == NULL)
 			error = ENOMSG;
-		} else {
+		else {
 			/* space for terminating nul */
 			descrlen = strlen(ifp->if_description) + 1;
 			if (ifr->ifr_buffer.length < descrlen)
-				error = ENAMETOOLONG;
+				ifr->ifr_buffer.buffer = NULL;
 			else
 				error = copyout(ifp->if_description,
 				    ifr->ifr_buffer.buffer, descrlen);