>Number: 146889
>Category: misc
>Synopsis: Not having NET_RT_IFLIST #defined causes getifaddrs.c (libc)
>to fail to build
>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 May 23 22:07:08 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator: Haven Hash
>Release: 8.0 Release
>Organization:
>Environment:
FreeBSD hashbsd 8.0-RELEASE FreeBSD 8.0-RELEASE #0: Sat Nov 21 15:48:17 UTC
2009 [email protected]:/usr/obj/usr/src/sys/GENERIC i386
>Description:
Very minor issue that is most likely completely ignorable, but since I had a
patch that seems to work I figured I'd put it here in case anyone else ever hit
this.
The getifaddrs() libc call does its magic by default by using the NET_RT_IFLIST
sysctl call, however it also looks to attempt to support another method using
the SIOCGIFCONF ioctl call. It prefers the sysctl method unless the
NET_RT_IFLIST #define is not defined. I had reason to want to use the
SIOCGIFCONF ioctl method so I undefined NET_RT_IFLIST in
lib/libc/net/getifaddrs.c (right after the first #ifdef check) however this
causes the getifaddrs.c file to fail to build. The build errors are slight
issues concerning variables only being declared inside the NET_RT_IFLIST ifdef
blocks and the need for one additional header file (unistd.h) in the #else
code. This looks to have always been the case (non-NET_RT_IFLIST code fails to
build) and maybe the right thing to do is to just remove all of the
non-NET_RT_IFLIST code? (given that is does not build it is unlikely anyone
uses it).
>How-To-Repeat:
Edit lib/libc/net/getifaddrs.c and add the following: #undef NET_RT_IFLIST
in between current lines 40 and 41 (immediately after the first #ifdef
NET_RT_IFLIST) to simulate building getifaddrs.c without this define.
Try to rebuild libc and you will see build errors in getifaddrs.c because some
variables are only declared inside #ifdef NET_RT_IFLIST specific code, but are
used outside of #ifdef NET_RT_IFLIST code.
>Fix:
Attached patch works for me.
It puts the declaration of the ifa and ift variables into non-#ifdef
NET_RT_IFLIST code, removes the variable m since it is not used, moves the
declaration of the len and alen variables into #ifdef NET_RT_IFLIST specific
code since that is the only code they are used in and adds the unistd.h include
because #else code makes use of a _close() call that prevented it from building
without this header.
To reiterate this is only helpful for the very rare case that someone would
like getifaddrs() to not use the NET_RT_IFLIST sysctl method to obtain
interface addresses from the kernel, since the getifaddrs() code looks to
support two methods this seems like something it is attempting to support,
however the second method currently fails to build. The NET_RT_IFLIST sysctl
method is definitely preferred (i.e. for instance the ioctl alternative will
not get you netmasks as the ifreq struct it gets back from the kernel does not
contain a netmask field).
Patch attached with submission follows:
Index: lib/libc/net/getifaddrs.c
===================================================================
--- lib/libc/net/getifaddrs.c (revision 208457)
+++ lib/libc/net/getifaddrs.c (working copy)
@@ -44,6 +44,7 @@
#include <net/if_dl.h>
#endif
+#include <unistd.h>
#include <errno.h>
#include <ifaddrs.h>
#include <stdlib.h>
@@ -97,6 +98,7 @@
int ntry = 0;
int mib[6];
size_t needed;
+ size_t len, alen;
char *buf;
char *next;
struct ifaddrs *cif = 0;
@@ -106,19 +108,18 @@
struct ifa_msghdr *ifam;
struct sockaddr_dl *dl;
struct sockaddr *sa;
- struct ifaddrs *ifa, *ift;
u_short idx = 0;
#else /* NET_RT_IFLIST */
char buf[1024];
- int m, sock;
+ int sock;
struct ifconf ifc;
struct ifreq *ifr;
struct ifreq *lifr;
#endif /* NET_RT_IFLIST */
int i;
- size_t len, alen;
char *data;
char *names;
+ struct ifaddrs *ifa, *ift;
#ifdef NET_RT_IFLIST
mib[0] = CTL_NET;
>Release-Note:
>Audit-Trail:
>Unformatted:
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-bugs
To unsubscribe, send any mail to "[email protected]"
