build: improved handling of <execinfo.h>, BSD <net/if.h>

FreeBSD and OpenBSD have a <net/if.h> that is not self-contained;
and mingw lacks the header altogether.  But gnulib has just taken
care of that for us, so we might as well simplify our code.  In
the process, I got a syntax-check failure if we don't also take
the gnulib execinfo module.

* .gnulib: Update to latest, for execinfo and net_if.
* bootstrap.conf (gnulib_modules): Add execinfo and net_if modules.
* configure.ac: Let gnulib check for headers.  Simplify check for
'struct ifreq', while also including enough prereq headers.
* src/internal.h (IF_NAMESIZE): Drop, now that gnulib guarantees it.
* src/nwfilter/nwfilter_learnipaddr.h: Use correct header for
IF_NAMESIZE.
* src/util/virnetdev.c (includes): Assume <net/if.h> exists.
* src/util/virnetdevbridge.c (includes): Likewise.
* src/util/virnetdevtap.c (includes): Likewise.
* src/util/logging.c (includes): Assume <execinfo.h> exists.
(virLogStackTraceToFd): Handle gnulib's fallback implementation.

.gnulib

@@ -1 +1 @@
-Subproject commit 271dd74fdf54ec2a03e73a5173b0b5697f6088f1
+Subproject commit 440a1dbe523e37f206252cb034c3a62f26867e42

bootstrap.conf

@@ -38,6 +38,7 @@ count-one-bits
 crypto/md5
 dirname-lgpl
 environ
+execinfo
 fclose
 fcntl
 fcntl-h
@@ -70,6 +71,7 @@ manywarnings
 mkstemp
 mkstemps
 mktempd
+net_if
 netdb
 nonblocking
 openpty

configure.ac

@@ -186,8 +186,7 @@ LIBS=$old_libs
 dnl Availability of various common headers (non-fatal if missing).
 AC_CHECK_HEADERS([pwd.h paths.h regex.h sys/un.h \
   sys/poll.h syslog.h mntent.h net/ethernet.h linux/magic.h \
-  sys/un.h sys/syscall.h netinet/tcp.h ifaddrs.h libtasn1.h \
-  net/if.h execinfo.h])
+  sys/un.h sys/syscall.h netinet/tcp.h ifaddrs.h libtasn1.h])
 
 dnl We need to decide at configure time if libvirt will use real atomic
 dnl operations ("lock free") or emulated ones with a mutex.
@@ -245,20 +244,12 @@ AM_CONDITIONAL([WITH_ATOMIC_OPS_PTHREAD],[test "$atomic_ops" = "pthread"])
 AC_MSG_RESULT([$atomic_ops])
 
 
-
-AC_MSG_CHECKING([for struct ifreq in net/if.h])
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
-   [[
+AC_CHECK_TYPE([struct ifreq],
+  [AC_DEFINE([HAVE_STRUCT_IFREQ],[1],
+    [Defined if struct ifreq exists in net/if.h])],
+  [], [[#include <sys/socket.h>
         #include <net/if.h>
-   ]],
-   [[
-     struct ifreq ifr;
-   ]])],[
-     AC_DEFINE([HAVE_STRUCT_IFREQ],[],[Defined if struct ifreq existsin net/if.h])
-     AC_MSG_RESULT([yes])
-   ],[
-     AC_MSG_RESULT([yes])
-   ])
+  ]])
 
 dnl Our only use of libtasn1.h is in the testsuite, and can be skipped
 dnl if the header is not present.  Assume -ltasn1 is present if the

src/internal.h

@@ -58,10 +58,6 @@
 #  define HOST_NAME_MAX 256
 # endif
 
-# ifndef IF_NAMESIZE
-#  define IF_NAMESIZE 16
-# endif
-
 # ifndef INET_ADDRSTRLEN
 #  define INET_ADDRSTRLEN 16
 # endif

src/nwfilter/nwfilter_learnipaddr.h

@@ -2,6 +2,7 @@
  * nwfilter_learnipaddr.h: support for learning IP address used by a VM
  *                         on an interface
  *
+ * Copyright (C) 2012 Red Hat, Inc.
  * Copyright (C) 2010 IBM Corp.
  * Copyright (C) 2010 Stefan Berger
  *
@@ -26,6 +27,7 @@
 # define __NWFILTER_LEARNIPADDR_H
 
 # include "conf/nwfilter_params.h"
+# include <net/if.h>
 
 enum howDetect {
   DETECT_DHCP = 1,

src/util/logging.c

@@ -31,12 +31,10 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <signal.h>
+#include <execinfo.h>
 #if HAVE_SYSLOG_H
 # include <syslog.h>
 #endif
-#ifdef HAVE_EXECINFO_H
-# include <execinfo.h>
-#endif
 
 #include "virterror_internal.h"
 #include "logging.h"
@@ -792,23 +790,21 @@ cleanup:
 
 static void virLogStackTraceToFd(int fd)
 {
-#ifdef HAVE_EXECINFO_H
     void *array[100];
     int size;
-
-# define STRIP_DEPTH 3
-
-    size = backtrace(array, ARRAY_CARDINALITY(array));
-    backtrace_symbols_fd(array +  STRIP_DEPTH, size - STRIP_DEPTH, fd);
-    ignore_value(safewrite(fd, "\n", 1));
-#else
     static bool doneWarning = false;
     const char *msg = "Stack trace not available on this platform\n";
-    if (!doneWarning) {
+
+#define STRIP_DEPTH 3
+    size = backtrace(array, ARRAY_CARDINALITY(array));
+    if (size) {
+        backtrace_symbols_fd(array +  STRIP_DEPTH, size - STRIP_DEPTH, fd);
+        ignore_value(safewrite(fd, "\n", 1));
+    } else if (!doneWarning) {
         ignore_value(safewrite(fd, msg, strlen(msg)));
         doneWarning = true;
     }
-#endif
+#undef STRIP_DEPTH
 }
 
 static int virLogOutputToFd(const char *category ATTRIBUTE_UNUSED,

src/util/virnetdev.c

@@ -32,9 +32,7 @@
 #include "logging.h"
 
 #include <sys/ioctl.h>
-#ifdef HAVE_NET_IF_H
 #include <net/if.h>
-#endif
 #include <fcntl.h>
 
 #ifdef __linux__

src/util/virnetdevbridge.c

@@ -31,10 +31,8 @@
 
 #include <sys/ioctl.h>
 #include <sys/socket.h>
-
-#ifdef HAVE_NET_IF_H
 #include <net/if.h>
-#endif
+
 #ifdef __linux__
 # include <linux/sockios.h>
 # include <linux/param.h>     /* HZ                 */
@@ -47,7 +45,7 @@
 #define VIR_FROM_THIS VIR_FROM_NONE
 
 
-#if defined(HAVE_NET_IF_H) && defined(SIOCBRADDBR)
+#ifdef SIOCBRADDBR
 static int virNetDevSetupControlFull(const char *ifname,
                                      struct ifreq *ifr,
                                      int domain,

src/util/virnetdevtap.c

@@ -35,9 +35,7 @@
 #include "util.h"
 
 #include <sys/ioctl.h>
-#ifdef HAVE_NET_IF_H
 #include <net/if.h>
-#endif
 #include <fcntl.h>
 #ifdef __linux__
 # include <linux/if_tun.h>    /* IFF_TUN, IFF_NO_PI */