From: Guy Harris <guy@alum.mit.edu>
Date: Sun, 14 Nov 2010 20:23:40 +0000 (-0800)
Subject: Make sure we can link with libpcap.
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/10dd5e6486f845ce3b9e7b0ab12fea728abf445d

Make sure we can link with libpcap.

After finding libpcap and getting a list of other flags needed when
linking, we check for "pcap_loop()", to make sure we found a working
libpcap and have all the right other libraries with which dnl to link.
(Otherwise, for example, the check for pcap_list_datalinks() will fail,
not because the routines are missing from the library, but because we
aren't linking properly with libpcap, and that will cause confusing
errors at build time.)
---

diff --git a/aclocal.m4 b/aclocal.m4
index 40b58664..1c3affab 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -417,6 +417,21 @@ AC_DEFUN(AC_LBL_LIBPCAP,
 	esac
     fi
 
+    dnl
+    dnl Check for "pcap_loop()", to make sure we found a working
+    dnl libpcap and have all the right other libraries with which
+    dnl to link.  (Otherwise, the checks below will fail, not
+    dnl because the routines are missing from the library, but
+    dnl because we aren't linking properly with libpcap, and
+    dnl that will cause confusing errors at build time.)
+    dnl
+    AC_CHECK_FUNC(pcap_loop,,
+	[
+	    AC_MSG_ERROR(
+[Report this to tcpdump-workers@tcpdump.org, and include the
+config.log file in your report])
+	])
+
     dnl
     dnl Check for "pcap_list_datalinks()", "pcap_set_datalink()",
     dnl and "pcap_datalink_name_to_val()", and use substitute versions
diff --git a/configure b/configure
index ff3fa692..92d67a08 100755
--- a/configure
+++ b/configure
@@ -9700,6 +9700,100 @@ echo "${ECHO_T}yes" >&6; }
 	esac
     fi
 
+                                    { echo "$as_me:$LINENO: checking for pcap_loop" >&5
+echo $ECHO_N "checking for pcap_loop... $ECHO_C" >&6; }
+if test "${ac_cv_func_pcap_loop+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+/* Define pcap_loop to an innocuous variant, in case <limits.h> declares pcap_loop.
+   For example, HP-UX 11i <limits.h> declares gettimeofday.  */
+#define pcap_loop innocuous_pcap_loop
+
+/* System header to define __stub macros and hopefully few prototypes,
+    which can conflict with char pcap_loop (); below.
+    Prefer <limits.h> to <assert.h> if __STDC__ is defined, since
+    <limits.h> exists even on freestanding compilers.  */
+
+#ifdef __STDC__
+# include <limits.h>
+#else
+# include <assert.h>
+#endif
+
+#undef pcap_loop
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char pcap_loop ();
+/* The GNU C library defines this for functions which it implements
+    to always fail with ENOSYS.  Some functions are actually named
+    something starting with __ and the normal name is an alias.  */
+#if defined __stub_pcap_loop || defined __stub___pcap_loop
+choke me
+#endif
+
+int
+main ()
+{
+return pcap_loop ();
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext &&
+       $as_test_x conftest$ac_exeext; then
+  ac_cv_func_pcap_loop=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv_func_pcap_loop=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
+      conftest$ac_exeext conftest.$ac_ext
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_func_pcap_loop" >&5
+echo "${ECHO_T}$ac_cv_func_pcap_loop" >&6; }
+if test $ac_cv_func_pcap_loop = yes; then
+  :
+else
+
+	    { { echo "$as_me:$LINENO: error: Report this to tcpdump-workers@tcpdump.org, and include the
+config.log file in your report" >&5
+echo "$as_me: error: Report this to tcpdump-workers@tcpdump.org, and include the
+config.log file in your report" >&2;}
+   { (exit 1); exit 1; }; }
+
+fi
+
+
                         { echo "$as_me:$LINENO: checking for pcap_list_datalinks" >&5
 echo $ECHO_N "checking for pcap_list_datalinks... $ECHO_C" >&6; }
 if test "${ac_cv_func_pcap_list_datalinks+set}" = set; then