Include alloca.h if we have it.

Bug: 14552
Change-Id: I799691f7f33ca56748ed4e51d7d548f37769837b
Reviewed-on: https://code.wireshark.org/review/26611
Petri-Dish: Guy Harris <guy@alum.mit.edu>
Tested-by: Petri Dish Buildbot
Reviewed-by: Guy Harris <guy@alum.mit.edu>

ConfigureChecks.cmake

@@ -89,11 +89,25 @@ cmake_pop_check_state()
 
 check_function_exists("getopt_long"      HAVE_GETOPT_LONG)
 if(HAVE_GETOPT_LONG)
+	#
+	# The OS has getopt_long(), so it might have optreset.
+	# Do we have it?
+	#
 	if(HAVE_GETOPT_H)
 		check_symbol_exists("optreset" "getopt.h" HAVE_OPTRESET)
 	else()
 		check_symbol_exists("optreset"           HAVE_OPTRESET)
 	endif()
+else()
+	#
+	# The OS doesn't have getopt_long(), so we're using the GNU libc
+	# version that we have in wsutil.  It doesn't have optreset, so we
+	# don't need to check for it.
+	#
+	# However, it uses alloca(), so we may need to include alloca.h;
+	# check for it.
+	#
+	check_include_file("alloca.h"    HAVE_ALLOCA_H)
 endif()
 check_function_exists("getifaddrs"       HAVE_GETIFADDRS)
 check_function_exists("issetugid"        HAVE_ISSETUGID)

cmakeconfig.h.in

@@ -41,6 +41,9 @@
 /* Enable AirPcap */
 #cmakedefine HAVE_AIRPCAP 1
 
+/* Define to 1 if you have the <alloca.h> header file. */
+#cmakedefine HAVE_ALLOCA_H 1
+
 /* Define to 1 if you have the <arpa/inet.h> header file. */
 #cmakedefine HAVE_ARPA_INET_H 1
 

configure.ac

@@ -2309,16 +2309,26 @@ AC_CHECK_MEMBERS([struct sockaddr.sa_len],,,
                   #endif])
 
 AC_REPLACE_FUNCS(getopt_long)
-dnl
-dnl Do we have optreset?
-dnl
 if test "x$ac_cv_func_getopt_long" = xyes; then
+  #
+  # The OS has getopt_long(), so it might have optreset.  Do we have it?
+  #
   AC_CACHE_CHECK([whether optreset is defined], ac_cv_have_optreset,
     AC_LINK_IFELSE([AC_LANG_SOURCE([[extern int optreset;return optreset;]])],
         ac_cv_have_optreset=yes, ac_cv_have_optreset=no))
   if test "$ac_cv_have_optreset" = yes ; then
     AC_DEFINE(HAVE_OPTRESET, 1, [Define to 1 if you have the optreset variable])
   fi
+else
+  #
+  # The OS doesn't have getopt_long(), so we're using the GNU libc
+  # version that we have in wsutil.  It doesn't have optreset, so we
+  # don't need to check for it.
+  #
+  # However, it uses alloca(), so we may need to include alloca.h;
+  # check for it.
+  #
+  AC_CHECK_HEADERS(alloca.h)
 fi
 
 AC_REPLACE_FUNCS(strptime)

wsutil/getopt_long.c

@@ -64,6 +64,14 @@
 # define _(msgid)      (msgid)
 #endif
 
+/*
+ * If we have alloca.h, we assume we need it.
+ */
+#
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#endif
+
 #ifdef _WIN32
 #  define alloca _alloca
 #endif