no reason to include sys/random.h all the time (#684)

External integrations don't need sys/random.h in order to compile, remove the dependency.  Try to fix building on legacy MacOS versions.

Fixes Issue: #682
Fix By: Brad House (@bradh352)

CMakeLists.txt

@@ -186,6 +186,7 @@ CARES_FUNCTION_IN_LIBRARY (clock_gettime rt HAVE_LIBRT)
 
 
 # Look for necessary includes
+CHECK_INCLUDE_FILES (AvailabilityMacros.h  HAVE_AVAILABILITYMACROS_H)
 CHECK_INCLUDE_FILES (sys/types.h           HAVE_SYS_TYPES_H)
 CHECK_INCLUDE_FILES (sys/random.h          HAVE_SYS_RANDOM_H)
 CHECK_INCLUDE_FILES (sys/socket.h          HAVE_SYS_SOCKET_H)
@@ -300,6 +301,7 @@ MACRO (CARES_EXTRAINCLUDE_IFSET var include)
 	ENDIF ()
 ENDMACRO ()
 
+CARES_EXTRAINCLUDE_IFSET (HAVE_AVAILABILITYMACROS_H AvailabilityMacros.h)
 CARES_EXTRAINCLUDE_IFSET (HAVE_STDBOOL_H      stdbool.h)
 CARES_EXTRAINCLUDE_IFSET (HAVE_SYS_TYPES_H    sys/types.h)
 CARES_EXTRAINCLUDE_IFSET (HAVE_ARPA_INET_H    arpa/inet.h)
@@ -633,9 +635,6 @@ ENDIF ()
 IF (HAVE_SYS_TYPES_H)
 	SET (CARES_HAVE_SYS_TYPES_H 1)
 ENDIF ()
-IF (HAVE_SYS_RANDOM_H)
-	SET (CARES_HAVE_SYS_RANDOM_H 1)
-ENDIF()
 IF (HAVE_SYS_SOCKET_H)
 	SET (CARES_HAVE_SYS_SOCKET_H 1)
 ENDIF()

configure.ac

@@ -409,6 +409,7 @@ dnl check for a few basic system headers we need
 AC_CHECK_HEADERS(
        malloc.h \
        memory.h \
+       AvailabilityMacros.h \
        sys/types.h \
        sys/time.h \
        sys/select.h \
@@ -469,6 +470,9 @@ dnl *Sigh* these are needed in order for net/if.h to get properly detected.
 cares_all_includes="
 #include <stdio.h>
 #include <stdlib.h>
+#ifdef HAVE_AVAILABILITYMACROS_H
+#  include <AvailabilityMacros.h>
+#endif
 #ifdef HAVE_SYS_UIO_H
 #  include <sys/uio.h>
 #endif
@@ -756,9 +760,6 @@ dnl ares_build.h.in specific defines
 if test "x$ac_cv_header_sys_types_h" = "xyes" ; then
   CARES_DEFINE_UNQUOTED([CARES_HAVE_SYS_TYPES_H],[1])
 fi
-if test "x$ac_cv_header_sys_random_h" = "xyes" ; then
-  CARES_DEFINE_UNQUOTED([CARES_HAVE_SYS_RANDOM_H],[1])
-fi
 if test "x$ac_cv_header_sys_socket_h" = "xyes" ; then
   CARES_DEFINE_UNQUOTED([CARES_HAVE_SYS_SOCKET_H],[1])
 fi

include/ares_build.h.cmake

@@ -12,7 +12,6 @@
  * files.  We need to include some dependent headers that may be system specific
  * for C-Ares */
 #cmakedefine CARES_HAVE_SYS_TYPES_H
-#cmakedefine CARES_HAVE_SYS_RANDOM_H
 #cmakedefine CARES_HAVE_SYS_SOCKET_H
 #cmakedefine CARES_HAVE_WINDOWS_H
 #cmakedefine CARES_HAVE_WS2TCPIP_H
@@ -25,10 +24,6 @@
 #  include <sys/types.h>
 #endif
 
-#ifdef CARES_HAVE_SYS_RANDOM_H
-#  include <sys/random.h>
-#endif
-
 #ifdef CARES_HAVE_SYS_SOCKET_H
 #  include <sys/socket.h>
 #endif

include/ares_build.h.in

@@ -12,7 +12,6 @@
  * files.  We need to include some dependent headers that may be system specific
  * for C-Ares */
 #undef CARES_HAVE_SYS_TYPES_H
-#undef CARES_HAVE_SYS_RANDOM_H
 #undef CARES_HAVE_SYS_SOCKET_H
 #undef CARES_HAVE_WINDOWS_H
 #undef CARES_HAVE_WS2TCPIP_H
@@ -25,10 +24,6 @@
 #  include <sys/types.h>
 #endif
 
-#ifdef CARES_HAVE_SYS_RANDOM_H
-#  include <sys/random.h>
-#endif
-
 #ifdef CARES_HAVE_SYS_SOCKET_H
 #  include <sys/socket.h>
 #endif

src/lib/ares_config.h.cmake

@@ -182,6 +182,9 @@
 /* Define to 1 if you have the memory.h header file. */
 #cmakedefine HAVE_MEMORY_H
 
+/* Define to 1 if you have the AvailabilityMacros.h header file. */
+#cmakedefine HAVE_AVAILABILITYMACROS_H
+
 /* Define to 1 if you have the MSG_NOSIGNAL flag. */
 #cmakedefine HAVE_MSG_NOSIGNAL
 

src/lib/ares_rand.c

@@ -28,6 +28,13 @@
 #include "ares.h"
 #include "ares_private.h"
 #include <stdlib.h>
+
+/* Older MacOS versions require including AvailabilityMacros.h before
+ * sys/random.h */
+#ifdef HAVE_AVAILABILITYMACROS_H
+#  include <AvailabilityMacros.h>
+#endif
+
 #ifdef HAVE_SYS_RANDOM_H
 #  include <sys/random.h>
 #endif

src/lib/setup_once.h

@@ -95,10 +95,6 @@
 #  endif
 #endif
 
-#ifdef HAVE_SYS_RANDOM_H
-#  include <sys/random.h>
-#endif
-
 #ifdef HAVE_SYS_SOCKET_H
 #  include <sys/socket.h>
 #endif