replace ENABLE_LIBCONFIG by HAVE_LIBCONFIG (use macro AC_CHECK_LIBdefault ACTION-IF-FOUND behavior)

fix unused write result in undefined HAVE_EXECINFO_H case

config.h

 /* config.h.  Generated from config.h.in by configure.  */
 /* config.h.in.  Generated from configure.ac by autoheader.  */
 
-/* enable libconfig */
-#define ENABLE_LIBCONFIG 1
-
 /* Define to 1 if you have the `alarm' function. */
 #define HAVE_ALARM 1
 
@@ -25,6 +22,9 @@
 /* Define to 1 if you have the <lauxlib.h> header file. */
 #define HAVE_LAUXLIB_H 1
 
+/* Define to 1 if you have the `config' library (-lconfig). */
+#define HAVE_LIBCONFIG 1
+
 /* Define to 1 if you have the `crypto' library (-lcrypto). */
 #define HAVE_LIBCRYPTO 1
 

config.h.in

 /* config.h.in.  Generated from configure.ac by autoheader.  */
 
-/* enable libconfig */
-#undef ENABLE_LIBCONFIG
-
 /* Define to 1 if you have the `alarm' function. */
 #undef HAVE_ALARM
 
@@ -24,6 +21,9 @@
 /* Define to 1 if you have the <lauxlib.h> header file. */
 #undef HAVE_LAUXLIB_H
 
+/* Define to 1 if you have the `config' library (-lconfig). */
+#undef HAVE_LIBCONFIG
+
 /* Define to 1 if you have the `crypto' library (-lcrypto). */
 #undef HAVE_LIBCRYPTO
 

configure

@@ -3562,14 +3562,16 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_config_config_init" >&5
 $as_echo "$ac_cv_lib_config_config_init" >&6; }
 if test "x$ac_cv_lib_config_config_init" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBCONFIG 1
+_ACEOF
 
-$as_echo "#define ENABLE_LIBCONFIG 1" >>confdefs.h
+  LIBS="-lconfig $LIBS"
 
 else
   as_fn_error $? "No libconfig found. Try --disable-libconfig" "$LINENO" 5
 fi
 
-    EXTRA_LIBS="${EXTRA_LIBS} -lconfig" ;
   fi
 
 else
@@ -3613,14 +3615,16 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_config_config_init" >&5
 $as_echo "$ac_cv_lib_config_config_init" >&6; }
 if test "x$ac_cv_lib_config_config_init" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBCONFIG 1
+_ACEOF
 
-$as_echo "#define ENABLE_LIBCONFIG 1" >>confdefs.h
+  LIBS="-lconfig $LIBS"
 
 else
   as_fn_error $? "No libconfig found. Try --disable-libconfig" "$LINENO" 5
 fi
 
-    EXTRA_LIBS="${EXTRA_LIBS} -lconfig" ;
 
 fi
 

configure.ac

@@ -35,13 +35,11 @@ AC_ARG_ENABLE(libconfig,[--enable-libconfig/--disable-libconfig],
     AC_MSG_RESULT([disabled])
   else
     AC_MSG_RESULT([enabled])
-    AC_CHECK_LIB([config],[config_init],AC_DEFINE(ENABLE_LIBCONFIG,1,[enable libconfig]),AC_MSG_ERROR([No libconfig found. Try --disable-libconfig]))
-    [EXTRA_LIBS="${EXTRA_LIBS} -lconfig" ; ]
+    AC_CHECK_LIB([config],[config_init],[],AC_MSG_ERROR([No libconfig found. Try --disable-libconfig]))
   fi 
   ],[
     AC_MSG_RESULT([enabled])
-    AC_CHECK_LIB([config],[config_init],AC_DEFINE(ENABLE_LIBCONFIG,1,[enable libconfig]),AC_MSG_ERROR([No libconfig found. Try --disable-libconfig]))
-    [EXTRA_LIBS="${EXTRA_LIBS} -lconfig" ; ]
+    AC_CHECK_LIB([config],[config_init],[],AC_MSG_ERROR([No libconfig found. Try --disable-libconfig]))
   ])
 
 AC_MSG_CHECKING([for liblua])

main.c

@@ -43,7 +43,7 @@
 #include <execinfo.h>
 #endif
 #include <signal.h>
-#ifdef ENABLE_LIBCONFIG
+#ifdef HAVE_LIBCONFIG
 #include <libconfig.h>
 #endif
 
@@ -247,7 +247,7 @@ void running_for_first_time (void) {
   }
 }
 
-#ifdef ENABLE_LIBCONFIG
+#ifdef HAVE_LIBCONFIG
 void parse_config_val (config_t *conf, char **s, char *param_name, const char *default_name, const char *path) {
   static char buf[1000]; 
   int l = 0;
@@ -433,7 +433,9 @@ void print_backtrace (void) {
 }
 #else
 void print_backtrace (void) {
-  write (1, "No libexec. Backtrace disabled\n", 32);
+  if (write (1, "No libexec. Backtrace disabled\n", 32) < 0) {
+    // Sad thing
+  }
 }
 #endif