Proper detection of installation directory and loading of plugins

SRC/configure.ac

@@ -271,8 +271,8 @@ fi
 
 interpolate() {  
   old=$1
+  AC_MSG_WARN(DEBUG-INTERPOLATE $old)
   eval new=$old
-  AC_MSG_WARN(DEBUG-INTERPOLATE $new)
   if test "$new" != "$old" ; then
 	interpolate $new
   else 
@@ -281,7 +281,20 @@ interpolate() {
 }
 dnl TODO: the following is broken because installation prefix can be changed at instal-time,
 dnl not compilation time.
-plugins_dir=`interpolate '$prefix/lib/echoping'`
+if test "x$libdir" = 'x${exec_prefix}/lib' ; then # Default value
+	if test "x$exec_prefix" = "xNONE" ; then # Default value
+		if test "x$prefix" = "xNONE" ; then # Default value
+  			plugins_dir=`interpolate '$ac_default_prefix/lib/echoping'`
+		else
+  			exec_prefix='${prefix}'	
+  			plugins_dir=`interpolate '$libdir/echoping'`
+		fi
+	else
+  		plugins_dir=`interpolate '$libdir/echoping'`
+	fi
+else
+	plugins_dir=`interpolate '$libdir/echoping'`
+fi
 AC_DEFINE_UNQUOTED(PLUGINS_DIR, "$plugins_dir", [Directory where the plugins will be installed])
 AC_CONFIG_SUBDIRS(plugins)
 AC_OUTPUT(Makefile)

SRC/echoping.c

@@ -84,7 +84,7 @@ main (argc, argv)
   unsigned int fill_i;
   unsigned short fill_requested = 0;
   unsigned int i = 0;
-  char *plugin_name = NULL;
+  char *plugin_name, *complete_plugin_name = NULL;
   char *ext;
   void *plugin;
   char *dl_result;
@@ -120,8 +120,6 @@ main (argc, argv)
 
   unsigned short stop_at_newlines = 1;
 
-  char *newenv, *curenv;
-
 #ifdef OPENSSL
   SSL_METHOD *meth;
   SSL_CTX *ctx = NULL;
@@ -436,17 +434,16 @@ main (argc, argv)
       ext = strstr(plugin_name, ".so");
       if ((ext == NULL) || (strcmp (ext, ".so") != 0)) 
 	sprintf (plugin_name, "%s.so", plugin_name);
-      curenv = getenv ("LD_LIBRARY_PATH");
-      if (! curenv)
-	newenv = PLUGINS_DIR;
-      else
-	sprintf (newenv, "%s:%s", curenv, PLUGINS_DIR);
-      if (setenv ("LD_LIBRARY_PATH", newenv, 1) == -1)
-	  err_sys ("Cannot change LD_LIBRARY_PATH");
       plugin = dlopen (plugin_name, RTLD_NOW);
+      if (!plugin) { /* retries with the absolute name */
+	complete_plugin_name = (char *) malloc(MAX_LINE);
+	sprintf (complete_plugin_name, "%s/%s", PLUGINS_DIR, plugin_name);
+	plugin = dlopen (complete_plugin_name, RTLD_NOW);
+      }
       if (!plugin)
 	{
-	  err_sys ("Cannot load \"%s\": %s", plugin_name, dlerror ());
+	  err_sys ("Cannot load \"%s\" (I tried the short name, then the complete name in \"%s\"): %s", 
+		   plugin_name, PLUGINS_DIR, dlerror ());
 	}
       plugin_init = dlsym (plugin, "init");
       dl_result = dlerror ();