New type. (glibtop_backend_module): New private type.

2000-01-12  Martin Baulig  <martin@home-of-linux.org>

	* include/glibtop/backend.h (glibtop_backend_entry): New type.
	(glibtop_backend_module): New private type.

	* lib/backend.c (glibtop_register_backend): This now takes a
	`glibtop_backend_entry' argument, not a `glibtop_backend_info' one.
	(glibtop_backend_by_id): Return a `glibtop_backend_entry' type,
	not a `glibtop_backend_info' one.
	(glibtop_backend_by_name): Likewise.

	* lib/init-backends.c: If we have libxml, read all `.backend' files
	in $(LIBGTOP_BACKEND_DIR), XML parse them and register them via
	`glibtop_backend_register'. This builds a list of all currently
	supported backends without actually loading them into memory.

	* lib/open-backend.c (glibtop_open_backend_l): GModule load the
	backend if it's not already in memory.

ChangeLog

@@ -1,3 +1,22 @@
+2000-01-12  Martin Baulig  <martin@home-of-linux.org>
+
+	* include/glibtop/backend.h (glibtop_backend_entry): New type.
+	(glibtop_backend_module): New private type.
+
+	* lib/backend.c (glibtop_register_backend): This now takes a
+	`glibtop_backend_entry' argument, not a `glibtop_backend_info' one.
+	(glibtop_backend_by_id): Return a `glibtop_backend_entry' type,
+	not a `glibtop_backend_info' one.
+	(glibtop_backend_by_name): Likewise.
+
+	* lib/init-backends.c: If we have libxml, read all `.backend' files
+	in $(LIBGTOP_BACKEND_DIR), XML parse them and register them via
+	`glibtop_backend_register'. This builds a list of all currently
+	supported backends without actually loading them into memory.
+
+	* lib/open-backend.c (glibtop_open_backend_l): GModule load the
+	backend if it's not already in memory.
+
 2000-01-12  Martin Baulig  <martin@home-of-linux.org>
 
 	* lib/init.c (glibtop_init_s): Comment out `_glibtop_init_hook_s'.

include/glibtop/backend.h

@@ -34,6 +34,8 @@
 BEGIN_LIBGTOP_DECLS
 
 typedef struct _glibtop_backend_info	glibtop_backend_info;
+typedef struct _glibtop_backend_entry	glibtop_backend_entry;
+typedef struct _glibtop_backend_module	glibtop_backend_module;
 typedef struct _glibtop_backend_private	glibtop_backend_private;
 
 typedef struct _glibtop_backend		glibtop_backend;
@@ -52,6 +54,29 @@ struct _glibtop_backend_info
     glibtop_call_vector *call_vector;
 };
 
+#ifdef _IN_LIBGTOP
+
+#include <gmodule.h>
+
+/* private structure */
+struct _glibtop_backend_module
+{
+    int refcount;
+    GModule *module;
+};
+
+#endif /* _IN_LIBGTOP */
+
+struct _glibtop_backend_entry
+{
+    char *name;
+    char *libtool_name;
+    char *shlib_name;
+
+    glibtop_backend_info *info;
+    glibtop_backend_module *_priv;
+};
+
 struct _glibtop_backend
 {
     glibtop_backend_info *info;
@@ -59,15 +84,15 @@ struct _glibtop_backend
 };
 
 long
-glibtop_register_backend (glibtop_backend_info *info);
+glibtop_register_backend (glibtop_backend_entry *entry);
 
 void
 glibtop_unregister_backend (long id);
 
-glibtop_backend_info *
+glibtop_backend_entry *
 glibtop_backend_by_id (long id);
 
-glibtop_backend_info *
+glibtop_backend_entry *
 glibtop_backend_by_name (const char *backend_name);
 
 void

lib/Makefile.am

@@ -9,6 +9,7 @@ libgtop_la_SOURCES		= init.c open.c close.c lib.c parameter.c \
 				  backend.c init-backends.c open-backend.c
 
 libgtop_la_LDFLAGS		= $(LT_VERSION_INFO)
+libgtop_la_LIBADD		= $(LIBGTOP_XML_LIB)
 
 glibtopdir			= $(includedir)/glibtop
 

lib/backend.c

@@ -33,7 +33,7 @@ static GHashTable *_glibtop_backend_list = NULL;
 static long _glibtop_backend_nr = 0;
 
 long
-glibtop_register_backend (glibtop_backend_info *info)
+glibtop_register_backend (glibtop_backend_entry *entry)
 {
     long id;
 
@@ -44,7 +44,7 @@ glibtop_register_backend (glibtop_backend_info *info)
 
     g_hash_table_insert (_glibtop_backend_list,
 			 GINT_TO_POINTER (id),
-			 info);
+			 entry);
 
     return id;
 }
@@ -56,7 +56,7 @@ glibtop_unregister_backend (long id)
 			 GINT_TO_POINTER (id));
 }
 
-glibtop_backend_info *
+glibtop_backend_entry *
 glibtop_backend_by_id (long id)
 {
     return g_hash_table_lookup (_glibtop_backend_list,
@@ -65,23 +65,23 @@ glibtop_backend_by_id (long id)
 
 typedef struct {
     const char *backend_name;
-    glibtop_backend_info *info;
+    glibtop_backend_entry *entry;
 } _find_by_name_param_t;
 
 static void
 find_by_name (gpointer key, gpointer value, gpointer user_data)
 {
     _find_by_name_param_t *param = (_find_by_name_param_t *) user_data;
-    glibtop_backend_info *info = (glibtop_backend_info *) value;
+    glibtop_backend_entry *entry = (glibtop_backend_entry *) value;
 
-    if (!info || !info->name || param->info)
+    if (!entry || !entry->name || param->entry)
 	return;
 
-    if (!strcmp (info->name, param->backend_name))
-	param->info = info;
+    if (!strcmp (entry->name, param->backend_name))
+	param->entry = entry;
 }
 
-glibtop_backend_info *
+glibtop_backend_entry *
 glibtop_backend_by_name (const char *backend_name)
 {
     _find_by_name_param_t param = { backend_name, NULL };
@@ -89,5 +89,5 @@ glibtop_backend_by_name (const char *backend_name)
     g_hash_table_foreach (_glibtop_backend_list,
 			  find_by_name, &param);
 
-    return param.info;
+    return param.entry;
 }

lib/init-backends.c

@@ -33,6 +33,18 @@ extern glibtop_backend_info glibtop_backend_server;
 extern glibtop_backend_info glibtop_backend_sysdeps;
 extern glibtop_backend_info glibtop_backend_common;
 
+#if HAVE_LIBXML
+
+#define LIBGTOP_XML_NAMESPACE	"http://www.home-of-linux.org/libgtop/1.1"
+
+#include <gnome-xml/parser.h>
+
+#include <dirent.h>
+
+static void _glibtop_init_gmodule_backends (const char *);
+
+#endif /* HAVE_LIBXML */
+
 void
 glibtop_init_backends (void)
 {
@@ -42,7 +54,147 @@ glibtop_init_backends (void)
 	return;
     backends_initialized = 1;
 
-    glibtop_register_backend (&glibtop_backend_server);
-    glibtop_register_backend (&glibtop_backend_sysdeps);
-    glibtop_register_backend (&glibtop_backend_common);
+#if HAVE_LIBXML
+    _glibtop_init_gmodule_backends (LIBGTOP_BACKEND_DIR);
+#endif
 }
+
+#if HAVE_LIBXML
+
+static gchar *
+_get_library_filename (xmlDocPtr doc, xmlNodePtr cur, const char *directory)
+{
+    char *filename = xmlNodeListGetString (doc, cur->childs, 1);
+    gchar *retval;
+
+    if (!filename)
+	return NULL;
+
+    /* already absolute */
+    if (filename [0] == '/')
+	retval = g_strdup (filename);
+    else
+	retval = g_strdup_printf ("%s/%s", directory, filename);
+
+    return retval;
+}
+
+static glibtop_backend_entry *
+_parseBackend (xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur, const char *dir)
+{
+    glibtop_backend_entry *ret = NULL;
+
+    /*
+     * allocate the struct
+     */
+    ret = g_new0 (glibtop_backend_entry, 1);
+
+    /* We don't care what the top level element name is */
+    cur = cur->childs;
+    while (cur != NULL) {
+        if ((!strcmp (cur->name, "Name")) && (cur->ns == ns))
+            ret->name = xmlNodeListGetString
+		(doc, cur->childs, 1);
+
+        if ((!strcmp (cur->name, "Location")) && (cur->ns == ns)) {
+	    xmlNodePtr sub = cur->childs;
+
+	    while (sub != NULL) {
+		if ((!strcmp (sub->name, "LibtoolName")) && (sub->ns == ns))
+		    ret->libtool_name = _get_library_filename (doc, sub, dir);
+		if ((!strcmp (sub->name, "ShlibName")) && (sub->ns == ns))
+		    ret->shlib_name = _get_library_filename (doc, sub, dir);
+
+		sub = sub->next;
+	    }
+	}
+
+        cur = cur->next;
+    }
+
+    return ret;
+}
+
+static void
+_glibtop_init_gmodule_backends (const char *directory)
+{
+    DIR *dir;
+    struct dirent *entry;
+
+    dir = opendir (directory);
+    if (!dir) return;
+
+    while ((entry = readdir (dir)) != NULL) {
+	size_t len = strlen (entry->d_name);
+	gchar *filename;
+	xmlDocPtr doc;
+	xmlNsPtr ns;
+	xmlNodePtr cur;
+
+	if (len < 8)
+	    continue;
+
+	if (strcmp (entry->d_name+len-8, ".backend"))
+	    continue;
+
+	filename = g_strdup_printf ("%s/%s", directory, entry->d_name);
+
+	doc = xmlParseFile (filename);
+
+	if (!doc) {
+	    g_warning ("Cannot parse %s", filename);
+	    g_free (filename);
+	    continue;
+	}
+
+	/* Make sure the document is of the right kind */
+
+	cur = xmlDocGetRootElement (doc);
+	if (!cur) {
+	    xmlFreeDoc (doc);
+	    g_free (filename);
+	    continue;
+	}
+
+	ns = xmlSearchNsByHref (doc, cur, LIBGTOP_XML_NAMESPACE);
+	if (!ns) {
+	    g_warning ("File %s of wrong type; LibGTop Namespace not found",
+		       filename);
+	    g_free (filename);
+	    xmlFreeDoc (doc);
+	    continue;
+	}
+
+	if (strcmp (cur->name, "Backends")) {
+	    g_warning ("File %s of the wrong type, root node != 'Backends'",
+		       filename);
+	    g_free (filename);
+	    xmlFreeDoc (doc);
+	    continue;
+	}
+
+	cur = cur->childs;
+	while (cur != NULL) {
+	    glibtop_backend_entry *backend;
+
+	    if ((!strcmp(cur->name, "Backend")) && (cur->ns == ns)) {
+		backend = _parseBackend (doc, ns, cur, directory);
+		if (!backend) {
+		    g_warning ("File %s of wrong type; cannot parse",
+			       filename);
+		    continue;
+		}
+
+		glibtop_register_backend (backend);
+	    }
+	    cur = cur->next;
+	}
+
+	g_free (filename);
+	xmlFreeDoc (doc);
+    }
+
+    closedir (dir);
+}
+
+#endif /* HAVE_LIBXML */

lib/open-backend.c

@@ -29,14 +29,49 @@
 
 #include <glibtop/backend.h>
 
+#include <gmodule.h>
+
 int
 glibtop_open_backend_l (glibtop *server, const char *backend_name,
 			u_int64_t features, const char **backend_args)
 {
+    glibtop_backend_entry *entry;
     glibtop_backend_info *info;
     glibtop_backend *backend;
 
-    info = glibtop_backend_by_name (backend_name);
+    entry = glibtop_backend_by_name (backend_name);
+    if (!entry) return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
+
+    if (!entry->_priv) {
+	entry->_priv = g_new0 (glibtop_backend_module, 1);
+
+	entry->_priv->module = g_module_open (entry->shlib_name,
+					      G_MODULE_BIND_LAZY);
+	if (!entry->_priv->module) {
+	    glibtop_warn_r (server, "Cannot open shared library `%s' "
+			    "for backend `%s'", entry->shlib_name,
+			    entry->name);
+	    return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
+	}
+
+	if (!g_module_symbol (entry->_priv->module,
+			      "LibGTopBackendInfo",
+			      (gpointer*) &entry->info)) {
+	    glibtop_warn_r (server, "Library `%s' is not a valid "
+			    "LibGTop Backend library (start symbol not found)",
+			    entry->shlib_name);
+
+	    g_module_close (entry->_priv->module);
+	    g_free (entry->_priv);
+	    entry->_priv = NULL;
+
+	    return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
+	}
+
+	entry->_priv->refcount++;
+    }
+
+    info = entry->info;
     if (!info) return -GLIBTOP_ERROR_NO_SUCH_BACKEND;
 
     backend = glibtop_calloc_r (server, 1, sizeof (glibtop_backend));