make sure previously allocated mem get free()'d if subsequent allocactions fail

server/screen.c

@@ -1,5 +1,5 @@
 /** \file server/screen.c
- * Does screen management
+ * Does screen management.
  */
 
 /* This file is part of LCDd, the lcdproc server.
@@ -9,6 +9,7 @@
  *
  * Copyright (c) 1999, William Ferrell, Scott Scriven
  *		 2003, Joris Robijn
+ *               2008, Peter Marschall
  */
 
 #include <stdlib.h>
@@ -40,30 +41,39 @@ char *pri_names[] = {
 	NULL,
 };
 
+
+/** Create a screen.
+ * \param id      Screen id; it's name.
+ * \param client  Client, the screen belongs to.
+ * \return        Pointer to freshly created screen.
+ */
 Screen *
 screen_create(char *id, Client *client)
 {
 	Screen *s;
 
-	debug(RPT_DEBUG, "%s(id=\"%.40s\", client=[%d])", __FUNCTION__, id, (client?client->sock:-1));
+	debug(RPT_DEBUG, "%s(id=\"%.40s\", client=[%d])",
+		 __FUNCTION__, id, (client?client->sock:-1));
 
-	s = malloc(sizeof(Screen));
-	if (!s) {
-		report(RPT_ERR, "%s: Error allocating", __FUNCTION__);
-		return NULL;
-	}
 	if (!id) {
 		report(RPT_ERR, "%s: Need id string", __FUNCTION__);
 		return NULL;
 	}
 	/* Client can be NULL for serverscreens and other client-less screens */
 
-	s->id = strdup(id);
-	if (!s->id) {
+	s = malloc(sizeof(Screen));
+	if (s == NULL) {
 		report(RPT_ERR, "%s: Error allocating", __FUNCTION__);
 		return NULL;
 	}
 
+	s->id = strdup(id);
+	if (s->id == NULL) {
+		report(RPT_ERR, "%s: Error allocating", __FUNCTION__);
+		free(s);
+		return NULL;
+	}
+
 	s->name = NULL;
 	s->priority = PRI_INFO;
 	s->duration = default_duration;
@@ -82,8 +92,10 @@ screen_create(char *id, Client *client)
 	s->cursor_y = 1;
 
 	s->widgetlist = LL_new();
-	if (!s->widgetlist) {
+	if (s->widgetlist == NULL) {
 		report(RPT_ERR, "%s: Error allocating", __FUNCTION__);
+		free(s);
+		free(s->id);
 		return NULL;
 	}
 
@@ -92,6 +104,12 @@ screen_create(char *id, Client *client)
 	return s;
 }
 
+
+/** Destroy a screen.
+ * \param s    Screen to destroy.
+ * \retval <0  Error; no screen given.
+ * \retval  0  Success.
+ */
 int
 screen_destroy(Screen *s)
 {
@@ -108,17 +126,30 @@ screen_destroy(Screen *s)
 		widget_destroy(w);
 	}
 	LL_Destroy(s->widgetlist);
+	s->widgetlist = NULL;
 
-	if (s->id)
+	if (s->id != NULL) {
 		free(s->id);
-	if (s->name)
+		s->id = NULL;
+	}
+	if (s->name != NULL) {
 		free(s->name);
+		s->name = NULL;
+	}
 
 	free(s);
+	s = NULL;
 
 	return 0;
 }
 
+
+/** Add a widget to a screen.
+ * \param s  Screen to add the widget \c w to.
+ * \param w  Widget to be added to \c s.
+ * \retval <0  Error.
+ * \retval  0  Success.
+ */
 int
 screen_add_widget(Screen *s, Widget *w)
 {
@@ -129,6 +160,13 @@ screen_add_widget(Screen *s, Widget *w)
 	return 0;
 }
 
+
+/** Remove a widget from a screen.
+ * \param s  Screen to remove the widget \c w from.
+ * \param w  Widget to be removed from \c s.
+ * \retval <0  Error.
+ * \retval  0  Success.
+ */
 int
 screen_remove_widget(Screen *s, Widget *w)
 {
@@ -139,6 +177,12 @@ screen_remove_widget(Screen *s, Widget *w)
 	return 0;
 }
 
+
+/** Find a widget on a screen by its id.
+ * \param s   Screen where to look for the widget.
+ * \param id  Identifier of the widget.
+ * \return    Pointerr to the widget; \c NULL if widget was not found or error.
+ */
 Widget *
 screen_find_widget(Screen *s, char *id)
 {
@@ -151,7 +195,7 @@ screen_find_widget(Screen *s, char *id)
 
 	debug(RPT_DEBUG, "%s(s=[%.40s], id=\"%.40s\")", __FUNCTION__, s->id, id);
 
-	for (w = LL_GetFirst(s->widgetlist); w; w = LL_GetNext(s->widgetlist)) {
+	for (w = LL_GetFirst(s->widgetlist); w != NULL; w = LL_GetNext(s->widgetlist)) {
 		if (0 == strcmp(w->id, id)) {
 			debug(RPT_DEBUG, "%s: Found %s", __FUNCTION__, id);
 			return w;
@@ -159,7 +203,7 @@ screen_find_widget(Screen *s, char *id)
 		/* Search subscreens recursively */
 		if (w->type == WID_FRAME) {
 			w = widget_search_subs(w, id);
-			if (w)
+			if (w != NULL)
 				return w;
 		}
 	}
@@ -167,6 +211,11 @@ screen_find_widget(Screen *s, char *id)
 	return NULL;
 }
 
+
+/** Convert a priority name to the priority id.
+ * \param priname  Name of the screen priority.
+ * \return         Priority id associatited with \c priname.
+ */
 Priority
 screen_pri_name_to_pri(char *priname)
 {
@@ -182,6 +231,11 @@ screen_pri_name_to_pri(char *priname)
 	return pri;
 }
 
+
+/** Convert a priority id to the associated name.
+ * \param pri  Priority id.
+ * \return     Priority name associated with \c pri.
+ */
 char *
 screen_pri_to_pri_name(Priority pri)
 {

server/screen.h

@@ -1,4 +1,5 @@
 /** \file server/screen.h
+ * Public interface to the screen management methods.
  */
 
 /* This file is part of LCDd, the lcdproc server.