avoid dereferencing NULL pointer

Closes https://github.com/mate-desktop/mate-applets/pull/114

4 files changed, 15 insertions, 8 deletions

diff --git a/battstat/acpi-linux.c b/battstat/acpi-linux.c
index 3ac91c29..6f9512ce 100644
--- a/battstat/acpi-linux.c
+++ b/battstat/acpi-linux.c
@@ -350,22 +350,28 @@ gboolean acpi_process_event(struct acpi_info * acpiinfo)
     buffer=g_string_new(NULL);
     g_io_channel_read_line_string   ( acpiinfo->channel,buffer,&i,&gerror);
 
+    gboolean result;
 
     evt = parse_acpi_event(buffer);
       switch (evt) {
         case ACPI_EVENT_AC:
-          return update_ac_info(acpiinfo);
+          result = update_ac_info(acpiinfo);
+          break;
         case ACPI_EVENT_BATTERY_INFO:
           if (update_battery_info(acpiinfo)) {
             /* Update AC info on battery info updates.  This works around
              * a bug in ACPI (as per bug #163013).
              */
-            return update_ac_info(acpiinfo);
+            result = update_ac_info(acpiinfo);
+            break;
           }
           /* fall-through */
         default:
-          return FALSE;
+          result = FALSE;
       }
+
+    g_string_free(buffer, FALSE);
+    return result;
 }
 
 /*
diff --git a/battstat/battstat-upower.c b/battstat/battstat-upower.c
index 792be860..1326a9cc 100644
--- a/battstat/battstat-upower.c
+++ b/battstat/battstat-upower.c
@@ -320,6 +320,7 @@ error_dialog( const char *fmt , ...)
   va_start(ap, fmt);
   char str[1000];
   vsprintf(str, fmt, ap);
+  va_end(ap);
   GtkWidget *dialog;
 
   dialog = gtk_message_dialog_new( NULL, 0, GTK_MESSAGE_ERROR,
diff --git a/battstat/power-management.c b/battstat/power-management.c
index c879bcaa..682f9683 100644
--- a/battstat/power-management.c
+++ b/battstat/power-management.c
@@ -443,7 +443,6 @@ const char *
 power_management_initialise (int no_hal, void (*callback) (void))
 {
   char *err;
-  err = g_strdup( ":(" );
 #ifdef __linux__
   struct stat statbuf;
 #endif
diff --git a/cpufreq/src/cpufreq-utils.c b/cpufreq/src/cpufreq-utils.c
index 7afe0db6..3e3325ca 100644
--- a/cpufreq/src/cpufreq-utils.c
+++ b/cpufreq/src/cpufreq-utils.c
@@ -299,11 +299,12 @@ cpufreq_file_get_contents (const gchar *filename,
 
 	g_free (display_filename);
 
-	if (buffer)
+	if (buffer) {
 		*contents = g_string_free (buffer, FALSE);
-	
-	if (length)
-		*length = strlen (*contents);
+
+		if (length)
+			*length = strlen (*contents);
+	}
 
 	close (fd);