Gracefully handle bad rc.xml

...by showing error message and exiting.

Fixes: #124

Author: johanmalm

src/maindialog.cpp

@@ -1,4 +1,5 @@
 #include <QDebug>
+#include <QMessageBox>
 #include <string>
 #include <unistd.h>
 #include "environment.h"
@@ -144,7 +145,15 @@ void MainDialog::activate()
 
 void MainDialog::initConfig(std::string &config_file)
 {
-    xml_init(config_file.data());
+    bool success = xml_init(config_file.data());
+
+    if (!success) {
+        QMessageBox msgBox;
+        msgBox.setText(tr("Error loading ") + QString(config_file.data()));
+        msgBox.setInformativeText(tr("Run labwc-tweaks from a terminal to view error messages"));
+        msgBox.exec();
+        exit(EXIT_FAILURE);
+    }
 
     /* Ensure all relevant nodes exist before we start getting/setting */
     xpath_add_node("/labwc_config/theme/cornerRadius");

src/xml.c

@@ -142,11 +142,13 @@ create_basic_rcxml(const char *filename)
 	fclose(file);
 }
 
-void
+bool
 xml_init(const char *filename)
 {
 	LIBXML_TEST_VERSION
 
+	bool success = true;
+
 	if (access(filename, F_OK)) {
 		create_basic_rcxml(filename);
 	}
@@ -156,12 +158,15 @@ xml_init(const char *filename)
 	ctx.doc = xmlReadFile(filename, NULL, XML_PARSE_NOBLANKS);
 	if (!ctx.doc) {
 		fprintf(stderr, "warn: xmlReadFile('%s')\n", filename);
+		success = false;
 	}
 	ctx.xpath_ctx_ptr = xmlXPathNewContext(ctx.doc);
 	if (!ctx.xpath_ctx_ptr) {
 		fprintf(stderr, "warn: xmlXPathNewContext()\n");
 		xmlFreeDoc(ctx.doc);
+		success = false;
 	}
+	return success;
 }
 
 void

src/xml.h

@@ -2,7 +2,7 @@
 #ifndef __XML_H
 #define __XML_H
 
-void xml_init(const char *filename);
+bool xml_init(const char *filename);
 void xml_save(void);
 void xml_save_as(const char *filename);
 void xml_finish(void);