tint2conf: Checksum files to identify and back up manually edited configs

src/tint2conf/properties_rw.c

@@ -86,7 +86,7 @@ void config_write_color(FILE *fp, char *name, GdkColor color, int opacity)
 
 void config_write_backgrounds(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Backgrounds\n");
 
 	int index;
@@ -128,7 +128,7 @@ void config_write_backgrounds(FILE *fp)
 
 void config_write_panel(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Panel\n");
 	char *items = get_panel_items();
 	fprintf(fp, "panel_items = %s\n", items);
@@ -219,7 +219,7 @@ void config_write_panel(FILE *fp)
 
 void config_write_taskbar(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Taskbar\n");
 
 	fprintf(fp,
@@ -309,7 +309,7 @@ void config_write_task_background(FILE *fp, char *name, GtkWidget *task_backgrou
 
 void config_write_task(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Task\n");
 
 	fprintf(fp, "task_text = %d\n", gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(task_show_text)) ? 1 : 0);
@@ -398,7 +398,7 @@ void config_write_task(FILE *fp)
 
 void config_write_systray(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# System tray (notification area)\n");
 
 	fprintf(fp,
@@ -436,7 +436,7 @@ void config_write_systray(FILE *fp)
 
 void config_write_launcher(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Launcher\n");
 
 	fprintf(fp,
@@ -495,7 +495,7 @@ void config_write_launcher(FILE *fp)
 
 void config_write_clock(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Clock\n");
 
 	fprintf(fp, "time1_format = %s\n", gtk_entry_get_text(GTK_ENTRY(clock_format_line1)));
@@ -527,7 +527,7 @@ void config_write_clock(FILE *fp)
 
 void config_write_battery(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Battery\n");
 
 	fprintf(fp, "battery_low_status = %g\n", gtk_spin_button_get_value(GTK_SPIN_BUTTON(battery_alert_if_lower)));
@@ -552,7 +552,7 @@ void config_write_battery(FILE *fp)
 
 void config_write_tooltip(FILE *fp)
 {
-	fprintf(fp, "#--------------------------------\n");
+	fprintf(fp, "#-------------------------------------\n");
 	fprintf(fp, "# Tooltip\n");
 
 	fprintf(fp, "tooltip_show_timeout = %g\n", gtk_spin_button_get_value(GTK_SPIN_BUTTON(tooltip_show_after)));
@@ -575,14 +575,38 @@ void config_write_tooltip(FILE *fp)
 	fprintf(fp, "\n");
 }
 
+// Similar to BSD checksum, except we skip the first line (metadata)
+unsigned short checksum_txt(FILE *f)
+{
+    unsigned int checksum = 0;
+	fseek(f, 0, SEEK_SET);
+
+	// Skip the first line
+	int c;
+	do {
+	  c = getc(f);
+	} while (c != EOF && c != '\n');
+
+	while ((c = getc(f)) != EOF) {
+		// Rotate right
+        checksum = (checksum >> 1) + ((checksum & 1) << 15);
+        // Update checksum
+		checksum += c;
+		// Truncate to 16 bits
+        checksum &= 0xffff;
+    }
+    return checksum;
+}
+
 void config_save_file(const char *path) {
 	printf("config_save_file : %s\n", path);
 
 	FILE *fp;
-	if ((fp = fopen(path, "wt")) == NULL)
+	if ((fp = fopen(path, "w+t")) == NULL)
 		return;
 
-	fprintf(fp, "#---- Generated by tint2conf ----\n");
+	unsigned short checksum = 0;
+	fprintf(fp, "#---- Generated by tint2conf %04x ----\n", checksum);
 
 	config_write_backgrounds(fp);
 	config_write_panel(fp);
@@ -594,6 +618,11 @@ void config_save_file(const char *path) {
 	config_write_battery(fp);
 	config_write_tooltip(fp);
 
+	checksum = checksum_txt(fp);
+	fseek(fp, 0, SEEK_SET);
+	fflush(fp);
+	fprintf(fp, "#---- Generated by tint2conf %04x ----\n", checksum);
+
 	fclose(fp);
 }
 
@@ -608,8 +637,16 @@ gboolean config_is_manual(const char *path)
 
 	result = TRUE;
 	if (fgets(line, sizeof(line), fp) != NULL) {
-		if (g_str_equal(line, "#---- Generated by tint2conf ----\n")) {
+		if (!g_regex_match_simple("^#---- Generated by tint2conf [0-9a-f][0-9a-f][0-9a-f][0-9a-f] ----\n$", line, 0, 0)) {
-			result = FALSE;
+			result = TRUE;
+		} else {
+			unsigned short checksum1 = checksum_txt(fp);
+			unsigned short checksum2 = 0;
+			if (sscanf(line, "#---- Generated by tint2conf %hxu", &checksum2) == 1) {
+				result = checksum1 != checksum2;
+			} else {
+				result = TRUE;
+			}
 		}
 	}
 	fclose(fp);