GUI: utility function for detecting BOMs and non-ASCII chars in a file

src/mkvtoolnix-gui/util/util.cpp

@@ -414,4 +414,34 @@ preventScrollingWithoutFocus(QObject *parent) {
     install(child);
 }
 
+BomAsciiCheckResult
+checkForBomAndNonAscii(QString const &fileName) {
+  QFile file{fileName};
+  if (!file.open(QIODevice::ReadOnly))
+    return {};
+
+  auto content = file.readAll();
+  file.close();
+
+  auto result   = BomAsciiCheckResult{};
+  auto dataSize = content.size();
+  auto dataPtr  = reinterpret_cast<unsigned char const *>(content.constData());
+  auto dataEnd  = dataPtr + dataSize;
+
+  mm_text_io_c::detect_byte_order_marker(dataPtr, dataSize, result.byteOrder, result.bomLength);
+
+  dataPtr += result.bomLength;
+
+  while (dataPtr < dataEnd) {
+    if (*dataPtr > 127) {
+      result.containsNonAscii = true;
+      break;
+    }
+
+    ++dataPtr;
+  }
+
+  return result;
+}
+
 }}}

src/mkvtoolnix-gui/util/util.h

@@ -98,6 +98,15 @@ QString displayableDate(QDateTime const &date);
 
 QString itemFlagsToString(Qt::ItemFlags const &flags);
 
+// File stuff
+struct BomAsciiCheckResult {
+  byte_order_e byteOrder{BO_NONE};
+  unsigned int bomLength{};
+  bool containsNonAscii{};
+};
+
+BomAsciiCheckResult checkForBomAndNonAscii(QString const &fileName);
+
 }}}
 
 #endif  // MTX_MKVTOOLNIX_GUI_UTIL_UTIL_H