Improved readString() for File

cores/esp8266/FS.cpp

@@ -121,6 +121,21 @@ const char* File::name() const {
     return _p->name();
 }
 
+String File::readString()
+{
+    String ret;
+    ret.reserve(size() - position());
+    char temp[256+1];
+    int countRead = readBytes(temp, sizeof(temp)-1);
+    while (countRead > 0)
+    {
+        temp[countRead] = 0;
+        ret += temp;
+        countRead = readBytes(temp, sizeof(temp)-1);
+    }
+    return ret;
+}
+
 File Dir::openFile(const char* mode) {
     if (!_impl) {
         return File();

cores/esp8266/FS.h

@@ -72,7 +72,8 @@ class File : public Stream
     void close();
     operator bool() const;
     const char* name() const;
-
+    String readString() override;
+
 protected:
     FileImplPtr _p;
 };

cores/esp8266/Stream.h

@@ -101,7 +101,7 @@ class Stream: public Print {
         // returns the number of characters placed in the buffer (0 means no valid data found)
 
         // Arduino String functions to be added here
-        String readString();
+        virtual String readString();
         String readStringUntil(char terminator);
 
     protected: