Reimplement SD.h write methods exactly in File

Replace the individual override with the existing SD.h File's
implementation for all methods of File::write.

Author: earlephilhower

cores/esp8266/FS.h

@@ -80,7 +80,29 @@ class File : public Stream
     bool isDirectory() const;
 
     // Arduino "class SD" methods for compatibility
-    size_t write(const char *str) { return write((const uint8_t*)str, strlen(str)); }
+    template<typename T> size_t write(T &src){
+      uint8_t obuf[512];
+      size_t doneLen = 0;
+      size_t sentLen;
+      int i;
+
+      while (src.available() > 512){
+        src.read(obuf, 512);
+        sentLen = write(obuf, 512);
+        doneLen = doneLen + sentLen;
+        if(sentLen != 512){
+          return doneLen;
+        }
+      }
+
+      size_t leftLen = src.available();
+      src.read(obuf, leftLen);
+      sentLen = write(obuf, leftLen);
+      doneLen = doneLen + sentLen;
+      return doneLen;
+    }
+    using Print::write;
+
     void rewindDirectory();
     File openNextFile();
 

tests/host/fs/test_fs.cpp

@@ -331,3 +331,18 @@ TEST_CASE("Listfiles.ino example", "[sd]")
     REQUIRE(readFileSD("/dir2/dir3/file4") == "bonjour");
 }
 
+TEST_CASE("Multisplendored File::writes", "[fs]")
+{
+    SDFS_MOCK_DECLARE();
+    SDFS.end();
+    SDFS.setConfig(SDFSConfig(0, SD_SCK_MHZ(1)));
+    REQUIRE(SDFS.format());
+    REQUIRE(SD.begin(4));
+
+    File f = SD.open("/file.txt", FILE_WRITE);
+    f.write('a');
+    f.write(65);
+    f.write("bbcc");
+    f.close();
+    REQUIRE(readFileSD("/file.txt") == "aAbbcc");
+}