add byte range handling to FileResourceRequest

libraries/networking/src/FileResourceRequest.cpp

@@ -11,6 +11,8 @@
 
 #include "FileResourceRequest.h"
 
+#include <cstdlib>
+
 #include <QFile>
 
 void FileResourceRequest::doSend() {
@@ -25,7 +27,35 @@ void FileResourceRequest::doSend() {
     QFile file(filename);
     if (file.exists()) {
         if (file.open(QFile::ReadOnly)) {
-            _data = file.readAll();
+
+            if (!_byteRange.isSet()) {
+                // no byte range, read the whole file
+                _data = file.readAll();
+            } else {
+                if (file.size() < std::abs(_byteRange.fromInclusive) || file.size() < _byteRange.toExclusive) {
+                    _result = ResourceRequest::InvalidByteRange;
+                } else {
+                    // we have a byte range to handle
+                    if (_byteRange.fromInclusive > 0) {
+                        // this is a positive byte range, simply skip to that part of the file and read from there
+                        file.seek(_byteRange.fromInclusive);
+                        _data = file.read(_byteRange.size());
+                    } else {
+                        // this is a negative byte range, we'll need to grab data from the end of the file first
+                        file.seek(file.size() + _byteRange.fromInclusive);
+                        _data = file.read(-_byteRange.fromInclusive);
+
+                        if (_byteRange.toExclusive > 0) {
+                            // there is additional data to read from the front of the file
+                            // handle that now
+                            file.seek(0);
+                            _data.append(file.read(_byteRange.toExclusive));
+                        }
+                    }
+                }
+
+            }
+
             _result = ResourceRequest::Success;
         } else {
             _result = ResourceRequest::AccessDenied;

libraries/networking/src/ResourceRequest.h

@@ -37,6 +37,7 @@ public:
         Timeout,
         ServerUnavailable,
         AccessDenied,
+        InvalidByteRange,
         InvalidURL,
         NotFound
     };