implement patch serving

src/SendCommands.cc

@@ -445,6 +445,28 @@ void send_enter_directory_patch(shared_ptr<Client> c, const string& dir) {
   send_command_t(c, 0x09, 0x00, cmd);
 }
 
+void send_patch_file(shared_ptr<Client> c, shared_ptr<const PatchFileIndex::File> f) {
+  S_OpenFile_Patch_06 open_cmd = {0, f->size, f->name};
+  send_command_t(c, 0x06, 0x00, open_cmd);
+
+  for (size_t x = 0; x < f->chunks.size(); x++) {
+    const auto& chunk = f->chunks[x];
+
+    // TODO: The use of StringWriter here is... unfortunate. Write a version of
+    // Channel::send that takes iovecs or something to avoid these dumb massive
+    // string copies.
+    StringWriter w;
+    S_WriteFileHeader_Patch_07 write_cmd_header = {
+        x, chunk.crc32, chunk.data.size()};
+    w.put(write_cmd_header);
+    w.write(chunk.data);
+    send_command(c, 0x07, 0x00, w.str());
+  }
+
+  S_CloseCurrentFile_Patch_08 close_cmd = {0};
+  send_command_t(c, 0x08, 0x00, close_cmd);
+}
+
 
 
 ////////////////////////////////////////////////////////////////////////////////