From 4ebdce7bb3b72f2d47a989b6e57908fc60a1fbc7 Mon Sep 17 00:00:00 2001
From: vng <viktor.govako@gmail.com>
Date: Mon, 29 Oct 2012 21:24:06 +0300
Subject: [PATCH] Add FileWriter::Reserve.

---
 coding/coding_tests/writer_test.cpp | 25 +++++++++++++++++++++++++
 coding/file_writer.cpp              | 10 ++++++++++
 coding/file_writer.hpp              |  2 ++
 3 files changed, 37 insertions(+)

diff --git a/coding/coding_tests/writer_test.cpp b/coding/coding_tests/writer_test.cpp
index aa51ee1877..8b3f7b2e8e 100644
--- a/coding/coding_tests/writer_test.cpp
+++ b/coding/coding_tests/writer_test.cpp
@@ -1,6 +1,9 @@
 #include "../../testing/testing.hpp"
+
 #include "../file_writer.hpp"
 #include "../file_reader.hpp"
+#include "../internal/file_data.hpp"
+
 
 namespace
 {
@@ -238,3 +241,25 @@ UNIT_TEST(MemWriter_Chunks)
     ReadTestData(r);
   }
 }
+
+UNIT_TEST(FileWriter_Reserve)
+{
+  string const TEST_FILE = "FileWriter_Reserve.test";
+  uint64_t TEST_SIZE = 666;
+
+  {
+    FileWriter w(TEST_FILE, FileWriter::OP_WRITE_TRUNCATE);
+    w.Reserve(TEST_SIZE);
+  }
+
+  {
+    uint64_t size;
+    TEST(my::GetFileSize(TEST_FILE, size), ());
+    TEST_EQUAL(size, TEST_SIZE, ());
+
+    FileWriter w(TEST_FILE, FileWriter::OP_WRITE_EXISTING);
+    TEST_EQUAL(w.Size(), TEST_SIZE, ());
+  }
+
+  FileWriter::DeleteFileX(TEST_FILE);
+}
diff --git a/coding/file_writer.cpp b/coding/file_writer.cpp
index 32ba752632..b5e4dd877f 100644
--- a/coding/file_writer.cpp
+++ b/coding/file_writer.cpp
@@ -55,6 +55,16 @@ void FileWriter::Flush()
   m_pFileData->Flush();
 }
 
+void FileWriter::Reserve(uint64_t size)
+{
+  if (size > 0)
+  {
+    m_pFileData->Seek(size-1);
+    uint8_t b = 0;
+    m_pFileData->Write(&b, 1);
+  }
+}
+
 void FileWriter::DeleteFileX(string const & fName)
 {
   (void)my::DeleteFileX(fName);
diff --git a/coding/file_writer.hpp b/coding/file_writer.hpp
index a468caa049..ad2f2afc1e 100644
--- a/coding/file_writer.hpp
+++ b/coding/file_writer.hpp
@@ -38,6 +38,8 @@ public:
   uint64_t Size() const;
   void Flush();
 
+  void Reserve(uint64_t size);
+
   static void DeleteFileX(string const & fName);
 
   string GetName() const;