function that compares files added

function tests

3 files changed, 90 insertions, 0 deletions

diff --git a/coding/coding_tests/file_data_test.cpp b/coding/coding_tests/file_data_test.cpp
index 69a1511638..85b0bcd272 100644
--- a/coding/coding_tests/file_data_test.cpp
+++ b/coding/coding_tests/file_data_test.cpp
@@ -17,6 +17,12 @@ namespace
     f.Write(name.c_str(), name.size());
   }
 
+  void MakeFile(string const & name, size_t const size, const char c)
+  {
+    my::FileData f(name, my::FileData::OP_WRITE_TRUNCATE);
+    f.Write(string(size, c).c_str(), size);
+  }
+
   void CheckFileOK(string const & name)
   {
     my::FileData f(name, my::FileData::OP_READ);
@@ -106,3 +112,58 @@ UNIT_TEST(FileData_SharingAV_Windows)
   TEST(my::DeleteFileX(name2), ());
 }
 #endif
+
+UNIT_TEST(Equal_Function_Test)
+{
+  MakeFile(name1);
+  MakeFile(name2);
+  TEST(my::IsEqualFiles(name1, name1), ());
+  TEST(my::IsEqualFiles(name2, name2), ());
+  TEST(!my::IsEqualFiles(name1, name2), ());
+
+  TEST(my::DeleteFileX(name1), ());
+  TEST(my::DeleteFileX(name2), ());
+}
+
+UNIT_TEST(Equal_Function_Test_For_Big_Files)
+{
+  {
+    MakeFile(name1, 1024 * 1024, 'a');
+    MakeFile(name2, 1024 * 1024, 'a');
+    TEST(my::IsEqualFiles(name1, name2), ());
+    TEST(my::DeleteFileX(name1), ());
+    TEST(my::DeleteFileX(name2), ());
+  }
+  {
+    MakeFile(name1, 1024 * 1024 + 512, 'a');
+    MakeFile(name2, 1024 * 1024 + 512, 'a');
+    TEST(my::IsEqualFiles(name1, name2), ());
+    TEST(my::DeleteFileX(name1), ());
+    TEST(my::DeleteFileX(name2), ());
+  }
+  {
+    MakeFile(name1, 1024 * 1024 + 1, 'a');
+    MakeFile(name2, 1024 * 1024 + 1, 'b');
+    TEST(my::IsEqualFiles(name1, name1), ());
+    TEST(my::IsEqualFiles(name2, name2), ());
+    TEST(!my::IsEqualFiles(name1, name2), ());
+    TEST(my::DeleteFileX(name1), ());
+    TEST(my::DeleteFileX(name2), ());
+  }
+  {
+    MakeFile(name1, 1024 * 1024, 'a');
+    MakeFile(name2, 1024 * 1024, 'b');
+    TEST(my::IsEqualFiles(name1, name1), ());
+    TEST(my::IsEqualFiles(name2, name2), ());
+    TEST(!my::IsEqualFiles(name1, name2), ());
+    TEST(my::DeleteFileX(name1), ());
+    TEST(my::DeleteFileX(name2), ());
+  }
+  {
+    MakeFile(name1, 1024 * 1024, 'a');
+    MakeFile(name2, 1024 * 1024 + 1, 'b');
+    TEST(!my::IsEqualFiles(name1, name2), ());
+    TEST(my::DeleteFileX(name1), ());
+    TEST(my::DeleteFileX(name2), ());
+  }
+}
diff --git a/coding/internal/file_data.cpp b/coding/internal/file_data.cpp
index cfdeb62fde..d437376599 100644
--- a/coding/internal/file_data.cpp
+++ b/coding/internal/file_data.cpp
@@ -263,4 +263,32 @@ bool CopyFile(string const & fOld, string const & fNew)
   return false;
 }
 
+bool IsEqualFiles(string const & firstFile, string const & secondFile)
+{
+  my::FileData first(firstFile, my::FileData::OP_READ);
+  my::FileData second(secondFile, my::FileData::OP_READ);
+  if (first.Size() != second.Size())
+    return false;
+
+  size_t const bufSize = 512 * 1024;
+  vector<char> buf1, buf2;
+  buf1.resize(bufSize);
+  buf2.resize(bufSize);
+  size_t const fileSize = first.Size();
+  size_t currSize = 0;
+
+  while (currSize < fileSize)
+  {
+    size_t toRead = fileSize - currSize;
+    if (toRead > bufSize)
+      toRead = bufSize;
+    first.Read(step * bufSize, &buf1[0], readingLength);
+    second.Read(step * bufSize, &buf2[0], readingLength);
+    if (buf1 != buf2)
+      return false;
+    currSize += toRead;
+  }
+  return true;
+}
+
 }
diff --git a/coding/internal/file_data.hpp b/coding/internal/file_data.hpp
index 8dd47d83d2..e5ec462ecb 100644
--- a/coding/internal/file_data.hpp
+++ b/coding/internal/file_data.hpp
@@ -49,5 +49,6 @@ bool DeleteFileX(string const & fName);
 bool RenameFileX(string const & fOld, string const & fNew);
 /// @return false if copy fails. DO NOT THROWS exceptions
 bool CopyFile(string const & fOld, string const & fNew);
+bool IsEqualFiles(string const & firstFile, string const & secondFile);
 
 }