Implement file mapping for UWP apps

[sergio-nsk]

Fixes #1773.

@yhirose I have not checked it - perhaps, the new code also can replace Windows Desktop code, but it needs a real UTF-8 to UTF-16 conversion.

[yhirose]

@sergio-nsk What does "I have not checked it" mean? At least, I would like you to confirm that this change works on your UWP apps, and also confirm that it doesn't break anything on Windows.

[sergio-nsk]

I mean, I have not checked if the new code can work on Windows Desktop and the inner #if #else can be eliminated. #else #endif works in UWP.
It should not break the current code for Windows Desktop, because it does not change it.

[yhirose]

@sergio-nsk thanks for the reply.

According to your comment in #1773, the only thing we have to do is to change CreateFileA to something else.

If CreateFile2 works on WinRT/UWP, I think the following small change is enough for both the regular Windows and WinRT/UWP. I confirmed that all the unit tests (test/test.cc) related to the code change passed successfully.

diff --git a/httplib.h b/httplib.h
index dfdd260..8ef4d01 100644
--- a/httplib.h
+++ b/httplib.h
@@ -2686,8 +2686,13 @@ inline bool mmap::open(const char *path) {
   close();

 #if defined(_WIN32)
-  hFile_ = ::CreateFileA(path, GENERIC_READ, FILE_SHARE_READ, NULL,
-                         OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+  std::wstring wpath;
+  for (size_t i = 0; i < strlen(path); i++) {
+     wpath += path[i];
+  }
+
+  hFile_ = ::CreateFile2(wpath.c_str(), GENERIC_READ, FILE_SHARE_READ,
+                         OPEN_EXISTING, NULL);

   if (hFile_ == INVALID_HANDLE_VALUE) { return false; }

Could you test the above code on your UWP environment? Thanks a lot!

[sergio-nsk]

Honestly, I talked only about the first compiler error. Other functions GetFileSize(), CreateFileMapping(), MapViewOfFile() are also unavailable in UWP apps. UnmapViewOfFile() is only available. That's why I suggest that you test the complete new code block.

- #if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
+ #if 0 && WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)

I can't test it at my end fairly, because I am getting same failures before and after my changes.

[  FAILED  ] 17 tests, listed below:
[  FAILED  ] ChunkedEncodingTest.FromHTTPWatch_Online
[  FAILED  ] ChunkedEncodingTest.WithContentReceiver_Online
[  FAILED  ] ChunkedEncodingTest.WithResponseHandlerAndContentReceiver_Online
[  FAILED  ] ServerTest.HeadMethod200Static
[  FAILED  ] ServerTest.GetMethodDir
[  FAILED  ] ServerTest.GetMethodDirTest
[  FAILED  ] ServerTest.GetMethodDirTestWithDoubleDots
[  FAILED  ] ServerTest.GetMethodDirMountTest
[  FAILED  ] ServerTest.GetMethodDirMountTestWithDoubleDots
[  FAILED  ] ServerTest.UserDefinedMIMETypeMapping
[  FAILED  ] ServerTest.StaticFileRange
[  FAILED  ] ServerTest.StaticFileRanges
[  FAILED  ] ServerTest.StaticFileRangeHead
[  FAILED  ] ServerTest.StaticFileRangeBigFile
[  FAILED  ] ServerTest.StaticFileRangeBigFile2
[  FAILED  ] ServerTest.StaticFileBigFile
[  FAILED  ] MountTest.Unmount

[yhirose]

Thank you for the details. I tested the following code on my machine and it worked successfully. Could you just change the current code with this, so that we can use the same code for both the regular Windows and WinRT/UWP?

  std::wstring wpath;
  for (size_t i = 0; i < strlen(path); i++) {
     wpath += path[i];
  }

  hFile_ = ::CreateFile2(wpath.c_str(), GENERIC_READ, FILE_SHARE_READ,
                         OPEN_EXISTING, NULL);

  if (hFile_ == INVALID_HANDLE_VALUE) { return false; }

  LARGE_INTEGER size{};
  if (!::GetFileSizeEx(hFile_, &size)) { return false; }
  size_ = static_cast<size_t>(size.QuadPart);

  hMapping_ = ::CreateFileMappingFromApp(hFile_, NULL, PAGE_READONLY, size_,
                                         NULL);

  if (hMapping_ == NULL) {
      close();
      return false;
  }

  addr_ = ::MapViewOfFileFromApp(hMapping_, FILE_MAP_READ, 0, 0);

[sergio-nsk]

Sorry, I just noticed that it will not compile on Windows 7. Are you sure you want to break that although you don't support it?

NOTE: Windows 8 or lower, Visual Studio 2013 or lower, and Cygwin and MSYS2 including MinGW are neither supported nor tested.

[yhirose]

I think that's fine, since the support for Windows 7 has already ended on January 14, 2020.

[sergio-nsk]

Done, with support of VS 2015.

[yhirose]

@sum01 @jimmy-park could you review the change in CMakeLists.txt, since I am not an expert of CMake? Thanks a lot.

[jimmy-park]

Won't this affect other CMake projects that use httplib?
I think the macro should remain in httplib.h.

[yhirose]

@jimmy-park thank you for the comment.
@sergio-nsk could you remove this change?

[sergio-nsk]

Won't this affect other CMake projects that use httplib? I think the macro should remain in httplib.h.

It will affect user projects if they don't define own _WIN32_WINNT values.

[yhirose]

@sergio-nsk thanks for your contribution!