Leverage fileapi for opening files on windows

spec/std/file_spec.cr

@@ -517,6 +517,15 @@ describe "File" do
       end
     end
 
+    it "deletes an open file" do
+      with_tempfile("delete-file.txt") do |filename|
+        file = File.open filename, "w"
+        File.exists?(file.path).should be_true
+        file.delete
+        File.exists?(file.path).should be_false
+      end
+    end
+
     it "deletes? a file" do
       with_tempfile("delete-file.txt") do |filename|
         File.open(filename, "w") { }

src/crystal/system/win32/file.cr

@@ -26,11 +26,86 @@ module Crystal::System::File
   end
 
   def self.open(filename : String, flags : Int32, perm : ::File::Permissions) : {LibC::Int, Errno}
-    flags |= LibC::O_BINARY | LibC::O_NOINHERIT
+    access, disposition, attributes, share = self.posix_to_open_opts flags, perm
 
-    fd = LibC._wopen(System.to_wstr(filename), flags, perm)
+    handle = LibC.CreateFileW(
+      System.to_wstr(filename),
+      access,
+      share, # UNIX semantics
+      nil,
+      disposition,
+      attributes,
+      LibC::HANDLE.null
+    )
+
+    if handle == LibC::INVALID_HANDLE_VALUE
+      # Map ERROR_FILE_EXISTS to Errno::EEXIST to avoid changing semantics of other systems
+      if WinError.value.error_file_exists?
+        Errno.value = Errno::EEXIST
+      end
+
+      return {-1, Errno.value}
+    end
+
+    fd = LibC._open_osfhandle handle, flags
+
+    if fd == -1
+      return {-1, Errno.value}
+    end
+
+    if flags & LibC::O_BINARY > 0
+      LibC._setmode fd, LibC::O_BINARY
+    elsif flags & LibC::O_TEXT > 0
+      LibC._setmode fd, LibC::O_TEXT
+    end
+
+    {fd, Errno::NONE}
+  end
+
+  private def self.posix_to_open_opts(flags : Int32, perm : ::File::Permissions)
+    access = disposition = attributes = 0
+
+    case flags & (LibC::O_RDONLY | LibC::O_WRONLY | LibC::O_RDWR)
+    when LibC::O_RDONLY then access = LibC::GENERIC_READ
+    when LibC::O_WRONLY then access = LibC::GENERIC_WRITE
+    when LibC::O_RDWR   then access = LibC::GENERIC_READ | LibC::GENERIC_WRITE
+    end
+
+    if flags & LibC::O_APPEND > 0
+      access |= LibC::FILE_APPEND_DATA
+      attributes &= ~LibC::FILE_FLAG_BACKUP_SEMANTICS
+    end
+
+    share = LibC::DEFAULT_SHARE_MODE
+
+    case flags & (LibC::O_CREAT | LibC::O_EXCL | LibC::O_TRUNC)
+    when 0, LibC::O_EXCL                                                            then disposition = LibC::OPEN_EXISTING
+    when LibC::O_CREAT                                                              then disposition = LibC::OPEN_ALWAYS
+    when LibC::O_CREAT | LibC::O_EXCL, LibC::O_CREAT | LibC::O_TRUNC | LibC::O_EXCL then disposition = LibC::CREATE_NEW
+    when LibC::O_TRUNC, LibC::O_TRUNC | LibC::O_EXCL                                then disposition = LibC::TRUNCATE_EXISTING
+    when LibC::O_CREAT | LibC::O_TRUNC                                              then disposition = LibC::CREATE_ALWAYS
+    end
+
+    attributes |= LibC::FILE_ATTRIBUTE_NORMAL
+    unless perm.owner_write?
+      attributes |= LibC::FILE_ATTRIBUTE_READONLY
+    end
+
+    if flags & LibC::O_TEMPORARY > 0
+      attributes |= LibC::FILE_FLAG_DELETE_ON_CLOSE | LibC::FILE_ATTRIBUTE_TEMPORARY
+      access |= LibC::DELETE
+    end
+
+    if flags & LibC::O_SHORT_LIVED > 0
+      attributes |= LibC::FILE_ATTRIBUTE_TEMPORARY
+    end
+
+    case flags & (LibC::O_SEQUENTIAL | LibC::O_RANDOM)
+    when LibC::O_SEQUENTIAL then attributes |= LibC::FILE_FLAG_SEQUENTIAL_SCAN
+    when LibC::O_RANDOM     then attributes |= LibC::FILE_FLAG_RANDOM_ACCESS
+    end
 
-    {fd, fd == -1 ? Errno.value : Errno::NONE}
+    {access, disposition, attributes, share}
   end
 
   NOT_FOUND_ERRORS = {

src/lib_c/x86_64-windows-msvc/c/fileapi.cr

@@ -41,19 +41,37 @@ lib LibC
   fun SetFileAttributesW(lpFileName : LPWSTR, dwFileAttributes : DWORD) : BOOL
   fun GetFileAttributesExW(lpFileName : LPWSTR, fInfoLevelId : GET_FILEEX_INFO_LEVELS, lpFileInformation : Void*) : BOOL
 
-  OPEN_EXISTING = 3
+  CREATE_NEW        = 1
+  CREATE_ALWAYS     = 2
+  OPEN_EXISTING     = 3
+  OPEN_ALWAYS       = 4
+  TRUNCATE_EXISTING = 5
 
-  FILE_ATTRIBUTE_NORMAL      =       0x80
-  FILE_FLAG_BACKUP_SEMANTICS = 0x02000000
+  FILE_ATTRIBUTE_NORMAL    =  0x80
+  FILE_ATTRIBUTE_TEMPORARY = 0x100
+
+  FILE_FLAG_BACKUP_SEMANTICS   = 0x02000000
+  FILE_FLAG_DELETE_ON_CLOSE    = 0x04000000
+  FILE_FLAG_OPEN_REPARSE_POINT = 0x00200000
+  FILE_FLAG_RANDOM_ACCESS      = 0x10000000
+  FILE_FLAG_SEQUENTIAL_SCAN    = 0x08000000
 
   FILE_SHARE_READ   = 0x1
   FILE_SHARE_WRITE  = 0x2
   FILE_SHARE_DELETE = 0x4
 
+  DEFAULT_SHARE_MODE = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE
+
+  GENERIC_READ  = 0x80000000
+  GENERIC_WRITE = 0x40000000
+
   fun CreateFileW(lpFileName : LPWSTR, dwDesiredAccess : DWORD, dwShareMode : DWORD,
                   lpSecurityAttributes : SECURITY_ATTRIBUTES*, dwCreationDisposition : DWORD,
                   dwFlagsAndAttributes : DWORD, hTemplateFile : HANDLE) : HANDLE
 
+  fun _open_osfhandle(osfhandle : HANDLE, flags : LibC::Int) : LibC::Int
+  fun _setmode(fd : LibC::Int, mode : LibC::Int) : LibC::Int
+
   fun ReadFile(hFile : HANDLE, lpBuffer : Void*, nNumberOfBytesToRead : DWORD, lpNumberOfBytesRead : DWORD*, lpOverlapped : OVERLAPPED*) : BOOL
 
   MAX_PATH = 260

src/lib_c/x86_64-windows-msvc/c/winnt.cr

@@ -19,8 +19,11 @@ lib LibC
   FILE_ATTRIBUTE_READONLY      =   0x1
   FILE_ATTRIBUTE_REPARSE_POINT = 0x400
 
-  FILE_READ_ATTRIBUTES  =   0x80
-  FILE_WRITE_ATTRIBUTES = 0x0100
+  FILE_APPEND_DATA = 0x00000004
+
+  DELETE                = 0x00010000
+  FILE_READ_ATTRIBUTES  =       0x80
+  FILE_WRITE_ATTRIBUTES =     0x0100
 
   # Memory protection constants
   PAGE_READWRITE = 0x04