Add WinError.wsa_value and specs for WinError

spec/std/winerror_spec.cr

@@ -0,0 +1,46 @@
+require "spec"
+
+describe WinError do
+  it ".value" do
+    {% if flag?(:win32) %}
+      WinError.value = WinError::ERROR_SUCCESS
+      WinError.value.should eq WinError::ERROR_SUCCESS
+      WinError.value = WinError::ERROR_BROKEN_PIPE
+      WinError.value.should eq WinError::ERROR_BROKEN_PIPE
+    {% else %}
+      expect_raises(NotImplementedError) do
+        WinError.value = WinError::ERROR_SUCCESS
+      end
+      expect_raises(NotImplementedError) do
+        WinError.value
+      end
+    {% end %}
+  end
+
+  it ".wsa_value" do
+    {% if flag?(:win32) %}
+      WinError.wsa_value = WinError::ERROR_SUCCESS
+      WinError.wsa_value.should eq WinError::ERROR_SUCCESS
+      WinError.wsa_value = WinError::WSAEBADF
+      WinError.wsa_value.should eq WinError::WSAEBADF
+    {% else %}
+      expect_raises(NotImplementedError) do
+        WinError.wsa_value = WinError::ERROR_SUCCESS
+      end
+      expect_raises(NotImplementedError) do
+        WinError.wsa_value
+      end
+    {% end %}
+  end
+
+  it "#message" do
+    message = WinError::ERROR_SUCCESS.message
+    {% if flag?(:win32) %}
+      # Not testing for specific content because the result is locale-specific
+      # and currently the message uses only default `LANGID`.
+      message.empty?.should be_false
+    {% else %}
+      message.should eq ""
+    {% end %}
+  end
+end

src/lib_c/x86_64-windows-msvc/c/winsock2.cr

@@ -18,5 +18,9 @@ lib LibC
 
   fun htons(hostshort : UShort) : UShort
   fun ntohs(netshort : UShort) : UShort
+
   fun WSAStartup(wVersionRequired : WORD, lpWSAData : WSAData*) : Int
+
+  fun WSASetLastError(iError : Int) : Void
+  fun WSAGetLastError : Int
 end

src/system_error.cr

@@ -108,15 +108,15 @@ module SystemError
     end
 
     # Builds an instance of the exception from the current windows error value (`WinError.value`).
+    #
     # The system message corresponding to the OS error value amends the *message*.
     # Additional keyword arguments are forwarded to the exception initializer `.new_from_os_error`.
     def from_winerror(message : String?, **opts)
       from_os_error(message, WinError.value, **opts)
     end
 
-    # Builds an instance of the exception from a `WinError`
+    # Builds an instance of the exception from the current Windows Socket API error value (`WinError.wsa_value`).
     #
-    # By default it takes the current `WinError` value (see `WinError.value`).
     # The system message corresponding to the OS error value amends the *message*.
     # Additional keyword arguments are forwarded to the exception initializer.
     def from_wsa_error(message : String? = nil, **opts)

src/winerror.cr

@@ -1,6 +1,7 @@
 {% if flag?(:win32) %}
   require "c/winbase"
   require "c/errhandlingapi"
+  require "c/winsock2"
 {% end %}
 
 # `WinError` represents Windows' [System Error Codes](https://docs.microsoft.com/en-us/windows/win32/debug/system-error-codes#system-error-codes-1).
@@ -17,6 +18,42 @@ enum WinError : UInt32
     {% end %}
   end
 
+  # Sets the value of [`SetLastError`](https://docs.microsoft.com/en-us/windows/win32/api/errhandlingapi/nf-errhandlingapi-setlasterror)
+  # which signifies the error code of the previously called win32 function.
+  #
+  # Raises `NotImplementedError` on non-win32 platforms.
+  def self.value=(winerror : self)
+    {% if flag?(:win32) %}
+      LibC.SetLastError(winerror.value)
+    {% else %}
+      raise NotImplementedError.new("WinError.value=")
+    {% end %}
+  end
+
+  # Returns the value of [`WSAGetLastError`](https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-wsagetlasterror)
+  # which is used to retrieve the error code of the previously called Windows Socket API function.
+  #
+  # Raises `NotImplementedError` on non-win32 platforms.
+  def self.wsa_value
+    {% if flag?(:win32) %}
+      WinError.new LibC.WSAGetLastError.to_u32!
+    {% else %}
+      raise NotImplementedError.new("WinError.wsa_value")
+    {% end %}
+  end
+
+  # Sets the value of [`WSASetLastError`](https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-wsasetlasterror)
+  # which signifies the error code of the previously called Windows Socket API function.
+  #
+  # Raises `NotImplementedError` on non-win32 platforms.
+  def self.wsa_value=(winerror : self)
+    {% if flag?(:win32) %}
+      LibC.WSASetLastError(winerror.value)
+    {% else %}
+      raise NotImplementedError.new("WinError.value=")
+    {% end %}
+  end
+
   # Returns the system error message associated with this error code.
   #
   # The message is retrieved via [`FormatMessageW`](https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-formatmessagew)