windows: fix compilation for Windows UWP platform

[dmitrykos]

Fix compilation for Windows UWP platform by including the afunix.h which is necessary for sockaddr_un when USE_UNIX_SOCKETS is defined.

[cvengler]

I have never heard of that header before. A google search doesn't lead me to any official microsoft pages. Are you sure this is contained in stock Windows and if so since which version? This must also be checked!

[jzakrzewski]

It's weird - about the only information about this header is on the MS blog: https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/

[dmitrykos]

On my machine this header is located like this:

C:\Program Files (x86)\Windows Kits\10\Include\10.0.19041.0\shared

It is bundled with Windows 10 SDK (10.0.19041.0), standard installation via Visual Studio. Check more details here: https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/

Usage example:
https://devblogs.microsoft.com/commandline/windowswsl-interop-with-af_unix/

This header is also mentioned in the sources too:

curl/lib/config-win32.h

Lines 723 to 730 in 70cf50f

	/* Replicating logic present in afunix.h of newer Windows 10 SDK versions */
	# define UNIX_PATH_MAX 108
	/* !checksrc! disable TYPEDEFSTRUCT 1 */
	typedef struct sockaddr_un {
	ADDRESS_FAMILY sun_family;
	char sun_path[UNIX_PATH_MAX];
	} SOCKADDR_UN, *PSOCKADDR_UN;
	#endif

[cvengler]

It is bundled with Windows 10 SDK (10.0.19041.0), standard installation via Visual Studio. Check more details here: https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/

Then please check for that build and don't discriminate users of older versions of Windows

[dmitrykos]

@emilengler, would you please elaborate on your comment?

Even though the SDK is one of the latest you can target the required min. Windows version for the build, in my case project is targeting 10.0.15063.0 which is fairly old 1703 Creators Update from early 2017 (https://en.wikipedia.org/wiki/Windows_10_version_history).

Without this correction curl can not be build successfully as explained in the PR description. Developers targeting the older versions could try to not define USE_UNIX_SOCKETS.

[cvengler]

Please also check if compiling with USE_UNIX_SOCKETS otherwise it won't compile on Windows systems that don't have the header

[dmitrykos]

I made an experiment and targeted the very first Windows 10 version (10.0.10240.0) and tried to compile curl:

Without a fix I am getting the following failure:

curl_addrinfo.c(483,8): error C2027: use of undefined type 'sockaddr_un'

With a fix applied source compiles successfully. So targeting the initial Windows 10 version (10.0.10240.0) with the standard latest Windows 10 SDK (10.0.19041.0) shipped with Visual Studio works fine.

The proposed PR covers only Windows 10 case, so Win32 family is not affected by this change.

[dmitrykos]

Added the proposed additional check for USE_UNIX_SOCKETS.

[jay]

Please run checksrc

./curl_addrinfo.c:53:96: warning: Longer than 79 columns (LONGLINE)
 #if defined(USE_UNIX_SOCKETS) && defined(WINAPI_FAMILY) && (WINAPI_FAMILY == WINAPI_FAMILY_APP)

[cvengler]

Okay as long as the CPP macros WINAPI_FAMILY and WINAPI_FAMILY_APP are available only on Windows 10 you have my go 👍

[dmitrykos]

(WINAPI_FAMILY == WINAPI_FAMILY_APP) is valid only for Windows 10 UWP platform and both defines are declared in winapifamily.h:

It is used for quite long time in PortAudio project without any issue for several years:
https://github.com/PortAudio/portaudio/blob/39bfe6c63df5b85bb651f16327e7386504089276/src/hostapi/wasapi/pa_win_wasapi.c#L68

[jay]

Thanks