Add support for sockaddr_un on Windows. (#6513)

* Windows: Fix warning about undefined if_indextoname()

* Windows: Fix UNIXSocket on MINGW and make .pair more reliable

* Windows: Use nonblock=true for read tests with scheduler

* Windows: Move socket detection from File.socket? to File.stat

Add S_IFSOCK to Windows and interpret reparse points accordingly.
Enable tests that work now.

* Windows: Use wide-char functions to UNIXSocket

This fixes behaviour with non-ASCII characters.
It also fixes deletion of temporary UNIXSocket.pair files.

* Windows: Add UNIXSocket tests for specifics of Windows impl.

* Windows: fix VC build due to missing _snwprintf

Avoid usage of _snwprintf, since it fails linking ruby.dll like so:

  linking shared-library x64-vcruntime140-ruby320.dll
  x64-vcruntime140-ruby320.def : error LNK2001: unresolved external symbol snwprintf
  x64-vcruntime140-ruby320.def : error LNK2001: unresolved external symbol vsnwprintf_l

whereas linking miniruby.exe succeeds.

This patch uses snprintf on the UTF-8 string instead.

Also remove branch GetWindowsDirectoryW, since it doesn't work.

* Windows: Fix dangling symlink test failures

Co-authored-by: Lars Kanis <kanis@comcard.de>

NEWS.md

@@ -103,7 +103,8 @@ Note that each entry is kept to a minimum, see links for details.
 Note: We're only listing outstanding class updates.
 
 * Fiber::Scheduler
-    * Introduce `Fiber::Scheduler#io_select` for non-blocking `IO.select`. [[Feature #19060]]
+    * Introduce `Fiber::Scheduler#io_select` for non-blocking `IO.select`.
+    [[Feature #19060]]
 
 * IO
     * Introduce `IO#timeout=` and `IO#timeout` which can cause
@@ -115,6 +116,11 @@ Note: We're only listing outstanding class updates.
     STDIN.read # => Blocking operation timed out! (IO::TimeoutError)
     ```
 
+* UNIXSocket
+    * Add support for UNIXSocket on Windows. Emulate anonymous sockets. Add
+    support for `File.socket?` and `File::Stat#socket?` where possible.
+    [[Feature #19135]]
+
 * Class
     * `Class#attached_object`, which returns the object for which
       the receiver is the singleton class. Raises `TypeError` if the
@@ -417,3 +423,4 @@ The following deprecated APIs are removed.
 [Feature #19026]: https://bugs.ruby-lang.org/issues/19026
 [Feature #19060]: https://bugs.ruby-lang.org/issues/19060
 [Bug #19100]:     https://bugs.ruby-lang.org/issues/19100
+[Feature #19135]: https://bugs.ruby-lang.org/issues/19135

configure.ac

@@ -1283,6 +1283,11 @@ dnl AC_HEADER_STDC has been checked in AC_USE_SYSTEM_EXTENSIONS
 AC_HEADER_STDBOOL
 AC_HEADER_SYS_WAIT
 
+AC_CHECK_HEADERS([afunix.h], [], [],
+[#ifdef _WIN32
+# include <winsock2.h>
+#endif
+])
 AC_CHECK_HEADERS(atomic.h)
 AC_CHECK_HEADERS(copyfile.h)
 AC_CHECK_HEADERS(direct.h)

ext/socket/extconf.rb

@@ -316,6 +316,7 @@ end
   netpacket/packet.h
   net/ethernet.h
   sys/un.h
+  afunix.h
   ifaddrs.h
   sys/ioctl.h
   sys/sockio.h

ext/socket/init.c

@@ -209,7 +209,7 @@ rsock_s_recvfrom(VALUE socket, int argc, VALUE *argv, enum sock_recv_type from)
         else
             return rb_assoc_new(str, Qnil);
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
       case RECV_UNIX:
         return rb_assoc_new(str, rsock_unixaddr(&arg.buf.un, arg.alen));
 #endif

ext/socket/lib/socket.rb

@@ -197,7 +197,7 @@ class Addrinfo
     sock = Socket.new(self.pfamily, self.socktype, self.protocol)
     begin
       sock.ipv6only! if self.ipv6?
-      sock.setsockopt(:SOCKET, :REUSEADDR, 1)
+      sock.setsockopt(:SOCKET, :REUSEADDR, 1) unless self.pfamily == Socket::PF_UNIX
       sock.bind(self)
       sock.listen(backlog)
     rescue Exception

ext/socket/option.c

@@ -670,10 +670,10 @@ rb_if_indextoname(const char *succ_prefix, const char *fail_prefix, unsigned int
 {
 #if defined(HAVE_IF_INDEXTONAME)
     char ifbuf[IFNAMSIZ];
-    if (if_indextoname(ifindex, ifbuf) == NULL)
+    if (if_indextoname(ifindex, ifbuf))
-        return snprintf(buf, len, "%s%u", fail_prefix, ifindex);
-    else
         return snprintf(buf, len, "%s%s", succ_prefix, ifbuf);
+    else
+        return snprintf(buf, len, "%s%u", fail_prefix, ifindex);
 #else
 #   ifndef IFNAMSIZ
 #       define IFNAMSIZ (sizeof(unsigned int)*3+1)
@@ -1229,7 +1229,7 @@ sockopt_inspect(VALUE self)
         else
             rb_str_catf(ret, " optname:%d", optname);
     }
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
     else if (family == AF_UNIX) {
         rb_str_catf(ret, " level:%d", level);
 
@@ -1393,7 +1393,7 @@ sockopt_inspect(VALUE self)
         }
         break;
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
       case AF_UNIX:
         switch (level) {
           case 0:

ext/socket/raddrinfo.c

@@ -644,7 +644,7 @@ rsock_ipaddr(struct sockaddr *sockaddr, socklen_t sockaddrlen, int norevlookup)
     return ary;
 }
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 static long
 unixsocket_len(const struct sockaddr_un *su, socklen_t socklen)
 {
@@ -1017,7 +1017,7 @@ addrinfo_list_new(VALUE node, VALUE service, VALUE family, VALUE socktype, VALUE
 }
 
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 static void
 init_unix_addrinfo(rb_addrinfo_t *rai, VALUE path, int socktype)
 {
@@ -1146,7 +1146,7 @@ addrinfo_initialize(int argc, VALUE *argv, VALUE self)
             break;
           }
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
           case AF_UNIX: /* ["AF_UNIX", "/tmp/sock"] */
           {
             VALUE path = rb_ary_entry(sockaddr_ary, 1);
@@ -1286,7 +1286,7 @@ rsock_inspect_sockaddr(struct sockaddr *sockaddr_arg, socklen_t socklen, VALUE r
           }
 #endif
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
           case AF_UNIX:
           {
             struct sockaddr_un *addr = &sockaddr->un;
@@ -1622,7 +1622,7 @@ addrinfo_mdump(VALUE self)
     afamily = rb_id2str(id);
 
     switch(afamily_int) {
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
       case AF_UNIX:
       {
         sockaddr = rb_str_new(rai->addr.un.sun_path, rai_unixsocket_len(rai));
@@ -1715,7 +1715,7 @@ addrinfo_mload(VALUE self, VALUE ary)
 
     v = rb_ary_entry(ary, 1);
     switch(afamily) {
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
       case AF_UNIX:
       {
         struct sockaddr_un uaddr;
@@ -2343,7 +2343,7 @@ addrinfo_ipv6_to_ipv4(VALUE self)
 
 #endif
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 /*
  * call-seq:
  *   addrinfo.unix_path => path
@@ -2491,7 +2491,7 @@ addrinfo_s_udp(VALUE self, VALUE host, VALUE port)
             INT2NUM(PF_UNSPEC), INT2NUM(SOCK_DGRAM), INT2NUM(IPPROTO_UDP), INT2FIX(0));
 }
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 
 /*
  * call-seq:
@@ -2629,7 +2629,7 @@ rsock_init_addrinfo(void)
     rb_define_singleton_method(rb_cAddrinfo, "ip", addrinfo_s_ip, 1);
     rb_define_singleton_method(rb_cAddrinfo, "tcp", addrinfo_s_tcp, 2);
     rb_define_singleton_method(rb_cAddrinfo, "udp", addrinfo_s_udp, 2);
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
     rb_define_singleton_method(rb_cAddrinfo, "unix", addrinfo_s_unix, -1);
 #endif
 
@@ -2670,7 +2670,7 @@ rsock_init_addrinfo(void)
     rb_define_method(rb_cAddrinfo, "ipv6_to_ipv4", addrinfo_ipv6_to_ipv4, 0);
 #endif
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
     rb_define_method(rb_cAddrinfo, "unix_path", addrinfo_unix_path, 0);
 #endif
 

ext/socket/rubysocket.h

@@ -33,6 +33,9 @@
 #endif
 
 #ifdef _WIN32
+#  include <winsock2.h>
+#  include <ws2tcpip.h>
+#  include <iphlpapi.h>
 #  if defined(_MSC_VER)
 #    undef HAVE_TYPE_STRUCT_SOCKADDR_DL
 #  endif
@@ -69,6 +72,11 @@
 #  include <sys/un.h>
 #endif
 
+#ifdef HAVE_AFUNIX_H
+// Windows doesn't have sys/un.h, but it does have afunix.h just to be special:
+#  include <afunix.h>
+#endif
+
 #if defined(HAVE_FCNTL)
 #  ifdef HAVE_SYS_SELECT_H
 #    include <sys/select.h>
@@ -268,7 +276,7 @@ extern VALUE rb_cIPSocket;
 extern VALUE rb_cTCPSocket;
 extern VALUE rb_cTCPServer;
 extern VALUE rb_cUDPSocket;
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 extern VALUE rb_cUNIXSocket;
 extern VALUE rb_cUNIXServer;
 #endif
@@ -336,7 +344,7 @@ VALUE rsock_sockaddr_obj(struct sockaddr *addr, socklen_t len);
 
 int rsock_revlookup_flag(VALUE revlookup, int *norevlookup);
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 VALUE rsock_unixpath_str(struct sockaddr_un *sockaddr, socklen_t len);
 VALUE rsock_unixaddr(struct sockaddr_un *sockaddr, socklen_t len);
 socklen_t rsock_unix_sockaddr_len(VALUE path);

ext/socket/socket.c

@@ -1383,7 +1383,7 @@ sock_s_unpack_sockaddr_in(VALUE self, VALUE addr)
     return rb_assoc_new(INT2NUM(ntohs(sockaddr->sin_port)), host);
 }
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 
 /*
  * call-seq:
@@ -1471,7 +1471,7 @@ sockaddr_len(struct sockaddr *addr)
         return (socklen_t)sizeof(struct sockaddr_in6);
 #endif
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
       case AF_UNIX:
         return (socklen_t)sizeof(struct sockaddr_un);
 #endif
@@ -2020,7 +2020,7 @@ Init_socket(void)
     rb_define_singleton_method(rb_cSocket, "sockaddr_in", sock_s_pack_sockaddr_in, 2);
     rb_define_singleton_method(rb_cSocket, "pack_sockaddr_in", sock_s_pack_sockaddr_in, 2);
     rb_define_singleton_method(rb_cSocket, "unpack_sockaddr_in", sock_s_unpack_sockaddr_in, 1);
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
     rb_define_singleton_method(rb_cSocket, "sockaddr_un", sock_s_pack_sockaddr_un, 1);
     rb_define_singleton_method(rb_cSocket, "pack_sockaddr_un", sock_s_pack_sockaddr_un, 1);
     rb_define_singleton_method(rb_cSocket, "unpack_sockaddr_un", sock_s_unpack_sockaddr_un, 1);

ext/socket/unixserver.c

@@ -10,7 +10,7 @@
 
 #include "rubysocket.h"
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 /*
  * call-seq:
  *   UNIXServer.new(path) => unixserver
@@ -101,7 +101,7 @@ unix_sysaccept(VALUE server)
 void
 rsock_init_unixserver(void)
 {
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
     /*
      * Document-class: UNIXServer < UNIXSocket
      *

ext/socket/unixsocket.c

@@ -10,7 +10,7 @@
 
 #include "rubysocket.h"
 
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
 struct unixsock_arg {
     struct sockaddr_un *sockaddr;
     socklen_t sockaddrlen;
@@ -42,6 +42,10 @@ unixsock_path_value(VALUE path)
             return name;             /* ignore encoding */
         }
     }
+#endif
+#ifdef _WIN32
+    /* UNIXSocket requires UTF-8 per spec. */
+    path = rb_str_export_to_enc(path, rb_utf8_encoding());
 #endif
     return rb_get_path(path);
 }
@@ -571,7 +575,7 @@ unix_s_socketpair(int argc, VALUE *argv, VALUE klass)
 void
 rsock_init_unixsocket(void)
 {
-#ifdef HAVE_SYS_UN_H
+#ifdef HAVE_TYPE_STRUCT_SOCKADDR_UN
     /*
      * Document-class: UNIXSocket < BasicSocket
      *

file.c

@@ -1765,8 +1765,8 @@ rb_file_socket_p(VALUE obj, VALUE fname)
 
     if (rb_stat(fname, &st) < 0) return Qfalse;
     if (S_ISSOCK(st.st_mode)) return Qtrue;
-
 #endif
+
     return Qfalse;
 }
 
@@ -5600,6 +5600,7 @@ rb_stat_init(VALUE obj, VALUE fname)
     if (STAT(StringValueCStr(fname), &st) == -1) {
         rb_sys_fail_path(fname);
     }
+
     if (DATA_PTR(obj)) {
         xfree(DATA_PTR(obj));
         DATA_PTR(obj) = NULL;

include/ruby/win32.h

@@ -18,11 +18,6 @@ RUBY_SYMBOL_EXPORT_BEGIN
  *
  */
 
-/*
- * Definitions for NT port of Perl
- */
-
-
 /*
  * Ok now we can include the normal include files.
  */
@@ -392,6 +387,7 @@ scalb(double a, long b)
 #endif
 
 #define S_IFLNK 0xa000
+#define S_IFSOCK 0xc000
 
 /*
  * define this so we can do inplace editing

test/fiber/test_enumerator.rb

@@ -10,12 +10,6 @@ class TestFiberEnumerator < Test::Unit::TestCase
 
     i, o = UNIXSocket.pair
 
-    unless i.nonblock? && o.nonblock?
-      i.close
-      o.close
-      omit "I/O is not non-blocking!"
-    end
-
     message = String.new
 
     thread = Thread.new do

test/fiber/test_io.rb

@@ -6,14 +6,12 @@ class TestFiberIO < Test::Unit::TestCase
   MESSAGE = "Hello World"
 
   def test_read
-    omit "UNIXSocket is not defined!" unless defined?(UNIXSocket)
+    omit unless defined?(UNIXSocket)
 
     i, o = UNIXSocket.pair
-
+    if RUBY_PLATFORM=~/mswin|mingw/
-    unless i.nonblock? && o.nonblock?
+      i.nonblock = true
-      i.close
+      o.nonblock = true
-      o.close
-      omit "I/O is not non-blocking!"
     end
 
     message = nil
@@ -46,6 +44,10 @@ class TestFiberIO < Test::Unit::TestCase
     16.times.map do
       Thread.new do
         i, o = UNIXSocket.pair
+        if RUBY_PLATFORM=~/mswin|mingw/
+          i.nonblock = true
+          o.nonblock = true
+        end
 
         scheduler = Scheduler.new
         Fiber.set_scheduler scheduler
@@ -64,16 +66,11 @@ class TestFiberIO < Test::Unit::TestCase
   end
 
   def test_epipe_on_read
-    omit "UNIXSocket is not defined!" unless defined?(UNIXSocket)
+    omit unless defined?(UNIXSocket)
+    omit "nonblock=true isn't properly supported on Windows" if RUBY_PLATFORM=~/mswin|mingw/
 
     i, o = UNIXSocket.pair
 
-    unless i.nonblock? && o.nonblock?
-      i.close
-      o.close
-      omit "I/O is not non-blocking!"
-    end
-
     error = nil
 
     thread = Thread.new do

test/fileutils/test_fileutils.rb

@@ -472,10 +472,14 @@ class TestFileUtils < Test::Unit::TestCase
   else
     def test_cp_r_socket
       pend "Skipping socket test on JRuby" if RUBY_ENGINE == 'jruby'
+
       Dir.mkdir('tmp/cpr_src')
       UNIXServer.new('tmp/cpr_src/socket').close
       cp_r 'tmp/cpr_src', 'tmp/cpr_dest'
       assert_equal(true, File.socket?('tmp/cpr_dest/socket'))
+    rescue Errno::EINVAL => error
+      # On some platforms (windows) sockets cannot be copied by FileUtils.
+      omit error.message
     end if defined?(UNIXServer)
   end
 

test/ruby/test_file_exhaustive.rb

@@ -649,7 +649,7 @@ class TestFileExhaustive < Test::Unit::TestCase
       # ignore unsupporting filesystems
     rescue Errno::EPERM
       # Docker prohibits statx syscall by the default.
-      skip("statx(2) is prohibited by seccomp")
+      omit("statx(2) is prohibited by seccomp")
     end
     assert_raise(Errno::ENOENT) { File.birthtime(nofile) }
   end if File.respond_to?(:birthtime)

test/ruby/test_io.rb

@@ -900,6 +900,10 @@ class TestIO < Test::Unit::TestCase
   end if defined? UNIXSocket
 
   def test_copy_stream_socket4
+    if RUBY_PLATFORM =~ /mingw|mswin/
+      omit "pread(2) is not implemented."
+    end
+
     with_bigsrc {|bigsrc, bigcontent|
       File.open(bigsrc) {|f|
         assert_equal(0, f.pos)
@@ -916,9 +920,13 @@ class TestIO < Test::Unit::TestCase
         }
       }
     }
-  end if defined? UNIXSocket
+  end
 
   def test_copy_stream_socket5
+    if RUBY_PLATFORM =~ /mingw|mswin/
+      omit "pread(2) is not implemented."
+    end
+
     with_bigsrc {|bigsrc, bigcontent|
       File.open(bigsrc) {|f|
         assert_equal(bigcontent[0,100], f.read(100))
@@ -936,9 +944,13 @@ class TestIO < Test::Unit::TestCase
         }
       }
     }
-  end if defined? UNIXSocket
+  end
 
   def test_copy_stream_socket6
+    if RUBY_PLATFORM =~ /mingw|mswin/
+      omit "pread(2) is not implemented."
+    end
+
     mkcdtmpdir {
       megacontent = "abc" * 1234567
       File.open("megasrc", "w") {|f| f << megacontent }
@@ -959,9 +971,13 @@ class TestIO < Test::Unit::TestCase
         assert_equal(megacontent, result)
       }
     }
-  end if defined? UNIXSocket
+  end
 
   def test_copy_stream_socket7
+    if RUBY_PLATFORM =~ /mingw|mswin/
+      omit "pread(2) is not implemented."
+    end
+
     GC.start
     mkcdtmpdir {
       megacontent = "abc" * 1234567
@@ -996,7 +1012,7 @@ class TestIO < Test::Unit::TestCase
         end
       }
     }
-  end if defined? UNIXSocket and IO.method_defined?("nonblock=")
+  end
 
   def test_copy_stream_strio
     src = StringIO.new("abcd")

test/ruby/test_io_timeout.rb

@@ -9,12 +9,6 @@ class TestIOTimeout < Test::Unit::TestCase
     begin
       i, o = UNIXSocket.pair
 
-      unless i.nonblock? && o.nonblock?
-        i.close
-        o.close
-        omit "I/O is not non-blocking!"
-      end
-
       yield i, o
     ensure
       i.close

test/socket/test_nonblock.rb

@@ -307,11 +307,13 @@ class TestSocketNonblock < Test::Unit::TestCase
           loop { s1.sendmsg_nonblock(buf) }
         end
       end
-    rescue NotImplementedError, Errno::ENOSYS, Errno::EPROTONOSUPPORT
+    rescue NotImplementedError, Errno::ENOSYS, Errno::EPROTONOSUPPORT, Errno::EPROTOTYPE
       omit "UNIXSocket.pair(:SEQPACKET) not implemented on this platform: #{$!}"
     end
 
     def test_sendmsg_nonblock_no_exception
+      omit "AF_UNIX + SEQPACKET is not supported on windows" if /mswin|mingw/ =~ RUBY_PLATFORM
+
       buf = '*' * 4096
       UNIXSocket.pair(:SEQPACKET) do |s1, s2|
         n = 0

test/socket/test_unix.rb

@@ -60,6 +60,8 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
       assert_not_equal s1.fileno, r.fileno
       r.close
     end
+  rescue NotImplementedError => error
+    omit error.message
   end
 
   def test_fd_passing_n
@@ -334,62 +336,70 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
   end
 
   def test_noname_path
-    s1, s2 = UNIXSocket.pair
+    if /mswin|mingw/ =~ RUBY_PLATFORM
-    assert_equal("", s1.path)
+      omit "unnamed pipe is emulated on windows"
-    assert_equal("", s2.path)
+    end
-  ensure
+
-    s1.close
+    UNIXSocket.pair do |s1, s2|
-    s2.close
+      assert_equal("", s1.path)
+      assert_equal("", s2.path)
+    end
   end
 
   def test_noname_addr
-    s1, s2 = UNIXSocket.pair
+    if /mswin|mingw/ =~ RUBY_PLATFORM
-    assert_equal(["AF_UNIX", ""], s1.addr)
+      omit "unnamed pipe is emulated on windows"
-    assert_equal(["AF_UNIX", ""], s2.addr)
+    end
-  ensure
+
-    s1.close
+    UNIXSocket.pair do |s1, s2|
-    s2.close
+      assert_equal(["AF_UNIX", ""], s1.addr)
+      assert_equal(["AF_UNIX", ""], s2.addr)
+    end
   end
 
   def test_noname_peeraddr
-    s1, s2 = UNIXSocket.pair
+    if /mswin|mingw/ =~ RUBY_PLATFORM
-    assert_equal(["AF_UNIX", ""], s1.peeraddr)
+      omit "unnamed pipe is emulated on windows"
-    assert_equal(["AF_UNIX", ""], s2.peeraddr)
+    end
-  ensure
+
-    s1.close
+    UNIXSocket.pair do |s1, s2|
-    s2.close
+      assert_equal(["AF_UNIX", ""], s1.peeraddr)
+      assert_equal(["AF_UNIX", ""], s2.peeraddr)
+    end
   end
 
   def test_noname_unpack_sockaddr_un
-    s1, s2 = UNIXSocket.pair
+    if /mswin|mingw/ =~ RUBY_PLATFORM
-    n = nil
+      omit "unnamed pipe is emulated on windows"
-    assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s1.getsockname) != ""
+    end
-    assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s1.getsockname) != ""
+
-    assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s2.getsockname) != ""
+    UNIXSocket.pair do |s1, s2|
-    assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s1.getpeername) != ""
+      n = nil
-    assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s2.getpeername) != ""
+      assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s1.getsockname) != ""
-  ensure
+      assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s1.getsockname) != ""
-    s1.close
+      assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s2.getsockname) != ""
-    s2.close
+      assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s1.getpeername) != ""
+      assert_equal("", Socket.unpack_sockaddr_un(n)) if (n = s2.getpeername) != ""
+    end
   end
 
   def test_noname_recvfrom
-    s1, s2 = UNIXSocket.pair
+    if /mswin|mingw/ =~ RUBY_PLATFORM
-    s2.write("a")
+      omit "unnamed pipe is emulated on windows"
-    assert_equal(["a", ["AF_UNIX", ""]], s1.recvfrom(10))
+    end
-  ensure
+
-    s1.close
+    UNIXSocket.pair do |s1, s2|
-    s2.close
+      s2.write("a")
+      assert_equal(["a", ["AF_UNIX", ""]], s1.recvfrom(10))
+    end
   end
 
   def test_noname_recv_nonblock
-    s1, s2 = UNIXSocket.pair
+    UNIXSocket.pair do |s1, s2|
-    s2.write("a")
+      s2.write("a")
-    IO.select [s1]
+      IO.select [s1]
-    assert_equal("a", s1.recv_nonblock(10))
+      assert_equal("a", s1.recv_nonblock(10))
-  ensure
+    end
-    s1.close
-    s2.close
   end
 
   def test_too_long_path
@@ -429,12 +439,18 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
     rv = s1.recv(100, 0, buf)
     assert_equal buf.object_id, rv.object_id
     assert_equal "BBBBBB", rv
+  rescue Errno::EPROTOTYPE => error
+    omit error.message
   ensure
     s1.close if s1
     s2.close if s2
   end
 
   def test_dgram_pair_sendrecvmsg_errno_set
+    if /mswin|mingw/ =~ RUBY_PLATFORM
+      omit("AF_UNIX + SOCK_DGRAM is not supported on windows")
+    end
+
     s1, s2 = to_close = UNIXSocket.pair(Socket::SOCK_DGRAM)
     pipe = IO.pipe
     to_close.concat(pipe)
@@ -457,9 +473,17 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
   end
 
   def test_epipe # [ruby-dev:34619]
+    # This is a good example of why reporting the exact `errno` is a terrible
+    # idea for platform abstractions.
+    if RUBY_PLATFORM =~ /mswin|mingw/
+      error = Errno::ESHUTDOWN
+    else
+      error = Errno::EPIPE
+    end
+
     UNIXSocket.pair {|s1, s2|
       s1.shutdown(Socket::SHUT_WR)
-      assert_raise(Errno::EPIPE) { s1.write "a" }
+      assert_raise(error) { s1.write "a" }
       assert_equal(nil, s2.read(1))
       s2.write "a"
       assert_equal("a", s1.read(1))
@@ -493,6 +517,45 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
     }
   end
 
+  if /mingw|mswin/ =~ RUBY_PLATFORM
+
+    def test_unix_socket_with_encoding
+      Dir.mktmpdir do |tmpdir|
+        path = "#{tmpdir}/sockäöü".encode("cp850")
+        UNIXServer.open(path) do |serv|
+          assert File.socket?(path)
+          assert File.stat(path).socket?
+          assert File.lstat(path).socket?
+          assert_equal path.encode("utf-8"), serv.path
+          UNIXSocket.open(path) do |s1|
+            s2 = serv.accept
+            s2.close
+          end
+        end
+      end
+    end
+
+    def test_windows_unix_socket_pair_with_umlaut
+      otmp = ENV['TMP']
+      ENV['TMP'] = File.join(Dir.tmpdir, "äöü€")
+      FileUtils.mkdir_p ENV['TMP']
+
+      s1, s2 = UNIXSocket.pair
+      assert !s1.path.empty?
+      assert !File.exist?(s1.path)
+    ensure
+      FileUtils.rm_rf ENV['TMP']
+      ENV['TMP'] = otmp
+    end
+
+    def test_windows_unix_socket_pair_paths
+      s1, s2 = UNIXSocket.pair
+      assert !s1.path.empty?
+      assert s2.path.empty?
+      assert !File.exist?(s1.path)
+    end
+  end
+
   def test_initialize
     Dir.mktmpdir {|d|
       Socket.open(Socket::AF_UNIX, Socket::SOCK_STREAM, 0) {|s|

win32/Makefile.sub

@@ -629,6 +629,9 @@ $(CONFIG_H): $(MKFILES) $(srcdir)/win32/Makefile.sub $(win_srcdir)/Makefile.sub
 #define HAVE_STDDEF_H 1
 #define HAVE_STRING_H 1
 #define HAVE_MEMORY_H 1
+!if $(MSC_VER) >= 1920
+#define HAVE_AFUNIX_H 1
+!endif
 !if $(MSC_VER) >= 1400
 #define HAVE_LONG_LONG 1
 !else

win32/file.h

@@ -1,6 +1,10 @@
 #ifndef RUBY_WIN32_FILE_H
 #define RUBY_WIN32_FILE_H
 
+#ifndef IO_REPARSE_TAG_AF_UNIX
+# define IO_REPARSE_TAG_AF_UNIX 0x80000023
+#endif
+
 enum {
     MINIMUM_REPARSE_BUFFER_PATH_LEN = 100
 };

win32/win32.c

@@ -49,6 +49,9 @@
 #ifdef __MINGW32__
 #include <mswsock.h>
 #endif
+#ifdef HAVE_AFUNIX_H
+# include <afunix.h>
+#endif
 #include "ruby/win32.h"
 #include "ruby/vm.h"
 #include "win32/dir.h"
@@ -4018,15 +4021,93 @@ rb_w32_getservbyport(int port, const char *proto)
     return r;
 }
 
+#ifdef HAVE_AFUNIX_H
+
+/* License: Ruby's */
+static size_t
+socketpair_unix_path(struct sockaddr_un *sock_un)
+{
+    SOCKET listener;
+    WCHAR wpath[sizeof(sock_un->sun_path)/sizeof(*sock_un->sun_path)] = L"";
+
+    /* AF_UNIX/SOCK_STREAM became available in Windows 10
+     * See https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows
+     */
+    listener = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (listener == INVALID_SOCKET)
+        return 0;
+
+    memset(sock_un, 0, sizeof(*sock_un));
+    sock_un->sun_family = AF_UNIX;
+
+    /* Abstract sockets (filesystem-independent) don't work, contrary to
+     * the claims of the aforementioned blog post:
+     * https://github.com/microsoft/WSL/issues/4240#issuecomment-549663217
+     *
+     * So we must use a named path, and that comes with all the attendant
+     * problems of permissions and collisions. Trying various temporary
+     * directories and putting high-res time and PID in the filename.
+     */
+    for (int try = 0; ; try++) {
+        LARGE_INTEGER ticks;
+        size_t path_len = 0;
+        const size_t maxpath = sizeof(sock_un->sun_path)/sizeof(*sock_un->sun_path);
+
+        switch (try) {
+        case 0:
+            /* user temp dir from TMP or TEMP env var, it ends with a backslash */
+            path_len = GetTempPathW(maxpath, wpath);
+            break;
+        case 1:
+            wcsncpy(wpath, L"C:/Temp/", maxpath);
+            path_len = lstrlenW(wpath);
+            break;
+        case 2:
+            /* Current directory */
+            path_len = 0;
+            break;
+        case 3:
+            closesocket(listener);
+            return 0;
+        }
+
+        /* Windows UNIXSocket implementation expects UTF-8 instead of UTF16 */
+        path_len = WideCharToMultiByte(CP_UTF8, 0, wpath, path_len, sock_un->sun_path, maxpath, NULL, NULL);
+        QueryPerformanceCounter(&ticks);
+        path_len += snprintf(sock_un->sun_path + path_len,
+                 maxpath - path_len,
+                 "%lld-%ld.($)",
+                 ticks.QuadPart,
+                 GetCurrentProcessId());
+
+        /* Convert to UTF16 for DeleteFileW */
+        MultiByteToWideChar(CP_UTF8, 0, sock_un->sun_path, -1, wpath, sizeof(wpath)/sizeof(*wpath));
+
+        if (bind(listener, (struct sockaddr *)sock_un, sizeof(*sock_un)) != SOCKET_ERROR)
+            break;
+    }
+    closesocket(listener);
+    DeleteFileW(wpath);
+    return sizeof(*sock_un);
+}
+#endif
+
 /* License: Ruby's */
 static int
 socketpair_internal(int af, int type, int protocol, SOCKET *sv)
 {
     SOCKET svr = INVALID_SOCKET, r = INVALID_SOCKET, w = INVALID_SOCKET;
     struct sockaddr_in sock_in4;
+
 #ifdef INET6
     struct sockaddr_in6 sock_in6;
 #endif
+
+#ifdef HAVE_AFUNIX_H
+    struct sockaddr_un sock_un = {0, {0}};
+    WCHAR wpath[sizeof(sock_un.sun_path)/sizeof(*sock_un.sun_path)] = L"";
+#endif
+
     struct sockaddr *addr;
     int ret = -1;
     int len;
@@ -4050,6 +4131,15 @@ socketpair_internal(int af, int type, int protocol, SOCKET *sv)
         addr = (struct sockaddr *)&sock_in6;
         len = sizeof(sock_in6);
         break;
+#endif
+#ifdef HAVE_AFUNIX_H
+      case AF_UNIX:
+        addr = (struct sockaddr *)&sock_un;
+        len = socketpair_unix_path(&sock_un);
+        MultiByteToWideChar(CP_UTF8, 0, sock_un.sun_path, -1, wpath, sizeof(wpath)/sizeof(*wpath));
+        if (len)
+            break;
+        /* fall through */
 #endif
       default:
         errno = EAFNOSUPPORT;
@@ -4101,6 +4191,10 @@ socketpair_internal(int af, int type, int protocol, SOCKET *sv)
         }
         if (svr != INVALID_SOCKET)
             closesocket(svr);
+#ifdef HAVE_AFUNIX_H
+        if (sock_un.sun_family == AF_UNIX)
+            DeleteFileW(wpath);
+#endif
     }
 
     return ret;
@@ -5632,10 +5726,8 @@ fileattr_to_unixmode(DWORD attr, const WCHAR *path, unsigned mode)
         /* format is already set */
     }
     else if (attr & FILE_ATTRIBUTE_REPARSE_POINT) {
-        if (rb_w32_reparse_symlink_p(path))
+        /* Only used by stat_by_find in the case the file can not be opened.
-            mode |= S_IFLNK | S_IEXEC;
+         * In this case we can't get more details. */
-        else
-            mode |= S_IFDIR | S_IEXEC;
     }
     else if (attr & FILE_ATTRIBUTE_DIRECTORY) {
         mode |= S_IFDIR | S_IEXEC;
@@ -5710,14 +5802,6 @@ stat_by_find(const WCHAR *path, struct stati128 *st)
 {
     HANDLE h;
     WIN32_FIND_DATAW wfd;
-    /* GetFileAttributesEx failed; check why. */
-    int e = GetLastError();
-
-    if ((e == ERROR_FILE_NOT_FOUND) || (e == ERROR_INVALID_NAME)
-        || (e == ERROR_PATH_NOT_FOUND || (e == ERROR_BAD_NETPATH))) {
-        errno = map_errno(e);
-        return -1;
-    }
 
     /* Fall back to FindFirstFile for ERROR_SHARING_VIOLATION */
     h = FindFirstFileW(path, &wfd);
@@ -5753,9 +5837,24 @@ winnt_stat(const WCHAR *path, struct stati128 *st, BOOL lstat)
     DWORD flags = lstat ? FILE_FLAG_OPEN_REPARSE_POINT : 0;
     HANDLE f;
     WCHAR finalname[PATH_MAX];
+    int open_error;
 
     memset(st, 0, sizeof(*st));
     f = open_special(path, 0, flags);
+    open_error = GetLastError();
+    if (f == INVALID_HANDLE_VALUE && !lstat) {
+        /* Support stat (not only lstat) of UNIXSocket */
+        FILE_ATTRIBUTE_TAG_INFO attr_info;
+        DWORD e;
+
+        f = open_special(path, 0, FILE_FLAG_OPEN_REPARSE_POINT);
+        e = GetFileInformationByHandleEx( f, FileAttributeTagInfo,
+                &attr_info, sizeof(attr_info));
+        if (!e || attr_info.ReparseTag != IO_REPARSE_TAG_AF_UNIX) {
+            CloseHandle(f);
+            f = INVALID_HANDLE_VALUE;
+        }
+    }
     if (f != INVALID_HANDLE_VALUE) {
         DWORD attr = stati128_handle(f, st);
         const DWORD len = get_final_path(f, finalname, numberof(finalname), 0);
@@ -5767,15 +5866,26 @@ winnt_stat(const WCHAR *path, struct stati128 *st, BOOL lstat)
           case FILE_TYPE_PIPE:
             mode = S_IFIFO;
             break;
+          default:
+            if (attr & FILE_ATTRIBUTE_REPARSE_POINT) {
+                FILE_ATTRIBUTE_TAG_INFO attr_info;
+                DWORD e;
+
+                e = GetFileInformationByHandleEx( f, FileAttributeTagInfo,
+                        &attr_info, sizeof(attr_info));
+                if (e && attr_info.ReparseTag == IO_REPARSE_TAG_AF_UNIX) {
+                    st->st_size = 0;
+                    mode |= S_IFSOCK;
+                } else if (rb_w32_reparse_symlink_p(path)) {
+                    /* TODO: size in which encoding? */
+                    st->st_size = 0;
+                    mode |= S_IFLNK | S_IEXEC;
+                } else {
+                    mode |= S_IFDIR | S_IEXEC;
+                }
+            }
         }
         CloseHandle(f);
-        if (attr & FILE_ATTRIBUTE_REPARSE_POINT) {
-            /* TODO: size in which encoding? */
-            if (rb_w32_reparse_symlink_p(path))
-                st->st_size = 0;
-            else
-                attr &= ~FILE_ATTRIBUTE_REPARSE_POINT;
-        }
         if (attr & FILE_ATTRIBUTE_DIRECTORY) {
             if (check_valid_dir(path)) return -1;
         }
@@ -5788,6 +5898,12 @@ winnt_stat(const WCHAR *path, struct stati128 *st, BOOL lstat)
         }
     }
     else {
+        if ((open_error == ERROR_FILE_NOT_FOUND) || (open_error == ERROR_INVALID_NAME)
+            || (open_error == ERROR_PATH_NOT_FOUND || (open_error == ERROR_BAD_NETPATH))) {
+            errno = map_errno(open_error);
+            return -1;
+        }
+
         if (stat_by_find(path, st)) return -1;
     }