Sort out getpeereid() and peer auth handling on Windows

The getpeereid() uses have so far been protected by HAVE_UNIX_SOCKETS,
so they didn't ever care about Windows support.  But in anticipation
of Unix-domain socket support on Windows, that needs to be handled
differently.

Windows doesn't support getpeereid() at this time, so we use the
existing not-supported code path.  We let configure do its usual thing
of picking up the replacement from libpgport, instead of the custom
overrides that it was doing before.

But then Windows doesn't have struct passwd, so this patch sprinkles
some additional #ifdef WIN32 around to make it work.  This is similar
to existing code that deals with this issue.
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/5974caea-1267-7708-40f2-6009a9d653b0@2ndquadrant.com

configure

@@ -15685,6 +15685,19 @@ esac
 
 fi
 
+ac_fn_c_check_func "$LINENO" "getpeereid" "ac_cv_func_getpeereid"
+if test "x$ac_cv_func_getpeereid" = xyes; then :
+  $as_echo "#define HAVE_GETPEEREID 1" >>confdefs.h
+
+else
+  case " $LIBOBJS " in
+  *" getpeereid.$ac_objext "* ) ;;
+  *) LIBOBJS="$LIBOBJS getpeereid.$ac_objext"
+ ;;
+esac
+
+fi
+
 ac_fn_c_check_func "$LINENO" "getrusage" "ac_cv_func_getrusage"
 if test "x$ac_cv_func_getrusage" = xyes; then :
   $as_echo "#define HAVE_GETRUSAGE 1" >>confdefs.h
@@ -15863,19 +15876,13 @@ $as_echo "$as_me: On $host_os we will use our strtof wrapper." >&6;}
 esac
 
 case $host_os in
-
         # Windows uses a specialised env handler
-        # and doesn't need a replacement getpeereid because it doesn't use
-        # Unix sockets.
         mingw*)
 
 $as_echo "#define HAVE_UNSETENV 1" >>confdefs.h
 
-
-$as_echo "#define HAVE_GETPEEREID 1" >>confdefs.h
-
                 ac_cv_func_unsetenv=yes
-                ac_cv_func_getpeereid=yes;;
+                ;;
         *)
                 ac_fn_c_check_func "$LINENO" "unsetenv" "ac_cv_func_unsetenv"
 if test "x$ac_cv_func_unsetenv" = xyes; then :
@@ -15890,21 +15897,8 @@ esac
 
 fi
 
-ac_fn_c_check_func "$LINENO" "getpeereid" "ac_cv_func_getpeereid"
-if test "x$ac_cv_func_getpeereid" = xyes; then :
-  $as_echo "#define HAVE_GETPEEREID 1" >>confdefs.h
 
-else
-  case " $LIBOBJS " in
-  *" getpeereid.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS getpeereid.$ac_objext"
- ;;
-esac
-
-fi
-
-
-		;;
+                ;;
 esac
 
 # System's version of getaddrinfo(), if any, may be used only if we found

configure.in

@@ -1729,6 +1729,7 @@ AC_REPLACE_FUNCS(m4_normalize([
 	explicit_bzero
 	fls
 	getopt
+	getpeereid
 	getrusage
 	inet_aton
 	mkdtemp
@@ -1757,18 +1758,14 @@ case $host_os in
 esac
 
 case $host_os in
-
         # Windows uses a specialised env handler
-        # and doesn't need a replacement getpeereid because it doesn't use
-        # Unix sockets.
         mingw*)
                 AC_DEFINE(HAVE_UNSETENV, 1, [Define to 1 because replacement version used.])
-                AC_DEFINE(HAVE_GETPEEREID, 1, [Define to 1 because function not required.])
                 ac_cv_func_unsetenv=yes
-                ac_cv_func_getpeereid=yes;;
+                ;;
         *)
-                AC_REPLACE_FUNCS([unsetenv getpeereid])
-		;;
+                AC_REPLACE_FUNCS([unsetenv])
+                ;;
 esac
 
 # System's version of getaddrinfo(), if any, may be used only if we found

src/backend/libpq/auth.c

@@ -77,9 +77,7 @@ static int	ident_inet(hbaPort *port);
  * Peer authentication
  *----------------------------------------------------------------
  */
-#ifdef HAVE_UNIX_SOCKETS
 static int	auth_peer(hbaPort *port);
-#endif
 
 
 /*----------------------------------------------------------------
@@ -559,11 +557,7 @@ ClientAuthentication(Port *port)
 			break;
 
 		case uaPeer:
-#ifdef HAVE_UNIX_SOCKETS
 			status = auth_peer(port);
-#else
-			Assert(false);
-#endif
 			break;
 
 		case uaIdent:
@@ -1984,16 +1978,16 @@ ident_inet_done:
  *
  *	Iff authorized, return STATUS_OK, otherwise return STATUS_ERROR.
  */
-#ifdef HAVE_UNIX_SOCKETS
-
 static int
 auth_peer(hbaPort *port)
 {
 	uid_t		uid;
 	gid_t		gid;
+#ifndef WIN32
 	struct passwd *pw;
 	char	   *peer_user;
 	int			ret;
+#endif
 
 	if (getpeereid(port->sock, &uid, &gid) != 0)
 	{
@@ -2009,6 +2003,7 @@ auth_peer(hbaPort *port)
 		return STATUS_ERROR;
 	}
 
+#ifndef WIN32
 	errno = 0;					/* clear errno before call */
 	pw = getpwuid(uid);
 	if (!pw)
@@ -2030,8 +2025,12 @@ auth_peer(hbaPort *port)
 	pfree(peer_user);
 
 	return ret;
+#else
+	/* should have failed with ENOSYS above */
+	Assert(false);
+	return STATUS_ERROR;
+#endif
 }
-#endif							/* HAVE_UNIX_SOCKETS */
 
 
 /*----------------------------------------------------------------

src/include/port.h

@@ -354,7 +354,7 @@ extern int	fls(int mask);
 #define ftello(a)		ftell(a)
 #endif
 
-#if !defined(HAVE_GETPEEREID) && !defined(WIN32)
+#ifndef HAVE_GETPEEREID
 extern int	getpeereid(int sock, uid_t *uid, gid_t *gid);
 #endif
 

src/interfaces/libpq/fe-connect.c

@@ -2733,8 +2733,6 @@ keep_going:						/* We will come back to here until there is
 				char	   *startpacket;
 				int			packetlen;
 
-#ifdef HAVE_UNIX_SOCKETS
-
 				/*
 				 * Implement requirepeer check, if requested and it's a
 				 * Unix-domain socket.
@@ -2742,10 +2740,12 @@ keep_going:						/* We will come back to here until there is
 				if (conn->requirepeer && conn->requirepeer[0] &&
 					IS_AF_UNIX(conn->raddr.addr.ss_family))
 				{
+#ifndef WIN32
 					char		pwdbuf[BUFSIZ];
 					struct passwd pass_buf;
 					struct passwd *pass;
 					int			passerr;
+#endif
 					uid_t		uid;
 					gid_t		gid;
 
@@ -2766,6 +2766,7 @@ keep_going:						/* We will come back to here until there is
 						goto error_return;
 					}
 
+#ifndef WIN32
 					passerr = pqGetpwuid(uid, &pass_buf, pwdbuf, sizeof(pwdbuf), &pass);
 					if (pass == NULL)
 					{
@@ -2788,8 +2789,11 @@ keep_going:						/* We will come back to here until there is
 										  conn->requirepeer, pass->pw_name);
 						goto error_return;
 					}
+#else							/* WIN32 */
+					/* should have failed with ENOSYS above */
+					Assert(false);
+#endif							/* WIN32 */
 				}
-#endif							/* HAVE_UNIX_SOCKETS */
 
 				if (IS_AF_UNIX(conn->raddr.addr.ss_family))
 				{

src/tools/msvc/Mkvcbuild.pm

@@ -94,7 +94,7 @@ sub mkvcbuild
 	$solution = CreateSolution($vsVersion, $config);
 
 	our @pgportfiles = qw(
-	  chklocale.c explicit_bzero.c fls.c fseeko.c getrusage.c inet_aton.c random.c
+	  chklocale.c explicit_bzero.c fls.c fseeko.c getpeereid.c getrusage.c inet_aton.c random.c
 	  srandom.c getaddrinfo.c gettimeofday.c inet_net_ntop.c kill.c open.c
 	  erand48.c snprintf.c strlcat.c strlcpy.c dirmod.c noblock.c path.c
 	  dirent.c dlopen.c getopt.c getopt_long.c