Portability fixes for sigwait.

Build farm animals running ancient HPUX and Solaris have a non-standard
sigwait() from draft versions of POSIX, so they didn't like commit
7c09d27.  To avoid the problem in general, only try to use sigwait() if
it's declared by <signal.h> and matches the expected declaration.  To
select the modern declaration on Solaris (even in non-threaded
programs), move -D_POSIX_PTHREAD_SEMANTICS into the right place to
affect all translation units.

Also fix the error checking.  Modern sigwait() doesn't set errno.

Thanks to Tom Lane for help with this.

Discussion: https://postgr.es/m/3187588.1626136248%40sss.pgh.pa.us

Author: macdice

config/thread_test.c

@@ -43,10 +43,6 @@
 #include <winsock2.h>
 #endif
 
-/* Test for POSIX.1c 2-arg sigwait() and fail on single-arg version */
-#include <signal.h>
-int			sigwait(const sigset_t *set, int *sig);
-
 
 #define		TEMP_FILENAME_1 "thread_test.1"
 #define		TEMP_FILENAME_2 "thread_test.2"

configure

@@ -7194,6 +7194,12 @@ $as_echo "#define PROFILE_PID_DIR 1" >>confdefs.h
   fi
 fi
 
+# On Solaris, we need this #define to get POSIX-conforming versions
+# of many interfaces (sigwait, getpwuid_r, ...).
+if test "$PORTNAME" = "solaris"; then
+  CPPFLAGS="$CPPFLAGS -D_POSIX_PTHREAD_SEMANTICS"
+fi
+
 # We already have this in Makefile.win32, but configure needs it too
 if test "$PORTNAME" = "win32"; then
   CPPFLAGS="$CPPFLAGS -I$srcdir/src/include/port/win32"
@@ -11296,9 +11302,8 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 	# set thread flags
 
 # Some platforms use these, so just define them.  They can't hurt if they
-# are not supported.  For example, on Solaris -D_POSIX_PTHREAD_SEMANTICS
-# enables 5-arg getpwuid_r, among other things.
-PTHREAD_CFLAGS="$PTHREAD_CFLAGS -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS"
+# are not supported.
+PTHREAD_CFLAGS="$PTHREAD_CFLAGS -D_REENTRANT -D_THREAD_SAFE"
 
 # Check for *_r functions
 _CFLAGS="$CFLAGS"
@@ -15861,9 +15866,11 @@ $as_echo "#define HAVE_FSEEKO 1" >>confdefs.h
 fi
 
 
-# posix_fadvise() is a no-op on Solaris, so don't incur function overhead
-# by calling it, 2009-04-02
-# http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libc/port/gen/posix_fadvise.c
+# Make sure there's a declaration for sigwait(), then make sure
+# that it conforms to the POSIX standard (there seem to still be
+# some platforms out there with pre-POSIX sigwait()).  On Solaris,
+# _POSIX_PTHREAD_SEMANTICS affects the result, but we already
+# added that to CPPFLAGS.
 # The Clang compiler raises a warning for an undeclared identifier that matches
 # a compiler builtin function.  All extant Clang versions are affected, as of
 # Clang 3.6.0.  Test a builtin known to every version.  This problem affects the
@@ -15952,6 +15959,62 @@ case $ac_cv_c_decl_report in
   *) ac_c_decl_warn_flag= ;;
 esac
 
+ac_fn_c_check_decl "$LINENO" "sigwait" "ac_cv_have_decl_sigwait" "#include <signal.h>
+"
+if test "x$ac_cv_have_decl_sigwait" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_SIGWAIT $ac_have_decl
+_ACEOF
+
+if test "x$ac_cv_have_decl_sigwait" = xyes; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for POSIX-conforming sigwait declaration" >&5
+$as_echo_n "checking for POSIX-conforming sigwait declaration... " >&6; }
+if ${pgac_cv_have_posix_decl_sigwait+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+      #include <signal.h>
+      int sigwait(const sigset_t *set, int *sig);
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_have_posix_decl_sigwait=yes
+else
+  pgac_cv_have_posix_decl_sigwait=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_have_posix_decl_sigwait" >&5
+$as_echo "$pgac_cv_have_posix_decl_sigwait" >&6; }
+fi
+if test "x$pgac_cv_have_posix_decl_sigwait" = xyes; then
+
+$as_echo "#define HAVE_POSIX_DECL_SIGWAIT 1" >>confdefs.h
+
+else
+  # On non-Windows, libpq requires POSIX sigwait() for thread safety.
+  if test "$enable_thread_safety" = yes -a "$PORTNAME" != "win32"; then
+    as_fn_error $? "POSIX-conforming sigwait is required to enable thread safety." "$LINENO" 5
+  fi
+fi
+
+# posix_fadvise() is a no-op on Solaris, so don't incur function overhead
+# by calling it, 2009-04-02
+# http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libc/port/gen/posix_fadvise.c
 if test "$PORTNAME" != "solaris"; then :
 
 for ac_func in posix_fadvise

configure.ac

@@ -610,6 +610,12 @@ if test "$enable_profiling" = yes && test "$ac_cv_prog_cc_g" = yes; then
   fi
 fi
 
+# On Solaris, we need this #define to get POSIX-conforming versions
+# of many interfaces (sigwait, getpwuid_r, ...).
+if test "$PORTNAME" = "solaris"; then
+  CPPFLAGS="$CPPFLAGS -D_POSIX_PTHREAD_SEMANTICS"
+fi
+
 # We already have this in Makefile.win32, but configure needs it too
 if test "$PORTNAME" = "win32"; then
   CPPFLAGS="$CPPFLAGS -I$srcdir/src/include/port/win32"
@@ -1122,9 +1128,8 @@ AS_IF([test "$enable_thread_safety" = yes -a "$PORTNAME" != "win32"],
 AX_PTHREAD	# set thread flags
 
 # Some platforms use these, so just define them.  They can't hurt if they
-# are not supported.  For example, on Solaris -D_POSIX_PTHREAD_SEMANTICS
-# enables 5-arg getpwuid_r, among other things.
-PTHREAD_CFLAGS="$PTHREAD_CFLAGS -D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS"
+# are not supported.
+PTHREAD_CFLAGS="$PTHREAD_CFLAGS -D_REENTRANT -D_THREAD_SAFE"
 
 # Check for *_r functions
 _CFLAGS="$CFLAGS"
@@ -1741,6 +1746,33 @@ PGAC_CHECK_BUILTIN_FUNC([__builtin_popcount], [unsigned int x])
 # in case it finds that _LARGEFILE_SOURCE has to be #define'd for that.
 AC_FUNC_FSEEKO
 
+# Make sure there's a declaration for sigwait(), then make sure
+# that it conforms to the POSIX standard (there seem to still be
+# some platforms out there with pre-POSIX sigwait()).  On Solaris,
+# _POSIX_PTHREAD_SEMANTICS affects the result, but we already
+# added that to CPPFLAGS.
+AC_CHECK_DECLS(sigwait, [], [], [#include <signal.h>])
+if test "x$ac_cv_have_decl_sigwait" = xyes; then
+  AC_CACHE_CHECK([for POSIX-conforming sigwait declaration],
+    [pgac_cv_have_posix_decl_sigwait],
+    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
+      #include <signal.h>
+      int sigwait(const sigset_t *set, int *sig);
+      ],
+      [])],
+      [pgac_cv_have_posix_decl_sigwait=yes],
+      [pgac_cv_have_posix_decl_sigwait=no])])
+fi
+if test "x$pgac_cv_have_posix_decl_sigwait" = xyes; then
+  AC_DEFINE(HAVE_POSIX_DECL_SIGWAIT, 1,
+            [Define to 1 if you have a POSIX-conforming sigwait declaration.])
+else
+  # On non-Windows, libpq requires POSIX sigwait() for thread safety.
+  if test "$enable_thread_safety" = yes -a "$PORTNAME" != "win32"; then
+    AC_MSG_ERROR([POSIX-conforming sigwait is required to enable thread safety.])
+  fi
+fi
+
 # posix_fadvise() is a no-op on Solaris, so don't incur function overhead
 # by calling it, 2009-04-02
 # http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libc/port/gen/posix_fadvise.c

src/bin/psql/command.c

@@ -4899,7 +4899,7 @@ do_watch(PQExpBuffer query_buf, double sleep)
 	FILE	   *pagerpipe = NULL;
 	int			title_len;
 	int			res = 0;
-#ifndef WIN32
+#ifdef HAVE_POSIX_DECL_SIGWAIT
 	sigset_t	sigalrm_sigchld_sigint;
 	sigset_t	sigalrm_sigchld;
 	sigset_t	sigint;
@@ -4913,7 +4913,7 @@ do_watch(PQExpBuffer query_buf, double sleep)
 		return false;
 	}
 
-#ifndef WIN32
+#ifdef HAVE_POSIX_DECL_SIGWAIT
 	sigemptyset(&sigalrm_sigchld_sigint);
 	sigaddset(&sigalrm_sigchld_sigint, SIGCHLD);
 	sigaddset(&sigalrm_sigchld_sigint, SIGALRM);
@@ -4952,7 +4952,7 @@ do_watch(PQExpBuffer query_buf, double sleep)
 	 * PAGER environment variables, because traditional pagers probably won't
 	 * be very useful for showing a stream of results.
 	 */
-#ifndef WIN32
+#ifdef HAVE_POSIX_DECL_SIGWAIT
 	pagerprog = getenv("PSQL_WATCH_PAGER");
 #endif
 	if (pagerprog && myopt.topt.pager)
@@ -5023,7 +5023,7 @@ do_watch(PQExpBuffer query_buf, double sleep)
 		if (pagerpipe && ferror(pagerpipe))
 			break;
 
-#ifdef WIN32
+#ifndef HAVE_POSIX_DECL_SIGWAIT
 
 		/*
 		 * Set up cancellation of 'watch' via SIGINT.  We redo this each time
@@ -5059,7 +5059,8 @@ do_watch(PQExpBuffer query_buf, double sleep)
 		{
 			int			signal_received;
 
-			if (sigwait(&sigalrm_sigchld_sigint, &signal_received) < 0)
+			errno = sigwait(&sigalrm_sigchld_sigint, &signal_received);
+			if (errno != 0)
 			{
 				/* Some other signal arrived? */
 				if (errno == EINTR)
@@ -5091,7 +5092,7 @@ do_watch(PQExpBuffer query_buf, double sleep)
 		restore_sigpipe_trap();
 	}
 
-#ifndef WIN32
+#ifdef HAVE_POSIX_DECL_SIGWAIT
 	/* Disable the interval timer. */
 	memset(&interval, 0, sizeof(interval));
 	setitimer(ITIMER_REAL, &interval, NULL);

src/bin/psql/startup.c

@@ -110,7 +110,7 @@ log_locus_callback(const char **filename, uint64 *lineno)
 	}
 }
 
-#ifndef WIN32
+#ifdef HAVE_POSIX_DECL_SIGWAIT
 static void
 empty_signal_handler(SIGNAL_ARGS)
 {
@@ -309,7 +309,7 @@ main(int argc, char *argv[])
 
 	psql_setup_cancel_handler();
 
-#ifndef WIN32
+#ifdef HAVE_POSIX_DECL_SIGWAIT
 
 	/*
 	 * do_watch() needs signal handlers installed (otherwise sigwait() will

src/include/pg_config.h.in

@@ -158,6 +158,10 @@
    don't. */
 #undef HAVE_DECL_RTLD_NOW
 
+/* Define to 1 if you have the declaration of `sigwait', and to 0 if you
+   don't. */
+#undef HAVE_DECL_SIGWAIT
+
 /* Define to 1 if you have the declaration of `strlcat', and to 0 if you
    don't. */
 #undef HAVE_DECL_STRLCAT
@@ -414,6 +418,9 @@
 /* Define to 1 if you have the <poll.h> header file. */
 #undef HAVE_POLL_H
 
+/* Define to 1 if you have a POSIX-conforming sigwait declaration. */
+#undef HAVE_POSIX_DECL_SIGWAIT
+
 /* Define to 1 if you have the `posix_fadvise' function. */
 #undef HAVE_POSIX_FADVISE
 

src/tools/msvc/Solution.pm

@@ -249,6 +249,7 @@ sub GenerateFiles
 		HAVE_DECL_PWRITEV                           => 0,
 		HAVE_DECL_RTLD_GLOBAL                       => 0,
 		HAVE_DECL_RTLD_NOW                          => 0,
+		HAVE_DECL_SIGWAIT                           => 0,
 		HAVE_DECL_STRLCAT                           => undef,
 		HAVE_DECL_STRLCPY                           => undef,
 		HAVE_DECL_STRNLEN                           => 1,
@@ -332,6 +333,7 @@ sub GenerateFiles
 		HAVE_PAM_PAM_APPL_H         => undef,
 		HAVE_POLL                   => undef,
 		HAVE_POLL_H                 => undef,
+		HAVE_POSIX_DECL_SIGWAIT     => undef,
 		HAVE_POSIX_FADVISE          => undef,
 		HAVE_POSIX_FALLOCATE        => undef,
 		HAVE_PPC_LWARX_MUTEX_HINT   => undef,