Remove configure probe and related tests for getrlimit.

getrlimit() is in SUSv2 and all targeted systems have it.

Windows doesn't have it.  We could just use #ifndef WIN32, but for a
little more explanation about why we're making things conditional, let's
retain the HAVE_GETRLIMIT macro.  It's defined in port.h for Unix systems.

On systems that have it, it's not necessary to test for RLIMIT_CORE,
RLIMIT_STACK or RLIMIT_NOFILE macros, since SUSv2 requires those and all
targeted systems have them.  Also remove references to a pre-historic
alternative spelling of RLIMIT_NOFILE, and coding that seemed to believe
that Cygwin didn't have it.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA+hUKGJ3LHeP9w5Fgzdr4G8AnEtJ=z=p6hGDEm4qYGEUX5B6fQ@mail.gmail.com

configure

@@ -16039,7 +16039,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-for ac_func in backtrace_symbols clock_gettime copyfile fdatasync getifaddrs getpeerucred getrlimit inet_pton kqueue mbstowcs_l memset_s poll posix_fallocate ppoll pthread_is_threaded_np readlink readv setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink syncfs sync_file_range uselocale wcstombs_l writev
+for ac_func in backtrace_symbols clock_gettime copyfile fdatasync getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s poll posix_fallocate ppoll pthread_is_threaded_np readlink readv setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink syncfs sync_file_range uselocale wcstombs_l writev
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"

configure.ac

@@ -1797,7 +1797,6 @@ AC_CHECK_FUNCS(m4_normalize([
 	fdatasync
 	getifaddrs
 	getpeerucred
-	getrlimit
 	inet_pton
 	kqueue
 	mbstowcs_l

src/backend/storage/file/fd.c

@@ -895,11 +895,7 @@ count_usable_fds(int max_to_probe, int *usable_fds, int *already_open)
 	fd = (int *) palloc(size * sizeof(int));
 
 #ifdef HAVE_GETRLIMIT
-#ifdef RLIMIT_NOFILE			/* most platforms use RLIMIT_NOFILE */
 	getrlimit_status = getrlimit(RLIMIT_NOFILE, &rlim);
-#else							/* but BSD doesn't ... */
-	getrlimit_status = getrlimit(RLIMIT_OFILE, &rlim);
-#endif							/* RLIMIT_NOFILE */
 	if (getrlimit_status != 0)
 		ereport(WARNING, (errmsg("getrlimit failed: %m")));
 #endif							/* HAVE_GETRLIMIT */

src/backend/tcop/postgres.c

@@ -4770,7 +4770,7 @@ forbidden_in_wal_sender(char firstchar)
 long
 get_stack_depth_rlimit(void)
 {
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_STACK)
+#if defined(HAVE_GETRLIMIT)
 	static long val = 0;
 
 	/* This won't change after process launch, so check just once */
@@ -4789,13 +4789,9 @@ get_stack_depth_rlimit(void)
 			val = rlim.rlim_cur;
 	}
 	return val;
-#else							/* no getrlimit */
+#else
-#if defined(WIN32) || defined(__CYGWIN__)
 	/* On Windows we set the backend stack size in src/backend/Makefile */
 	return WIN32_STACK_RLIMIT;
-#else							/* not windows ... give up */
-	return -1;
-#endif
 #endif
 }
 

src/bin/pg_ctl/pg_ctl.c

@@ -160,7 +160,7 @@ static bool wait_for_postmaster_stop(void);
 static bool wait_for_postmaster_promote(void);
 static bool postmaster_is_alive(pid_t pid);
 
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
+#if defined(HAVE_GETRLIMIT)
 static void unlimit_core_size(void);
 #endif
 
@@ -776,7 +776,7 @@ wait_for_postmaster_promote(void)
 }
 
 
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
+#if defined(HAVE_GETRLIMIT)
 static void
 unlimit_core_size(void)
 {
@@ -949,7 +949,7 @@ do_start(void)
 	if (exec_path == NULL)
 		exec_path = find_other_exec_or_die(argv0, "postgres", PG_BACKEND_VERSIONSTR);
 
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
+#if defined(HAVE_GETRLIMIT)
 	if (allow_core_files)
 		unlimit_core_size();
 #endif
@@ -2069,7 +2069,7 @@ do_help(void)
 	printf(_("If the -D option is omitted, the environment variable PGDATA is used.\n"));
 
 	printf(_("\nOptions for start or restart:\n"));
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
+#if defined(HAVE_GETRLIMIT)
 	printf(_("  -c, --core-files       allow postgres to produce core files\n"));
 #else
 	printf(_("  -c, --core-files       not applicable on this platform\n"));

src/bin/pgbench/pgbench.c

@@ -6662,11 +6662,7 @@ main(int argc, char **argv)
 					exit(1);
 				}
 #ifdef HAVE_GETRLIMIT
-#ifdef RLIMIT_NOFILE			/* most platforms use RLIMIT_NOFILE */
 				if (getrlimit(RLIMIT_NOFILE, &rlim) == -1)
-#else							/* but BSD doesn't ... */
-				if (getrlimit(RLIMIT_OFILE, &rlim) == -1)
-#endif							/* RLIMIT_NOFILE */
 					pg_fatal("getrlimit failed: %m");
 				if (rlim.rlim_cur < nclients + 3)
 				{

src/include/pg_config.h.in

@@ -229,9 +229,6 @@
 /* Define to 1 if you have the `getpeerucred' function. */
 #undef HAVE_GETPEERUCRED
 
-/* Define to 1 if you have the `getrlimit' function. */
-#undef HAVE_GETRLIMIT
-
 /* Define to 1 if you have the `gettimeofday' function. */
 #undef HAVE_GETTIMEOFDAY
 

src/include/port.h

@@ -519,4 +519,12 @@ extern char *wait_result_to_str(int exit_status);
 extern bool wait_result_is_signal(int exit_status, int signum);
 extern bool wait_result_is_any_signal(int exit_status, bool include_command_not_found);
 
+/*
+ * Interfaces that we assume all Unix system have.  We retain individual macros
+ * for better documentation.
+ */
+#ifndef WIN32
+#define HAVE_GETRLIMIT 1
+#endif
+
 #endif							/* PG_PORT_H */

src/test/regress/pg_regress.c

@@ -129,7 +129,7 @@ static void psql_end_command(StringInfo buf, const char *database);
 /*
  * allow core files if possible.
  */
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
+#if defined(HAVE_GETRLIMIT)
 static void
 unlimit_core_size(void)
 {
@@ -2229,7 +2229,7 @@ regression_main(int argc, char *argv[],
 
 	initialize_environment();
 
-#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
+#if defined(HAVE_GETRLIMIT)
 	unlimit_core_size();
 #endif
 

src/tools/msvc/Solution.pm

@@ -271,7 +271,6 @@ sub GenerateFiles
 		HAVE_GETOPT_LONG                            => undef,
 		HAVE_GETPEEREID                             => undef,
 		HAVE_GETPEERUCRED                           => undef,
-		HAVE_GETRLIMIT                              => undef,
 		HAVE_GETTIMEOFDAY                           => undef,
 		HAVE_GSSAPI_GSSAPI_H                        => undef,
 		HAVE_GSSAPI_H                               => undef,