Assume that we have functional, 64-bit fseeko()/ftello().

Windows has this, and so do all other live platforms according to the
buildfarm, so remove the configure probe and src/port/ substitution.

Keep the probe that detects whether _LARGEFILE_SOURCE has to be
defined to get that, though ... that seems to be still relevant in
some places.

This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code.  I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.

Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us

src/bin/pg_dump/pg_backup_archiver.c

@@ -3872,15 +3872,6 @@ checkSeek(FILE *fp)
 {
 	pgoff_t		tpos;
 
-	/*
-	 * If pgoff_t is wider than long, we must have "real" fseeko and not an
-	 * emulation using fseek.  Otherwise report no seek capability.
-	 */
-#ifndef HAVE_FSEEKO
-	if (sizeof(pgoff_t) > sizeof(long))
-		return false;
-#endif
-
 	/* Check that ftello works on this file */
 	tpos = ftello(fp);
 	if (tpos < 0)

src/include/port.h

@@ -331,13 +331,9 @@ extern int	gettimeofday(struct timeval *tp, struct timezone *tzp);
  * When necessary, these routines are provided by files in src/port/.
  */
 
-/* WIN32 handled in port/win32_port.h */
-#ifndef WIN32
+/* Type to use with fseeko/ftello */
+#ifndef WIN32					/* WIN32 is handled in port/win32_port.h */
 #define pgoff_t off_t
-#ifdef __NetBSD__
-extern int	fseeko(FILE *stream, off_t offset, int whence);
-extern off_t ftello(FILE *stream);
-#endif
 #endif
 
 extern double pg_erand48(unsigned short xseed[3]);
@@ -349,11 +345,6 @@ extern void pg_srand48(long seed);
 extern int	fls(int mask);
 #endif
 
-#ifndef HAVE_FSEEKO
-#define fseeko(a, b, c) fseek(a, b, c)
-#define ftello(a)		ftell(a)
-#endif
-
 #ifndef HAVE_GETPEEREID
 /* On Windows, Perl might have incompatible definitions of uid_t and gid_t. */
 #ifndef PLPERL_HAVE_UID_GID

src/include/port/win32_port.h

@@ -193,6 +193,7 @@ int			setitimer(int which, const struct itimerval *value, struct itimerval *oval
  * with 64-bit offsets.
  */
 #define pgoff_t __int64
+
 #ifdef _MSC_VER
 #define fseeko(stream, offset, origin) _fseeki64(stream, offset, origin)
 #define ftello(stream) _ftelli64(stream)

src/port/fseeko.c

@@ -1,84 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * fseeko.c
- *	  64-bit versions of fseeko/ftello()
- *
- * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- *	  src/port/fseeko.c
- *
- *-------------------------------------------------------------------------
- */
-
-/*
- * We have to use the native defines here because configure hasn't
- * completed yet.
- */
-#ifdef __NetBSD__
-
-#include "c.h"
-
-#include <sys/stat.h>
-
-
-/*
- *	On NetBSD, off_t and fpos_t are the same.  Standards
- *	say off_t is an arithmetic type, but not necessarily integral,
- *	while fpos_t might be neither.
- */
-
-int
-fseeko(FILE *stream, off_t offset, int whence)
-{
-	off_t		floc;
-	struct stat filestat;
-
-	switch (whence)
-	{
-		case SEEK_CUR:
-			if (fgetpos(stream, &floc) != 0)
-				goto failure;
-			floc += offset;
-			if (fsetpos(stream, &floc) != 0)
-				goto failure;
-			return 0;
-			break;
-		case SEEK_SET:
-			if (fsetpos(stream, &offset) != 0)
-				return -1;
-			return 0;
-			break;
-		case SEEK_END:
-			fflush(stream);		/* force writes to fd for stat() */
-			if (fstat(fileno(stream), &filestat) != 0)
-				goto failure;
-			floc = filestat.st_size;
-			floc += offset;
-			if (fsetpos(stream, &floc) != 0)
-				goto failure;
-			return 0;
-			break;
-		default:
-			errno = EINVAL;
-			return -1;
-	}
-
-failure:
-	return -1;
-}
-
-
-off_t
-ftello(FILE *stream)
-{
-	off_t		floc;
-
-	if (fgetpos(stream, &floc) != 0)
-		return -1;
-	return floc;
-}
-
-#endif

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 getpeereid.c getrusage.c inet_aton.c random.c
+	  chklocale.c explicit_bzero.c fls.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