Fix our Windows stat() emulation to handle file sizes > 4GB.

Hack things so that our idea of "struct stat" is equivalent to Windows'
struct __stat64, allowing it to have a wide enough st_size field.

Instead of relying on native stat(), use GetFileInformationByHandle().
This avoids a number of issues with Microsoft's multiple and rather
slipshod emulations of stat().  We still need to jump through hoops
to deal with ERROR_DELETE_PENDING, though :-(

Pull the relevant support code out of dirmod.c and put it into
its own file, win32stat.c.

Still TODO: do we need to do something different with lstat(),
rather than treating it identically to stat()?

Juan José Santamaría Flecha, reviewed by Emil Iggland;
based on prior work by Michael Paquier, Sergey Zubkovsky, and others

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905CF5099@g01jpexmbkw24
Discussion: https://postgr.es/m/15858-9572469fd3b73263@postgresql.org

Author: tglsfdc

configure

@@ -16137,6 +16137,12 @@ esac
  ;;
 esac
 
+  case " $LIBOBJS " in
+  *" win32stat.$ac_objext "* ) ;;
+  *) LIBOBJS="$LIBOBJS win32stat.$ac_objext"
+ ;;
+esac
+
 
 $as_echo "#define HAVE_SYMLINK 1" >>confdefs.h
 

configure.ac

@@ -1807,6 +1807,7 @@ if test "$PORTNAME" = "win32"; then
   AC_LIBOBJ(win32error)
   AC_LIBOBJ(win32security)
   AC_LIBOBJ(win32setlocale)
+  AC_LIBOBJ(win32stat)
   AC_DEFINE([HAVE_SYMLINK], 1,
             [Define to 1 if you have the `symlink' function.])
   AC_CHECK_TYPES(MINIDUMP_TYPE, [pgac_minidump_type=yes], [pgac_minidump_type=no], [

src/include/port/win32_port.h

@@ -51,7 +51,13 @@
 #include <signal.h>
 #include <direct.h>
 #undef near
-#include <sys/stat.h>			/* needed before sys/stat hacking below */
+
+/* needed before sys/stat hacking below: */
+#define fstat microsoft_native_fstat
+#define stat microsoft_native_stat
+#include <sys/stat.h>
+#undef fstat
+#undef stat
 
 /* Must be here to avoid conflicting with prototype in windows.h */
 #define mkdir(a,b)	mkdir(a)
@@ -240,20 +246,34 @@ typedef int pid_t;
  * Supplement to <sys/stat.h>.
  *
  * We must pull in sys/stat.h before this part, else our overrides lose.
- */
-#define lstat(path, sb) stat(path, sb)
-
-/*
+ *
  * stat() is not guaranteed to set the st_size field on win32, so we
- * redefine it to our own implementation that is.
+ * redefine it to our own implementation.  See src/port/win32stat.c.
  *
- * Some frontends don't need the size from stat, so if UNSAFE_STAT_OK
- * is defined we don't bother with this.
+ * The struct stat is 32 bit in MSVC, so we redefine it as a copy of
+ * struct __stat64.  This also fixes the struct size for MINGW builds.
  */
-#ifndef UNSAFE_STAT_OK
-extern int	pgwin32_safestat(const char *path, struct stat *buf);
-#define stat(a,b) pgwin32_safestat(a,b)
-#endif
+struct stat						/* This should match struct __stat64 */
+{
+	_dev_t		st_dev;
+	_ino_t		st_ino;
+	unsigned short st_mode;
+	short		st_nlink;
+	short		st_uid;
+	short		st_gid;
+	_dev_t		st_rdev;
+	__int64		st_size;
+	__time64_t	st_atime;
+	__time64_t	st_mtime;
+	__time64_t	st_ctime;
+};
+
+extern int	_pgfstat64(int fileno, struct stat *buf);
+extern int	_pgstat64(const char *name, struct stat *buf);
+
+#define fstat(fileno, sb)	_pgfstat64(fileno, sb)
+#define stat(path, sb)		_pgstat64(path, sb)
+#define lstat(path, sb)		_pgstat64(path, sb)
 
 /* These macros are not provided by older MinGW, nor by MSVC */
 #ifndef S_IRUSR

src/port/dirmod.c

@@ -353,55 +353,3 @@ pgwin32_is_junction(const char *path)
 	return ((attr & FILE_ATTRIBUTE_REPARSE_POINT) == FILE_ATTRIBUTE_REPARSE_POINT);
 }
 #endif							/* defined(WIN32) && !defined(__CYGWIN__) */
-
-
-#if defined(WIN32) && !defined(__CYGWIN__)
-
-#undef stat
-
-/*
- * The stat() function in win32 is not guaranteed to update the st_size
- * field when run. So we define our own version that uses the Win32 API
- * to update this field.
- */
-int
-pgwin32_safestat(const char *path, struct stat *buf)
-{
-	int			r;
-	WIN32_FILE_ATTRIBUTE_DATA attr;
-
-	r = stat(path, buf);
-	if (r < 0)
-	{
-		if (GetLastError() == ERROR_DELETE_PENDING)
-		{
-			/*
-			 * File has been deleted, but is not gone from the filesystem yet.
-			 * This can happen when some process with FILE_SHARE_DELETE has it
-			 * open and it will be fully removed once that handle is closed.
-			 * Meanwhile, we can't open it, so indicate that the file just
-			 * doesn't exist.
-			 */
-			errno = ENOENT;
-			return -1;
-		}
-
-		return r;
-	}
-
-	if (!GetFileAttributesEx(path, GetFileExInfoStandard, &attr))
-	{
-		_dosmaperr(GetLastError());
-		return -1;
-	}
-
-	/*
-	 * XXX no support for large files here, but we don't do that in general on
-	 * Win32 yet.
-	 */
-	buf->st_size = attr.nFileSizeLow;
-
-	return 0;
-}
-
-#endif