Create wrapper pgwin32_safestat() and redefine stat() to it

on win32, because the stat() function in the runtime cannot
be trusted to always update the st_size field.

Per report and research by Sergey Zubkovsky.

src/include/port.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/port.h,v 1.118 2008/02/29 15:31:33 mha Exp $
+ * $PostgreSQL: pgsql/src/include/port.h,v 1.119 2008/04/10 16:58:51 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -298,6 +298,19 @@ extern FILE *pgwin32_fopen(const char *, const char *);
 #define popen(a,b) _popen(a,b)
 #define pclose(a) _pclose(a)
 
+/* 
+ * stat() is not guaranteed to set the st_size field on win32, so we
+ * redefine it to our own implementation that is.
+ *
+ * We must pull in sys/stat.h here so the system header definition
+ * goes in first, and we redefine that, and not the other way around.
+ */
+extern int pgwin32_safestat(const char *path, struct stat *buf);
+#if !defined(FRONTEND) && !defined(_DIRMOD_C)
+#include <sys/stat.h>
+#define stat(a,b) pgwin32_safestat(a,b)
+#endif
+
 /* Missing rand functions */
 extern long lrand48(void);
 extern void srand48(long seed);

src/port/dirmod.c

@@ -10,7 +10,7 @@
  *	Win32 (NT, Win2k, XP).	replace() doesn't work on Win95/98/Me.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.51 2008/01/01 19:46:00 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.52 2008/04/10 16:58:51 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -447,3 +447,37 @@ report_and_fail:
 	pgfnames_cleanup(filenames);
 	return false;
 }
+
+
+#ifdef WIN32
+/*
+ * 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.
+ */
+#undef stat
+int 
+pgwin32_safestat(const char *path, struct stat *buf)
+{
+	int r;
+	WIN32_FILE_ATTRIBUTE_DATA attr;
+
+	r = stat(path, buf);
+	if (r < 0)
+		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