Enable large file support on Win32 systems.

Curious:  the MS docs say stati64 etc are supported even on Win95, but
Win95 doesn't support a filesystem that allows partitions > 2 Gb.

test_largefile:  This was opening its test file in text mode.  I have no
idea how that worked under Win64, but it sure needs binary mode on Win98.
BTW, on Win98 test_largefile runs quickly (under a second).

Lib/test/test_largefile.py

@@ -12,7 +12,7 @@ import os, struct, stat, sys
 
 
 # only run if the current system support large files
-f = open(test_support.TESTFN, 'w')
+f = open(test_support.TESTFN, 'wb')
 try:
     # 2**31 == 2147483648
     f.seek(2147483649L)
@@ -58,13 +58,13 @@ def expect(got_this, expect_this):
 
 if test_support.verbose:
     print 'create large file via seek (may be sparse file) ...'
-f = open(name, 'w')
+f = open(name, 'wb')
 f.seek(size)
 f.write('a')
 f.flush()
-expect(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
 if test_support.verbose:
     print 'check file size with os.fstat'
+expect(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
 f.close()
 if test_support.verbose:
     print 'check file size with os.stat'
@@ -72,7 +72,7 @@ expect(os.stat(name)[stat.ST_SIZE], size+1)
 
 if test_support.verbose:
     print 'play around with seek() and read() with the built largefile'
-f = open(name, 'r')
+f = open(name, 'rb')
 expect(f.tell(), 0)
 expect(f.read(1), '\000')
 expect(f.tell(), 1)

Misc/NEWS

@@ -155,6 +155,12 @@ Tests
 
 Windows
 
+- Large file support is now enabled on Win32 platforms as well as on
+  Win64.  This means that, for example, you can use f.tell() and f.seek()
+  to manipulate files larger than 2 gigabytes (provided you have enough
+  disk space, and are using a Windows filesystem that supports large
+  partitions).
+
 - The w9xpopen hack is now used on Windows NT and 2000 too when COMPSPEC
   points to command.com (patch from Brian Quinlan).
 

Modules/posixmodule.c

@@ -264,7 +264,7 @@ extern int lstat(const char *, struct stat *);
 
 /* choose the appropriate stat and fstat functions and return structs */
 #undef STAT
-#ifdef MS_WIN64
+#if defined(MS_WIN64) || defined(MS_WIN32)
 #	define STAT _stati64
 #	define FSTAT _fstati64
 #	define STRUCT_STAT struct _stati64
@@ -3491,7 +3491,7 @@ static PyObject *
 posix_lseek(PyObject *self, PyObject *args)
 {
 	int fd, how;
-#ifdef MS_WIN64
+#if defined(MS_WIN64) || defined(MS_WIN32)
 	LONG_LONG pos, res;
 #else
 	off_t pos, res;
@@ -3518,7 +3518,7 @@ posix_lseek(PyObject *self, PyObject *args)
 		return NULL;
 
 	Py_BEGIN_ALLOW_THREADS
-#ifdef MS_WIN64
+#if defined(MS_WIN64) || defined(MS_WIN32)
 	res = _lseeki64(fd, pos, how);
 #else
 	res = lseek(fd, pos, how);

Objects/fileobject.c

@@ -367,7 +367,7 @@ file_truncate(PyFileObject *f, PyObject *args)
 	} else {
 		Py_BEGIN_ALLOW_THREADS
 		errno = 0;
-		ret = _chsize(fileno(f->f_fp), newsize);
+		ret = _chsize(fileno(f->f_fp), (long)newsize);
 		Py_END_ALLOW_THREADS
 		if (ret != 0) goto onioerror;
 	}

PC/pyconfig.h

@@ -313,6 +313,7 @@ typedef int pid_t;
 #	define HAVE_LARGEFILE_SUPPORT
 #elif defined(MS_WIN32)
 #	define PLATFORM "win32"
+#	define HAVE_LARGEFILE_SUPPORT
 #	ifdef _M_ALPHA
 #		define SIZEOF_VOID_P 8
 #		define SIZEOF_TIME_T 8