Add largefile support for Linux64 and WIn64. Add test_largefile and some minor
change to regrtest.py to allow optional running of test_largefile ('cause it's
slow on Win64).

This closes patches:
http://sourceforge.net/patch/index.php?func=detailpatch&patch_id=100510&group_id=5470
and
http://sourceforge.net/patch/index.php?func=detailpatch&patch_id=100511&group_id=5470
diff --git a/Lib/test/test_largefile.py b/Lib/test/test_largefile.py
new file mode 100644
index 0000000..5b65237
--- /dev/null
+++ b/Lib/test/test_largefile.py
@@ -0,0 +1,129 @@
+#!python
+
+#----------------------------------------------------------------------
+# test largefile support on system where this makes sense
+#
+#XXX how to only run this when support is there
+#XXX how to only optionally run this, it will take along time
+#----------------------------------------------------------------------
+
+import test_support
+import os, struct, stat, sys
+
+
+# only run if the current system support large files
+f = open(test_support.TESTFN, 'w')
+try:
+	# 2**31 == 2147483648
+	f.seek(2147483649L)
+except OverflowError:
+	raise test_support.TestSkipped, "platform does not have largefile support"
+else:
+	f.close()
+
+
+# create >2GB file (2GB = 2147483648 bytes)
+size = 2500000000L
+name = test_support.TESTFN
+
+
+# on Windows this test comsumes large resources:
+#  it takes a long time to build the >2GB file and takes >2GB of disk space
+# therefore test_support.use_large_resources must be defined to run this test
+if sys.platform[:3] == 'win' and not test_support.use_large_resources:
+	raise test_support.TestSkipped, \
+		"test requires %s bytes and a long time to run" % str(size)
+
+
+
+def expect(got_this, expect_this):
+	if test_support.verbose:
+		print '%s =?= %s ...' % (`got_this`, `expect_this`),
+	if got_this != expect_this:
+		if test_support.verbose:
+			print 'no'
+		raise test_support.TestFailed, 'got %s, but expected %s' %\
+			(str(got_this), str(expect_this))
+	else:
+		if test_support.verbose:
+			print 'yes'
+
+
+# test that each file function works as expected for a large (i.e. >2GB, do
+# we have to check >4GB) files
+
+if test_support.verbose:
+	print 'create large file via seek (may be sparse file) ...'
+f = open(name, 'w')
+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'
+f.close()
+if test_support.verbose:
+	print 'check file size with os.stat'
+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')
+expect(f.tell(), 0)
+expect(f.read(1), '\000')
+expect(f.tell(), 1)
+f.seek(0)
+expect(f.tell(), 0)
+f.seek(0, 0)
+expect(f.tell(), 0)
+f.seek(42)
+expect(f.tell(), 42)
+f.seek(42, 0)
+expect(f.tell(), 42)
+f.seek(42, 1)
+expect(f.tell(), 84)
+f.seek(0, 1)
+expect(f.tell(), 84)
+f.seek(0, 2) # seek from the end
+expect(f.tell(), size + 1 + 0)
+f.seek(-10, 2)
+expect(f.tell(), size + 1 - 10)
+f.seek(-size-1, 2)
+expect(f.tell(), 0)
+f.seek(size)
+expect(f.tell(), size)
+expect(f.read(1), 'a') # the 'a' that was written at the end of the file above
+f.close()
+
+if test_support.verbose:
+	print 'play around with os.lseek() with the built largefile'
+f = open(name, 'r')
+expect(os.lseek(f.fileno(), 0, 0), 0)
+expect(os.lseek(f.fileno(), 42, 0), 42)
+expect(os.lseek(f.fileno(), 42, 1), 84)
+expect(os.lseek(f.fileno(), 0, 1), 84)
+expect(os.lseek(f.fileno(), 0, 2), size+1+0)
+expect(os.lseek(f.fileno(), -10, 2), size+1-10)
+expect(os.lseek(f.fileno(), -size-1, 2), 0)
+expect(os.lseek(f.fileno(), size, 0), size)
+expect(f.read(1), 'a') # the 'a' that was written at the end of the file above
+f.close()
+
+
+# XXX add tests for truncate if it exists
+# XXX has truncate ever worked on Windows? specifically on WinNT I get:
+#     "IOError: [Errno 13] Permission denied"
+##try:
+##	newsize = size - 10
+##	f.seek(newsize)
+##	f.truncate()
+##	expect(f.tell(), newsize)
+##	newsize = newsize - 1
+##	f.seek(0)
+##	f.truncate(newsize)
+##	expect(f.tell(), newsize)
+##except AttributeError:
+##	pass
+
+os.unlink(name)
+