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"""Test largefile support on system where this makes sense.
"""
import os
import stat
import sys
import unittest
from test.support import TESTFN, requires, unlink, bigmemtest
import io # C implementation of io
import _pyio as pyio # Python implementation of io
# size of file to create (>2 GiB; 2 GiB == 2,147,483,648 bytes)
size = 2_500_000_000
class LargeFileTest:
"""Test that each file function works as expected for large
(i.e. > 2 GiB) files.
"""
def setUp(self):
if os.path.exists(TESTFN):
mode = 'r+b'
else:
mode = 'w+b'
with self.open(TESTFN, mode) as f:
current_size = os.fstat(f.fileno())[stat.ST_SIZE]
if current_size == size+1:
return
if current_size == 0:
f.write(b'z')
f.seek(0)
f.seek(size)
f.write(b'a')
f.flush()
self.assertEqual(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
@classmethod
def tearDownClass(cls):
with cls.open(TESTFN, 'wb'):
pass
if not os.stat(TESTFN)[stat.ST_SIZE] == 0:
raise cls.failureException('File was not truncated by opening '
'with mode "wb"')
# _pyio.FileIO.readall() uses a temporary bytearray then casted to bytes,
# so memuse=2 is needed
@bigmemtest(size=size, memuse=2, dry_run=False)
def test_large_read(self, _size):
# bpo-24658: Test that a read greater than 2GB does not fail.
with self.open(TESTFN, "rb") as f:
self.assertEqual(len(f.read()), size + 1)
self.assertEqual(f.tell(), size + 1)
def test_osstat(self):
self.assertEqual(os.stat(TESTFN)[stat.ST_SIZE], size+1)
def test_seek_read(self):
with self.open(TESTFN, 'rb') as f:
self.assertEqual(f.tell(), 0)
self.assertEqual(f.read(1), b'z')
self.assertEqual(f.tell(), 1)
f.seek(0)
self.assertEqual(f.tell(), 0)
f.seek(0, 0)
self.assertEqual(f.tell(), 0)
f.seek(42)
self.assertEqual(f.tell(), 42)
f.seek(42, 0)
self.assertEqual(f.tell(), 42)
f.seek(42, 1)
self.assertEqual(f.tell(), 84)
f.seek(0, 1)
self.assertEqual(f.tell(), 84)
f.seek(0, 2) # seek from the end
self.assertEqual(f.tell(), size + 1 + 0)
f.seek(-10, 2)
self.assertEqual(f.tell(), size + 1 - 10)
f.seek(-size-1, 2)
self.assertEqual(f.tell(), 0)
f.seek(size)
self.assertEqual(f.tell(), size)
# the 'a' that was written at the end of file above
self.assertEqual(f.read(1), b'a')
f.seek(-size-1, 1)
self.assertEqual(f.read(1), b'z')
self.assertEqual(f.tell(), 1)
def test_lseek(self):
with self.open(TESTFN, 'rb') as f:
self.assertEqual(os.lseek(f.fileno(), 0, 0), 0)
self.assertEqual(os.lseek(f.fileno(), 42, 0), 42)
self.assertEqual(os.lseek(f.fileno(), 42, 1), 84)
self.assertEqual(os.lseek(f.fileno(), 0, 1), 84)
self.assertEqual(os.lseek(f.fileno(), 0, 2), size+1+0)
self.assertEqual(os.lseek(f.fileno(), -10, 2), size+1-10)
self.assertEqual(os.lseek(f.fileno(), -size-1, 2), 0)
self.assertEqual(os.lseek(f.fileno(), size, 0), size)
# the 'a' that was written at the end of file above
self.assertEqual(f.read(1), b'a')
def test_truncate(self):
with self.open(TESTFN, 'r+b') as f:
if not hasattr(f, 'truncate'):
raise unittest.SkipTest("open().truncate() not available "
"on this system")
f.seek(0, 2)
# else we've lost track of the true size
self.assertEqual(f.tell(), size+1)
# Cut it back via seek + truncate with no argument.
newsize = size - 10
f.seek(newsize)
f.truncate()
self.assertEqual(f.tell(), newsize) # else pointer moved
f.seek(0, 2)
self.assertEqual(f.tell(), newsize) # else wasn't truncated
# Ensure that truncate(smaller than true size) shrinks
# the file.
newsize -= 1
f.seek(42)
f.truncate(newsize)
self.assertEqual(f.tell(), 42)
f.seek(0, 2)
self.assertEqual(f.tell(), newsize)
# XXX truncate(larger than true size) is ill-defined
# across platform; cut it waaaaay back
f.seek(0)
f.truncate(1)
self.assertEqual(f.tell(), 0) # else pointer moved
f.seek(0)
self.assertEqual(len(f.read()), 1) # else wasn't truncated
def test_seekable(self):
# Issue #5016; seekable() can return False when the current position
# is negative when truncated to an int.
for pos in (2**31-1, 2**31, 2**31+1):
with self.open(TESTFN, 'rb') as f:
f.seek(pos)
self.assertTrue(f.seekable())
def setUpModule():
try:
import signal
# The default handler for SIGXFSZ is to abort the process.
# By ignoring it, system calls exceeding the file size resource
# limit will raise OSError instead of crashing the interpreter.
signal.signal(signal.SIGXFSZ, signal.SIG_IGN)
except (ImportError, AttributeError):
pass
# On Windows and Mac OSX this test consumes large resources; It
# takes a long time to build the >2 GiB file and takes >2 GiB of disk
# space therefore the resource must be enabled to run this test.
# If not, nothing after this line stanza will be executed.
if sys.platform[:3] == 'win' or sys.platform == 'darwin':
requires('largefile',
'test requires %s bytes and a long time to run' % str(size))
else:
# Only run if the current filesystem supports large files.
# (Skip this test on Windows, since we now always support
# large files.)
f = open(TESTFN, 'wb', buffering=0)
try:
# 2**31 == 2147483648
f.seek(2147483649)
# Seeking is not enough of a test: you must write and flush, too!
f.write(b'x')
f.flush()
except (OSError, OverflowError):
raise unittest.SkipTest("filesystem does not have "
"largefile support")
finally:
f.close()
unlink(TESTFN)
class CLargeFileTest(LargeFileTest, unittest.TestCase):
open = staticmethod(io.open)
class PyLargeFileTest(LargeFileTest, unittest.TestCase):
open = staticmethod(pyio.open)
def tearDownModule():
unlink(TESTFN)
if __name__ == '__main__':
unittest.main()
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