cpython/Lib/test/test_largefile.py

181 lines
6.4 KiB
Python

"""Test largefile support on system where this makes sense.
"""
import os
import stat
import sys
import unittest
from test.support import TESTFN, requires, unlink
import io # C implementation of io
import _pyio as pyio # Python implementation of io
# size of file to create (>2GB; 2GB == 2147483648 bytes)
size = 2500000000
class LargeFileTest:
"""Test that each file function works as expected for large
(i.e. > 2GB) 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"')
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 comsumes large resources; It
# takes a long time to build the >2GB file and takes >2GB 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()