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"""Test largefile support on system where this makes sense.
"""
import os
import stat
import sys
import unittest
from test.test_support import run_unittest, TESTFN, verbose, requires, \
TestSkipped, unlink
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 IOError instead of crashing the interpreter.
oldhandler = signal.signal(signal.SIGXFSZ, signal.SIG_IGN)
except (ImportError, AttributeError):
pass
# create >2GB file (2GB = 2147483648 bytes)
size = 2500000000
class TestCase(unittest.TestCase):
"""Test that each file function works as expected for a large
(i.e. > 2GB, do we have to check > 4GB) files.
"""
def test_seek(self):
if verbose:
print('create large file via seek (may be sparse file) ...')
f = open(TESTFN, 'wb')
try:
f.write('z')
f.seek(0)
f.seek(size)
f.write('a')
f.flush()
if verbose:
print('check file size with os.fstat')
self.assertEqual(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
finally:
f.close()
def test_osstat(self):
if verbose:
print('check file size with os.stat')
self.assertEqual(os.stat(TESTFN)[stat.ST_SIZE], size+1)
def test_seek_read(self):
if verbose:
print('play around with seek() and read() with the built largefile')
f = open(TESTFN, 'rb')
try:
self.assertEqual(f.tell(), 0)
self.assertEqual(f.read(1), '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), 'a')
f.seek(-size-1, 1)
self.assertEqual(f.read(1), 'z')
self.assertEqual(f.tell(), 1)
finally:
f.close()
def test_lseek(self):
if verbose:
print('play around with os.lseek() with the built largefile')
f = open(TESTFN, 'rb')
try:
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), 'a')
finally:
f.close()
def test_truncate(self):
if verbose:
print('try truncate')
f = open(TESTFN, 'r+b')
# this is already decided before start running the test suite
# but we do it anyway for extra protection
if not hasattr(f, 'truncate'):
raise TestSkipped("open().truncate() not available on this system")
try:
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) # else pointer moved
f.seek(0, 2)
self.assertEqual(f.tell(), newsize) # else wasn't truncated
# 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
self.assertEqual(len(f.read()), 1) # else wasn't truncated
finally:
f.close()
def main_test():
# 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')
try:
# 2**31 == 2147483648
f.seek(2147483649)
# Seeking is not enough of a test: you must write and
# flush, too!
f.write("x")
f.flush()
except (IOError, OverflowError):
f.close()
unlink(TESTFN)
raise TestSkipped("filesystem does not have largefile support")
else:
f.close()
suite = unittest.TestSuite()
suite.addTest(TestCase('test_seek'))
suite.addTest(TestCase('test_osstat'))
suite.addTest(TestCase('test_seek_read'))
suite.addTest(TestCase('test_lseek'))
f = open(TESTFN, 'w')
if hasattr(f, 'truncate'):
suite.addTest(TestCase('test_truncate'))
if __name__ == '__main__':
main_test()
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