/usr/lib/python2.7/test/test_largefile.py is in libpython2.7-testsuite 2.7.11-7ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 | """Test largefile support on system where this makes sense.
"""
from __future__ import print_function
import os
import stat
import sys
import unittest
from test.test_support import run_unittest, TESTFN, verbose, requires, \
unlink
import io # C implementation of io
import _pyio as pyio # Python implementation of io
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 LargeFileTest(unittest.TestCase):
"""Test that each file function works as expected for a large
(i.e. > 2GB, do we have to check > 4GB) files.
NOTE: the order of execution of the test methods is important! test_seek
must run first to create the test file. File cleanup must also be handled
outside the test instances because of this.
"""
def test_seek(self):
if verbose:
print('create large file via seek (may be sparse file) ...')
with self.open(TESTFN, 'wb') as f:
f.write(b'z')
f.seek(0)
f.seek(size)
f.write(b'a')
f.flush()
if verbose:
print('check file size with os.fstat')
self.assertEqual(os.fstat(f.fileno())[stat.ST_SIZE], size+1)
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')
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):
if verbose:
print('play around with os.lseek() with the built largefile')
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):
if verbose:
print('try truncate')
with self.open(TESTFN, 'r+b') as f:
# this is already decided before start running the test suite
# but we do it anyway for extra protection
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)
if self.new_io:
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)
if self.new_io:
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.
if not self.new_io:
self.skipTest("builtin file doesn't have seekable()")
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 test_main():
# 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 (IOError, OverflowError):
f.close()
unlink(TESTFN)
raise unittest.SkipTest("filesystem does not have largefile support")
else:
f.close()
suite = unittest.TestSuite()
for _open, prefix in [(io.open, 'C'), (pyio.open, 'Py'),
(open, 'Builtin')]:
class TestCase(LargeFileTest):
pass
TestCase.open = staticmethod(_open)
TestCase.new_io = _open is not open
TestCase.__name__ = prefix + LargeFileTest.__name__
suite.addTest(TestCase('test_seek'))
suite.addTest(TestCase('test_osstat'))
suite.addTest(TestCase('test_seek_read'))
suite.addTest(TestCase('test_lseek'))
with _open(TESTFN, 'wb') as f:
if hasattr(f, 'truncate'):
suite.addTest(TestCase('test_truncate'))
suite.addTest(TestCase('test_seekable'))
unlink(TESTFN)
try:
run_unittest(suite)
finally:
unlink(TESTFN)
if __name__ == '__main__':
test_main()
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