"""Test largefile support on system where this makes sense. """ import os import stat import sys import unittest from test.support import run_unittest, TESTFN, verbose, requires, \ TestSkipped, 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 TestSkipped("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(), newsize) # else wasn't truncated 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(), 1) # else pointer moved f.seek(0) self.assertEqual(len(f.read()), 1) # else wasn't truncated 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 TestSkipped("filesystem does not have largefile support") else: f.close() suite = unittest.TestSuite() for _open, prefix in [(io.open, 'C'), (pyio.open, 'Py')]: class TestCase(LargeFileTest): pass TestCase.open = staticmethod(_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')) unlink(TESTFN) try: run_unittest(suite) finally: unlink(TESTFN) if __name__ == '__main__': test_main()