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//usr/lib/python2.4/test/test_largefile.py
#! /usr/bin/env python2.4 #---------------------------------------------------------------------- # test largefile support on system where this makes sense # #---------------------------------------------------------------------- from test import test_support import os, struct, stat, sys 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 = 2500000000L name = test_support.TESTFN # 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': test_support.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(test_support.TESTFN, 'wb') try: # 2**31 == 2147483648 f.seek(2147483649L) # Seeking is not enough of a test: you must write and flush, too! f.write("x") f.flush() except (IOError, OverflowError): f.close() os.unlink(test_support.TESTFN) raise test_support.TestSkipped, \ "filesystem does not have largefile support" else: f.close() def expect(got_this, expect_this): if test_support.verbose: print '%r =?= %r ...' % (got_this, expect_this), if got_this != expect_this: if test_support.verbose: print 'no' raise test_support.TestFailed, 'got %r, but expected %r' %\ (got_this, expect_this) else: if test_support.verbose: print 'yes' # test that each file function works as expected for a large (i.e. >2GB, do # we have to check >4GB) files if test_support.verbose: print 'create large file via seek (may be sparse file) ...' f = open(name, 'wb') try: f.write('z') f.seek(0) f.seek(size) f.write('a') f.flush() if test_support.verbose: print 'check file size with os.fstat' expect(os.fstat(f.fileno())[stat.ST_SIZE], size+1) finally: f.close() if test_support.verbose: print 'check file size with os.stat' expect(os.stat(name)[stat.ST_SIZE], size+1) if test_support.verbose: print 'play around with seek() and read() with the built largefile' f = open(name, 'rb') try: expect(f.tell(), 0) expect(f.read(1), 'z') expect(f.tell(), 1) f.seek(0) expect(f.tell(), 0) f.seek(0, 0) expect(f.tell(), 0) f.seek(42) expect(f.tell(), 42) f.seek(42, 0) expect(f.tell(), 42) f.seek(42, 1) expect(f.tell(), 84) f.seek(0, 1) expect(f.tell(), 84) f.seek(0, 2) # seek from the end expect(f.tell(), size + 1 + 0) f.seek(-10, 2) expect(f.tell(), size + 1 - 10) f.seek(-size-1, 2) expect(f.tell(), 0) f.seek(size) expect(f.tell(), size) expect(f.read(1), 'a') # the 'a' that was written at the end of file above f.seek(-size-1, 1) expect(f.read(1), 'z') expect(f.tell(), 1) finally: f.close() if test_support.verbose: print 'play around with os.lseek() with the built largefile' f = open(name, 'rb') try: expect(os.lseek(f.fileno(), 0, 0), 0) expect(os.lseek(f.fileno(), 42, 0), 42) expect(os.lseek(f.fileno(), 42, 1), 84) expect(os.lseek(f.fileno(), 0, 1), 84) expect(os.lseek(f.fileno(), 0, 2), size+1+0) expect(os.lseek(f.fileno(), -10, 2), size+1-10) expect(os.lseek(f.fileno(), -size-1, 2), 0) expect(os.lseek(f.fileno(), size, 0), size) expect(f.read(1), 'a') # the 'a' that was written at the end of file above finally: f.close() if hasattr(f, 'truncate'): if test_support.verbose: print 'try truncate' f = open(name, 'r+b') try: f.seek(0, 2) expect(f.tell(), size+1) # else we've lost track of the true size # Cut it back via seek + truncate with no argument. newsize = size - 10 f.seek(newsize) f.truncate() expect(f.tell(), newsize) # else pointer moved f.seek(0, 2) expect(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) expect(f.tell(), 42) # else pointer moved f.seek(0, 2) expect(f.tell(), newsize) # else wasn't truncated # XXX truncate(larger than true size) is ill-defined across platforms # cut it waaaaay back f.seek(0) f.truncate(1) expect(f.tell(), 0) # else pointer moved expect(len(f.read()), 1) # else wasn't truncated finally: f.close() os.unlink(name)