#!python

#----------------------------------------------------------------------

# 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)