python学习-06（模块化编程）

 

1：模块定义

         模块：用来从逻辑上组织Python代码（变量，函数、类，逻辑：实现一个功能），本质就是.py结尾的Python文件（文件名:test.py,对应的模块名，test）。

         包：本质就是一个文件夹或者是目录（必须带有一个_init_.py文件），包是用来从逻辑上组织模块的。

2.导入方法：

1):import module_test, module_test1 （调用方法的时候，需要module_test.   ）

2):form moudule_test import * （* 表示所有的方法）(不建议使用，这个就相当于导入了程序。)  容易造成覆盖，出现问题。

3):form module_test import module_ajun  as module_ajun_test(作为一个别名来使用)

3：import本质 （路径 搜索和搜索路径）

1)      import module_test  相当于把module_test 的所有代码解释一遍，全部传递给module_test. 调用module_test的变量和方法。

2)      form moudule_test import name 相当于值调用了name变量，在当前模块，就不需要加前缀了。

总结：导入模块的本质就是把Python文件解释一遍。(import test  test=’test.py  all code’)

           导入包的本质就是执行包下面的_init_.py文件

            Import module_name--》mudule_name.py--》module_name.py的路径--》sys.path

 

 

os.path.abspath(_file_)=获取 当前目录

os.path.dirname(os.path.abspath(_file_))=获取当前目录的父目录

os.path.dirname(os.path.dirname (os.path.abspath(_file_)))=获取当前目录的父目录 的父目录

form .（点表示当前目录，就是_init_的目录）  import 包名

4.导入优化

        

怎么优化？每次都去找，很浪费时间？

使用from module_test  import test 这个方法，节约时间。

5.模块的分类

A:标准库

B：开源模块

C：自定义模块

 

A标准库

5.1time与datetime 两个库。

1）表示时间，格式化的时间格式：2017-07-28

2）时间戳：从1970.1.1日到现在总共经过了多少秒？

为什么从1970年1月1日开始呢？

3）元祖，共有九个元素表示。

UTC（Coordinated Universal Time，世界协调时）亦即格林威治天文时间，世界标准时间。在中国为UTC+8。DST（Daylight Saving Time）即夏令时。 

时间戳（timestamp）的方式：通常来说，时间戳表示的是从1970年1月1日00:00:00开始按秒计算的偏移量。我们运行“type(time.time())”，返回的是float类型。返回时间戳方式的函数主要有time()，clock()等。 

元组（struct_time）方式：struct_time元组共有9个元素，返回struct_time的函数主要有gmtime()，localtime()，strptime()。下面列出这种方式元组中的几个元素：　

#Author:ajun
import time

#print(time.process_time())#测量处理器运算时间,不包括sleep时间,不稳定
#print(time.altzone)  #返回与utc时间的时间差,以秒计算\
#print(time.asctime()) #返回时间格式Wed Jun 28 21:38:29 2017 格式,
#print(time.localtime()) #返回本地时间 的struct time对象格式
#print(time.gmtime(time.time()-800000)) #返回utc时间的struc时间对象格式
#print(time.asctime(time.localtime())) #返回时间格式"Fri Aug 19 11:14:16 2016",
#print(time.ctime()) #返回Wed Jun 28 21:38:29 2017 格式, 同上
# 日期字符串 转成  时间戳
string_2_struct = time.strptime("2017/06/28","%Y/%m/%d") #将 日期字符串 转成 struct时间对象格式
print(string_2_struct)
# #
struct_2_stamp = time.mktime(string_2_struct) #将struct时间对象转成时间戳
print(struct_2_stamp)

#将时间戳转为字符串格式
print(time.gmtime(time.time()-86640)) #将utc时间戳转换成struct_time格式
print(time.strftime("%Y-%m-%d %H:%M:%S",time.gmtime()) ) #将utc struct_time格式转成指定的字符串格式

#时间加减
import datetime

print(datetime.datetime.now()) #返回 2017-06-28 21:11:01.433280
print(datetime.date.fromtimestamp(time.time()) )  # 时间戳直接转成日期格式 2017-06-28
# print(datetime.datetime.now() )
# print(datetime.datetime.now() + datetime.timedelta(3)) #当前时间+3天
# print(datetime.datetime.now() + datetime.timedelta(-3)) #当前时间-3天
# print(datetime.datetime.now() + datetime.timedelta(hours=3)) #当前时间+3小时
# print(datetime.datetime.now() + datetime.timedelta(minutes=30)) #当前时间+30分

#修改时间
c_time  = datetime.datetime.now()
print(c_time.replace(minute=3,hour=2)) #时间替换)) #时间替换

时间转换图（一个来自alex，一个来自海峰老师）

 

%a    本地（locale）简化星期名称    
%A    本地完整星期名称    
%b    本地简化月份名称    
%B    本地完整月份名称    
%c    本地相应的日期和时间表示    
%d    一个月中的第几天（01 - 31）    
%H    一天中的第几个小时（24小时制，00 - 23）    
%I    第几个小时（12小时制，01 - 12）    
%j    一年中的第几天（001 - 366）    
%m    月份（01 - 12）    
%M    分钟数（00 - 59）    
%p    本地am或者pm的相应符    一    
%S    秒（01 - 61）    二    
%U    一年中的星期数。（00 - 53星期天是一个星期的开始。）第一个星期天之前的所有天数都放在第0周。    三    
%w    一个星期中的第几天（0 - 6，0是星期天）    三    
%W    和%U基本相同，不同的是%W以星期一为一个星期的开始。    
%x    本地相应日期    
%X    本地相应时间    
%y    去掉世纪的年份（00 - 99）    
%Y    完整的年份    
%Z    时区的名字（如果不存在为空字符）    
%%    ‘%’字符

 5.2random模块

随机数

import random
print (random.random())  #0.6445010863311293  
#random.random()用于生成一个0到1的随机符点数: 0 <= n < 1.0
print (random.randint(1,7)) #4
#random.randint()的函数原型为：random.randint(a, b)，用于生成一个指定范围内的整数。
# 其中参数a是下限，参数b是上限，生成的随机数n: a <= n <= b
print (random.randrange(1,10)) #5
#random.randrange的函数原型为：random.randrange([start], stop[, step])，
# 从指定范围内，按指定基数递增的集合中 获取一个随机数。如：random.randrange(10, 100, 2)，
# 结果相当于从[10, 12, 14, 16, ... 96, 98]序列中获取一个随机数。
# random.randrange(10, 100, 2)在结果上与 random.choice(range(10, 100, 2) 等效。
print(random.choice('liukuni')) #i
#random.choice从序列中获取一个随机元素。
# 其函数原型为：random.choice(sequence)。参数sequence表示一个有序类型。
# 这里要说明一下：sequence在python不是一种特定的类型，而是泛指一系列的类型。
# list, tuple, 字符串都属于sequence。有关sequence可以查看python手册数据模型这一章。
# 下面是使用choice的一些例子：
print(random.choice("学习Python"))#学
print(random.choice(["JGood","is","a","handsome","boy"]))  #List
print(random.choice(("Tuple","List","Dict")))   #List
print(random.sample([1,2,3,4,5],3))    #[1, 2, 5]
#random.sample的函数原型为：random.sample(sequence, k)，从指定序列中随机获取指定长度的片断。sample函数不会修改原有序列。

#!/usr/bin/env python
# encoding: utf-8
import random
import string
#随机整数：
print( random.randint(0,99))  #70
 
#随机选取0到100间的偶数：
print(random.randrange(0, 101, 2)) #4
 
#随机浮点数：
print( random.random()) #0.2746445568079129
print(random.uniform(1, 10)) #9.887001463194844
 
#随机字符：
print(random.choice('abcdefg&#%^*f')) #f
 
#多个字符中选取特定数量的字符：
print(random.sample('abcdefghij',3)) #['f', 'h', 'd']
 
#随机选取字符串：
print( random.choice ( ['apple', 'pear', 'peach', 'orange', 'lemon'] )) #apple
#洗牌#
items = [1,2,3,4,5,6,7]
print(items) #[1, 2, 3, 4, 5, 6, 7]
random.shuffle(items)
print(items) #[1, 4, 7, 2, 5, 3, 6]

import random
checkcode=''
for i in range(5):
    current_a=random.randint(1,6)
    if current_a%2:
        temp = chr(random.randint(65,90))
    else:
        temp = random.randint(0,9)
    checkcode+=str(temp)
print(checkcode)

 5.3os模块

参考：https://docs.python.org/2/library/os.html?highlight=os#module-os （帮助）

http://www.cnblogs.com/alex3714/articles/5161349.html（alex）

http://egon09.blog.51cto.com/9161406/1840425（海峰老师）

#Author:ajun
os.getcwd() #获取当前工作目录，即当前python脚本工作的目录路径
os.chdir("dirname")  #改变当前脚本工作目录；相当于shell下cd
os.curdir # 返回当前目录: ('.')
os.pardir # 获取当前目录的父目录字符串名：('..')
os.makedirs('dirname1/dirname2')    #可生成多层递归目录
os.removedirs('dirname1')  #  若目录为空，则删除，并递归到上一级目录，如若也为空，则删除，依此类推
os.mkdir('dirname')   # 生成单级目录；相当于shell中mkdir dirname
os.rmdir('dirname')   # 删除单级空目录，若目录不为空则无法删除，报错；相当于shell中rmdir dirname
os.listdir('dirname')    #列出指定目录下的所有文件和子目录，包括隐藏文件，并以列表方式打印
os.remove()  #删除一个文件
os.rename("oldname","newname")  #重命名文件/目录
os.stat('path/filename')  获取文件/目录信息
os.sep    #输出操作系统特定的路径分隔符，win下为"\\",Linux下为"/"
os.linesep    #输出当前平台使用的行终止符，win下为"\t\n",Linux下为"\n"
os.pathsep   # 输出用于分割文件路径的字符串
os.name   # 输出字符串指示当前使用平台。win->'nt'; Linux->'posix'
os.system("bash command")  #运行shell命令，直接显示
os.environ # 获取系统环境变量
os.path.abspath(path)  #返回path规范化的绝对路径
os.path.split(path)  #将path分割成目录和文件名二元组返回
os.path.dirname(path)  #返回path的目录。其实就是os.path.split(path)的第一个元素
os.path.basename(path)  #返回path最后的文件名。如何path以／或\结尾，那么就会返回空值。即os.path.split(path)的第二个元素
os.path.exists(path)  #如果path存在，返回True；如果path不存在，返回False
os.path.isabs(path)  #如果path是绝对路径，返回True
os.path.isfile(path)  #如果path是一个存在的文件，返回True。否则返回False
os.path.isdir(path)  #如果path是一个存在的目录，则返回True。否则返回False
os.path.join(path1[,path2[, ...]]) # 将多个路径组合后返回，第一个绝对路径之前的参数将被忽略
os.path.getatime(path)  #返回path所指向的文件或者目录的最后存取时间
os.path.getmtime(path)  #返回path所指向的文件或者目录的最后修改时间

5.4sys模块

sys.argv           #命令行参数List，第一个元素是程序本身路径
sys.exit(n)       # 退出程序，正常退出时exit(0)
sys.version        #获取Python解释程序的版本信息
sys.maxint         #最大的Int值
sys.path           返回模块的搜索路径，初始化时使用PYTHONPATH环境变量的值#
sys.platform     #  返回操作系统平台名称
sys.stdout.write('please:')  #写进度条就需要这个函数
val = sys.stdin.readline()[:-1]

5.5shutil模块

主要就是用于文件的拷贝和压缩包。

参考http://www.cnblogs.com/wupeiqi/articles/4963027.html 

高级的 文件、文件夹、压缩包 处理模块

shutil.copyfileobj(fsrc, fdst[, length])
将文件内容拷贝到另一个文件中，可以部分内容

def copyfileobj(fsrc, fdst, length=16*1024):
    """copy data from file-like object fsrc to file-like object fdst"""
    while 1:
        buf = fsrc.read(length)
        if not buf:
            break
        fdst.write(buf)

shutil.copyfile(src, dst)
拷贝文件

def copyfile(src, dst):
    """Copy data from src to dst"""
    if _samefile(src, dst):
        raise Error("`%s` and `%s` are the same file" % (src, dst))

    for fn in [src, dst]:
        try:
            st = os.stat(fn)
        except OSError:
            # File most likely does not exist
            pass
        else:
            # XXX What about other special files? (sockets, devices...)
            if stat.S_ISFIFO(st.st_mode):
                raise SpecialFileError("`%s` is a named pipe" % fn)

    with open(src, 'rb') as fsrc:
        with open(dst, 'wb') as fdst:
            copyfileobj(fsrc, fdst)

shutil.copymode(src, dst)
仅拷贝权限。内容、组、用户均不变

def copymode(src, dst):
    """Copy mode bits from src to dst"""
    if hasattr(os, 'chmod'):
        st = os.stat(src)
        mode = stat.S_IMODE(st.st_mode)
        os.chmod(dst, mode)

shutil.copystat(src, dst)
拷贝状态的信息，包括：mode bits, atime, mtime, flags

def copystat(src, dst):
    """Copy all stat info (mode bits, atime, mtime, flags) from src to dst"""
    st = os.stat(src)
    mode = stat.S_IMODE(st.st_mode)
    if hasattr(os, 'utime'):
        os.utime(dst, (st.st_atime, st.st_mtime))
    if hasattr(os, 'chmod'):
        os.chmod(dst, mode)
    if hasattr(os, 'chflags') and hasattr(st, 'st_flags'):
        try:
            os.chflags(dst, st.st_flags)
        except OSError, why:
            for err in 'EOPNOTSUPP', 'ENOTSUP':
                if hasattr(errno, err) and why.errno == getattr(errno, err):
                    break
            else:
                raise

shutil.copy(src, dst)
拷贝文件和权限

def copy(src, dst):
    """Copy data and mode bits ("cp src dst").

    The destination may be a directory.

    """
    if os.path.isdir(dst):
        dst = os.path.join(dst, os.path.basename(src))
    copyfile(src, dst)
    copymode(src, dst)

shutil.copy2(src, dst)
拷贝文件和状态信息

def copy2(src, dst):
    """Copy data and all stat info ("cp -p src dst").

    The destination may be a directory.

    """
    if os.path.isdir(dst):
        dst = os.path.join(dst, os.path.basename(src))
    copyfile(src, dst)
    copystat(src, dst)

shutil.ignore_patterns(*patterns)
shutil.copytree(src, dst, symlinks=False, ignore=None)
递归的去拷贝文件

例如：copytree(source, destination, ignore=ignore_patterns('*.pyc', 'tmp*'))

def ignore_patterns(*patterns):
    """Function that can be used as copytree() ignore parameter.

    Patterns is a sequence of glob-style patterns
    that are used to exclude files"""
    def _ignore_patterns(path, names):
        ignored_names = []
        for pattern in patterns:
            ignored_names.extend(fnmatch.filter(names, pattern))
        return set(ignored_names)
    return _ignore_patterns

def copytree(src, dst, symlinks=False, ignore=None):
    """Recursively copy a directory tree using copy2().

    The destination directory must not already exist.
    If exception(s) occur, an Error is raised with a list of reasons.

    If the optional symlinks flag is true, symbolic links in the
    source tree result in symbolic links in the destination tree; if
    it is false, the contents of the files pointed to by symbolic
    links are copied.

    The optional ignore argument is a callable. If given, it
    is called with the `src` parameter, which is the directory
    being visited by copytree(), and `names` which is the list of
    `src` contents, as returned by os.listdir():

        callable(src, names) -> ignored_names

    Since copytree() is called recursively, the callable will be
    called once for each directory that is copied. It returns a
    list of names relative to the `src` directory that should
    not be copied.

    XXX Consider this example code rather than the ultimate tool.

    """
    names = os.listdir(src)
    if ignore is not None:
        ignored_names = ignore(src, names)
    else:
        ignored_names = set()

    os.makedirs(dst)
    errors = []
    for name in names:
        if name in ignored_names:
            continue
        srcname = os.path.join(src, name)
        dstname = os.path.join(dst, name)
        try:
            if symlinks and os.path.islink(srcname):
                linkto = os.readlink(srcname)
                os.symlink(linkto, dstname)
            elif os.path.isdir(srcname):
                copytree(srcname, dstname, symlinks, ignore)
            else:
                # Will raise a SpecialFileError for unsupported file types
                copy2(srcname, dstname)
        # catch the Error from the recursive copytree so that we can
        # continue with other files
        except Error, err:
            errors.extend(err.args[0])
        except EnvironmentError, why:
            errors.append((srcname, dstname, str(why)))
    try:
        copystat(src, dst)
    except OSError, why:
        if WindowsError is not None and isinstance(why, WindowsError):
            # Copying file access times may fail on Windows
            pass
        else:
            errors.append((src, dst, str(why)))
    if errors:
        raise Error, errors

shutil.rmtree(path[, ignore_errors[, onerror]])
递归的去删除文件

def rmtree(path, ignore_errors=False, onerror=None):
    """Recursively delete a directory tree.

    If ignore_errors is set, errors are ignored; otherwise, if onerror
    is set, it is called to handle the error with arguments (func,
    path, exc_info) where func is os.listdir, os.remove, or os.rmdir;
    path is the argument to that function that caused it to fail; and
    exc_info is a tuple returned by sys.exc_info().  If ignore_errors
    is false and onerror is None, an exception is raised.

    """
    if ignore_errors:
        def onerror(*args):
            pass
    elif onerror is None:
        def onerror(*args):
            raise
    try:
        if os.path.islink(path):
            # symlinks to directories are forbidden, see bug #1669
            raise OSError("Cannot call rmtree on a symbolic link")
    except OSError:
        onerror(os.path.islink, path, sys.exc_info())
        # can't continue even if onerror hook returns
        return
    names = []
    try:
        names = os.listdir(path)
    except os.error, err:
        onerror(os.listdir, path, sys.exc_info())
    for name in names:
        fullname = os.path.join(path, name)
        try:
            mode = os.lstat(fullname).st_mode
        except os.error:
            mode = 0
        if stat.S_ISDIR(mode):
            rmtree(fullname, ignore_errors, onerror)
        else:
            try:
                os.remove(fullname)
            except os.error, err:
                onerror(os.remove, fullname, sys.exc_info())
    try:
        os.rmdir(path)
    except os.error:
        onerror(os.rmdir, path, sys.exc_info())

shutil.move(src, dst)
递归的去移动文件

def move(src, dst):
    """Recursively move a file or directory to another location. This is
    similar to the Unix "mv" command.

    If the destination is a directory or a symlink to a directory, the source
    is moved inside the directory. The destination path must not already
    exist.

    If the destination already exists but is not a directory, it may be
    overwritten depending on os.rename() semantics.

    If the destination is on our current filesystem, then rename() is used.
    Otherwise, src is copied to the destination and then removed.
    A lot more could be done here...  A look at a mv.c shows a lot of
    the issues this implementation glosses over.

    """
    real_dst = dst
    if os.path.isdir(dst):
        if _samefile(src, dst):
            # We might be on a case insensitive filesystem,
            # perform the rename anyway.
            os.rename(src, dst)
            return

        real_dst = os.path.join(dst, _basename(src))
        if os.path.exists(real_dst):
            raise Error, "Destination path '%s' already exists" % real_dst
    try:
        os.rename(src, real_dst)
    except OSError:
        if os.path.isdir(src):
            if _destinsrc(src, dst):
                raise Error, "Cannot move a directory '%s' into itself '%s'." % (src, dst)
            copytree(src, real_dst, symlinks=True)
            rmtree(src)
        else:
            copy2(src, real_dst)
            os.unlink(src)

shutil.make_archive(base_name, format,...)

创建压缩包并返回文件路径，例如：zip、tar

• base_name： 压缩包的文件名，也可以是压缩包的路径。只是文件名时，则保存至当前目录，否则保存至指定路径，
  如：www                        =>保存至当前路径
  如：/Users/wupeiqi/www =>保存至/Users/wupeiqi/
• format： 压缩包种类，“zip”, “tar”, “bztar”，“gztar”
• root_dir： 要压缩的文件夹路径（默认当前目录）
• owner： 用户，默认当前用户
• group： 组，默认当前组
• logger： 用于记录日志，通常是logging.Logger对象

• #将 /Users/wupeiqi/Downloads/test 下的文件打包放置当前程序目录
   
  import shutil
  ret = shutil.make_archive("wwwwwwwwww", 'gztar', root_dir='/Users/wupeiqi/Downloads/test')
   
   
  #将 /Users/wupeiqi/Downloads/test 下的文件打包放置 /Users/wupeiqi/目录
  import shutil
  ret = shutil.make_archive("/Users/wupeiqi/wwwwwwwwww", 'gztar', root_dir='/Users/wupeiqi/Downloads/test')

  def make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,
                   dry_run=0, owner=None, group=None, logger=None):
      """Create an archive file (eg. zip or tar).
  
      'base_name' is the name of the file to create, minus any format-specific
      extension; 'format' is the archive format: one of "zip", "tar", "bztar"
      or "gztar".
  
      'root_dir' is a directory that will be the root directory of the
      archive; ie. we typically chdir into 'root_dir' before creating the
      archive.  'base_dir' is the directory where we start archiving from;
      ie. 'base_dir' will be the common prefix of all files and
      directories in the archive.  'root_dir' and 'base_dir' both default
      to the current directory.  Returns the name of the archive file.
  
      'owner' and 'group' are used when creating a tar archive. By default,
      uses the current owner and group.
      """
      save_cwd = os.getcwd()
      if root_dir is not None:
          if logger is not None:
              logger.debug("changing into '%s'", root_dir)
          base_name = os.path.abspath(base_name)
          if not dry_run:
              os.chdir(root_dir)
  
      if base_dir is None:
          base_dir = os.curdir
  
      kwargs = {'dry_run': dry_run, 'logger': logger}
  
      try:
          format_info = _ARCHIVE_FORMATS[format]
      except KeyError:
          raise ValueError, "unknown archive format '%s'" % format
  
      func = format_info[0]
      for arg, val in format_info[1]:
          kwargs[arg] = val
  
      if format != 'zip':
          kwargs['owner'] = owner
          kwargs['group'] = group
  
      try:
          filename = func(base_name, base_dir, **kwargs)
      finally:
          if root_dir is not None:
              if logger is not None:
                  logger.debug("changing back to '%s'", save_cwd)
              os.chdir(save_cwd)
  
      return filename

   

• shutil 对压缩包的处理是调用 ZipFile 和 TarFile 两个模块来进行的，详细：

• import zipfile
  
  # 压缩
  z = zipfile.ZipFile('laxi.zip', 'w')
  z.write('a.log')
  z.write('data.data')
  z.close()
  
  # 解压
  z = zipfile.ZipFile('laxi.zip', 'r')
  z.extractall()
  z.close()

  import tarfile
  
  # 压缩
  tar = tarfile.open('your.tar','w')
  tar.add('/Users/wupeiqi/PycharmProjects/bbs2.zip', arcname='bbs2.zip')
  tar.add('/Users/wupeiqi/PycharmProjects/cmdb.zip', arcname='cmdb.zip')
  tar.close()
  
  # 解压
  tar = tarfile.open('your.tar','r')
  tar.extractall()  # 可设置解压地址
  tar.close()

  class ZipFile(object):
      """ Class with methods to open, read, write, close, list zip files.
  
      z = ZipFile(file, mode="r", compression=ZIP_STORED, allowZip64=False)
  
      file: Either the path to the file, or a file-like object.
            If it is a path, the file will be opened and closed by ZipFile.
      mode: The mode can be either read "r", write "w" or append "a".
      compression: ZIP_STORED (no compression) or ZIP_DEFLATED (requires zlib).
      allowZip64: if True ZipFile will create files with ZIP64 extensions when
                  needed, otherwise it will raise an exception when this would
                  be necessary.
  
      """
  
      fp = None                   # Set here since __del__ checks it
  
      def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=False):
          """Open the ZIP file with mode read "r", write "w" or append "a"."""
          if mode not in ("r", "w", "a"):
              raise RuntimeError('ZipFile() requires mode "r", "w", or "a"')
  
          if compression == ZIP_STORED:
              pass
          elif compression == ZIP_DEFLATED:
              if not zlib:
                  raise RuntimeError,\
                        "Compression requires the (missing) zlib module"
          else:
              raise RuntimeError, "That compression method is not supported"
  
          self._allowZip64 = allowZip64
          self._didModify = False
          self.debug = 0  # Level of printing: 0 through 3
          self.NameToInfo = {}    # Find file info given name
          self.filelist = []      # List of ZipInfo instances for archive
          self.compression = compression  # Method of compression
          self.mode = key = mode.replace('b', '')[0]
          self.pwd = None
          self._comment = ''
  
          # Check if we were passed a file-like object
          if isinstance(file, basestring):
              self._filePassed = 0
              self.filename = file
              modeDict = {'r' : 'rb', 'w': 'wb', 'a' : 'r+b'}
              try:
                  self.fp = open(file, modeDict[mode])
              except IOError:
                  if mode == 'a':
                      mode = key = 'w'
                      self.fp = open(file, modeDict[mode])
                  else:
                      raise
          else:
              self._filePassed = 1
              self.fp = file
              self.filename = getattr(file, 'name', None)
  
          try:
              if key == 'r':
                  self._RealGetContents()
              elif key == 'w':
                  # set the modified flag so central directory gets written
                  # even if no files are added to the archive
                  self._didModify = True
              elif key == 'a':
                  try:
                      # See if file is a zip file
                      self._RealGetContents()
                      # seek to start of directory and overwrite
                      self.fp.seek(self.start_dir, 0)
                  except BadZipfile:
                      # file is not a zip file, just append
                      self.fp.seek(0, 2)
  
                      # set the modified flag so central directory gets written
                      # even if no files are added to the archive
                      self._didModify = True
              else:
                  raise RuntimeError('Mode must be "r", "w" or "a"')
          except:
              fp = self.fp
              self.fp = None
              if not self._filePassed:
                  fp.close()
              raise
  
      def __enter__(self):
          return self
  
      def __exit__(self, type, value, traceback):
          self.close()
  
      def _RealGetContents(self):
          """Read in the table of contents for the ZIP file."""
          fp = self.fp
          try:
              endrec = _EndRecData(fp)
          except IOError:
              raise BadZipfile("File is not a zip file")
          if not endrec:
              raise BadZipfile, "File is not a zip file"
          if self.debug > 1:
              print endrec
          size_cd = endrec[_ECD_SIZE]             # bytes in central directory
          offset_cd = endrec[_ECD_OFFSET]         # offset of central directory
          self._comment = endrec[_ECD_COMMENT]    # archive comment
  
          # "concat" is zero, unless zip was concatenated to another file
          concat = endrec[_ECD_LOCATION] - size_cd - offset_cd
          if endrec[_ECD_SIGNATURE] == stringEndArchive64:
              # If Zip64 extension structures are present, account for them
              concat -= (sizeEndCentDir64 + sizeEndCentDir64Locator)
  
          if self.debug > 2:
              inferred = concat + offset_cd
              print "given, inferred, offset", offset_cd, inferred, concat
          # self.start_dir:  Position of start of central directory
          self.start_dir = offset_cd + concat
          fp.seek(self.start_dir, 0)
          data = fp.read(size_cd)
          fp = cStringIO.StringIO(data)
          total = 0
          while total < size_cd:
              centdir = fp.read(sizeCentralDir)
              if len(centdir) != sizeCentralDir:
                  raise BadZipfile("Truncated central directory")
              centdir = struct.unpack(structCentralDir, centdir)
              if centdir[_CD_SIGNATURE] != stringCentralDir:
                  raise BadZipfile("Bad magic number for central directory")
              if self.debug > 2:
                  print centdir
              filename = fp.read(centdir[_CD_FILENAME_LENGTH])
              # Create ZipInfo instance to store file information
              x = ZipInfo(filename)
              x.extra = fp.read(centdir[_CD_EXTRA_FIELD_LENGTH])
              x.comment = fp.read(centdir[_CD_COMMENT_LENGTH])
              x.header_offset = centdir[_CD_LOCAL_HEADER_OFFSET]
              (x.create_version, x.create_system, x.extract_version, x.reserved,
                  x.flag_bits, x.compress_type, t, d,
                  x.CRC, x.compress_size, x.file_size) = centdir[1:12]
              x.volume, x.internal_attr, x.external_attr = centdir[15:18]
              # Convert date/time code to (year, month, day, hour, min, sec)
              x._raw_time = t
              x.date_time = ( (d>>9)+1980, (d>>5)&0xF, d&0x1F,
                                       t>>11, (t>>5)&0x3F, (t&0x1F) * 2 )
  
              x._decodeExtra()
              x.header_offset = x.header_offset + concat
              x.filename = x._decodeFilename()
              self.filelist.append(x)
              self.NameToInfo[x.filename] = x
  
              # update total bytes read from central directory
              total = (total + sizeCentralDir + centdir[_CD_FILENAME_LENGTH]
                       + centdir[_CD_EXTRA_FIELD_LENGTH]
                       + centdir[_CD_COMMENT_LENGTH])
  
              if self.debug > 2:
                  print "total", total
  
  
      def namelist(self):
          """Return a list of file names in the archive."""
          l = []
          for data in self.filelist:
              l.append(data.filename)
          return l
  
      def infolist(self):
          """Return a list of class ZipInfo instances for files in the
          archive."""
          return self.filelist
  
      def printdir(self):
          """Print a table of contents for the zip file."""
          print "%-46s %19s %12s" % ("File Name", "Modified    ", "Size")
          for zinfo in self.filelist:
              date = "%d-%02d-%02d %02d:%02d:%02d" % zinfo.date_time[:6]
              print "%-46s %s %12d" % (zinfo.filename, date, zinfo.file_size)
  
      def testzip(self):
          """Read all the files and check the CRC."""
          chunk_size = 2 ** 20
          for zinfo in self.filelist:
              try:
                  # Read by chunks, to avoid an OverflowError or a
                  # MemoryError with very large embedded files.
                  with self.open(zinfo.filename, "r") as f:
                      while f.read(chunk_size):     # Check CRC-32
                          pass
              except BadZipfile:
                  return zinfo.filename
  
      def getinfo(self, name):
          """Return the instance of ZipInfo given 'name'."""
          info = self.NameToInfo.get(name)
          if info is None:
              raise KeyError(
                  'There is no item named %r in the archive' % name)
  
          return info
  
      def setpassword(self, pwd):
          """Set default password for encrypted files."""
          self.pwd = pwd
  
      @property
      def comment(self):
          """The comment text associated with the ZIP file."""
          return self._comment
  
      @comment.setter
      def comment(self, comment):
          # check for valid comment length
          if len(comment) > ZIP_MAX_COMMENT:
              import warnings
              warnings.warn('Archive comment is too long; truncating to %d bytes'
                            % ZIP_MAX_COMMENT, stacklevel=2)
              comment = comment[:ZIP_MAX_COMMENT]
          self._comment = comment
          self._didModify = True
  
      def read(self, name, pwd=None):
          """Return file bytes (as a string) for name."""
          return self.open(name, "r", pwd).read()
  
      def open(self, name, mode="r", pwd=None):
          """Return file-like object for 'name'."""
          if mode not in ("r", "U", "rU"):
              raise RuntimeError, 'open() requires mode "r", "U", or "rU"'
          if not self.fp:
              raise RuntimeError, \
                    "Attempt to read ZIP archive that was already closed"
  
          # Only open a new file for instances where we were not
          # given a file object in the constructor
          if self._filePassed:
              zef_file = self.fp
              should_close = False
          else:
              zef_file = open(self.filename, 'rb')
              should_close = True
  
          try:
              # Make sure we have an info object
              if isinstance(name, ZipInfo):
                  # 'name' is already an info object
                  zinfo = name
              else:
                  # Get info object for name
                  zinfo = self.getinfo(name)
  
              zef_file.seek(zinfo.header_offset, 0)
  
              # Skip the file header:
              fheader = zef_file.read(sizeFileHeader)
              if len(fheader) != sizeFileHeader:
                  raise BadZipfile("Truncated file header")
              fheader = struct.unpack(structFileHeader, fheader)
              if fheader[_FH_SIGNATURE] != stringFileHeader:
                  raise BadZipfile("Bad magic number for file header")
  
              fname = zef_file.read(fheader[_FH_FILENAME_LENGTH])
              if fheader[_FH_EXTRA_FIELD_LENGTH]:
                  zef_file.read(fheader[_FH_EXTRA_FIELD_LENGTH])
  
              if fname != zinfo.orig_filename:
                  raise BadZipfile, \
                          'File name in directory "%s" and header "%s" differ.' % (
                              zinfo.orig_filename, fname)
  
              # check for encrypted flag & handle password
              is_encrypted = zinfo.flag_bits & 0x1
              zd = None
              if is_encrypted:
                  if not pwd:
                      pwd = self.pwd
                  if not pwd:
                      raise RuntimeError, "File %s is encrypted, " \
                          "password required for extraction" % name
  
                  zd = _ZipDecrypter(pwd)
                  # The first 12 bytes in the cypher stream is an encryption header
                  #  used to strengthen the algorithm. The first 11 bytes are
                  #  completely random, while the 12th contains the MSB of the CRC,
                  #  or the MSB of the file time depending on the header type
                  #  and is used to check the correctness of the password.
                  bytes = zef_file.read(12)
                  h = map(zd, bytes[0:12])
                  if zinfo.flag_bits & 0x8:
                      # compare against the file type from extended local headers
                      check_byte = (zinfo._raw_time >> 8) & 0xff
                  else:
                      # compare against the CRC otherwise
                      check_byte = (zinfo.CRC >> 24) & 0xff
                  if ord(h[11]) != check_byte:
                      raise RuntimeError("Bad password for file", name)
  
              return ZipExtFile(zef_file, mode, zinfo, zd,
                      close_fileobj=should_close)
          except:
              if should_close:
                  zef_file.close()
              raise
  
      def extract(self, member, path=None, pwd=None):
          """Extract a member from the archive to the current working directory,
             using its full name. Its file information is extracted as accurately
             as possible. `member' may be a filename or a ZipInfo object. You can
             specify a different directory using `path'.
          """
          if not isinstance(member, ZipInfo):
              member = self.getinfo(member)
  
          if path is None:
              path = os.getcwd()
  
          return self._extract_member(member, path, pwd)
  
      def extractall(self, path=None, members=None, pwd=None):
          """Extract all members from the archive to the current working
             directory. `path' specifies a different directory to extract to.
             `members' is optional and must be a subset of the list returned
             by namelist().
          """
          if members is None:
              members = self.namelist()
  
          for zipinfo in members:
              self.extract(zipinfo, path, pwd)
  
      def _extract_member(self, member, targetpath, pwd):
          """Extract the ZipInfo object 'member' to a physical
             file on the path targetpath.
          """
          # build the destination pathname, replacing
          # forward slashes to platform specific separators.
          arcname = member.filename.replace('/', os.path.sep)
  
          if os.path.altsep:
              arcname = arcname.replace(os.path.altsep, os.path.sep)
          # interpret absolute pathname as relative, remove drive letter or
          # UNC path, redundant separators, "." and ".." components.
          arcname = os.path.splitdrive(arcname)[1]
          arcname = os.path.sep.join(x for x in arcname.split(os.path.sep)
                      if x not in ('', os.path.curdir, os.path.pardir))
          if os.path.sep == '\\':
              # filter illegal characters on Windows
              illegal = ':<>|"?*'
              if isinstance(arcname, unicode):
                  table = {ord(c): ord('_') for c in illegal}
              else:
                  table = string.maketrans(illegal, '_' * len(illegal))
              arcname = arcname.translate(table)
              # remove trailing dots
              arcname = (x.rstrip('.') for x in arcname.split(os.path.sep))
              arcname = os.path.sep.join(x for x in arcname if x)
  
          targetpath = os.path.join(targetpath, arcname)
          targetpath = os.path.normpath(targetpath)
  
          # Create all upper directories if necessary.
          upperdirs = os.path.dirname(targetpath)
          if upperdirs and not os.path.exists(upperdirs):
              os.makedirs(upperdirs)
  
          if member.filename[-1] == '/':
              if not os.path.isdir(targetpath):
                  os.mkdir(targetpath)
              return targetpath
  
          with self.open(member, pwd=pwd) as source, \
               file(targetpath, "wb") as target:
              shutil.copyfileobj(source, target)
  
          return targetpath
  
      def _writecheck(self, zinfo):
          """Check for errors before writing a file to the archive."""
          if zinfo.filename in self.NameToInfo:
              import warnings
              warnings.warn('Duplicate name: %r' % zinfo.filename, stacklevel=3)
          if self.mode not in ("w", "a"):
              raise RuntimeError, 'write() requires mode "w" or "a"'
          if not self.fp:
              raise RuntimeError, \
                    "Attempt to write ZIP archive that was already closed"
          if zinfo.compress_type == ZIP_DEFLATED and not zlib:
              raise RuntimeError, \
                    "Compression requires the (missing) zlib module"
          if zinfo.compress_type not in (ZIP_STORED, ZIP_DEFLATED):
              raise RuntimeError, \
                    "That compression method is not supported"
          if not self._allowZip64:
              requires_zip64 = None
              if len(self.filelist) >= ZIP_FILECOUNT_LIMIT:
                  requires_zip64 = "Files count"
              elif zinfo.file_size > ZIP64_LIMIT:
                  requires_zip64 = "Filesize"
              elif zinfo.header_offset > ZIP64_LIMIT:
                  requires_zip64 = "Zipfile size"
              if requires_zip64:
                  raise LargeZipFile(requires_zip64 +
                                     " would require ZIP64 extensions")
  
      def write(self, filename, arcname=None, compress_type=None):
          """Put the bytes from filename into the archive under the name
          arcname."""
          if not self.fp:
              raise RuntimeError(
                    "Attempt to write to ZIP archive that was already closed")
  
          st = os.stat(filename)
          isdir = stat.S_ISDIR(st.st_mode)
          mtime = time.localtime(st.st_mtime)
          date_time = mtime[0:6]
          # Create ZipInfo instance to store file information
          if arcname is None:
              arcname = filename
          arcname = os.path.normpath(os.path.splitdrive(arcname)[1])
          while arcname[0] in (os.sep, os.altsep):
              arcname = arcname[1:]
          if isdir:
              arcname += '/'
          zinfo = ZipInfo(arcname, date_time)
          zinfo.external_attr = (st[0] & 0xFFFF) << 16L      # Unix attributes
          if compress_type is None:
              zinfo.compress_type = self.compression
          else:
              zinfo.compress_type = compress_type
  
          zinfo.file_size = st.st_size
          zinfo.flag_bits = 0x00
          zinfo.header_offset = self.fp.tell()    # Start of header bytes
  
          self._writecheck(zinfo)
          self._didModify = True
  
          if isdir:
              zinfo.file_size = 0
              zinfo.compress_size = 0
              zinfo.CRC = 0
              zinfo.external_attr |= 0x10  # MS-DOS directory flag
              self.filelist.append(zinfo)
              self.NameToInfo[zinfo.filename] = zinfo
              self.fp.write(zinfo.FileHeader(False))
              return
  
          with open(filename, "rb") as fp:
              # Must overwrite CRC and sizes with correct data later
              zinfo.CRC = CRC = 0
              zinfo.compress_size = compress_size = 0
              # Compressed size can be larger than uncompressed size
              zip64 = self._allowZip64 and \
                      zinfo.file_size * 1.05 > ZIP64_LIMIT
              self.fp.write(zinfo.FileHeader(zip64))
              if zinfo.compress_type == ZIP_DEFLATED:
                  cmpr = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
                       zlib.DEFLATED, -15)
              else:
                  cmpr = None
              file_size = 0
              while 1:
                  buf = fp.read(1024 * 8)
                  if not buf:
                      break
                  file_size = file_size + len(buf)
                  CRC = crc32(buf, CRC) & 0xffffffff
                  if cmpr:
                      buf = cmpr.compress(buf)
                      compress_size = compress_size + len(buf)
                  self.fp.write(buf)
          if cmpr:
              buf = cmpr.flush()
              compress_size = compress_size + len(buf)
              self.fp.write(buf)
              zinfo.compress_size = compress_size
          else:
              zinfo.compress_size = file_size
          zinfo.CRC = CRC
          zinfo.file_size = file_size
          if not zip64 and self._allowZip64:
              if file_size > ZIP64_LIMIT:
                  raise RuntimeError('File size has increased during compressing')
              if compress_size > ZIP64_LIMIT:
                  raise RuntimeError('Compressed size larger than uncompressed size')
          # Seek backwards and write file header (which will now include
          # correct CRC and file sizes)
          position = self.fp.tell()       # Preserve current position in file
          self.fp.seek(zinfo.header_offset, 0)
          self.fp.write(zinfo.FileHeader(zip64))
          self.fp.seek(position, 0)
          self.filelist.append(zinfo)
          self.NameToInfo[zinfo.filename] = zinfo
  
      def writestr(self, zinfo_or_arcname, bytes, compress_type=None):
          """Write a file into the archive.  The contents is the string
          'bytes'.  'zinfo_or_arcname' is either a ZipInfo instance or
          the name of the file in the archive."""
          if not isinstance(zinfo_or_arcname, ZipInfo):
              zinfo = ZipInfo(filename=zinfo_or_arcname,
                              date_time=time.localtime(time.time())[:6])
  
              zinfo.compress_type = self.compression
              if zinfo.filename[-1] == '/':
                  zinfo.external_attr = 0o40775 << 16   # drwxrwxr-x
                  zinfo.external_attr |= 0x10           # MS-DOS directory flag
              else:
                  zinfo.external_attr = 0o600 << 16     # ?rw-------
          else:
              zinfo = zinfo_or_arcname
  
          if not self.fp:
              raise RuntimeError(
                    "Attempt to write to ZIP archive that was already closed")
  
          if compress_type is not None:
              zinfo.compress_type = compress_type
  
          zinfo.file_size = len(bytes)            # Uncompressed size
          zinfo.header_offset = self.fp.tell()    # Start of header bytes
          self._writecheck(zinfo)
          self._didModify = True
          zinfo.CRC = crc32(bytes) & 0xffffffff       # CRC-32 checksum
          if zinfo.compress_type == ZIP_DEFLATED:
              co = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
                   zlib.DEFLATED, -15)
              bytes = co.compress(bytes) + co.flush()
              zinfo.compress_size = len(bytes)    # Compressed size
          else:
              zinfo.compress_size = zinfo.file_size
          zip64 = zinfo.file_size > ZIP64_LIMIT or \
                  zinfo.compress_size > ZIP64_LIMIT
          if zip64 and not self._allowZip64:
              raise LargeZipFile("Filesize would require ZIP64 extensions")
          self.fp.write(zinfo.FileHeader(zip64))
          self.fp.write(bytes)
          if zinfo.flag_bits & 0x08:
              # Write CRC and file sizes after the file data
              fmt = '<LQQ' if zip64 else '<LLL'
              self.fp.write(struct.pack(fmt, zinfo.CRC, zinfo.compress_size,
                    zinfo.file_size))
          self.fp.flush()
          self.filelist.append(zinfo)
          self.NameToInfo[zinfo.filename] = zinfo
  
      def __del__(self):
          """Call the "close()" method in case the user forgot."""
          self.close()
  
      def close(self):
          """Close the file, and for mode "w" and "a" write the ending
          records."""
          if self.fp is None:
              return
  
          try:
              if self.mode in ("w", "a") and self._didModify: # write ending records
                  pos1 = self.fp.tell()
                  for zinfo in self.filelist:         # write central directory
                      dt = zinfo.date_time
                      dosdate = (dt[0] - 1980) << 9 | dt[1] << 5 | dt[2]
                      dostime = dt[3] << 11 | dt[4] << 5 | (dt[5] // 2)
                      extra = []
                      if zinfo.file_size > ZIP64_LIMIT \
                              or zinfo.compress_size > ZIP64_LIMIT:
                          extra.append(zinfo.file_size)
                          extra.append(zinfo.compress_size)
                          file_size = 0xffffffff
                          compress_size = 0xffffffff
                      else:
                          file_size = zinfo.file_size
                          compress_size = zinfo.compress_size
  
                      if zinfo.header_offset > ZIP64_LIMIT:
                          extra.append(zinfo.header_offset)
                          header_offset = 0xffffffffL
                      else:
                          header_offset = zinfo.header_offset
  
                      extra_data = zinfo.extra
                      if extra:
                          # Append a ZIP64 field to the extra's
                          extra_data = struct.pack(
                                  '<HH' + 'Q'*len(extra),
                                  1, 8*len(extra), *extra) + extra_data
  
                          extract_version = max(45, zinfo.extract_version)
                          create_version = max(45, zinfo.create_version)
                      else:
                          extract_version = zinfo.extract_version
                          create_version = zinfo.create_version
  
                      try:
                          filename, flag_bits = zinfo._encodeFilenameFlags()
                          centdir = struct.pack(structCentralDir,
                          stringCentralDir, create_version,
                          zinfo.create_system, extract_version, zinfo.reserved,
                          flag_bits, zinfo.compress_type, dostime, dosdate,
                          zinfo.CRC, compress_size, file_size,
                          len(filename), len(extra_data), len(zinfo.comment),
                          0, zinfo.internal_attr, zinfo.external_attr,
                          header_offset)
                      except DeprecationWarning:
                          print >>sys.stderr, (structCentralDir,
                          stringCentralDir, create_version,
                          zinfo.create_system, extract_version, zinfo.reserved,
                          zinfo.flag_bits, zinfo.compress_type, dostime, dosdate,
                          zinfo.CRC, compress_size, file_size,
                          len(zinfo.filename), len(extra_data), len(zinfo.comment),
                          0, zinfo.internal_attr, zinfo.external_attr,
                          header_offset)
                          raise
                      self.fp.write(centdir)
                      self.fp.write(filename)
                      self.fp.write(extra_data)
                      self.fp.write(zinfo.comment)
  
                  pos2 = self.fp.tell()
                  # Write end-of-zip-archive record
                  centDirCount = len(self.filelist)
                  centDirSize = pos2 - pos1
                  centDirOffset = pos1
                  requires_zip64 = None
                  if centDirCount > ZIP_FILECOUNT_LIMIT:
                      requires_zip64 = "Files count"
                  elif centDirOffset > ZIP64_LIMIT:
                      requires_zip64 = "Central directory offset"
                  elif centDirSize > ZIP64_LIMIT:
                      requires_zip64 = "Central directory size"
                  if requires_zip64:
                      # Need to write the ZIP64 end-of-archive records
                      if not self._allowZip64:
                          raise LargeZipFile(requires_zip64 +
                                             " would require ZIP64 extensions")
                      zip64endrec = struct.pack(
                              structEndArchive64, stringEndArchive64,
                              44, 45, 45, 0, 0, centDirCount, centDirCount,
                              centDirSize, centDirOffset)
                      self.fp.write(zip64endrec)
  
                      zip64locrec = struct.pack(
                              structEndArchive64Locator,
                              stringEndArchive64Locator, 0, pos2, 1)
                      self.fp.write(zip64locrec)
                      centDirCount = min(centDirCount, 0xFFFF)
                      centDirSize = min(centDirSize, 0xFFFFFFFF)
                      centDirOffset = min(centDirOffset, 0xFFFFFFFF)
  
                  endrec = struct.pack(structEndArchive, stringEndArchive,
                                      0, 0, centDirCount, centDirCount,
                                      centDirSize, centDirOffset, len(self._comment))
                  self.fp.write(endrec)
                  self.fp.write(self._comment)
                  self.fp.flush()
          finally:
              fp = self.fp
              self.fp = None
              if not self._filePassed:
                  fp.close()

  class TarFile(object):
      """The TarFile Class provides an interface to tar archives.
      """
  
      debug = 0                   # May be set from 0 (no msgs) to 3 (all msgs)
  
      dereference = False         # If true, add content of linked file to the
                                  # tar file, else the link.
  
      ignore_zeros = False        # If true, skips empty or invalid blocks and
                                  # continues processing.
  
      errorlevel = 1              # If 0, fatal errors only appear in debug
                                  # messages (if debug >= 0). If > 0, errors
                                  # are passed to the caller as exceptions.
  
      format = DEFAULT_FORMAT     # The format to use when creating an archive.
  
      encoding = ENCODING         # Encoding for 8-bit character strings.
  
      errors = None               # Error handler for unicode conversion.
  
      tarinfo = TarInfo           # The default TarInfo class to use.
  
      fileobject = ExFileObject   # The default ExFileObject class to use.
  
      def __init__(self, name=None, mode="r", fileobj=None, format=None,
              tarinfo=None, dereference=None, ignore_zeros=None, encoding=None,
              errors=None, pax_headers=None, debug=None, errorlevel=None):
          """Open an (uncompressed) tar archive `name'. `mode' is either 'r' to
             read from an existing archive, 'a' to append data to an existing
             file or 'w' to create a new file overwriting an existing one. `mode'
             defaults to 'r'.
             If `fileobj' is given, it is used for reading or writing data. If it
             can be determined, `mode' is overridden by `fileobj's mode.
             `fileobj' is not closed, when TarFile is closed.
          """
          modes = {"r": "rb", "a": "r+b", "w": "wb"}
          if mode not in modes:
              raise ValueError("mode must be 'r', 'a' or 'w'")
          self.mode = mode
          self._mode = modes[mode]
  
          if not fileobj:
              if self.mode == "a" and not os.path.exists(name):
                  # Create nonexistent files in append mode.
                  self.mode = "w"
                  self._mode = "wb"
              fileobj = bltn_open(name, self._mode)
              self._extfileobj = False
          else:
              if name is None and hasattr(fileobj, "name"):
                  name = fileobj.name
              if hasattr(fileobj, "mode"):
                  self._mode = fileobj.mode
              self._extfileobj = True
          self.name = os.path.abspath(name) if name else None
          self.fileobj = fileobj
  
          # Init attributes.
          if format is not None:
              self.format = format
          if tarinfo is not None:
              self.tarinfo = tarinfo
          if dereference is not None:
              self.dereference = dereference
          if ignore_zeros is not None:
              self.ignore_zeros = ignore_zeros
          if encoding is not None:
              self.encoding = encoding
  
          if errors is not None:
              self.errors = errors
          elif mode == "r":
              self.errors = "utf-8"
          else:
              self.errors = "strict"
  
          if pax_headers is not None and self.format == PAX_FORMAT:
              self.pax_headers = pax_headers
          else:
              self.pax_headers = {}
  
          if debug is not None:
              self.debug = debug
          if errorlevel is not None:
              self.errorlevel = errorlevel
  
          # Init datastructures.
          self.closed = False
          self.members = []       # list of members as TarInfo objects
          self._loaded = False    # flag if all members have been read
          self.offset = self.fileobj.tell()
                                  # current position in the archive file
          self.inodes = {}        # dictionary caching the inodes of
                                  # archive members already added
  
          try:
              if self.mode == "r":
                  self.firstmember = None
                  self.firstmember = self.next()
  
              if self.mode == "a":
                  # Move to the end of the archive,
                  # before the first empty block.
                  while True:
                      self.fileobj.seek(self.offset)
                      try:
                          tarinfo = self.tarinfo.fromtarfile(self)
                          self.members.append(tarinfo)
                      except EOFHeaderError:
                          self.fileobj.seek(self.offset)
                          break
                      except HeaderError, e:
                          raise ReadError(str(e))
  
              if self.mode in "aw":
                  self._loaded = True
  
                  if self.pax_headers:
                      buf = self.tarinfo.create_pax_global_header(self.pax_headers.copy())
                      self.fileobj.write(buf)
                      self.offset += len(buf)
          except:
              if not self._extfileobj:
                  self.fileobj.close()
              self.closed = True
              raise
  
      def _getposix(self):
          return self.format == USTAR_FORMAT
      def _setposix(self, value):
          import warnings
          warnings.warn("use the format attribute instead", DeprecationWarning,
                        2)
          if value:
              self.format = USTAR_FORMAT
          else:
              self.format = GNU_FORMAT
      posix = property(_getposix, _setposix)
  
      #--------------------------------------------------------------------------
      # Below are the classmethods which act as alternate constructors to the
      # TarFile class. The open() method is the only one that is needed for
      # public use; it is the "super"-constructor and is able to select an
      # adequate "sub"-constructor for a particular compression using the mapping
      # from OPEN_METH.
      #
      # This concept allows one to subclass TarFile without losing the comfort of
      # the super-constructor. A sub-constructor is registered and made available
      # by adding it to the mapping in OPEN_METH.
  
      @classmethod
      def open(cls, name=None, mode="r", fileobj=None, bufsize=RECORDSIZE, **kwargs):
          """Open a tar archive for reading, writing or appending. Return
             an appropriate TarFile class.
  
             mode:
             'r' or 'r:*' open for reading with transparent compression
             'r:'         open for reading exclusively uncompressed
             'r:gz'       open for reading with gzip compression
             'r:bz2'      open for reading with bzip2 compression
             'a' or 'a:'  open for appending, creating the file if necessary
             'w' or 'w:'  open for writing without compression
             'w:gz'       open for writing with gzip compression
             'w:bz2'      open for writing with bzip2 compression
  
             'r|*'        open a stream of tar blocks with transparent compression
             'r|'         open an uncompressed stream of tar blocks for reading
             'r|gz'       open a gzip compressed stream of tar blocks
             'r|bz2'      open a bzip2 compressed stream of tar blocks
             'w|'         open an uncompressed stream for writing
             'w|gz'       open a gzip compressed stream for writing
             'w|bz2'      open a bzip2 compressed stream for writing
          """
  
          if not name and not fileobj:
              raise ValueError("nothing to open")
  
          if mode in ("r", "r:*"):
              # Find out which *open() is appropriate for opening the file.
              for comptype in cls.OPEN_METH:
                  func = getattr(cls, cls.OPEN_METH[comptype])
                  if fileobj is not None:
                      saved_pos = fileobj.tell()
                  try:
                      return func(name, "r", fileobj, **kwargs)
                  except (ReadError, CompressionError), e:
                      if fileobj is not None:
                          fileobj.seek(saved_pos)
                      continue
              raise ReadError("file could not be opened successfully")
  
          elif ":" in mode:
              filemode, comptype = mode.split(":", 1)
              filemode = filemode or "r"
              comptype = comptype or "tar"
  
              # Select the *open() function according to
              # given compression.
              if comptype in cls.OPEN_METH:
                  func = getattr(cls, cls.OPEN_METH[comptype])
              else:
                  raise CompressionError("unknown compression type %r" % comptype)
              return func(name, filemode, fileobj, **kwargs)
  
          elif "|" in mode:
              filemode, comptype = mode.split("|", 1)
              filemode = filemode or "r"
              comptype = comptype or "tar"
  
              if filemode not in ("r", "w"):
                  raise ValueError("mode must be 'r' or 'w'")
  
              stream = _Stream(name, filemode, comptype, fileobj, bufsize)
              try:
                  t = cls(name, filemode, stream, **kwargs)
              except:
                  stream.close()
                  raise
              t._extfileobj = False
              return t
  
          elif mode in ("a", "w"):
              return cls.taropen(name, mode, fileobj, **kwargs)
  
          raise ValueError("undiscernible mode")
  
      @classmethod
      def taropen(cls, name, mode="r", fileobj=None, **kwargs):
          """Open uncompressed tar archive name for reading or writing.
          """
          if mode not in ("r", "a", "w"):
              raise ValueError("mode must be 'r', 'a' or 'w'")
          return cls(name, mode, fileobj, **kwargs)
  
      @classmethod
      def gzopen(cls, name, mode="r", fileobj=None, compresslevel=9, **kwargs):
          """Open gzip compressed tar archive name for reading or writing.
             Appending is not allowed.
          """
          if mode not in ("r", "w"):
              raise ValueError("mode must be 'r' or 'w'")
  
          try:
              import gzip
              gzip.GzipFile
          except (ImportError, AttributeError):
              raise CompressionError("gzip module is not available")
  
          try:
              fileobj = gzip.GzipFile(name, mode, compresslevel, fileobj)
          except OSError:
              if fileobj is not None and mode == 'r':
                  raise ReadError("not a gzip file")
              raise
  
          try:
              t = cls.taropen(name, mode, fileobj, **kwargs)
          except IOError:
              fileobj.close()
              if mode == 'r':
                  raise ReadError("not a gzip file")
              raise
          except:
              fileobj.close()
              raise
          t._extfileobj = False
          return t
  
      @classmethod
      def bz2open(cls, name, mode="r", fileobj=None, compresslevel=9, **kwargs):
          """Open bzip2 compressed tar archive name for reading or writing.
             Appending is not allowed.
          """
          if mode not in ("r", "w"):
              raise ValueError("mode must be 'r' or 'w'.")
  
          try:
              import bz2
          except ImportError:
              raise CompressionError("bz2 module is not available")
  
          if fileobj is not None:
              fileobj = _BZ2Proxy(fileobj, mode)
          else:
              fileobj = bz2.BZ2File(name, mode, compresslevel=compresslevel)
  
          try:
              t = cls.taropen(name, mode, fileobj, **kwargs)
          except (IOError, EOFError):
              fileobj.close()
              if mode == 'r':
                  raise ReadError("not a bzip2 file")
              raise
          except:
              fileobj.close()
              raise
          t._extfileobj = False
          return t
  
      # All *open() methods are registered here.
      OPEN_METH = {
          "tar": "taropen",   # uncompressed tar
          "gz":  "gzopen",    # gzip compressed tar
          "bz2": "bz2open"    # bzip2 compressed tar
      }
  
      #--------------------------------------------------------------------------
      # The public methods which TarFile provides:
  
      def close(self):
          """Close the TarFile. In write-mode, two finishing zero blocks are
             appended to the archive.
          """
          if self.closed:
              return
  
          if self.mode in "aw":
              self.fileobj.write(NUL * (BLOCKSIZE * 2))
              self.offset += (BLOCKSIZE * 2)
              # fill up the end with zero-blocks
              # (like option -b20 for tar does)
              blocks, remainder = divmod(self.offset, RECORDSIZE)
              if remainder > 0:
                  self.fileobj.write(NUL * (RECORDSIZE - remainder))
  
          if not self._extfileobj:
              self.fileobj.close()
          self.closed = True
  
      def getmember(self, name):
          """Return a TarInfo object for member `name'. If `name' can not be
             found in the archive, KeyError is raised. If a member occurs more
             than once in the archive, its last occurrence is assumed to be the
             most up-to-date version.
          """
          tarinfo = self._getmember(name)
          if tarinfo is None:
              raise KeyError("filename %r not found" % name)
          return tarinfo
  
      def getmembers(self):
          """Return the members of the archive as a list of TarInfo objects. The
             list has the same order as the members in the archive.
          """
          self._check()
          if not self._loaded:    # if we want to obtain a list of
              self._load()        # all members, we first have to
                                  # scan the whole archive.
          return self.members
  
      def getnames(self):
          """Return the members of the archive as a list of their names. It has
             the same order as the list returned by getmembers().
          """
          return [tarinfo.name for tarinfo in self.getmembers()]
  
      def gettarinfo(self, name=None, arcname=None, fileobj=None):
          """Create a TarInfo object for either the file `name' or the file
             object `fileobj' (using os.fstat on its file descriptor). You can
             modify some of the TarInfo's attributes before you add it using
             addfile(). If given, `arcname' specifies an alternative name for the
             file in the archive.
          """
          self._check("aw")
  
          # When fileobj is given, replace name by
          # fileobj's real name.
          if fileobj is not None:
              name = fileobj.name
  
          # Building the name of the member in the archive.
          # Backward slashes are converted to forward slashes,
          # Absolute paths are turned to relative paths.
          if arcname is None:
              arcname = name
          drv, arcname = os.path.splitdrive(arcname)
          arcname = arcname.replace(os.sep, "/")
          arcname = arcname.lstrip("/")
  
          # Now, fill the TarInfo object with
          # information specific for the file.
          tarinfo = self.tarinfo()
          tarinfo.tarfile = self
  
          # Use os.stat or os.lstat, depending on platform
          # and if symlinks shall be resolved.
          if fileobj is None:
              if hasattr(os, "lstat") and not self.dereference:
                  statres = os.lstat(name)
              else:
                  statres = os.stat(name)
          else:
              statres = os.fstat(fileobj.fileno())
          linkname = ""
  
          stmd = statres.st_mode
          if stat.S_ISREG(stmd):
              inode = (statres.st_ino, statres.st_dev)
              if not self.dereference and statres.st_nlink > 1 and \
                      inode in self.inodes and arcname != self.inodes[inode]:
                  # Is it a hardlink to an already
                  # archived file?
                  type = LNKTYPE
                  linkname = self.inodes[inode]
              else:
                  # The inode is added only if its valid.
                  # For win32 it is always 0.
                  type = REGTYPE
                  if inode[0]:
                      self.inodes[inode] = arcname
          elif stat.S_ISDIR(stmd):
              type = DIRTYPE
          elif stat.S_ISFIFO(stmd):
              type = FIFOTYPE
          elif stat.S_ISLNK(stmd):
              type = SYMTYPE
              linkname = os.readlink(name)
          elif stat.S_ISCHR(stmd):
              type = CHRTYPE
          elif stat.S_ISBLK(stmd):
              type = BLKTYPE
          else:
              return None
  
          # Fill the TarInfo object with all
          # information we can get.
          tarinfo.name = arcname
          tarinfo.mode = stmd
          tarinfo.uid = statres.st_uid
          tarinfo.gid = statres.st_gid
          if type == REGTYPE:
              tarinfo.size = statres.st_size
          else:
              tarinfo.size = 0L
          tarinfo.mtime = statres.st_mtime
          tarinfo.type = type
          tarinfo.linkname = linkname
          if pwd:
              try:
                  tarinfo.uname = pwd.getpwuid(tarinfo.uid)[0]
              except KeyError:
                  pass
          if grp:
              try:
                  tarinfo.gname = grp.getgrgid(tarinfo.gid)[0]
              except KeyError:
                  pass
  
          if type in (CHRTYPE, BLKTYPE):
              if hasattr(os, "major") and hasattr(os, "minor"):
                  tarinfo.devmajor = os.major(statres.st_rdev)
                  tarinfo.devminor = os.minor(statres.st_rdev)
          return tarinfo
  
      def list(self, verbose=True):
          """Print a table of contents to sys.stdout. If `verbose' is False, only
             the names of the members are printed. If it is True, an `ls -l'-like
             output is produced.
          """
          self._check()
  
          for tarinfo in self:
              if verbose:
                  print filemode(tarinfo.mode),
                  print "%s/%s" % (tarinfo.uname or tarinfo.uid,
                                   tarinfo.gname or tarinfo.gid),
                  if tarinfo.ischr() or tarinfo.isblk():
                      print "%10s" % ("%d,%d" \
                                      % (tarinfo.devmajor, tarinfo.devminor)),
                  else:
                      print "%10d" % tarinfo.size,
                  print "%d-%02d-%02d %02d:%02d:%02d" \
                        % time.localtime(tarinfo.mtime)[:6],
  
              print tarinfo.name + ("/" if tarinfo.isdir() else ""),
  
              if verbose:
                  if tarinfo.issym():
                      print "->", tarinfo.linkname,
                  if tarinfo.islnk():
                      print "link to", tarinfo.linkname,
              print
  
      def add(self, name, arcname=None, recursive=True, exclude=None, filter=None):
          """Add the file `name' to the archive. `name' may be any type of file
             (directory, fifo, symbolic link, etc.). If given, `arcname'
             specifies an alternative name for the file in the archive.
             Directories are added recursively by default. This can be avoided by
             setting `recursive' to False. `exclude' is a function that should
             return True for each filename to be excluded. `filter' is a function
             that expects a TarInfo object argument and returns the changed
             TarInfo object, if it returns None the TarInfo object will be
             excluded from the archive.
          """
          self._check("aw")
  
          if arcname is None:
              arcname = name
  
          # Exclude pathnames.
          if exclude is not None:
              import warnings
              warnings.warn("use the filter argument instead",
                      DeprecationWarning, 2)
              if exclude(name):
                  self._dbg(2, "tarfile: Excluded %r" % name)
                  return
  
          # Skip if somebody tries to archive the archive...
          if self.name is not None and os.path.abspath(name) == self.name:
              self._dbg(2, "tarfile: Skipped %r" % name)
              return
  
          self._dbg(1, name)
  
          # Create a TarInfo object from the file.
          tarinfo = self.gettarinfo(name, arcname)
  
          if tarinfo is None:
              self._dbg(1, "tarfile: Unsupported type %r" % name)
              return
  
          # Change or exclude the TarInfo object.
          if filter is not None:
              tarinfo = filter(tarinfo)
              if tarinfo is None:
                  self._dbg(2, "tarfile: Excluded %r" % name)
                  return
  
          # Append the tar header and data to the archive.
          if tarinfo.isreg():
              with bltn_open(name, "rb") as f:
                  self.addfile(tarinfo, f)
  
          elif tarinfo.isdir():
              self.addfile(tarinfo)
              if recursive:
                  for f in os.listdir(name):
                      self.add(os.path.join(name, f), os.path.join(arcname, f),
                              recursive, exclude, filter)
  
          else:
              self.addfile(tarinfo)
  
      def addfile(self, tarinfo, fileobj=None):
          """Add the TarInfo object `tarinfo' to the archive. If `fileobj' is
             given, tarinfo.size bytes are read from it and added to the archive.
             You can create TarInfo objects using gettarinfo().
             On Windows platforms, `fileobj' should always be opened with mode
             'rb' to avoid irritation about the file size.
          """
          self._check("aw")
  
          tarinfo = copy.copy(tarinfo)
  
          buf = tarinfo.tobuf(self.format, self.encoding, self.errors)
          self.fileobj.write(buf)
          self.offset += len(buf)
  
          # If there's data to follow, append it.
          if fileobj is not None:
              copyfileobj(fileobj, self.fileobj, tarinfo.size)
              blocks, remainder = divmod(tarinfo.size, BLOCKSIZE)
              if remainder > 0:
                  self.fileobj.write(NUL * (BLOCKSIZE - remainder))
                  blocks += 1
              self.offset += blocks * BLOCKSIZE
  
          self.members.append(tarinfo)
  
      def extractall(self, path=".", members=None):
          """Extract all members from the archive to the current working
             directory and set owner, modification time and permissions on
             directories afterwards. `path' specifies a different directory
             to extract to. `members' is optional and must be a subset of the
             list returned by getmembers().
          """
          directories = []
  
          if members is None:
              members = self
  
          for tarinfo in members:
              if tarinfo.isdir():
                  # Extract directories with a safe mode.
                  directories.append(tarinfo)
                  tarinfo = copy.copy(tarinfo)
                  tarinfo.mode = 0700
              self.extract(tarinfo, path)
  
          # Reverse sort directories.
          directories.sort(key=operator.attrgetter('name'))
          directories.reverse()
  
          # Set correct owner, mtime and filemode on directories.
          for tarinfo in directories:
              dirpath = os.path.join(path, tarinfo.name)
              try:
                  self.chown(tarinfo, dirpath)
                  self.utime(tarinfo, dirpath)
                  self.chmod(tarinfo, dirpath)
              except ExtractError, e:
                  if self.errorlevel > 1:
                      raise
                  else:
                      self._dbg(1, "tarfile: %s" % e)
  
      def extract(self, member, path=""):
          """Extract a member from the archive to the current working directory,
             using its full name. Its file information is extracted as accurately
             as possible. `member' may be a filename or a TarInfo object. You can
             specify a different directory using `path'.
          """
          self._check("r")
  
          if isinstance(member, basestring):
              tarinfo = self.getmember(member)
          else:
              tarinfo = member
  
          # Prepare the link target for makelink().
          if tarinfo.islnk():
              tarinfo._link_target = os.path.join(path, tarinfo.linkname)
  
          try:
              self._extract_member(tarinfo, os.path.join(path, tarinfo.name))
          except EnvironmentError, e:
              if self.errorlevel > 0:
                  raise
              else:
                  if e.filename is None:
                      self._dbg(1, "tarfile: %s" % e.strerror)
                  else:
                      self._dbg(1, "tarfile: %s %r" % (e.strerror, e.filename))
          except ExtractError, e:
              if self.errorlevel > 1:
                  raise
              else:
                  self._dbg(1, "tarfile: %s" % e)
  
      def extractfile(self, member):
          """Extract a member from the archive as a file object. `member' may be
             a filename or a TarInfo object. If `member' is a regular file, a
             file-like object is returned. If `member' is a link, a file-like
             object is constructed from the link's target. If `member' is none of
             the above, None is returned.
             The file-like object is read-only and provides the following
             methods: read(), readline(), readlines(), seek() and tell()
          """
          self._check("r")
  
          if isinstance(member, basestring):
              tarinfo = self.getmember(member)
          else:
              tarinfo = member
  
          if tarinfo.isreg():
              return self.fileobject(self, tarinfo)
  
          elif tarinfo.type not in SUPPORTED_TYPES:
              # If a member's type is unknown, it is treated as a
              # regular file.
              return self.fileobject(self, tarinfo)
  
          elif tarinfo.islnk() or tarinfo.issym():
              if isinstance(self.fileobj, _Stream):
                  # A small but ugly workaround for the case that someone tries
                  # to extract a (sym)link as a file-object from a non-seekable
                  # stream of tar blocks.
                  raise StreamError("cannot extract (sym)link as file object")
              else:
                  # A (sym)link's file object is its target's file object.
                  return self.extractfile(self._find_link_target(tarinfo))
          else:
              # If there's no data associated with the member (directory, chrdev,
              # blkdev, etc.), return None instead of a file object.
              return None
  
      def _extract_member(self, tarinfo, targetpath):
          """Extract the TarInfo object tarinfo to a physical
             file called targetpath.
          """
          # Fetch the TarInfo object for the given name
          # and build the destination pathname, replacing
          # forward slashes to platform specific separators.
          targetpath = targetpath.rstrip("/")
          targetpath = targetpath.replace("/", os.sep)
  
          # Create all upper directories.
          upperdirs = os.path.dirname(targetpath)
          if upperdirs and not os.path.exists(upperdirs):
              # Create directories that are not part of the archive with
              # default permissions.
              os.makedirs(upperdirs)
  
          if tarinfo.islnk() or tarinfo.issym():
              self._dbg(1, "%s -> %s" % (tarinfo.name, tarinfo.linkname))
          else:
              self._dbg(1, tarinfo.name)
  
          if tarinfo.isreg():
              self.makefile(tarinfo, targetpath)
          elif tarinfo.isdir():
              self.makedir(tarinfo, targetpath)
          elif tarinfo.isfifo():
              self.makefifo(tarinfo, targetpath)
          elif tarinfo.ischr() or tarinfo.isblk():
              self.makedev(tarinfo, targetpath)
          elif tarinfo.islnk() or tarinfo.issym():
              self.makelink(tarinfo, targetpath)
          elif tarinfo.type not in SUPPORTED_TYPES:
              self.makeunknown(tarinfo, targetpath)
          else:
              self.makefile(tarinfo, targetpath)
  
          self.chown(tarinfo, targetpath)
          if not tarinfo.issym():
              self.chmod(tarinfo, targetpath)
              self.utime(tarinfo, targetpath)
  
      #--------------------------------------------------------------------------
      # Below are the different file methods. They are called via
      # _extract_member() when extract() is called. They can be replaced in a
      # subclass to implement other functionality.
  
      def makedir(self, tarinfo, targetpath):
          """Make a directory called targetpath.
          """
          try:
              # Use a safe mode for the directory, the real mode is set
              # later in _extract_member().
              os.mkdir(targetpath, 0700)
          except EnvironmentError, e:
              if e.errno != errno.EEXIST:
                  raise
  
      def makefile(self, tarinfo, targetpath):
          """Make a file called targetpath.
          """
          source = self.extractfile(tarinfo)
          try:
              with bltn_open(targetpath, "wb") as target:
                  copyfileobj(source, target)
          finally:
              source.close()
  
      def makeunknown(self, tarinfo, targetpath):
          """Make a file from a TarInfo object with an unknown type
             at targetpath.
          """
          self.makefile(tarinfo, targetpath)
          self._dbg(1, "tarfile: Unknown file type %r, " \
                       "extracted as regular file." % tarinfo.type)
  
      def makefifo(self, tarinfo, targetpath):
          """Make a fifo called targetpath.
          """
          if hasattr(os, "mkfifo"):
              os.mkfifo(targetpath)
          else:
              raise ExtractError("fifo not supported by system")
  
      def makedev(self, tarinfo, targetpath):
          """Make a character or block device called targetpath.
          """
          if not hasattr(os, "mknod") or not hasattr(os, "makedev"):
              raise ExtractError("special devices not supported by system")
  
          mode = tarinfo.mode
          if tarinfo.isblk():
              mode |= stat.S_IFBLK
          else:
              mode |= stat.S_IFCHR
  
          os.mknod(targetpath, mode,
                   os.makedev(tarinfo.devmajor, tarinfo.devminor))
  
      def makelink(self, tarinfo, targetpath):
          """Make a (symbolic) link called targetpath. If it cannot be created
            (platform limitation), we try to make a copy of the referenced file
            instead of a link.
          """
          if hasattr(os, "symlink") and hasattr(os, "link"):
              # For systems that support symbolic and hard links.
              if tarinfo.issym():
                  if os.path.lexists(targetpath):
                      os.unlink(targetpath)
                  os.symlink(tarinfo.linkname, targetpath)
              else:
                  # See extract().
                  if os.path.exists(tarinfo._link_target):
                      if os.path.lexists(targetpath):
                          os.unlink(targetpath)
                      os.link(tarinfo._link_target, targetpath)
                  else:
                      self._extract_member(self._find_link_target(tarinfo), targetpath)
          else:
              try:
                  self._extract_member(self._find_link_target(tarinfo), targetpath)
              except KeyError:
                  raise ExtractError("unable to resolve link inside archive")
  
      def chown(self, tarinfo, targetpath):
          """Set owner of targetpath according to tarinfo.
          """
          if pwd and hasattr(os, "geteuid") and os.geteuid() == 0:
              # We have to be root to do so.
              try:
                  g = grp.getgrnam(tarinfo.gname)[2]
              except KeyError:
                  g = tarinfo.gid
              try:
                  u = pwd.getpwnam(tarinfo.uname)[2]
              except KeyError:
                  u = tarinfo.uid
              try:
                  if tarinfo.issym() and hasattr(os, "lchown"):
                      os.lchown(targetpath, u, g)
                  else:
                      if sys.platform != "os2emx":
                          os.chown(targetpath, u, g)
              except EnvironmentError, e:
                  raise ExtractError("could not change owner")
  
      def chmod(self, tarinfo, targetpath):
          """Set file permissions of targetpath according to tarinfo.
          """
          if hasattr(os, 'chmod'):
              try:
                  os.chmod(targetpath, tarinfo.mode)
              except EnvironmentError, e:
                  raise ExtractError("could not change mode")
  
      def utime(self, tarinfo, targetpath):
          """Set modification time of targetpath according to tarinfo.
          """
          if not hasattr(os, 'utime'):
              return
          try:
              os.utime(targetpath, (tarinfo.mtime, tarinfo.mtime))
          except EnvironmentError, e:
              raise ExtractError("could not change modification time")
  
      #--------------------------------------------------------------------------
      def next(self):
          """Return the next member of the archive as a TarInfo object, when
             TarFile is opened for reading. Return None if there is no more
             available.
          """
          self._check("ra")
          if self.firstmember is not None:
              m = self.firstmember
              self.firstmember = None
              return m
  
          # Read the next block.
          self.fileobj.seek(self.offset)
          tarinfo = None
          while True:
              try:
                  tarinfo = self.tarinfo.fromtarfile(self)
              except EOFHeaderError, e:
                  if self.ignore_zeros:
                      self._dbg(2, "0x%X: %s" % (self.offset, e))
                      self.offset += BLOCKSIZE
                      continue
              except InvalidHeaderError, e:
                  if self.ignore_zeros:
                      self._dbg(2, "0x%X: %s" % (self.offset, e))
                      self.offset += BLOCKSIZE
                      continue
                  elif self.offset == 0:
                      raise ReadError(str(e))
              except EmptyHeaderError:
                  if self.offset == 0:
                      raise ReadError("empty file")
              except TruncatedHeaderError, e:
                  if self.offset == 0:
                      raise ReadError(str(e))
              except SubsequentHeaderError, e:
                  raise ReadError(str(e))
              break
  
          if tarinfo is not None:
              self.members.append(tarinfo)
          else:
              self._loaded = True
  
          return tarinfo
  
      #--------------------------------------------------------------------------
      # Little helper methods:
  
      def _getmember(self, name, tarinfo=None, normalize=False):
          """Find an archive member by name from bottom to top.
             If tarinfo is given, it is used as the starting point.
          """
          # Ensure that all members have been loaded.
          members = self.getmembers()
  
          # Limit the member search list up to tarinfo.
          if tarinfo is not None:
              members = members[:members.index(tarinfo)]
  
          if normalize:
              name = os.path.normpath(name)
  
          for member in reversed(members):
              if normalize:
                  member_name = os.path.normpath(member.name)
              else:
                  member_name = member.name
  
              if name == member_name:
                  return member
  
      def _load(self):
          """Read through the entire archive file and look for readable
             members.
          """
          while True:
              tarinfo = self.next()
              if tarinfo is None:
                  break
          self._loaded = True
  
      def _check(self, mode=None):
          """Check if TarFile is still open, and if the operation's mode
             corresponds to TarFile's mode.
          """
          if self.closed:
              raise IOError("%s is closed" % self.__class__.__name__)
          if mode is not None and self.mode not in mode:
              raise IOError("bad operation for mode %r" % self.mode)
  
      def _find_link_target(self, tarinfo):
          """Find the target member of a symlink or hardlink member in the
             archive.
          """
          if tarinfo.issym():
              # Always search the entire archive.
              linkname = "/".join(filter(None, (os.path.dirname(tarinfo.name), tarinfo.linkname)))
              limit = None
          else:
              # Search the archive before the link, because a hard link is
              # just a reference to an already archived file.
              linkname = tarinfo.linkname
              limit = tarinfo
  
          member = self._getmember(linkname, tarinfo=limit, normalize=True)
          if member is None:
              raise KeyError("linkname %r not found" % linkname)
          return member
  
      def __iter__(self):
          """Provide an iterator object.
          """
          if self._loaded:
              return iter(self.members)
          else:
              return TarIter(self)
  
      def _dbg(self, level, msg):
          """Write debugging output to sys.stderr.
          """
          if level <= self.debug:
              print >> sys.stderr, msg
  
      def __enter__(self):
          self._check()
          return self
  
      def __exit__(self, type, value, traceback):
          if type is None:
              self.close()
          else:
              # An exception occurred. We must not call close() because
              # it would try to write end-of-archive blocks and padding.
              if not self._extfileobj:
                  self.fileobj.close()
              self.closed = True
  # class TarFile

   

5.6json和pickle模块

json主要应用于Python中的数据交换，pickle应用于不用的编程语言之间的数据交换。

用于序列化的两个模块

• json，用于字符串 和 python数据类型间进行转换
• pickle，用于python特有的类型 和 python的数据类型间进行转换

Json模块提供了四个功能：dumps、dump、loads、load

pickle模块提供了四个功能：dumps、dump、loads、load

下面例子为Python2.7中的例子。

5.7shelve模块

shelve模块是一个简单的k,v将内存数据通过文件持久化的模块，可以持久化任何pickle可支持的python数据格式。是对pickle的更上一次的封装。

import shelve
 
d = shelve.open('shelve_test') #打开一个文件
 
class Test(object):
    def __init__(self,n):
        self.n = n
 
 
t = Test(123) 
t2 = Test(123334)
 
name = ["alex","rain","test"]
d["test"] = name #持久化列表
d["t1"] = t      #持久化类
d["t2"] = t2
 
d.close()

5.8xml模块

xml是实现不同语言或程序之间进行数据交换的协议，跟json差不多，但json使用起来更简单，不过，古时候，在json还没诞生的黑暗年代，大家只能选择用xml呀，至今很多传统公司如金融行业的很多系统的接口还主要是xml。

xml的格式如下，就是通过<>节点来区别数据结构的:

<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <rank updated="yes">2</rank>
        <year>2008</year>
        <gdppc>141100</gdppc>
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <rank updated="yes">5</rank>
        <year>2011</year>
        <gdppc>59900</gdppc>
        <neighbor name="Malaysia" direction="N"/>
    </country>
    <country name="Panama">
        <rank updated="yes">69</rank>
        <year>2011</year>
        <gdppc>13600</gdppc>
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
</data>

xml协议在各个语言里的都 是支持的，在python中可以用以下模块操作xml

import xml.etree.ElementTree as ET
 
tree = ET.parse("xmltest.xml")
root = tree.getroot()
print(root.tag)
 
#遍历xml文档
for child in root:
    print(child.tag, child.attrib)
    for i in child:
        print(i.tag,i.text)
 
#只遍历year 节点
for node in root.iter('year'):
    print(node.tag,node.text)

修改和删除xml文档内容

import xml.etree.ElementTree as ET
 
tree = ET.parse("xmltest.xml")
root = tree.getroot()
 
#修改
for node in root.iter('year'):
    new_year = int(node.text) + 1
    node.text = str(new_year)
    node.set("updated","yes")
 
tree.write("xmltest.xml")
 
 
#删除node
for country in root.findall('country'):
   rank = int(country.find('rank').text)
   if rank > 50:
     root.remove(country)
 
tree.write('output.xml')

自己 创建Xml

import xml.etree.ElementTree as ET
 
 
new_xml = ET.Element("namelist")
name = ET.SubElement(new_xml,"name",attrib={"enrolled":"yes"})
age = ET.SubElement(name,"age",attrib={"checked":"no"})
sex = ET.SubElement(name,"sex")
sex.text = '33'
name2 = ET.SubElement(new_xml,"name",attrib={"enrolled":"no"})
age = ET.SubElement(name2,"age")
age.text = '19'
 
et = ET.ElementTree(new_xml) #生成文档对象
et.write("test.xml", encoding="utf-8",xml_declaration=True)
 
ET.dump(new_xml) #打印生成的格式

5.9PyYAML模块

pyyaml主要实现配置文档的书写。

load一下，编程字典的格式。

Python也可以很容易的处理ymal文档格式，只不过需要安装一个模块，参考文档：http://pyyaml.org/wiki/PyYAMLDocumentation

5.10ConfigParser模块

用于生成和修改常见配置文档，当前模块的名称在 python 3.x 版本中变更为 configparser。

一般都是读配置文件，解析配置文件。修改用的不是很多。

来看一个好多软件的常见文档格式如下：

[DEFAULT]
ServerAliveInterval = 45
Compression = yes
CompressionLevel = 9
ForwardX11 = yes
 
[bitbucket.org]
User = hg
 
[topsecret.server.com]
Port = 50022
ForwardX11 = no

如果想用python生成一个这样的文档怎么做呢？

import configparser
 
config = configparser.ConfigParser()
config["DEFAULT"] = {'ServerAliveInterval': '45',
                      'Compression': 'yes',
                     'CompressionLevel': '9'}
 
config['bitbucket.org'] = {}
config['bitbucket.org']['User'] = 'hg'
config['topsecret.server.com'] = {}
topsecret = config['topsecret.server.com']
topsecret['Host Port'] = '50022'     # mutates the parser
topsecret['ForwardX11'] = 'no'  # same here
config['DEFAULT']['ForwardX11'] = 'yes'
with open('example.ini', 'w') as configfile:
   config.write(configfile)

写完了还可以再读出来哈。

>>> import configparser
>>> config = configparser.ConfigParser()
>>> config.sections()
[]
>>> config.read('example.ini')
['example.ini']
>>> config.sections()
['bitbucket.org', 'topsecret.server.com']
>>> 'bitbucket.org' in config
True
>>> 'bytebong.com' in config
False
>>> config['bitbucket.org']['User']
'hg'
>>> config['DEFAULT']['Compression']
'yes'
>>> topsecret = config['topsecret.server.com']
>>> topsecret['ForwardX11']
'no'
>>> topsecret['Port']
'50022'
>>> for key in config['bitbucket.org']: print(key)
...
user
compressionlevel
serveraliveinterval
compression
forwardx11
>>> config['bitbucket.org']['ForwardX11']
'yes'

configparser增删改查语法

[section1]
k1 = v1
k2:v2
  
[section2]
k1 = v1
 
import ConfigParser
  
config = ConfigParser.ConfigParser()
config.read('i.cfg')
  
# ########## 读 ##########
#secs = config.sections()
#print secs
#options = config.options('group2')
#print options
  
#item_list = config.items('group2')
#print item_list
  
#val = config.get('group1','key')
#val = config.getint('group1','key')
  
# ########## 改写 ##########
#sec = config.remove_section('group1')
#config.write(open('i.cfg', "w"))
  
#sec = config.has_section('wupeiqi')
#sec = config.add_section('wupeiqi')
#config.write(open('i.cfg', "w"))
  
  
#config.set('group2','k1',11111)
#config.write(open('i.cfg', "w"))
  
#config.remove_option('group2','age')
#config.write(open('i.cfg', "w"))

5.11hashlib模块　　

用于加密相关的操作，3.x里代替了md5模块和sha模块，主要提供 SHA1, SHA224, SHA256, SHA384, SHA512 ，MD5 算法

MD5不能反解的

import hashlib
 
m = hashlib.md5()
m.update(b"Hello")
m.update(b"It's me")
print(m.digest())
m.update(b"It's been a long time since last time we ...")
 
print(m.digest()) #2进制格式hash
print(len(m.hexdigest())) #16进制格式hash
'''
def digest(self, *args, **kwargs): # real signature unknown
    """ Return the digest value as a string of binary data. """
    pass
 
def hexdigest(self, *args, **kwargs): # real signature unknown
    """ Return the digest value as a string of hexadecimal digits. """
    pass
 
'''
import hashlib
 
# ######## md5 ########
 
hash = hashlib.md5()
hash.update('admin')
print(hash.hexdigest())
 
# ######## sha1 ########
 
hash = hashlib.sha1()
hash.update('admin')
print(hash.hexdigest())
 
# ######## sha256 ########
 
hash = hashlib.sha256()
hash.update('admin')
print(hash.hexdigest())
 
 
# ######## sha384 ########
 
hash = hashlib.sha384()
hash.update('admin')
print(hash.hexdigest())
 
# ######## sha512 ########
 
hash = hashlib.sha512()
hash.update('admin')
print(hash.hexdigest())

python 还有一个 hmac 模块，它内部对我们创建 key 和 内容 再进行处理然后再加密

散列消息鉴别码，简称HMAC，是一种基于消息鉴别码MAC（Message Authentication Code）的鉴别机制。使用HMAC时,消息通讯的双方，通过验证消息中加入的鉴别密钥K来鉴别消息的真伪；

一般用于网络通信中消息加密，前提是双方先要约定好key,就像接头暗号一样，然后消息发送把用key把消息加密，接收方用key ＋ 消息明文再加密，拿加密后的值 跟 发送者的相对比是否相等，这样就能验证消息的真实性，及发送者的合法性了。

 

import hmac
h = hmac.new(b'天王盖地虎', b'宝塔镇河妖')
print h.hexdigest()

更多关于md5,sha1,sha256等介绍的文章看这里https://www.tbs-certificates.co.uk/FAQ/en/sha256.html 

5.12Subprocess模块 

常用subprocess方法示例

#执行命令，返回命令执行状态 ， 0 or 非0
>>> retcode = subprocess.call(["ls", "-l"])

#执行命令，如果命令结果为0，就正常返回，否则抛异常
>>> subprocess.check_call(["ls", "-l"])
0

#接收字符串格式命令，返回元组形式，第1个元素是执行状态，第2个是命令结果 
>>> subprocess.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')

#接收字符串格式命令，并返回结果
>>> subprocess.getoutput('ls /bin/ls')
'/bin/ls'

#执行命令，并返回结果，注意是返回结果，不是打印，下例结果返回给res
>>> res=subprocess.check_output(['ls','-l'])
>>> res
b'total 0\ndrwxr-xr-x 12 alex staff 408 Nov 2 11:05 OldBoyCRM\n'

#上面那些方法，底层都是封装的subprocess.Popen
poll()
Check if child process has terminated. Returns returncode

wait()
Wait for child process to terminate. Returns returncode attribute.

terminate() 杀掉所启动进程
communicate() 等待任务结束

stdin 标准输入

stdout 标准输出

stderr 标准错误

pid
The process ID of the child process.

#例子
>>> p = subprocess.Popen("df -h|grep disk",stdin=subprocess.PIPE,stdout=subprocess.PIPE,shell=True)
>>> p.stdout.read()
b'/dev/disk1 465Gi 64Gi 400Gi 14% 16901472 104938142 14% /\n'

调用subprocess.run(...)是推荐的常用方法，在大多数情况下能满足需求，但如果你可能需要进行一些复杂的与系统的交互的话，你还可以用subprocess.Popen(),语法如下：

p = subprocess.Popen("find / -size +1000000 -exec ls -shl {} \;",shell=True,stdout=subprocess.PIPE)
print(p.stdout.read())

可用参数：

• args：shell命令，可以是字符串或者序列类型（如：list，元组）
• bufsize：指定缓冲。0 无缓冲,1 行缓冲,其他 缓冲区大小,负值 系统缓冲
• stdin, stdout, stderr：分别表示程序的标准输入、输出、错误句柄
• preexec_fn：只在Unix平台下有效，用于指定一个可执行对象（callable object），它将在子进程运行之前被调用
• close_sfs：在windows平台下，如果close_fds被设置为True，则新创建的子进程将不会继承父进程的输入、输出、错误管道。
  所以不能将close_fds设置为True同时重定向子进程的标准输入、输出与错误(stdin, stdout, stderr)。
• shell：同上
• cwd：用于设置子进程的当前目录
• env：用于指定子进程的环境变量。如果env = None，子进程的环境变量将从父进程中继承。
• universal_newlines：不同系统的换行符不同，True -> 同意使用 \n
• startupinfo与createionflags只在windows下有效
  将被传递给底层的CreateProcess()函数，用于设置子进程的一些属性，如：主窗口的外观，进程的优先级等等

终端输入的命令分为两种：

• 输入即可得到输出，如：ifconfig
• 输入进行某环境，依赖再输入，如：python

需要交互的命令示例

import subprocess
 
obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
obj.stdin.write('print 1 \n ')
obj.stdin.write('print 2 \n ')
obj.stdin.write('print 3 \n ')
obj.stdin.write('print 4 \n ')
 
out_error_list = obj.communicate(timeout=10)
print out_error_list

subprocess实现sudo 自动输入密码

import subprocess
 
def mypass():
    mypass = '123' #or get the password from anywhere
    return mypass
 
echo = subprocess.Popen(['echo',mypass()],
                        stdout=subprocess.PIPE,
                        )
 
sudo = subprocess.Popen(['sudo','-S','iptables','-L'],
                        stdin=echo.stdout,
                        stdout=subprocess.PIPE,
                        )
 
end_of_pipe = sudo.stdout
 
print "Password ok \n Iptables Chains %s" % end_of_pipe.read()

5.13logging模块

很多程序都有记录日志的需求，并且日志中包含的信息即有正常的程序访问日志，还可能有错误、警告等信息输出，python的logging模块提供了标准的日志接口，你可以通过它存储各种格式的日志，logging的日志可以分为 debug(), info(), warning(), error() and critical() 5个级别，下面我们看一下怎么用。

import logging
 
logging.warning("user [alex] attempted wrong password more than 3 times")
logging.critical("server is down")
 
#输出
WARNING:root:user [alex] attempted wrong password more than 3 times
CRITICAL:root:server is down

如果想把日志写到文件里，也很简单

import logging
 
logging.basicConfig(filename='example.log',level=logging.INFO)
logging.debug('This message should go to the log file')
logging.info('So should this')
logging.warning('And this, too')

其中下面这句中的level=loggin.INFO意思是，把日志纪录级别设置为INFO，也就是说，只有比日志是INFO或比INFO级别更高的日志才会被纪录到文件里，在这个例子， 第一条日志是不会被纪录的，如果希望纪录debug的日志，那把日志级别改成DEBUG就行了。

logging.basicConfig(filename='example.log',level=logging.INFO)

感觉上面的日志格式忘记加上时间啦，日志不知道时间怎么行呢，下面就来加上!

import logging
logging.basicConfig(format='%(asctime)s %(message)s', datefmt='%m/%d/%Y %I:%M:%S %p')
logging.warning('is when this event was logged.')
 
#输出
12/12/2010 11:46:36 AM is when this event was logged.

如果想同时把log打印在屏幕和文件日志里，就需要了解一点复杂的知识 了

Python 使用logging模块记录日志涉及四个主要类，使用官方文档中的概括最为合适：

logger提供了应用程序可以直接使用的接口；

handler将(logger创建的)日志记录发送到合适的目的输出；

filter提供了细度设备来决定输出哪条日志记录；

formatter决定日志记录的最终输出格式。

 

日志的格式

%(name)s	Logger的名字
%(levelno)s	数字形式的日志级别
%(levelname)s	文本形式的日志级别
%(pathname)s	调用日志输出函数的模块的完整路径名，可能没有
%(filename)s	调用日志输出函数的模块的文件名
%(module)s	调用日志输出函数的模块名
%(funcName)s	调用日志输出函数的函数名
%(lineno)d	调用日志输出函数的语句所在的代码行
%(created)f	当前时间，用UNIX标准的表示时间的浮 点数表示
%(relativeCreated)d	输出日志信息时的，自Logger创建以 来的毫秒数
%(asctime)s	字符串形式的当前时间。默认格式是 “2003-07-08 16:49:45,896”。逗号后面的是毫秒
%(thread)d	线程ID。可能没有
%(threadName)s	线程名。可能没有
%(process)d	进程ID。可能没有
%(message)s	用户输出的消息

logger
每个程序在输出信息之前都要获得一个Logger。Logger通常对应了程序的模块名，比如聊天工具的图形界面模块可以这样获得它的Logger：
LOG=logging.getLogger(”chat.gui”)
而核心模块可以这样：
LOG=logging.getLogger(”chat.kernel”)

Logger.setLevel(lel):指定最低的日志级别，低于lel的级别将被忽略。debug是最低的内置级别，critical为最高
Logger.addFilter(filt)、Logger.removeFilter(filt):添加或删除指定的filter
Logger.addHandler(hdlr)、Logger.removeHandler(hdlr)：增加或删除指定的handler
Logger.debug()、Logger.info()、Logger.warning()、Logger.error()、Logger.critical()：可以设置的日志级别

 

handler

handler对象负责发送相关的信息到指定目的地。Python的日志系统有多种Handler可以使用。有些Handler可以把信息输出到控制台，有些Logger可以把信息输出到文件，还有些 Handler可以把信息发送到网络上。如果觉得不够用，还可以编写自己的Handler。可以通过addHandler()方法添加多个多handler
Handler.setLevel(lel):指定被处理的信息级别，低于lel级别的信息将被忽略
Handler.setFormatter()：给这个handler选择一个格式
Handler.addFilter(filt)、Handler.removeFilter(filt)：新增或删除一个filter对象

每个Logger可以附加多个Handler。接下来我们就来介绍一些常用的Handler：
1) logging.StreamHandler
使用这个Handler可以向类似与sys.stdout或者sys.stderr的任何文件对象(file object)输出信息。它的构造函数是：
StreamHandler([strm])
其中strm参数是一个文件对象。默认是sys.stderr

2) logging.FileHandler
和StreamHandler类似，用于向一个文件输出日志信息。不过FileHandler会帮你打开这个文件。它的构造函数是：
FileHandler(filename[,mode])
filename是文件名，必须指定一个文件名。
mode是文件的打开方式。参见Python内置函数open()的用法。默认是’a'，即添加到文件末尾。

3) logging.handlers.RotatingFileHandler
这个Handler类似于上面的FileHandler，但是它可以管理文件大小。当文件达到一定大小之后，它会自动将当前日志文件改名，然后创建 一个新的同名日志文件继续输出。比如日志文件是chat.log。当chat.log达到指定的大小之后，RotatingFileHandler自动把 文件改名为chat.log.1。不过，如果chat.log.1已经存在，会先把chat.log.1重命名为chat.log.2。。。最后重新创建 chat.log，继续输出日志信息。它的构造函数是：
RotatingFileHandler( filename[, mode[, maxBytes[, backupCount]]])
其中filename和mode两个参数和FileHandler一样。
maxBytes用于指定日志文件的最大文件大小。如果maxBytes为0，意味着日志文件可以无限大，这时上面描述的重命名过程就不会发生。
backupCount用于指定保留的备份文件的个数。比如，如果指定为2，当上面描述的重命名过程发生时，原有的chat.log.2并不会被更名，而是被删除。

4) logging.handlers.TimedRotatingFileHandler
这个Handler和RotatingFileHandler类似，不过，它没有通过判断文件大小来决定何时重新创建日志文件，而是间隔一定时间就 自动创建新的日志文件。重命名的过程与RotatingFileHandler类似，不过新的文件不是附加数字，而是当前时间。它的构造函数是：
TimedRotatingFileHandler( filename [,when [,interval [,backupCount]]])
其中filename参数和backupCount参数和RotatingFileHandler具有相同的意义。
interval是时间间隔。
when参数是一个字符串。表示时间间隔的单位，不区分大小写。它有以下取值：
S 秒
M 分
H 小时
D 天
W 每星期（interval==0时代表星期一）
midnight 每天凌晨

import logging
 
#create logger
logger = logging.getLogger('TEST-LOG')
logger.setLevel(logging.DEBUG)
 
 
# create console handler and set level to debug
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
 
# create file handler and set level to warning
fh = logging.FileHandler("access.log")
fh.setLevel(logging.WARNING)
# create formatter
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
 
# add formatter to ch and fh
ch.setFormatter(formatter)
fh.setFormatter(formatter)
 
# add ch and fh to logger
logger.addHandler(ch)
logger.addHandler(fh)
 
# 'application' code
logger.debug('debug message')
logger.info('info message')
logger.warn('warn message')
logger.error('error message')
logger.critical('critical message')

文件自动截断例子

import logging

from logging import handlers

logger = logging.getLogger(__name__)

log_file = "timelog.log"
#fh = handlers.RotatingFileHandler(filename=log_file,maxBytes=10,backupCount=3)
fh = handlers.TimedRotatingFileHandler(filename=log_file,when="S",interval=5,backupCount=3)


formatter = logging.Formatter('%(asctime)s %(module)s:%(lineno)d %(message)s')

fh.setFormatter(formatter)

logger.addHandler(fh)


logger.warning("test1")
logger.warning("test12")
logger.warning("test13")
logger.warning("test14")

5.14 RE模块

常用正则表达式符号

'.'     默认匹配除\n之外的任意一个字符，若指定flag DOTALL,则匹配任意字符，包括换行
'^'     匹配字符开头，若指定flags MULTILINE,这种也可以匹配上(r"^a","\nabc\neee",flags=re.MULTILINE)
'$'     匹配字符结尾，或e.search("foo$","bfoo\nsdfsf",flags=re.MULTILINE).group()也可以
'*'     匹配*号前的字符0次或多次，re.findall("ab*","cabb3abcbbac")  结果为['abb', 'ab', 'a']
'+'     匹配前一个字符1次或多次，re.findall("ab+","ab+cd+abb+bba") 结果['ab', 'abb']
'?'     匹配前一个字符1次或0次
'{m}'   匹配前一个字符m次
'{n,m}' 匹配前一个字符n到m次，re.findall("ab{1,3}","abb abc abbcbbb") 结果'abb', 'ab', 'abb']
'|'     匹配|左或|右的字符，re.search("abc|ABC","ABCBabcCD").group() 结果'ABC'
'(...)' 分组匹配，re.search("(abc){2}a(123|456)c", "abcabca456c").group() 结果 abcabca456c
 
 
'\A'    只从字符开头匹配，re.search("\Aabc","alexabc") 是匹配不到的
'\Z'    匹配字符结尾，同$
'\d'    匹配数字0-9
'\D'    匹配非数字
'\w'    匹配[A-Za-z0-9]
'\W'    匹配非[A-Za-z0-9]
's'     匹配空白字符、\t、\n、\r , re.search("\s+","ab\tc1\n3").group() 结果 '\t'
 
'(?P<name>...)' 分组匹配 re.search("(?P<province>[0-9]{4})(?P<city>[0-9]{2})(?P<birthday>[0-9]{4})","371481199306143242").groupdict("city") 结果{'province': '3714', 'city': '81', 'birthday': '1993'}

最常用的匹配语法

re.match 从头开始匹配
re.search 匹配包含
re.findall 把所有匹配到的字符放到以列表中的元素返回
re.split 以匹配到的字符当做列表分隔符
re.sub      匹配字符并替换

反斜杠的困扰

转义\ 和分组（2）
与大多数编程语言相同，正则表达式里使用"\"作为转义字符，这就可能造成反斜杠困扰。假如你需要匹配文本中的字符"\"，那么使用编程语言表示的正则表达式里将需要4个反斜杠"\\\\"：前两个和后两个分别用于在编程语言里转义成反斜杠，转换成两个反斜杠后再在正则表达式里转义成一个反斜杠。Python里的原生字符串很好地解决了这个问题，这个例子中的正则表达式可以使用r"\\"表示。同样，匹配一个数字的"\\d"可以写成r"\d"。有了原生字符串，你再也不用担心是不是漏写了反斜杠，写出来的表达式也更直观。

 

仅需轻轻知道的几个匹配模式

re.I(re.IGNORECASE): 忽略大小写（括号内是完整写法，下同）
M(MULTILINE): 多行模式，改变'^'和'$'的行为
S(DOTALL): 点任意匹配模式，改变'.'的行为

 六、作业

6.1  开发一个简单的python计算器

1. 实现加减乘除及拓号优先级解析
2. 用户输入 1 - 2 * ( (60-30 +(-40/5) * (9-2*5/3 + 7 /3*99/4*2998 +10 * 568/14 )) - (-4*3)/ (16-3*2) )等类似公式后，必须自己解析里面的(),+,-,*,/符号和公式(不能调用eval等类似功能偷懒实现)，运算后得出结果，结果必须与真实的计算器所得出的结果一致

 6.2模块化练习：

#实现效果：随机生成一个6位验证码（包含数字和字母）

import random
def make_code(n):
    res=''
    for i in range(n):
        s1=chr(random.randint(65,90))
        s2=str(random.randint(0,9))
        res+=random.choice([s1,s2])
    return res
print(make_code(6))

6.3 模拟一个抢红包的例子， 实现效果： 10块钱，随机分层5份，要求精确到分。

num=5
total=1000#先扩大100倍，在缩小100倍 剩余的钱
list_1=[]
for i in range(4):
    a=random.randint(1,total-num+1)
    list_1.append(a/100)
    total=total-a
    num=num-1
list_1.append(total/100)
print(list_1)