python python将字符串直接写入tarfile
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python write string directly to tarfile
提问by gatoatigrado
Is there a way to write a string directly to a tarfile? From http://docs.python.org/library/tarfile.htmlit looks like only files already written to the file system can be added.
有没有办法将字符串直接写入 tarfile？从http://docs.python.org/library/tarfile.html看来，只能添加已经写入文件系统的文件。
采纳答案by Stefano Borini
I would say it's possible, by playing with TarInfo e TarFile.addfile passing a StringIO as a fileobject.
我会说这是可能的，通过使用 TarInfo e TarFile.addfile 将 StringIO 作为文件对象传递。
Very rough, but works
非常粗糙，但有效
import tarfile
import StringIO
tar = tarfile.TarFile("test.tar","w")
string = StringIO.StringIO()
string.write("hello")
string.seek(0)
info = tarfile.TarInfo(name="foo")
info.size=len(string.buf)
tar.addfile(tarinfo=info, fileobj=string)
tar.close()
回答by avakar
As Stefano pointed out, you can use TarFile.addfileand StringIO.
正如 Stefano 指出的那样，您可以使用TarFile.addfileand StringIO。
import tarfile, StringIO
data = 'hello, world!'
tarinfo = tarfile.TarInfo('test.txt')
tarinfo.size = len(data)
tar = tarfile.open('test.tar', 'a')
tar.addfile(tarinfo, StringIO.StringIO(data))
tar.close()
You'll probably want to fill other fields of tarinfo(e.g. mtime, unameetc.) as well.
您可能还想填写tarinfo（例如mtime，uname等）的其他字段。
回答by scythargon
I found this looking how to serve in Django a just created in memory .tgz archive, may be somebody else will find my code usefull:
我发现这看起来如何在 Django 中提供一个刚刚在内存中创建的 .tgz 存档，可能其他人会发现我的代码有用：
import tarfile
from io import BytesIO
def serve_file(request):
out = BytesIO()
tar = tarfile.open(mode = "w:gz", fileobj = out)
data = 'lala'.encode('utf-8')
file = BytesIO(data)
info = tarfile.TarInfo(name="1.txt")
info.size = len(data)
tar.addfile(tarinfo=info, fileobj=file)
tar.close()
response = HttpResponse(out.getvalue(), content_type='application/tgz')
response['Content-Disposition'] = 'attachment; filename=myfile.tgz'
return response
回答by Todd Owen
The solution in Python 3 uses io.BytesIO. Be sure to set TarInfo.sizeto the length of the bytes, not the length of the string.
Python 3 中的解决方案使用io.BytesIO. 一定要设置TarInfo.size为字节的长度，而不是字符串的长度。
Given a single string, the simplest solution is to call .encode()on it to obtain bytes. In this day and age you probably want UTF-8, but if the recipient is expecting a specific encoding, such as ASCII (i.e. no multi-byte characters), then use that instead.
给定一个字符串，最简单的解决方案是调用.encode()它来获取字节。在当今时代，您可能需要 UTF-8，但如果接收者希望使用特定的编码，例如 ASCII（即没有多字节字符），那么请改用它。
import io
import tarfile
data = 'hello\n'.encode('utf8')
info = tarfile.TarInfo(name='foo.txt')
info.size = len(data)
with tarfile.TarFile('test.tar', 'w') as tar:
tar.addfile(info, io.BytesIO(data))
If you really need a writable stringbuffer, similar to the accepted answer by @Stefano Borini for Python 2, then the solution is to use io.TextIOWrapperover an underlying io.BytesIObuffer.
如果您确实需要一个可写的字符串缓冲区，类似于 @Stefano Borini 为 Python 2 接受的答案，那么解决方案是使用io.TextIOWrapper底层io.BytesIO缓冲区。
import io
import tarfile
textIO = io.TextIOWrapper(io.BytesIO(), encoding='utf8')
textIO.write('hello\n')
bytesIO = textIO.detach()
info = tarfile.TarInfo(name='foo.txt')
info.size = bytesIO.tell()
with tarfile.TarFile('test.tar', 'w') as tar:
bytesIO.seek(0)
tar.addfile(info, bytesIO)
回答by Alias_Knagg
Just for the record:
StringIO objects have a .len property.
No need to seek(0) and do len(foo.buf)
No need to keep the entire string around to do len() on, or God forbid, do the accounting yourself.
只是为了记录：
StringIO 对象有一个 .len 属性。
不需要seek(0) 和做len(foo.buf)
不需要保留整个字符串来执行len()，或者上帝保佑，自己做会计。
( Maybe it did not at the time the OP was written. )
（也许在编写 OP 时还没有。）
回答by Eli Courtwright
You have to use TarInfo objects and the addfile method instead of the usual add method:
您必须使用 TarInfo 对象和 addfile 方法而不是通常的 add 方法：
from StringIO import StringIO
from tarfile import open, TarInfo
s = "Hello World!"
ti = TarInfo("test.txt")
ti.size = len(s)
tf = open("testtar.tar", "w")
tf.addfile(ti, StringIO(s))
回答by z0r
In my case I wanted to read from an existing tar file, append some data to the contents, and write it to a new file. Something like:
就我而言，我想从现有的 tar 文件中读取数据，将一些数据附加到内容中，然后将其写入一个新文件。就像是：
for ti in tar_in:
buf_in = tar.extractfile(ti)
buf_out = io.BytesIO()
size = buf_out.write(buf_in.read())
size += buf_out.write(other data)
buf_out.seek(0)
ti.size = size
tar_out.addfile(ti, fileobj=buf_out)
Extra code is needed for handling directories and links.
处理目录和链接需要额外的代码。
