python - 当文件小于1kByte时，cStringIO.StringO无法保存上传的文件流

Question

我借用了这段代码来将文件流保存到磁盘，它可以工作，除非文件大小小于 1kb。我收到此错误:

in stuff_uploaded:
copy(theFile.file.name, './tmp/'+theFile.filename) #saves temporary file to /cp2/tmp/

AttributeError:“cStringIO.StringO”对象没有属性“name”

@cherrypy.expose
@cherrypy.tools.noBodyProcess()
def stuff_uploaded(self, theFile=None):
    import cgi
    import tempfile
    # convert the header keys to lower case
    lcHDRS = {key.lower():val for key, val in cherrypy.request.headers.iteritems()}
    class myFieldStorage(cgi.FieldStorage):
        """uses a named temporary file instead of the default non-named file; keeping it visibile (named), allows us to create a
        2nd link after the upload is done, thus avoiding the overhead of making a copy to the destination filename."""
        def make_file(self, binary=None):
            return tempfile.NamedTemporaryFile()
    formFields = myFieldStorage(fp=cherrypy.request.rfile,
                                headers=lcHDRS,
                                environ={'REQUEST_METHOD':'POST'},
                                keep_blank_values=True)
    theFile = formFields['theFile']
    # we now create a 2nd link to the file, using the submitted filename.
    from shutil import copy
    copy(theFile.file.name, './tmp/'+theFile.filename) #saves temporary file 
    msgs = csv_to_survey.match_fieldnames('./tmp/'+theFile.filename)
    return './tmp/'+theFile.filename

那么我该怎么做才能确保 cStringIO.StringO 处理上传的小文件呢？

Answer 1

直接打开并写入文件:

with open('./tmp/'+theFile.filename, "w") as f:
    f.write(theFile.file.getvalue())

或者无论文件是在磁盘上还是StringIO上都可以处理它，将其用作类似文件的对象:

import shutil

with open('./tmp/'+theFile.filename, "w") as f:
    # If the file pointer might not be at the beginning of theFile.file, add:
    # theFile.file.seek(0)
    shutil.copyfileobj(theFile.file, f)
    # While:
    #     f.write(theFile.file.read())
    # would work most of the time, it involves holding the whole contents of the
    # file in memory at once (which you want to avoid; that's why CherryPy
    # uses temp files for larger data). shutil.copyfileobj does block by
    # block copies, which have fixed peak memory usage while still running
    # (almost) as fast

注意:这(以及您的原始解决方案)是不安全的，因为上传同一文件两次将覆盖以前的文件，并且(取决于名称上的服务器过滤器)文件名可能会遍历文件系统以覆盖 tmp 之外的意外文件目录。