Re: [Duplicity-talk] gpg key password asked for backup after verify

[edgar . soldin]

Ken,

On 29.05.2017 14:27, edgar.soldin--- via Duplicity-talk wrote:
> On 29.05.2017 13:26, Kenneth Loafman wrote:
>> 1) This was from the README for 0.7.05:
>>
>>         * Fix bug #1494228 CygWin: TypeError: basis_file must be a (true) 
>> file
>>
>>           - The problem that caused the change to tempfile.TemporaryFile was 
>> due
>>
>>             to the fact that os.tmpfile always creates its file in the system
>>
>>             temp directory, not in the directory specified.  The fix applied 
>> was
>>
>>             to use os.tmpfile in cygwin/windows and tempfile.TemporaryFile 
>> in all
>>
>>             the rest.  This means that cygwin is now broken with respect to 
>> temp
>>
>>             file placement of this one file (deleted automatically on close).
> 
> wrt. os.tmpfile() .. afaics. does 
> 
>    https://hg.python.org/cpython/file/2.7/Lib/tempfile.py#l484
> 
> use the os module ( os.open, os.fdopen ) all around to create temp files. 
> aren't these supposed to return a (true) file? the docs say nothing in this 
> regard. https://docs.python.org/2/library/os.html#file-object-creation
> 
> ..ede
> 

ok answering myself here, after reading the original bug report thoroughly, 
which says
"
The problem is that, as explained in the Python documentation 
(http://docs.python.org/library/tempfile.html), tempfile.TemporaryFile returns 
a *file-like* object, not a file object. Under Linux, it effectively returns a 
file object but under windows it does not. Hence, the type of the object 
returned is *not* a types.FileType, causing the exception to be raised.
"
  https://bugs.launchpad.net/duplicity/+bug/670891

further reading shows that the error stems from 'duplicity/librsync.py'
"
  File "/usr/lib/python2.6/site-packages/duplicity/librsync.py", line 167, in 
__init__
    raise TypeError("basis_file must be a (true) file")
"


so obviously something is done differently in the 
'duplicity/_librsyncmodule.c', that needs a delta patch file to be a plain File 
object. let's see 'duplicity/librsync.py' says
"
class PatchedFile(LikeFile):
    """File-like object which applies a librsync delta incrementally"""
    def __init__(self, basis_file, delta_file):
        """PatchedFile initializer - call with basis delta

        Here basis_file must be a true Python file, because we may
        need to seek() around in it a lot, and this is done in C.
        delta_file only needs read() and close() methods.

        """
        LikeFile.__init__(self, delta_file)
        if not isinstance(basis_file, types.FileType):
            raise TypeError("basis_file must be a (true) file")
        try:
            self.maker = _librsync.new_patchmaker(basis_file)
        except _librsync.librsyncError as e:
            raise librsyncError(str(e))
"
http://bazaar.launchpad.net/~duplicity-team/duplicity/0.8-series/view/head:/duplicity/librsync.py#L163


and in 'duplicity/_librsyncmodule.c' it tries to utilize 
'PyObject_AsFileDescriptor(python_file)'
"
/* Call with the basis file */
static PyObject*
_librsync_new_patchmaker(PyObject* self, PyObject* args)
{
  _librsync_PatchMakerObject* pm;
  PyObject *python_file;
  int fd;

  if (!PyArg_ParseTuple(args, "O:new_patchmaker", &python_file))
    return NULL;
  fd = PyObject_AsFileDescriptor(python_file);
"
http://bazaar.launchpad.net/~duplicity-team/duplicity/0.8-series/view/head:/duplicity/_librsyncmodule.c#L294


so, if i understand correctly, we just have to implement the method 'fileno()' 
as described here
  https://docs.python.org/2/c-api/object.html#c.PyObject_AsFileDescriptor
in another wrapper around the tempfile.TemporaryFile() return value
  https://docs.python.org/2/library/tempfile.html#tempfile.TemporaryFile
, utilizing (if necessary) the file-like object's file attribute as mentioned 
in the python doc and return 
"
The returned object is a true file object on POSIX platforms. On other 
platforms, it is a file-like object whose file attribute is the underlying true 
file object.
"

implementing that should render the failing TypeError("basis_file must be a 
(true) file") in 'duplicity/librsync.py' meaningless, so it could be removed or?

alternatively, we could simply extend 'duplicity/librsync.py', to test for a 
file attribute, in case the "file" object given is just a wrapper. on success 
we then simply deliver that (pseudo code)
"
self.maker = _librsync.new_patchmaker(basis_file.file)
"

what do you think Ken? would that work? which approach would you prefer? ..ede