ExternalVendorCode/tahoe-lafs
1
0
Fork 0
mirror of https://github.com/tahoe-lafs/tahoe-lafs.git synced 2025-04-09 20:01:23 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

fileutil: docstrings for non-obvious usage restrictions on methods of EncryptedTemporaryFile.

Browse Source
This commit is contained in:
david-sarah 2010-07-16 22:46:47 -07:00
parent 05022dca36
commit 752897450d
1 changed files with 6 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/allmydata/util/fileutil.py
View File

@ -144,17 +144,23 @@ class EncryptedTemporaryFile:
return offset
def read(self, size=-1):
"""A read must not follow a write, or vice-versa, without an intervening seek."""
index = self.file.tell()
ciphertext = self.file.read(size)
plaintext = self._crypt(index, ciphertext)
return plaintext
def write(self, plaintext):
"""A read must not follow a write, or vice-versa, without an intervening seek.
If seeking and then writing causes a 'hole' in the file, the contents of the
hole are unspecified."""
index = self.file.tell()
ciphertext = self._crypt(index, plaintext)
self.file.write(ciphertext)
def truncate(self, newsize):
"""Truncate or extend the file to 'newsize'. If it is extended, the contents after the
old end-of-file are unspecified. The file position after this operation is unspecified."""
self.file.truncate(newsize)