From: david-sarah Date: Sat, 3 Sep 2011 22:23:04 +0000 (-0700) Subject: SFTP: add a comment about a subtle interaction between OverwriteableFileConsumer... X-Git-Tag: allmydata-tahoe-1.9.0a2~62 X-Git-Url: https://git.rkrishnan.org/?a=commitdiff_plain;h=1b7b3bd0d4c92d8a2774106979a084485adf9f8a;p=tahoe-lafs%2Ftahoe-lafs.git SFTP: add a comment about a subtle interaction between OverwriteableFileConsumer and GeneralSFTPFile, and test the case it is commenting on. --- diff --git a/src/allmydata/frontends/sftpd.py b/src/allmydata/frontends/sftpd.py index 59952a99..887786e7 100644 --- a/src/allmydata/frontends/sftpd.py +++ b/src/allmydata/frontends/sftpd.py @@ -461,6 +461,12 @@ class OverwriteableFileConsumer(PrefixingLogMixin): The caller must perform no more overwrites until the Deferred has fired.""" if noisy: self.log(".read(%r, %r), current_size = %r" % (offset, length, self.current_size), level=NOISY) + + # Note that the overwrite method is synchronous. When a write request is processed + # (e.g. a writeChunk request on the async queue of GeneralSFTPFile), overwrite will + # be called and will update self.current_size if necessary before returning. Therefore, + # self.current_size will be up-to-date for a subsequent call to this read method, and + # so it is correct to do the check for a read past the end-of-file here. if offset >= self.current_size: def _eof(): raise EOFError("read past end of file") return defer.execute(_eof) diff --git a/src/allmydata/test/test_sftp.py b/src/allmydata/test/test_sftp.py index 6095b18f..a45d71d0 100644 --- a/src/allmydata/test/test_sftp.py +++ b/src/allmydata/test/test_sftp.py @@ -913,6 +913,9 @@ class Handler(GridTestMixin, ShouldFailMixin, ReallyEqualMixin, unittest.TestCas self.handler.openFile("small", sftp.FXF_READ | sftp.FXF_WRITE, {})) def _read_write(rwf): d2 = rwf.writeChunk(8, "0123") + # test immediate read starting after the old end-of-file + d2.addCallback(lambda ign: rwf.readChunk(11, 1)) + d2.addCallback(lambda data: self.failUnlessReallyEqual(data, "3")) d2.addCallback(lambda ign: rwf.readChunk(0, 100)) d2.addCallback(lambda data: self.failUnlessReallyEqual(data, "012345670123")) d2.addCallback(lambda ign: rwf.close())