On Tue, 22 Feb 2022, Dmitry Belyavskiy wrote: > Hello, > > We came across a weird bug using SCP in SFTP mode > Current master, command > > ./scp -s -S `which ssh` qq localhost:`pwd`/qq > > effectively truncates the file to be copied. > > SCP mode deals normally. > > I understand that it's a corner case but still think it's worth reporting. Yes, this is because scp/rcp does open(path, O_CREAT) and then ftruncate() at close() time, whereas scp/sftp does open(path, O_CREAT|O_TRUNC) on the basis that in an aborted transfer it's better to leave truncated files around than files with inconsistent contents. I don't want to change the behaviour of sftp's upload code, because I think it is better (at the very least, it allows resumption of transfers without needing rsync-like tricks), so IMO the best way to avoid this would be to teach the upload code to go via a temporary file. Not sure whether this is worth the hassle though for such a corner-case. -d _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
