Scp freezes on named pipe

[Tero Karvinen]

Binary package hint: openssh-client

Scp stops copying files when it meets a named pipe (fifo). No error message is displayed, not even the name of the problem file.

This can make copying /home/ impossible.

## Example

To show a minimal example of this bug that can easily happen, I attempt to copy configuration directory of Quod Libet music player from a remote computer "foobar". User foo has his login automated.

$ scp -r foo@foobar:.quodlibet/ .
queries 100% 1 0.0KB/s 00:00
accels 100% 2638 2.6KB/s 00:00
queue 100% 0 0.0KB/s 00:00
songs 100% 259KB 259.3KB/s 00:01
config 100% 1106 1.1KB/s 00:00

Here, scp stops working. Waiting for 20 minutes does not help. Rest of the files from that directory are not copied. Scp can be terminated with ctrl-C.

Correct action would obviously be skipping files that cannot be processed and displaying an error. This is especially clear if you consider copying a larger system where many users could have named pipes in their home directories.

Files actually copied were normal files, and copy happened quickly. Even though "config" is the last file shown, the problem is probably named pipe (fifo) "control", which next in the alphabet.

Misleadingly scp only displays names for files it handles correctly, and the name of problem file "control" is not shown.

$ ssh foo@foobar 'ls -l .quodlibet/c*'
-rw-r--r-- 1 foo foo 1106 2008-08-14 23:42 .quodlibet/config
prw------- 1 foo foo 0 2008-08-14 12:07 .quodlibet/control

[Ralph Janke (txwikinger)]

Thanks for reporting this issue an helping to make Ubuntu better.

Could you please provide the scp version on your client and the sshd version on your server, as well as the Ubuntu versions of both.

Thanks

[Tero Karvinen (karvinen+launchpad)]

OpenSSH client 1:4.7p1-8ubuntu1.2 on Hardy amd64. Server 32 bit Dapper.

Client:
~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu 8.04.1"
~$ dpkg --list openssh-client |grep ii
ii openssh-client 1:4.7p1-8ubuntu1.2 secure shell client, an rlogin/rsh/rcp replacement

Server:
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=6.06
DISTRIB_CODENAME=dapper
DISTRIB_DESCRIPTION="Ubuntu 6.06.2 LTS"

I don't have the server at hand to test it's sshd version.

[Sergio Zanchetta (primes2h)]

Could this bug #259505 be related in some way?
It happens when copying via GUI.

[Evan Carroll (evancarroll)]

Re; Sergio
Not a dupe of said bug that one was specific with nautilus handling FIFOs. Though it is typically the same issue. FIFOs block until you get EOF, if there is no EOF they block. This is an inherent danger in reading from a FIFO.

[Chuck Short (zulcss)]

Hi,

I was wondering if you were still having this problem?

Thanks
chuck

[Chuck Short (zulcss)]

We are closing this bug report because it lacks the information we need to investigate the problem, as described in the previous comments. Please reopen it if you can give us the missing information, and don't hesitate to submit bug reports in the future. To reopen the bug report you can click on the current status, under the Status column, and change the Status back to "New". Thanks again!