[Bug 275418] [NEW] Scp freezes on named pipe

[Tero Karvinen]

Public bug reported:

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 at 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 at 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

** Affects: openssh (Ubuntu)
     Importance: Undecided
         Status: New

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Scp freezes on named pipe
https://bugs.launchpad.net/bugs/275418
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