not sure why it was done, but it seems to serve no functional purpose at
all and breaks displaying flags in :windowlist
display is used by AddWindowFlags to check whether we should show some
of flags and they are not shown when display == 0
Signed-off-by: Amadeusz Sławiński <amade@asmblr.net>
This issue has been discussed before:
https://bbs.archlinux.org/viewtopic.php?id=108640
Copy mode and “hardcopy -h” always begin at the start of the scrollback buffer.
If a user sets a large scrollback limit with little output, then copy mode and
the file written by “hardcopy -h” will begin with many blank lines before the
first line of output.
The attached patch limits the scrollback buffer traversal to begin at the first
line of output, instead of the beginning of the scrollback buffer.
Also, code for moving to %age of buffer is changed to use float division so
that two different rep_cnt will not jump to the same location, except for
buffers less than 100 lines. Previously, the computed line number is rounded
down to the nearest 100th due to integer division.
Bug: 49377
So far screen could only support either sockets or fifos but not both. This
proved to be a blocker for any upgrade. This adds a compatibility layer to
screen v4 to support both sockets and fifos at the same time. The strategy here
is to only support fifos for legacy sessions that already exist. All new
sessions will use sockets by default.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Various programs that deal with namespaces will use pty devices that exist in
another namespace. One obvious candidate are containers. So far ttyname() was
incorrectly handling this case because the pts device stems from the host and
thus cannot be found amongst the current namespace's /dev/pts/<n> entries.
Serge Hallyn and I recently upstreamed patches to glibc that allow ttyname{_r}()
to correctly handle this case. At a minimum, ttyname{_r}() will set errno to
ENODEV in case it finds that the /dev/pts/<n> device that the symlink points to
exists in another namespace.
(The next comment is a little longer but tries to ensure that one can still
understand what is going on after some time has passed.)
In case we detect that ttyname{_r}() returns NULL and sets errno to ENODEV we
have ample reason to assume that the pts device exists in a different
namespace. In this case, the code will set a global flag indicating this case
to true. Furthermore, all operations (e.g. chmod(), chown(), etc.) will now
need to operate on the symbolic link /proc/self/fd/0 directly. While this
sounds straightforward, it becomes difficult to handle this case correctly when
we reattach to an already existing screen session from a different pts device
than the original one. Let's look at the general reattach logic a little
closer:
Assume we are running a shell that uses a pts device from a different
namespace:
root@zest1:~# ls -al /proc/self/fd/
total 0
dr-x------ 2 root root 0 Apr 2 20:22 .
dr-xr-xr-x 9 root root 0 Apr 2 20:22 ..
lrwx------ 1 root root 64 Apr 2 20:22 0 -> /dev/pts/6
lrwx------ 1 root root 64 Apr 2 20:22 1 -> /dev/pts/6
lrwx------ 1 root root 64 Apr 2 20:22 2 -> /dev/pts/6
l-wx------ 1 root root 64 Apr 2 20:22 3 -> pipe:[3067913]
lr-x------ 1 root root 64 Apr 2 20:22 4 -> /proc/27413/fd
lrwx------ 1 root root 64 Apr 2 20:22 9 -> socket:[32944]
root@zest1:~# ls -al /dev/pts/
total 0
drwxr-xr-x 2 root root 0 Mar 30 17:55 .
drwxr-xr-x 8 root root 580 Mar 30 17:55 ..
crw--w---- 1 root tty 136, 0 Mar 30 17:55 0
crw--w---- 1 root tty 136, 1 Mar 30 17:55 1
crw--w---- 1 root tty 136, 2 Mar 30 17:55 2
crw--w---- 1 root tty 136, 3 Mar 30 17:55 3
crw--w---- 1 root tty 136, 4 Mar 30 17:55 4
crw-rw-rw- 1 root root 5, 2 Apr 2 20:22 ptmx
(As one can see /dev/pts/6 does not exist in the current namespace.)
Now, start a screen session in this shell. In this case this patch will have
screen directly operate on /proc/self/fd/0.
Let's look at the attach case. When we attach to an existing screen session
where the associated pts device lives in another namespace we need a way to
uniquely identify the pts device that is used and also need a way to get a
valid fd when we need one. This patch solves this by ensuring that a valid file
descriptor to the pts device is sent via a unix socket and SCM_RIGHTS to the
socket and display handling part of screen. However, screen also sends around
the name of the associated pts device or, in the case where the pts device
exists in another namespace, the symlink /proc/self/fd/0. But after having sent
the fd this part of the codebase cannot simply operate on /proc/self/fd/0 since
it very likely refers to a different file. So we need to operate on
/proc/self/fd/<fd-sent-via-SCM_RIGHTS> but also need to ensure that we haven't
been tricked into operating on a tampered with file or device. So we cannot
simply sent /proc/self/fd/0 via the unix socket. Instead we read the contents
of the symbolic link /proc/self/fd/0 in the main function and sent it via the
unix socket. Then in the socket and display handling part of screen, we read
the contents of the /proc/self/fd/<fd-sent-via-SCM_RIGHTS> as well and compare
the pts device names. If they match we know that everything is well. However,
now we also need to update any tty handling code to directly operate on
/proc/self/fd/<fd-sent-via-SCM_RIGHTS>.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Various programs that deal with namespaces will use pty devices that exist in
another namespace. One obvious candiate are containers. So far ttyname() was
incorrectly handling this case because the pts device stems from the host and
thus cannot be found amongst the current namespace's /dev/pts/<n> entries.
Serge Hallyn and I recently upstreamed patches to glibc that allow ttyname{_r}()
to correctly handle this case. At a minimum, ttyname{_r}() will set errno to
ENODEV in case it finds that the /dev/pts/<n> device that the symlink points to
exists in another namespace. This commit will allow screen to handle this case
and behave correctly in a container.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Also drop file checking, as it became clear that it doesn't make much
sense for example with "-Logfile 'logfile.%n'" each window would have
it's own logfile and in theory we would need to check them all and still
someone could prevent us to open logfile at runtime due to creating
conflicting file with properly crafted permissions, before we open a
window.
This fixes API:
To enable logging we use -L option. But in case of
default logfile name (screenlog.0) we will need to
define it anyway. Because screen will try to interpret
next option as a parameter for -L option (which is
logfile name). It will fails ALWAYS, because next
parameter will always start with "-" symbol...
what is not permited for logfile name of course.
For example:
$ screen -L -D -m ./configure
In this case logfile name is screenlog.0, because "-D"
will not be interpreted by screen as a name of logfile.
Signed-off-by: Alexander Naumov <alexander_naumov@opensuse.org>
Screen shows error message and terminates if you
specify not available (permissions problem?) logfile
name (-L parameter).
bug #49491
Signed-off-by: Alexander Naumov <alexander_naumov@opensuse.org>
