lsns: interpolate missing namespaces for converting forests to a tree
The tree of *parent* and *owner* could be forests because *lsns*
cannot track a namespace having no process.
This change tries interpolating the missing namespaces by calling
ioctl(NS_GET_PARENT) and ioctl(NS_GET_USERNS) recursively.
The original output for -Tparent:
# ./lsns -Tparent
NS TYPE NPROCS PID USER COMMAND
4026531837 user 404 1 root /usr/lib/systemd/sy
├─4026532508 user 1 29376 yamato /usr/lib64/firefox/
...
└─4026533513 user 1 24245 yamato /usr/lib64/firefox/
...
4026533733 user 1 30839 yamato /opt/google/chrome-
4026533734 user 15 10076 yamato /opt/google/chrome-
user namespaces 4026533733 and 4026533734 are orphans.
lsns could not find their parents.
With this change:
# ./lsns-with-changes -Tparent
NS TYPE NPROCS PID USER COMMAND
4026531837 user 404 1 root /usr/lib/systemd/
├─4026532508 user 1 29376 yamato /usr/lib64/firefo
...
├─4026532639 user 0
│ ├─4026532637 user 0
│ │ └─4026533733 user 1 30839 yamato /opt/google/chrom
│ └─4026533734 user 14 10076 yamato /opt/google/chrom
Now user namespaces 4026533733 and 4026533734 are integrated to the
tree. lsns interpolates the missing namespace 4026532639 and
4026532637 for the integration.
The original output for -Towner:
# ./lsns -Towner
NS TYPE NPROCS PID USER COMMAND
4026531837 user 405 1 root /usr/lib/systemd/s
├─4026531835 cgroup 431 1 root /usr/lib/systemd/s
...
4026532638 pid 1 30839 yamato /opt/google/chrome
4026532640 pid 2 30837 yamato /opt/google/chrome
...
pid namespaces 4026532638 and 4026532640 are orphans.
lsns could not find their owners.
With this change:
# ./lsns-with-changes -Towner
NS TYPE NPROCS PID USER COMMAND
4026531837 user 403 1 root /usr/lib/systemd
├─4026531835 cgroup 429 1 root /usr/lib/systemd
...
├─4026532639 user 0
...
│ ├─4026532637 user 0
│ │ ├─4026532638 pid 1 30839 yamato /opt/google/chro
│ │ ├─4026533638 net 1 30839 yamato /opt/google/chro
│ │ └─4026533733 user 1 30839 yamato /opt/google/chro
│ ├─4026532640 pid 2 30837 yamato /opt/google/chro
Now pid namespaces 4026532638 and 4026532640 are integrated to the
tree. lsns interpolates the missing namespace 4026532639 and
4026532637 for the integration.
Signed-off-by: Masatake YAMATO <yamato@redhat.com>
2 files changed
