[RFC] auxstr: show namespaces when -e namespace=switch is given

[masatake]

While analyzing how a container engine works with strace, I want to have a feature printing namespace IDs. The prototype works like this:

    $ src/strace -qq -e signal=none -e unshare -e namespace=switch unshare --user --net /bin/true
    unshare(CLONE_NEWUSER|CLONE_NEWNET)     = 0 (net:[4026537408], user:[4026537407])
    $ src/strace -qq -f -e signal=none -e unshare,clone -e namespace=switch \
      		 podman run --rm -ti registry.access.redhat.com/ubi7/ubi:latest /bin/true
    [pid 1089104] clone(child_stack=NULL, flags=CLONE_NEWNS|CLONE_NEWUSER|SIGCHLD) = 1089110 (mnt:[4026531841], user:[4026531837])
    [pid 1089104] clone(child_stack=NULL, flags=CLONE_VM|CLONE_VFORK|SIGCHLD) = 1089111
    ERRO[0000] running `/usr/bin/newuidmap 1089110 0 1000 1 1 100000 65536`: newuidmap: write to uid_map failed: Operation not permitted
    Error: cannot set up namespace using "/usr/bin/newuidmap": exit status 1

If this one is an acceptable idea, I want to get the comment about the name of the option: -e namespace=switch.

TODO

• update the --help message
• add a test case for the option syntax
• add a test case for unshare(2)
• add a test case for setns(2)
• add a test case for clone(2)
• add a test case for clone3(2)
• write commit logs in ChangeLog style
• update the man page

[ldv-alt]

Interesting. What's the idea behind the name namespace=switch?

[masatake]

Interesting. What's the idea behind the name namespace=switch?

With the option, strace reports namespaces when processes switch them.

Anyway, I'll continue developing this feature.