Exec erros from the exec() syscall in the container's init should be
treated as if the container ran but couldn't execute the process for the
user instead of returning a libcontainer error as if it was an issue in
the library.
Before specifying different commands like `/etc`, `asldfkjasdlfj`, or
`/alsdjfkasdlfj` would always return 1 on the command line with a
libcontainer specific error message. Now they return the correct
message and exit status defined for unix processes.
Example:
```bash
root@deathstar:/containers/redis# runc start test
exec: "/asdlfkjasldkfj": file does not exist
root@deathstar:/containers/redis# echo $?
127
root@deathstar:/containers/redis# runc start test
exec: "asdlfkjasldkfj": executable file not found in $PATH
root@deathstar:/containers/redis# echo $?
127
root@deathstar:/containers/redis# runc start test
exec: "/etc": permission denied
root@deathstar:/containers/redis# echo $?
126
```
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
This rather naively fixes an error observed where a processes stdio
streams are not written to when there is an error upon starting up the
process, such as when the executable doesn't exist within the
container's rootfs.
Before the "fix", when an error occurred on start, `terminate` is called
immediately, which calls `cmd.Process.Kill()`, then calling `Wait()` on
the process. In some cases when this `Kill` is called the stdio stream
have not yet been written to, causing non-deterministic output. The
error itself is properly preserved but users attached to the process
will not see this error.
With the fix it is just calling `Wait()` when an error occurs rather
than trying to `Kill()` the process first. This seems to preserve stdio.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Michael Crosby
Daniel, Dao Quang Minh
Mrunal Patel
Brian Goff
Vishnu Kannan