Re: [PATCH] python: Hide error message when modifying non-local fcontext

[James Carter <jwcart2@gmail.com>]

On Wed, Sep 14, 2022 at 6:08 PM Vit Mojzis <vmojzis@redhat.com> wrote:
>
> Fixes:
>   # semanage fcontext -f f -m -t passwd_file_t /etc/security/opasswd
>   libsemanage.dbase_llist_query: could not query record value (No such file or directory).
>
> Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
> ---
>  python/semanage/seobject.py | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/python/semanage/seobject.py b/python/semanage/seobject.py
> index 0782c082..2d52f53c 100644
> --- a/python/semanage/seobject.py
> +++ b/python/semanage/seobject.py
> @@ -177,6 +177,22 @@ except (OSError, ImportError):
>              for l in self.log_list:
>                  syslog.syslog(syslog.LOG_INFO, message + l)
>
> +# Define a context manager to suppress stderr.
> +class suppress_stderr(object):
> +    def __init__(self):
> +        # Open a /dev/null file to be used as stderr
> +        self.null =  os.open(os.devnull,os.O_RDWR)
> +        self.save_fd = os.dup(2)
> +
> +    def __enter__(self):
> +        # Set stderr to the null file
> +        os.dup2(self.null,2)
> +
> +    def __exit__(self, *_):
> +        # Restore stderr
> +        os.dup2(self.save_fd,2)
> +        os.close(self.null)
> +
>
>  class nulllogger:
>
> @@ -2510,7 +2526,8 @@ class fcontextRecords(semanageRecords):
>                  raise ValueError(_("File context for %s is not defined") % target)
>
>          try:
> -            (rc, fcontext) = semanage_fcontext_query_local(self.sh, k)
> +            with suppress_stderr():
> +                (rc, fcontext) = semanage_fcontext_query_local(self.sh, k)
>          except OSError:
>              try:
>                  (rc, fcontext) = semanage_fcontext_query(self.sh, k)
> --
> 2.35.3
>

I think it is better to rework semanage/seobject.py so that there is
no error. I sent a patch to the list that should fix this.
Thanks for the report. Sorry that it took so long to get to.
Jim