[PATCH] Print more error messages

[Dmitry V. Levin]

On Thu, Aug 20, 2020 at 06:39:30PM +0200, Ákos Uzonyi wrote:
> ---
> 
> Could you please run the dup-y test again with this patch applied?
> Hopefully we'll see where the problem comes from.
> 
>  pidns.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/pidns.c b/pidns.c
> index 9d8695da..7e7d8212 100644
> --- a/pidns.c
> +++ b/pidns.c
> @@ -168,14 +168,18 @@ get_ns_hierarchy(int proc_pid, unsigned int *ns_buf, size_t ns_buf_size)
>  	xsprintf(path, "/proc/%s/ns/pid", pid_to_str(proc_pid));
> 
>  	int fd = open_file(path, O_RDONLY);
> -	if (fd < 0)
> +	if (fd < 0) {
> +		perror_func_msg("opening %s", path);
>  		return 0;
> +	}

There are quite a few of these, e.g.
get_ns_hierarchy: opening /proc/1/ns/pid: Permission denied
but they are harmless.

> @@ -248,6 +254,9 @@ get_id_list(int proc_pid, int *id_buf, enum pid_type type)
>  		}
>  	}
> 
> +	if (!p)
> +		error_func_msg("no line found starting with %s", ns_str);

Yes, that was it, it prints "no line found starting with NSpid:".
On that system I also see the following:
$ grep -c ^NS /proc/self/status 
0


-- 
ldv