Re: XDP/BPF C and python libraries?

[David Ahern <dsahern@xxxxxxxxx>]

On 7/23/17 5:54 PM, Jakub Kicinski wrote:
> On Sat, 22 Jul 2017 00:20:50 -0700, Jakub Kicinski wrote:
>> One thing which is not clear to me is how to get the association
>> between programs and maps?  Would we need to extend
>> BPF_OBJ_GET_INFO_BY_FD to provide this info?
> 
> Another thing that I can't find a way of doing is telling whether BPF fs
> file is representing a map or a program.  Is there a way to do this
> today?
> 

Once you have the fd you should be able to look at /proc/pid/fd/%d

I have been using this:

static int bpf_get_type(__u32 fd, __u32 pid, enum bpf_type *type)
{
        char file[PATH_MAX];
        char buf[512];
        ssize_t n;

        *type = BPF_TYPE_UNSPEC;

        snprintf(file, sizeof(file), "/proc/%d/fd/%d", pid, fd);

        n = readlink(file, buf, sizeof(buf));
        if (n < 0)
                return -1;

        if (strstr(buf, "bpf-prog"))
                *type = BPF_TYPE_PROG;
        else if (strstr(buf, "bpf-map"))
                *type = BPF_TYPE_MAP;

        return 0;
}