bpftool: add bash completions for btf command

Add full support for btf command in bash-completion script.

Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/bpf/bpftool/bash-completion/bpftool

@@ -217,6 +217,7 @@ _bpftool()
     done
     cur=${words[cword]}
     prev=${words[cword - 1]}
+    pprev=${words[cword - 2]}
 
     local object=${words[1]} command=${words[2]}
 
@@ -607,6 +608,51 @@ _bpftool()
                     ;;
             esac
             ;;
+        btf)
+            local PROG_TYPE='id pinned tag'
+            local MAP_TYPE='id pinned'
+            case $command in
+                dump)
+                    case $prev in
+                        $command)
+                            COMPREPLY+=( $( compgen -W "id map prog file" -- \
+                                "$cur" ) )
+                            return 0
+                            ;;
+                        prog)
+                            COMPREPLY=( $( compgen -W "$PROG_TYPE" -- "$cur" ) )
+                            return 0
+                            ;;
+                        map)
+                            COMPREPLY=( $( compgen -W "$MAP_TYPE" -- "$cur" ) )
+                            return 0
+                            ;;
+                        id)
+                            case $pprev in
+                                prog)
+                                    _bpftool_get_prog_ids
+                                    ;;
+                                map)
+                                    _bpftool_get_map_ids
+                                    ;;
+                            esac
+                            return 0
+                            ;;
+                        *)
+                            if [[ $cword == 6 ]] && [[ ${words[3]} == "map" ]]; then
+                                 COMPREPLY+=( $( compgen -W 'key value kv all' -- \
+                                     "$cur" ) )
+                            fi
+                            return 0
+                            ;;
+                    esac
+                    ;;
+                *)
+                    [[ $prev == $object ]] && \
+                        COMPREPLY=( $( compgen -W 'dump help' -- "$cur" ) )
+                    ;;
+            esac
+            ;;
         cgroup)
             case $command in
                 show|list)