tools: bpftool: add bash completion for cgroup commands

Add bash completion for "bpftool cgroup" command family. While at it,
also fix the formatting of some keywords in the man page for cgroups.

Fixes: 5ccda64d ("bpftool: implement cgroup bpf operations")
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/bpf/bpftool/Documentation/bpftool-cgroup.rst

@@ -26,8 +26,8 @@ MAP COMMANDS
 |	**bpftool** **cgroup help**
 |
 |	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
-|	*ATTACH_TYPE* := { *ingress* | *egress* | *sock_create* | *sock_ops* | *device* }
-|	*ATTACH_FLAGS* := { *multi* | *override* }
+|	*ATTACH_TYPE* := { **ingress** | **egress** | **sock_create** | **sock_ops** | **device** }
+|	*ATTACH_FLAGS* := { **multi** | **override** }
 
 DESCRIPTION
 ===========

tools/bpf/bpftool/bash-completion/bpftool

@@ -52,16 +52,24 @@ _bpftool_once_attr()
     done
 }
 
-# Takes a list of words in argument; adds them all to COMPREPLY if none of them
-# is already present on the command line. Returns no value.
-_bpftool_one_of_list()
+# Takes a list of words as argument; if any of those words is present on the
+# command line, return 0. Otherwise, return 1.
+_bpftool_search_list()
 {
     local w idx
     for w in $*; do
         for (( idx=3; idx < ${#words[@]}-1; idx++ )); do
-            [[ $w == ${words[idx]} ]] && return 1
+            [[ $w == ${words[idx]} ]] && return 0
         done
     done
+    return 1
+}
+
+# Takes a list of words in argument; adds them all to COMPREPLY if none of them
+# is already present on the command line. Returns no value.
+_bpftool_one_of_list()
+{
+    _bpftool_search_list $* && return 1
     COMPREPLY+=( $( compgen -W "$*" -- "$cur" ) )
 }
 
@@ -351,6 +359,54 @@ _bpftool()
                     ;;
             esac
             ;;
+        cgroup)
+            case $command in
+                show|list)
+                    _filedir
+                    return 0
+                    ;;
+                attach|detach)
+                    local ATTACH_TYPES='ingress egress sock_create sock_ops \
+                        device'
+                    local ATTACH_FLAGS='multi override'
+                    local PROG_TYPE='id pinned tag'
+                    case $prev in
+                        $command)
+                            _filedir
+                            return 0
+                            ;;
+                        ingress|egress|sock_create|sock_ops|device)
+                            COMPREPLY=( $( compgen -W "$PROG_TYPE" -- \
+                                "$cur" ) )
+                            return 0
+                            ;;
+                        id)
+                            _bpftool_get_prog_ids
+                            return 0
+                            ;;
+                        *)
+                            if ! _bpftool_search_list "$ATTACH_TYPES"; then
+                                COMPREPLY=( $( compgen -W "$ATTACH_TYPES" -- \
+                                    "$cur" ) )
+                            elif [[ "$command" == "attach" ]]; then
+                                # We have an attach type on the command line,
+                                # but it is not the previous word, or
+                                # "id|pinned|tag" (we already checked for
+                                # that). This should only leave the case when
+                                # we need attach flags for "attach" commamnd.
+                                _bpftool_one_of_list "$ATTACH_FLAGS"
+                            fi
+                            return 0
+                            ;;
+                    esac
+                    ;;
+                *)
+                    [[ $prev == $object ]] && \
+                        COMPREPLY=( $( compgen -W 'help attach detach \
+                            show list' -- "$cur" ) )
+                    ;;
+            esac
+            ;;
     esac
 } &&
 complete -F _bpftool bpftool