tools: bpftool: add bash completion for bpftool

Add a completion file for bash. The completion function runs bpftool
when needed, making it smart enough to help users complete ids or tags
for eBPF programs and maps currently on the system.

Update Makefile to install completion file to
/usr/share/bash-completion/completions when running `make install`.

Emacs file mode and (at the end) Vim modeline have been added, to keep
the style in use for most existing bash completion files. In this, it
differs from tools/perf/perf-completion.sh, which seems to be the only
other completion file among the kernel sources repository. This is also
valid for indent style: 4-space indents, as in other completion files.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/bpf/bpftool/Makefile

@@ -46,6 +46,7 @@ $(LIBBPF)-clean:
 	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(OUTPUT) clean >/dev/null
 
 prefix = /usr
+bash_compdir ?= $(prefix)/share/bash-completion/completions
 
 CC = gcc
 
@@ -76,6 +77,8 @@ clean: $(LIBBPF)-clean
 
 install:
 	install $(OUTPUT)bpftool $(prefix)/sbin/bpftool
+	install -m 0755 -d $(bash_compdir)
+	install -m 0644 bash-completion/bpftool $(bash_compdir)
 
 doc:
 	$(Q)$(MAKE) -C Documentation/

tools/bpf/bpftool/bash-completion/bpftool

@@ -0,0 +1,354 @@
+# bpftool(8) bash completion                               -*- shell-script -*-
+#
+# Copyright (C) 2017 Netronome Systems, Inc.
+#
+# This software is dual licensed under the GNU General License
+# Version 2, June 1991 as shown in the file COPYING in the top-level
+# directory of this source tree or the BSD 2-Clause License provided
+# below.  You have the option to license this software under the
+# complete terms of either license.
+#
+# The BSD 2-Clause License:
+#
+#     Redistribution and use in source and binary forms, with or
+#     without modification, are permitted provided that the following
+#     conditions are met:
+#
+#      1. Redistributions of source code must retain the above
+#         copyright notice, this list of conditions and the following
+#         disclaimer.
+#
+#      2. Redistributions in binary form must reproduce the above
+#         copyright notice, this list of conditions and the following
+#         disclaimer in the documentation and/or other materials
+#         provided with the distribution.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+#
+# Author: Quentin Monnet <quentin.monnet@netronome.com>
+
+# Takes a list of words in argument; each one of them is added to COMPREPLY if
+# it is not already present on the command line. Returns no value.
+_bpftool_once_attr()
+{
+    local w idx found
+    for w in $*; do
+        found=0
+        for (( idx=3; idx < ${#words[@]}-1; idx++ )); do
+            if [[ $w == ${words[idx]} ]]; then
+                found=1
+                break
+            fi
+        done
+        [[ $found -eq 0 ]] && \
+            COMPREPLY+=( $( compgen -W "$w" -- "$cur" ) )
+    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()
+{
+    local w idx
+    for w in $*; do
+        for (( idx=3; idx < ${#words[@]}-1; idx++ )); do
+            [[ $w == ${words[idx]} ]] && return 1
+        done
+    done
+    COMPREPLY+=( $( compgen -W "$*" -- "$cur" ) )
+}
+
+_bpftool_get_map_ids()
+{
+    COMPREPLY+=( $( compgen -W "$( bpftool -jp map  2>&1 | \
+        command sed -n 's/.*"id": \(.*\),$/\1/p' )" -- "$cur" ) )
+}
+
+_bpftool_get_prog_ids()
+{
+    COMPREPLY+=( $( compgen -W "$( bpftool -jp prog 2>&1 | \
+        command sed -n 's/.*"id": \(.*\),$/\1/p' )" -- "$cur" ) )
+}
+
+_bpftool_get_prog_tags()
+{
+    COMPREPLY+=( $( compgen -W "$( bpftool -jp prog 2>&1 | \
+        command sed -n 's/.*"tag": "\(.*\)",$/\1/p' )" -- "$cur" ) )
+}
+
+# For bpftool map update: retrieve type of the map to update.
+_bpftool_map_update_map_type()
+{
+    local keyword ref
+    for (( idx=3; idx < ${#words[@]}-1; idx++ )); do
+        if [[ ${words[$((idx-2))]} == "update" ]]; then
+            keyword=${words[$((idx-1))]}
+            ref=${words[$((idx))]}
+        fi
+    done
+    [[ -z $ref ]] && return 0
+
+    local type
+    type=$(bpftool -jp map show $keyword $ref | \
+        command sed -n 's/.*"type": "\(.*\)",$/\1/p')
+    printf $type
+}
+
+_bpftool_map_update_get_id()
+{
+    # Is it the map to update, or a map to insert into the map to update?
+    # Search for "value" keyword.
+    local idx value
+    for (( idx=7; idx < ${#words[@]}-1; idx++ )); do
+        if [[ ${words[idx]} == "value" ]]; then
+            value=1
+            break
+        fi
+    done
+    [[ $value -eq 0 ]] && _bpftool_get_map_ids && return 0
+
+    # Id to complete is for a value. It can be either prog id or map id. This
+    # depends on the type of the map to update.
+    local type=$(_bpftool_map_update_map_type)
+    case $type in
+        array_of_maps|hash_of_maps)
+            _bpftool_get_map_ids
+            return 0
+            ;;
+        prog_array)
+            _bpftool_get_prog_ids
+            return 0
+            ;;
+        *)
+            return 0
+            ;;
+    esac
+}
+
+_bpftool()
+{
+    local cur prev words objword
+    _init_completion || return
+
+    # Deal with simplest keywords
+    case $prev in
+        help|key|opcodes)
+            return 0
+            ;;
+        tag)
+            _bpftool_get_prog_tags
+            return 0
+            ;;
+        file|pinned)
+            _filedir
+            return 0
+            ;;
+        batch)
+            COMPREPLY=( $( compgen -W 'file' -- "$cur" ) )
+            return 0
+            ;;
+    esac
+
+    # Search for object and command
+    local object command cmdword
+    for (( cmdword=1; cmdword < ${#words[@]}-1; cmdword++ )); do
+        [[ -n $object ]] && command=${words[cmdword]} && break
+        [[ ${words[cmdword]} != -* ]] && object=${words[cmdword]}
+    done
+
+    if [[ -z $object ]]; then
+        case $cur in
+            -*)
+                local c='--version --json --pretty'
+                COMPREPLY=( $( compgen -W "$c" -- "$cur" ) )
+                return 0
+                ;;
+            *)
+                COMPREPLY=( $( compgen -W "$( bpftool help 2>&1 | \
+                    command sed \
+                    -e '/OBJECT := /!d' \
+                    -e 's/.*{//' \
+                    -e 's/}.*//' \
+                    -e 's/|//g' )" -- "$cur" ) )
+                COMPREPLY+=( $( compgen -W 'batch help' -- "$cur" ) )
+                return 0
+                ;;
+        esac
+    fi
+
+    [[ $command == help ]] && return 0
+
+    # Completion depends on object and command in use
+    case $object in
+        prog)
+            case $prev in
+                id)
+                    _bpftool_get_prog_ids
+                    return 0
+                    ;;
+            esac
+
+            local PROG_TYPE='id pinned tag'
+            case $command in
+                show)
+                    [[ $prev != "$command" ]] && return 0
+                    COMPREPLY=( $( compgen -W "$PROG_TYPE" -- "$cur" ) )
+                    return 0
+                    ;;
+                dump)
+                    case $prev in
+                        $command)
+                            COMPREPLY+=( $( compgen -W "xlated jited" -- \
+                                "$cur" ) )
+                            return 0
+                            ;;
+                        xlated|jited)
+                            COMPREPLY=( $( compgen -W "$PROG_TYPE" -- \
+                                "$cur" ) )
+                            return 0
+                            ;;
+                    *)
+                            _bpftool_once_attr 'file'
+                            COMPREPLY+=( $( compgen -W 'opcodes' -- \
+                                "$cur" ) )
+                            return 0
+                            ;;
+                    esac
+                    ;;
+                pin)
+                    if [[ $prev == "$command" ]]; then
+                        COMPREPLY=( $( compgen -W "$PROG_TYPE" -- "$cur" ) )
+                    else
+                        _filedir
+                    fi
+                    return 0
+                    ;;
+                *)
+                    [[ $prev == $object ]] && \
+                        COMPREPLY=( $( compgen -W 'dump help pin show' -- \
+                            "$cur" ) )
+                    ;;
+            esac
+            ;;
+        map)
+            local MAP_TYPE='id pinned'
+            case $command in
+                show|dump)
+                    case $prev in
+                        $command)
+                            COMPREPLY=( $( compgen -W "$MAP_TYPE" -- "$cur" ) )
+                            return 0
+                            ;;
+                        id)
+                            _bpftool_get_map_ids
+                            return 0
+                            ;;
+                        *)
+                            return 0
+                            ;;
+                    esac
+                    ;;
+                lookup|getnext|delete)
+                    case $prev in
+                        $command)
+                            COMPREPLY=( $( compgen -W "$MAP_TYPE" -- "$cur" ) )
+                            return 0
+                            ;;
+                        id)
+                            _bpftool_get_map_ids
+                            return 0
+                            ;;
+                        key)
+                            return 0
+                            ;;
+                        *)
+                            _bpftool_once_attr 'key'
+                            return 0
+                            ;;
+                    esac
+                    ;;
+                update)
+                    case $prev in
+                        $command)
+                            COMPREPLY=( $( compgen -W "$MAP_TYPE" -- "$cur" ) )
+                            return 0
+                            ;;
+                        id)
+                            _bpftool_map_update_get_id
+                            return 0
+                            ;;
+                        key)
+                            return 0
+                            ;;
+                        value)
+                            # We can have bytes, or references to a prog or a
+                            # map, depending on the type of the map to update.
+                            case $(_bpftool_map_update_map_type) in
+                                array_of_maps|hash_of_maps)
+                                    local MAP_TYPE='id pinned'
+                                    COMPREPLY+=( $( compgen -W "$MAP_TYPE" \
+                                        -- "$cur" ) )
+                                    return 0
+                                    ;;
+                                prog_array)
+                                    local PROG_TYPE='id pinned tag'
+                                    COMPREPLY+=( $( compgen -W "$PROG_TYPE" \
+                                        -- "$cur" ) )
+                                    return 0
+                                    ;;
+                                *)
+                                    return 0
+                                    ;;
+                            esac
+                            return 0
+                            ;;
+                        *)
+                            _bpftool_once_attr 'key'
+                            local UPDATE_FLAGS='any exist noexist'
+                            for (( idx=3; idx < ${#words[@]}-1; idx++ )); do
+                                if [[ ${words[idx]} == 'value' ]]; then
+                                    # 'value' is present, but is not the last
+                                    # word i.e. we can now have UPDATE_FLAGS.
+                                    _bpftool_one_of_list "$UPDATE_FLAGS"
+                                    return 0
+                                fi
+                            done
+                            for (( idx=3; idx < ${#words[@]}-1; idx++ )); do
+                                if [[ ${words[idx]} == 'key' ]]; then
+                                    # 'key' is present, but is not the last
+                                    # word i.e. we can now have 'value'.
+                                    _bpftool_once_attr 'value'
+                                    return 0
+                                fi
+                            done
+                            return 0
+                            ;;
+                    esac
+                    ;;
+                pin)
+                    if [[ $prev == "$command" ]]; then
+                        COMPREPLY=( $( compgen -W "$PROG_TYPE" -- "$cur" ) )
+                    else
+                        _filedir
+                    fi
+                    return 0
+                    ;;
+                *)
+                    [[ $prev == $object ]] && \
+                        COMPREPLY=( $( compgen -W 'delete dump getnext help \
+                            lookup pin show update' -- "$cur" ) )
+                    ;;
+            esac
+            ;;
+    esac
+} &&
+complete -F _bpftool bpftool
+
+# ex: ts=4 sw=4 et filetype=sh