Add kill command.

CHANGELOG.md

@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file. The format
 ## [0.30.00] - 2021-12-15
 ### Added
  - chown command.
+ - kill command.
  - wget command.
 ## [0.29.00] - 2021-12-15
 ### Added

docs/introduction/en/CommandAppletList.md

@@ -21,6 +21,7 @@
 | hostid   | Print hostid (Host Identity Number, hex)|
 |       id | Print User ID and Group ID|
 |  ischroot| Detect if running in a chroot|
+|   kill   | Kill process or send signal to process|
 |       ln | Create hard link or symbolic link|
 |     mbsh | Mimix Box Shell (In development)|
 |    md5sum| Calculate or Check md5sum message digest|

internal/applets/applet.go

@@ -47,6 +47,7 @@ import (
 	"github.com/nao1215/mimixbox/internal/applets/shellutils/hostid"
 	"github.com/nao1215/mimixbox/internal/applets/shellutils/id"
 	"github.com/nao1215/mimixbox/internal/applets/shellutils/ischroot"
+	"github.com/nao1215/mimixbox/internal/applets/shellutils/kill"
 	"github.com/nao1215/mimixbox/internal/applets/shellutils/mbsh"
 	"github.com/nao1215/mimixbox/internal/applets/shellutils/path"
 	"github.com/nao1215/mimixbox/internal/applets/shellutils/sddf"
@@ -101,10 +102,11 @@ func init() {
 		"false":     {false.Run, "Do nothing. Return unsuccess(1)"},
 		"ghrdc":     {ghrdc.Run, "GitHub Relase Download Counter"},
 		"groups":    {groups.Run, "Print the groups to which USERNAME belongs"},
+		"head":      {head.Run, "Print the first NUMBER(default=10) lines"},
 		"hostid":    {hostid.Run, "Print hostid (Host Identity Number, hex)!!!Does not work properly!!!"},
 		"id":        {id.Run, "Print User ID and Group ID"},
-		"head":      {head.Run, "Print the first NUMBER(default=10) lines"},
 		"ischroot":  {ischroot.Run, "Detect if running in a chroot"},
+		"kill":      {kill.Run, "Kill process or send signal to process"},
 		"ln":        {ln.Run, "Create hard or symbolic link"},
 		"mbsh":      {mbsh.Run, "Mimix Box Shell"},
 		"md5sum":    {md5sum.Run, "Calculate or Check md5sum message digest"},

internal/applets/shellutils/kill/kill.go

@@ -0,0 +1,203 @@
+//
+// mimixbox/internal/applets/shellutils/kill/kill.go
+//
+// Copyright 2021 Naohiro CHIKAMATSU
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package kill
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"syscall"
+
+	mb "github.com/nao1215/mimixbox/internal/lib"
+)
+
+const cmdName string = "kill"
+const version = "1.0.0"
+
+var osExit = os.Exit
+
+// Exit code
+const (
+	ExitSuccess int = iota // 0
+	ExitFailuer
+)
+
+type options struct {
+	nameFlg      bool
+	signalName   string
+	numberFlg    bool
+	signalNumber string
+	listFlg      bool
+	list         string
+	directFlg    bool
+	direct       string
+}
+
+func Run() (int, error) {
+	process, opts := parseArgs(os.Args)
+
+	valid(process, opts)
+	if opts.listFlg {
+		if opts.list == "" {
+			mb.PrintSignalList()
+		} else {
+			mb.PrintSignal(opts.list)
+		}
+		osExit(ExitSuccess)
+	}
+
+	return kill(process, opts)
+}
+
+func kill(process []string, opts options) (int, error) {
+	status := ExitSuccess
+	for _, v := range process {
+		pid, err := strconv.Atoi(v)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "kill: "+err.Error()+": "+v)
+			status = ExitFailuer
+			continue
+		}
+
+		p, err := os.FindProcess(pid)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "kill: "+err.Error()+": "+v)
+			status = ExitFailuer
+			continue
+		}
+
+		signal := decideSignal(opts)
+		err = p.Signal(syscall.Signal(signal))
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "kill: "+err.Error())
+			status = ExitFailuer
+			continue
+		}
+	}
+	return status, nil
+}
+
+func decideSignal(opts options) int32 {
+	var signal int32 = 0
+	// TODO: Workaround. I have not investigated the response
+	// when multiple signals are specified.
+	if opts.directFlg {
+		str := strings.TrimLeft(opts.direct, "-")
+		if len(str) <= 2 {
+			signal = mb.SignalAtoi(str)
+		} else {
+			signal = mb.ConvSignalNameToNum(str)
+		}
+	} else if opts.nameFlg {
+		signal = mb.ConvSignalNameToNum(opts.signalName)
+	} else if opts.numberFlg {
+		signal = mb.SignalAtoi(opts.signalNumber)
+	} else {
+		signal = 9
+	}
+	return signal
+}
+
+func valid(process []string, opts options) {
+	if len(process) == 0 && !opts.listFlg {
+		showHelp()
+		osExit(ExitFailuer)
+	}
+	if opts.nameFlg && !mb.IsSignalName(opts.signalName) {
+		fmt.Fprintln(os.Stderr, "kill: -s: invalid signal specification:"+opts.signalName)
+		osExit(ExitFailuer)
+	}
+	if opts.numberFlg && !mb.IsSignalName(opts.signalNumber) {
+		fmt.Fprintln(os.Stderr, "kill: -n: invalid signal specification:"+opts.signalNumber)
+		osExit(ExitFailuer)
+	}
+
+	trim := strings.TrimLeft(opts.direct, "-")
+	if opts.directFlg && !mb.IsSignalName(trim) && !mb.IsSignalNumber(trim) {
+		fmt.Fprintln(os.Stderr, "kill: "+opts.direct+": invalid signal specification")
+		osExit(ExitFailuer)
+	}
+}
+
+func parseArgs(args []string) ([]string, options) {
+	if mb.HasVersionOpt(args) {
+		mb.ShowVersion(cmdName, version)
+		osExit(ExitSuccess)
+	}
+
+	if mb.HasHelpOpt(args) {
+		showHelp()
+		osExit(ExitSuccess)
+	}
+
+	var opts options = options{false, "", false, "", false, "", false, ""}
+	args = args[1:]
+	for i, v := range args {
+		if v == "-s" {
+			opts.nameFlg = true
+			if len(args) > i+1 {
+				opts.signalName = args[i+1]
+			} else {
+				fmt.Fprintln(os.Stderr, "kill: -s: option requires an argument")
+				osExit(ExitFailuer)
+			}
+			continue
+		} else if v == "-n" {
+			opts.numberFlg = true
+			if len(args) > i+1 {
+				opts.signalNumber = args[i+1]
+			} else {
+				fmt.Fprintln(os.Stderr, "kill: -n: option requires an argument")
+				osExit(ExitFailuer)
+			}
+			continue
+		} else if v == "-l" {
+			opts.listFlg = true
+			if len(args) > i+1 {
+				opts.list = args[i+1]
+			}
+		} else if strings.Contains(v, "-") {
+			opts.directFlg = true
+			opts.direct = v
+		}
+	}
+	return decideProcess(args[1:], opts), opts
+}
+
+func decideProcess(args []string, opts options) []string {
+	new := mb.Remove(args, "-s")
+	new = mb.Remove(new, "-n")
+	new = mb.Remove(new, "-l")
+	new = mb.Remove(new, opts.list)
+	new = mb.Remove(new, opts.signalName)
+	new = mb.Remove(new, opts.signalNumber)
+	new = mb.Remove(new, opts.direct)
+	return new
+}
+
+func showHelp() {
+	fmt.Fprintln(os.Stdout, "Usage:")
+	fmt.Fprintln(os.Stdout, "  kill [-s sigspec | -n signum | -sigspec] PID  or")
+	fmt.Fprintln(os.Stdout, "  kill -l [PID]")
+	fmt.Fprintln(os.Stdout, "")
+	fmt.Fprintln(os.Stdout, "Application Options:")
+	fmt.Fprintln(os.Stdout, "  -v, --version       Show kill command version")
+	fmt.Fprintln(os.Stdout, "")
+	fmt.Fprintln(os.Stdout, "Help Options:")
+	fmt.Fprintln(os.Stdout, "  -h, --help          Show this help message")
+}

internal/lib/signal.go

@@ -0,0 +1,131 @@
+//
+// mimixbox/internal/lib/signal.go
+//
+// Copyright 2021 Naohiro CHIKAMATSU
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package mb
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type signal struct {
+	number string
+	name   string
+	desc   string
+}
+
+// [Reference]
+// https://www-uxsup.csx.cam.ac.uk/courses/moved.Building/signals.pdf
+var Signals []signal = []signal{
+	{"1", "SIGHUP", "Hangup detected on controlling terminal or death of controlling process"},
+	{"2", "SIGINT", "The process was interrupted (When user hits Cnrl+C)"},
+	{"3", "SIGQUIT", "Quit program"},
+	{"4", "SIGILL", "Illegal instruction"},
+	{"5", "SIGTRAP", "Trace trap for debugging"},
+	{"6", "SIGABRT", "Emegency stop.  Abort program (formerly SIGIOT)"},
+	{"7", "SIGBUS", "Bus error. e.g. alignment errors in memory access"},
+	{"8", "SIGFPE", "A floating point exception happened in the program."},
+	{"9", "SIGKILL", "Kill program"},
+	{"10", "SIGUSR1", "Left for the programmers to do whatever they want"},
+	{"11", "SIGSEGV", "Segmentation violation"},
+	{"12", "SIGUSR2", "Left for the programmers to do whatever they want"},
+	{"13", "SIGPIPE", "Write on a pipe with no reader"},
+	{"14", "SIGALRM", "Real-time timer (request a wake up call) expired"},
+	{"15", "SIGTERM", "Software termination"},
+	{"16", "SIGSTKFLT", "Unused (Stack fault in the FPU)"},
+	{"17", "SIGCHLD", "Stop or exit child process"},
+	{"18", "SIGCONT", "Restart from stop"},
+	{"19", "SIGSTOP", "Stop process"},
+	{"20", "SIGTSTP", "Stop process from terminal (When user hits Cnrl+Z)"},
+	{"21", "SIGTTIN", "Signal to a backgrounded process when it tries to read input from its terminal"},
+	{"22", "SIGTTOU", "Signal to a backgrounded process when it tries to write output to its terminal"},
+	{"23", "SIGURG", "Network connection when urgent out of band data is sent to it"},
+	{"24", "SIGXCPU", "Exceeded CPU limit"},
+	{"25", "SIGXFSZ", "Exceeded file size limit"},
+	{"26", "SIGVTALRM", "Virtual alram cloc"},
+	{"27", "SIGPROF", "Profiling timer's timeout"},
+	{"28", "SIGWINCH", "Window resize signal"},
+	{"29", "SIGIO", "Input / output is possible"},
+	{"30", "SIGPWR", "Power failure"},
+	{"31", "SIGSYS", "Unused (Illegal argument to routine)"},
+	// signal number 33-64 is real-time signal.
+	// It has no predefined meaning and can be used for application-defined purposes.
+}
+
+func IsSignalNumber(num string) bool {
+	for _, v := range Signals {
+		if num == v.number {
+			return true
+		}
+	}
+	return false
+}
+
+func IsSignalName(name string) bool {
+	for _, v := range Signals {
+		if name == v.name {
+			return true
+		}
+		shortName := strings.TrimPrefix(v.name, "SIG")
+		if name == shortName {
+			return true
+		}
+	}
+	return false
+}
+
+func SignalAtoi(num string) int32 {
+	n, err := strconv.Atoi(num)
+	if err != nil {
+		return int32(-1)
+	}
+	return int32(n)
+}
+
+func ConvSignalNameToNum(name string) int32 {
+	if !strings.HasPrefix(name, "SIG") {
+		name = "SIG" + name
+	}
+	for _, v := range Signals {
+		if name == v.name {
+			return SignalAtoi(v.number)
+		}
+	}
+	return int32(-1)
+}
+
+func PrintSignalList() {
+	for _, v := range Signals {
+		fmt.Fprintf(os.Stdout, "%2s  %10s  %s\n", v.number, v.name, v.desc)
+	}
+}
+
+func PrintSignal(numOrName string) {
+	for _, v := range Signals {
+		if numOrName == v.name {
+			fmt.Fprintln(os.Stdout, v.number)
+		}
+		shortName := strings.TrimPrefix(v.name, "SIG")
+		if numOrName == shortName {
+			fmt.Fprintln(os.Stdout, v.number)
+		}
+		if numOrName == v.number {
+			fmt.Fprintln(os.Stdout, strings.TrimPrefix(v.name, "SIG"))
+		}
+	}
+}