Added chgrp command.

Author: nao1215

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to this project will be documented in this file. The format
 ## [0.29.00] - 2021-12-15
 ### Added
  - uuidgen command.
+ - chgrp command.
  - dirname command (with integration tests.)
 ### Changed
  - mimixbox

docs/introduction/en/CommandAppletList.md

@@ -5,6 +5,7 @@
 |  basename| Print basename (PATH without "/") from file path |
 |      cat | Concatenate files and print on the standard output|
 |		cawsay | Print message with cow's ASCII art|
+|   chgrp  | Change the group of each FILE to GROUP|
 |   chroot | Run command or interactive shell with special root directory|
 |       cp | Copy file(s) otr Directory(s) |
 |  dirname | Print only directory path |

internal/applets/applet.go

@@ -23,6 +23,7 @@ import (
 	"sort"
 	"strconv"
 
+	"github.com/nao1215/mimixbox/internal/applets/fileutils/chgrp"
 	"github.com/nao1215/mimixbox/internal/applets/fileutils/cp"
 	"github.com/nao1215/mimixbox/internal/applets/fileutils/ln"
 	"github.com/nao1215/mimixbox/internal/applets/fileutils/mkdir"
@@ -86,6 +87,7 @@ func init() {
 		"basename":  {basename.Run, "Print basename (PATH without\"/\") from file path"},
 		"cat":       {cat.Run, "Concatenate files and print on the standard output"},
 		"cowsay":    {cowsay.Run, "Print message with cow's ASCII art"},
+		"chgrp":     {chgrp.Run, "Change the group of each FILE to GROUP"},
 		"chroot":    {chroot.Run, "Run command or interactive shell with special root directory"},
 		"cp":        {cp.Run, "Copy file(s) otr Directory(s)"},
 		"dirname":   {dirname.Run, "Print only directory path"},

internal/applets/fileutils/chgrp/chgrp.go

@@ -0,0 +1,166 @@
+//
+// mimixbox/internal/applets/fileutils/chgrp/chgrp.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 chgrp
+
+import (
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+	"strconv"
+	"syscall"
+
+	mb "github.com/nao1215/mimixbox/internal/lib"
+
+	"github.com/jessevdk/go-flags"
+)
+
+const cmdName string = "chgrp"
+
+const version = "1.0.0"
+
+var osExit = os.Exit
+
+// Exit code
+const (
+	ExitSuccess int = iota // 0
+	ExitFailuer
+)
+
+type groupInfo struct {
+	group string
+	files []string
+}
+
+type options struct {
+	Recursive bool `short:"R" long:"recursive" description:"Change file group IDs recursively"`
+	Version   bool `short:"v" long:"version" description:"Show chgrp command version"`
+}
+
+func Run() (int, error) {
+	var opts options
+	var args []string
+	var err error
+
+	if args, err = parseArgs(&opts); err != nil {
+		return ExitFailuer, nil
+	}
+
+	groupInfo := groupInfo{args[0], args[1:]}
+	return chgrp(groupInfo, opts)
+}
+
+func chgrp(gInfo groupInfo, opts options) (int, error) {
+	gid, err := lookupGid(gInfo.group)
+	if err != nil {
+		return ExitFailuer, err
+	}
+
+	status := ExitSuccess
+	for _, path := range gInfo.files {
+		path = os.ExpandEnv(path)
+		if opts.Recursive {
+			if err := changeGroupRecursive(path, gid); err != nil {
+				status = ExitFailuer
+				fmt.Fprintln(os.Stderr, cmdName+": "+err.Error())
+				continue
+			}
+		} else {
+			if err := changeGroup(path, gid); err != nil {
+				status = ExitFailuer
+				fmt.Fprintln(os.Stderr, cmdName+": "+err.Error())
+				continue
+			}
+		}
+
+	}
+	return status, nil
+}
+
+func changeGroupRecursive(path string, gid int) error {
+	err := filepath.Walk(path, func(p string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if err := changeGroup(p, gid); err != nil {
+			return err
+		}
+		return nil
+	})
+	return err
+}
+
+func changeGroup(path string, gid int) error {
+	var st syscall.Stat_t
+	if err := syscall.Stat(path, &st); err != nil {
+		return err
+	}
+	return os.Chown(path, int(st.Uid), gid)
+}
+
+func lookupGid(gidFromUserInput string) (int, error) {
+	group, err := user.LookupGroupId(gidFromUserInput)
+	if err != nil {
+		group, err = user.LookupGroup(gidFromUserInput)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	gid, err := strconv.Atoi(group.Gid)
+	if err != nil {
+		return 0, err
+	}
+
+	return gid, nil
+}
+
+func parseArgs(opts *options) ([]string, error) {
+	p := initParser(opts)
+
+	args, err := p.Parse()
+	if err != nil {
+		return nil, err
+	}
+
+	if opts.Version {
+		mb.ShowVersion(cmdName, version)
+		osExit(ExitSuccess)
+	}
+
+	if !isValidArgNr(args) {
+		if len(args) == 0 {
+			fmt.Fprintln(os.Stderr, cmdName+": no operand")
+		} else if len(args) == 1 {
+			fmt.Fprintln(os.Stderr, cmdName+": no operand after "+args[0])
+		}
+		osExit(ExitFailuer)
+	}
+	return args, nil
+}
+
+func initParser(opts *options) *flags.Parser {
+	parser := flags.NewParser(opts, flags.Default)
+	parser.Name = cmdName
+	parser.Usage = "[OPTIONS] GROUP FILES"
+
+	return parser
+}
+
+func isValidArgNr(args []string) bool {
+	return len(args) >= 2
+}