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/
group.go
134 lines (110 loc) · 2.79 KB
/
group.go
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// Copyright 2015 The rkt Authors
//
// 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 group
import (
"bufio"
"errors"
"fmt"
"io"
"os"
"strconv"
"strings"
"github.com/hashicorp/errwrap"
)
const (
groupFilePath = "/etc/group"
)
// Group represents an entry in the group file.
type Group struct {
Name string
Pass string
Gid int
Users []string
}
// LookupGid reads the group file specified by groupFile, and returns the gid of the group
// specified by groupName.
func LookupGidFromFile(groupName, groupFile string) (gid int, err error) {
groups, err := parseGroupFile(groupFile)
if err != nil {
return -1, errwrap.Wrap(fmt.Errorf("error parsing %q file", groupFile), err)
}
group, ok := groups[groupName]
if !ok {
return -1, fmt.Errorf("%q group not found", groupName)
}
return group.Gid, nil
}
// LookupGid reads the group file and returns the gid of the group
// specified by groupName.
func LookupGid(groupName string) (gid int, err error) {
return LookupGidFromFile(groupName, groupFilePath)
}
func parseGroupFile(path string) (group map[string]*Group, err error) {
groupFile, err := os.Open(path)
if err != nil {
return nil, err
}
defer groupFile.Close()
return parseGroups(groupFile)
}
func parseGroups(r io.Reader) (group map[string]*Group, err error) {
s := bufio.NewScanner(r)
out := make(map[string]*Group)
for s.Scan() {
if err := s.Err(); err != nil {
return nil, err
}
text := s.Text()
if text == "" {
continue
}
p, err := parseGroupLine(text)
if err != nil {
return nil, errwrap.Wrap(errors.New("error parsing line"), err)
}
out[p.Name] = p
}
return out, nil
}
func parseGroupLine(line string) (*Group, error) {
const (
NameIdx = iota
PassIdx
GidIdx
UsersIdx
)
var err error
if line == "" {
return nil, errors.New("cannot parse empty line")
}
splits := strings.Split(line, ":")
if len(splits) < 4 {
return nil, fmt.Errorf("expected at least 4 fields, got %d", len(splits))
}
group := &Group{
Name: splits[NameIdx],
Pass: splits[PassIdx],
}
group.Gid, err = strconv.Atoi(splits[GidIdx])
if err != nil {
return nil, errwrap.Wrap(errors.New("unable to parse gid"), err)
}
u := splits[UsersIdx]
if u != "" {
group.Users = strings.Split(u, ",")
} else {
group.Users = []string{}
}
return group, nil
}