forked from Plemya-x/fakeroot
70 lines
1.5 KiB
Go
70 lines
1.5 KiB
Go
package loginshell
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import (
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"bufio"
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"errors"
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"io/fs"
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"os"
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"strconv"
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"strings"
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)
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var (
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// ErrInvalidPasswd is returned when the passwd file is invalid and can't be parsed
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ErrInvalidPasswd = errors.New("loginshell: invalid passwd file")
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// ErrNoSuchUser is returned when a given user isn't in the passwd file
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ErrNoSuchUser = errors.New("loginshell: provided uid not found in passwd file")
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// ErrUnsupported is returned on unsupported platforms, such as Windows
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ErrUnsupported = errors.New("loginshell: unsupported platform")
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)
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// Get returns the login shell belonging to the provided uid by parsing the passwd file.
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// If uid is less than zero, the current uid will be used instead.
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func Get(uid int) (string, error) {
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if uid < 0 {
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uid = os.Getuid()
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}
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// os.Getuid returns -1 on unsupported platforms
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if uid == -1 {
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return "", ErrUnsupported
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}
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fl, err := os.Open("/etc/passwd")
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if errors.Is(err, fs.ErrNotExist) {
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return "", ErrUnsupported
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} else if err != nil {
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return "", err
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}
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defer fl.Close()
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s := bufio.NewScanner(fl)
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for s.Scan() {
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luid, shell, err := parsePasswdLine(s.Text())
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if err != nil {
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return "", err
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}
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if luid == uid {
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return shell, nil
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}
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}
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if err := s.Err(); err != nil {
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return "", err
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}
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return "", ErrNoSuchUser
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}
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func parsePasswdLine(line string) (int, string, error) {
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sline := strings.Split(line, ":")
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if len(sline) < 7 {
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return 0, "", ErrInvalidPasswd
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}
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uid, err := strconv.Atoi(sline[2])
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if err != nil {
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return 0, "", err
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}
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return uid, sline[6], nil
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}
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