func lookupGidByName(nameOrGid string) (int, error) {
groupFile, err := user.GetGroupFile()
if err != nil {
return -1, err
}
groups, err := user.ParseGroupFileFilter(groupFile, func(g user.Group) bool {
return g.Name == nameOrGid || strconv.Itoa(g.Gid) == nameOrGid
})
if err != nil {
return -1, err
}
if groups != nil && len(groups) > 0 {
return groups[0].Gid, nil
}
return -1, fmt.Errorf("Group %s not found", nameOrGid)
}
// SetupUser changes the groups, gid, and uid for the user inside the container
func SetupUser(u string) error {
// Set up defaults.
defaultExecUser := user.ExecUser{
Uid: syscall.Getuid(),
Gid: syscall.Getgid(),
Home: "/",
}
passwdFile, err := user.GetPasswdFile()
if err != nil {
return err
}
groupFile, err := user.GetGroupFile()
if err != nil {
return err
}
execUser, err := user.GetExecUserFile(u, &defaultExecUser, passwdFile, groupFile)
if err != nil {
return fmt.Errorf("get supplementary groups %s", err)
}
if err := syscall.Setgroups(execUser.Sgids); err != nil {
return fmt.Errorf("setgroups %s", err)
}
if err := system.Setgid(execUser.Gid); err != nil {
return fmt.Errorf("setgid %s", err)
}
if err := system.Setuid(execUser.Uid); err != nil {
return fmt.Errorf("setuid %s", err)
}
// if we didn't get HOME already, set it based on the user's HOME
if envHome := os.Getenv("HOME"); envHome == "" {
if err := os.Setenv("HOME", execUser.Home); err != nil {
return fmt.Errorf("set HOME %s", err)
}
}
return nil
}