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tailscale/util/osuser/group_ids.go

55 lines
1.4 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package osuser
import (
"context"
"fmt"
"os/exec"
"os/user"
"runtime"
"strings"
"time"
"tailscale.com/version/distro"
)
// GetGroupIds returns the list of group IDs that the user is a member of, or
// an error. It will first try to use the 'id' command to get the group IDs,
// and if that fails, it will fall back to the user.GroupIds method.
func GetGroupIds(user *user.User) ([]string, error) {
if runtime.GOOS != "linux" {
return user.GroupIds()
}
if distro.Get() == distro.Gokrazy {
// Gokrazy is a single-user appliance with ~no userspace.
// There aren't users to look up (no /etc/passwd, etc)
// so rather than fail below, just hardcode root.
// TODO(bradfitz): fix os/user upstream instead?
return []string{"0"}, nil
}
if ids, err := getGroupIdsWithId(user.Username); err == nil {
return ids, nil
}
return user.GroupIds()
}
func getGroupIdsWithId(usernameOrUID string) ([]string, error) {
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
cmd := exec.CommandContext(ctx, "id", "-Gz", usernameOrUID)
out, err := cmd.Output()
if err != nil {
return nil, fmt.Errorf("running 'id' command: %w", err)
}
return parseGroupIds(out), nil
}
func parseGroupIds(cmdOutput []byte) []string {
return strings.Split(strings.Trim(string(cmdOutput), "\n\x00"), "\x00")
}