file.go

package system

import (
	"crypto/md5"
	"crypto/sha256"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"

	"github.com/aelsabbahy/goss/util"
	"github.com/opencontainers/runc/libcontainer/user"
)

type File interface {
	Path() string
	Exists() (bool, error)
	Contains() (io.Reader, error)
	Mode() (string, error)
	Size() (int, error)
	Filetype() (string, error)
	Owner() (string, error)
	Group() (string, error)
	LinkedTo() (string, error)
	Md5() (string, error)
	Sha256() (string, error)
}

type DefFile struct {
	path     string
	realPath string
	fi       os.FileInfo
	loaded   bool
	err      error
}

func NewDefFile(path string, system *System, config util.Config) File {
	if !strings.HasPrefix(path, "~") {
		// FIXME: we probably shouldn't ignore errors here
		path, _ = filepath.Abs(path)
	}
	return &DefFile{path: path}
}

func (f *DefFile) setup() error {
	if f.loaded {
		return f.err
	}
	f.loaded = true
	if f.realPath, f.err = realPath(f.path); f.err != nil {
		return f.err
	}

	return f.err
}

func (f *DefFile) Path() string {
	return f.path
}

func (f *DefFile) Exists() (bool, error) {
	if err := f.setup(); err != nil {
		return false, err
	}

	if _, err := os.Lstat(f.realPath); os.IsNotExist(err) {
		return false, nil
	}
	return true, nil
}

func (f *DefFile) Contains() (io.Reader, error) {
	if err := f.setup(); err != nil {
		return nil, err
	}

	fh, err := os.Open(f.realPath)
	if err != nil {
		return nil, err
	}
	return fh, nil
}

func (f *DefFile) Mode() (string, error) {
	if err := f.setup(); err != nil {
		return "", err
	}

	fi, err := os.Lstat(f.realPath)
	if err != nil {
		return "", err
	}

	sys := fi.Sys()
	stat := sys.(*syscall.Stat_t)
	mode := fmt.Sprintf("%04o", (stat.Mode & 07777))
	return mode, nil
}

func (f *DefFile) Size() (int, error) {
	if err := f.setup(); err != nil {
		return 0, err
	}

	fi, err := os.Lstat(f.realPath)
	if err != nil {
		return 0, err
	}

	size := fi.Size()
	return int(size), nil
}

func (f *DefFile) Filetype() (string, error) {
	if err := f.setup(); err != nil {
		return "", err
	}

	fi, err := os.Lstat(f.realPath)
	if err != nil {
		return "", err
	}

	switch {
	case fi.Mode()&os.ModeSymlink == os.ModeSymlink:
		return "symlink", nil
	case fi.IsDir():
		return "directory", nil
	case fi.Mode().IsRegular():
		return "file", nil
	}
	// FIXME: file as a catchall?
	return "file", nil
}

func (f *DefFile) Owner() (string, error) {
	if err := f.setup(); err != nil {
		return "", err
	}

	fi, err := os.Lstat(f.realPath)
	if err != nil {
		return "", err
	}

	uidS := fmt.Sprint(fi.Sys().(*syscall.Stat_t).Uid)
	uid, err := strconv.Atoi(uidS)
	if err != nil {
		return "", err
	}
	return getUserForUid(uid)
}

func (f *DefFile) Group() (string, error) {
	if err := f.setup(); err != nil {
		return "", err
	}

	fi, err := os.Lstat(f.realPath)
	if err != nil {
		return "", err
	}

	gidS := fmt.Sprint(fi.Sys().(*syscall.Stat_t).Gid)
	gid, err := strconv.Atoi(gidS)
	if err != nil {
		return "", err
	}
	return getGroupForGid(gid)
}

func (f *DefFile) LinkedTo() (string, error) {
	if err := f.setup(); err != nil {
		return "", err
	}

	dst, err := os.Readlink(f.realPath)
	if err != nil {
		return "", err
	}
	return dst, nil
}

func realPath(path string) (string, error) {
	if !strings.HasPrefix(path, "~") {
		return path, nil
	}
	pathS := strings.Split(path, "/")
	f := pathS[0]

	var usr user.User
	var err error
	if f == "~" {
		usr, err = user.CurrentUser()
	} else {
		usr, err = user.LookupUser(f[1:len(f)])
	}
	if err != nil {
		return "", err
	}
	pathS[0] = usr.Home

	realPath := strings.Join(pathS, "/")
	realPath, err = filepath.Abs(realPath)

	return realPath, err
}

func (f *DefFile) Md5() (string, error) {

	if err := f.setup(); err != nil {
		return "", err
	}

	fh, err := os.Open(f.realPath)
	if err != nil {
		return "", err
	}
	defer fh.Close()

	hash := md5.New()
	if _, err := io.Copy(hash, fh); err != nil {
		return "", err
	}

	return fmt.Sprintf("%x", hash.Sum(nil)), nil
}

func (f *DefFile) Sha256() (string, error) {

	if err := f.setup(); err != nil {
		return "", err
	}

	fh, err := os.Open(f.realPath)
	if err != nil {
		return "", err
	}
	defer fh.Close()

	hash := sha256.New()
	if _, err := io.Copy(hash, fh); err != nil {
		return "", err
	}

	return fmt.Sprintf("%x", hash.Sum(nil)), nil
}

func getUserForUid(uid int) (string, error) {
	if user, err := user.LookupUid(uid); err == nil {
		return user.Name, nil
	}

	cmd := util.NewCommand("getent", "passwd", strconv.Itoa(uid))
	if err := cmd.Run(); err != nil {
		return "", fmt.Errorf("Error: no matching entries in passwd file. getent passwd: %v", err)
	}
	userS := strings.Split(cmd.Stdout.String(), ":")[0]

	return userS, nil
}

func getGroupForGid(gid int) (string, error) {
	if group, err := user.LookupGid(gid); err == nil {
		return group.Name, nil
	}

	cmd := util.NewCommand("getent", "group", strconv.Itoa(gid))
	if err := cmd.Run(); err != nil {
		return "", fmt.Errorf("Error: no matching entries in passwd file. getent group: %v", err)
	}
	groupS := strings.Split(cmd.Stdout.String(), ":")[0]

	return groupS, nil
}