package filemode
import (
"encoding/binary"
"fmt"
"os"
"strconv"
)
// A FileMode represents the kind of tree entries used by git. It
// resembles regular file systems modes, although FileModes are
// considerably simpler (there are not so many), and there are some,
// like Submodule that has no file system equivalent.
type FileMode uint32
const (
// Empty is used as the FileMode of tree elements when comparing
// trees in the following situations:
//
// - the mode of tree elements before their creation. - the mode of
// tree elements after their deletion. - the mode of unmerged
// elements when checking the index.
//
// Empty has no file system equivalent. As Empty is the zero value
// of FileMode, it is also returned by New and
// NewFromOsNewFromOSFileMode along with an error, when they fail.
Empty FileMode = 0
// Dir represent a Directory.
Dir FileMode = 0040000
// Regular represent non-executable files. Please note this is not
// the same as golang regular files, which include executable files.
Regular FileMode = 0100644
// Deprecated represent non-executable files with the group writable
// bit set. This mode was supported by the first versions of git,
// but it has been deprecatred nowadays. This library uses them
// internally, so you can read old packfiles, but will treat them as
// Regulars when interfacing with the outside world. This is the
// standard git behaviuor.
Deprecated FileMode = 0100664
// Executable represents executable files.
Executable FileMode = 0100755
// Symlink represents symbolic links to files.
Symlink FileMode = 0120000
// Submodule represents git submodules. This mode has no file system
// equivalent.
Submodule FileMode = 0160000
)
// New takes the octal string representation of a FileMode and returns
// the FileMode and a nil error. If the string can not be parsed to a
// 32 bit unsigned octal number, it returns Empty and the parsing error.
//
// Example: "40000" means Dir, "100644" means Regular.
//
// Please note this function does not check if the returned FileMode
// is valid in git or if it is malformed. For instance, "1" will
// return the malformed FileMode(1) and a nil error.
func New(s string) (FileMode, error) {
n, err := strconv.ParseUint(s, 8, 32)
if err != nil {
return Empty, err
}
return FileMode(n), nil
}
// NewFromOSFileMode returns the FileMode used by git to represent
// the provided file system modes and a nil error on success. If the
// file system mode cannot be mapped to any valid git mode (as with
// sockets or named pipes), it will return Empty and an error.
//
// Note that some git modes cannot be generated from os.FileModes, like
// Deprecated and Submodule; while Empty will be returned, along with an
// error, only when the method fails.
func NewFromOSFileMode(m os.FileMode) (FileMode, error) {
if m.IsRegular() {
if isSetTemporary(m) {
return Empty, fmt.Errorf("no equivalent git mode for %s", m)
}
if isSetCharDevice(m) {
return Empty, fmt.Errorf("no equivalent git mode for %s", m)
}
if isSetUserExecutable(m) {
return Executable, nil
}
return Regular, nil
}
if m.IsDir() {
return Dir, nil
}
if isSetSymLink(m) {
return Symlink, nil
}
return Empty, fmt.Errorf("no equivalent git mode for %s", m)
}
func isSetCharDevice(m os.FileMode) bool {
return m&os.ModeCharDevice != 0
}
func isSetTemporary(m os.FileMode) bool {
return m&os.ModeTemporary != 0
}
func isSetUserExecutable(m os.FileMode) bool {
return m&0100 != 0
}
func isSetSymLink(m os.FileMode) bool {
return m&os.ModeSymlink != 0
}
// Bytes return a slice of 4 bytes with the mode in little endian
// encoding.
func (m FileMode) Bytes() []byte {
ret := make([]byte, 4)
binary.LittleEndian.PutUint32(ret, uint32(m))
return ret[:]
}
// IsMalformed returns if the FileMode should not appear in a git packfile,
// this is: Empty and any other mode not mentioned as a constant in this
// package.
func (m FileMode) IsMalformed() bool {
return m != Dir &&
m != Regular &&
m != Deprecated &&
m != Executable &&
m != Symlink &&
m != Submodule
}
// String returns the FileMode as a string in the standatd git format,
// this is, an octal number padded with ceros to 7 digits. Malformed
// modes are printed in that same format, for easier debugging.
//
// Example: Regular is "0100644", Empty is "0000000".
func (m FileMode) String() string {
return fmt.Sprintf("%07o", uint32(m))
}
// IsRegular returns if the FileMode represents that of a regular file,
// this is, either Regular or Deprecated. Please note that Executable
// are not regular even though in the UNIX tradition, they usually are:
// See the IsFile method.
func (m FileMode) IsRegular() bool {
return m == Regular ||
m == Deprecated
}
// IsFile returns if the FileMode represents that of a file, this is,
// Regular, Deprecated, Excutable or Link.
func (m FileMode) IsFile() bool {
return m == Regular ||
m == Deprecated ||
m == Executable ||
m == Symlink
}
// ToOSFileMode returns the os.FileMode to be used when creating file
// system elements with the given git mode and a nil error on success.
//
// When the provided mode cannot be mapped to a valid file system mode
// (e.g. Submodule) it returns os.FileMode(0) and an error.
//
// The returned file mode does not take into account the umask.
func (m FileMode) ToOSFileMode() (os.FileMode, error) {
switch m {
case Dir:
return os.ModePerm | os.ModeDir, nil
case Submodule:
return os.ModePerm | os.ModeDir, nil
case Regular:
return os.FileMode(0644), nil
// Deprecated is no longer allowed: treated as a Regular instead
case Deprecated:
return os.FileMode(0644), nil
case Executable:
return os.FileMode(0755), nil
case Symlink:
return os.ModePerm | os.ModeSymlink, nil
}
return os.FileMode(0), fmt.Errorf("malformed mode (%s)", m)
}
