// Readlink returns the destination of the named symbolic link.
// If there is an error, it will be of type *PathError.
func Readlink(name string) (string, error) {
for len := 128; ; len *= 2 {
b := make([]byte, len)
n, e := syscall.Readlink(name, b)
if e != nil {
return "", &PathError{"readlink", name, e}
}
if n < len {
return string(b[0:n]), nil
}
}
}
// Readlink reads the contents of a symbolic link: the destination of
// the link. It returns the contents and an Error, if any.
func Readlink(name string) (string, Error) {
for len := 128; ; len *= 2 {
b := make([]byte, len)
n, e := syscall.Readlink(name, b)
if e != 0 {
return "", &PathError{"readlink", name, Errno(e)}
}
if n < len {
return string(b[0:n]), nil
}
}
// Silence 6g.
return "", nil
}
// GetFdName returns file name for given descriptor.
func GetFdName(fd uintptr) (name string, err error) {
path := fmt.Sprintf("/proc/self/fd/%d", int(fd))
var (
fi os.FileInfo
n int
)
if fi, err = os.Lstat(path); err != nil {
return
}
buf := make([]byte, fi.Size()+1)
if n, err = syscall.Readlink(path, buf); err == nil {
name = string(buf[:n])
}
return
}
// Readlink returns the file pointed to by the given soft link, or an error of
// type PathError otherwise. This mimics the os.Readlink() function, but works
// around a bug we've seen in CentOS 5.10 (kernel 2.6.27.10 on x86_64) where the
// underlying OS function readlink() returns a wrong number of bytes for the
// result (see man readlink). Here we don't rely blindly on that value; if
// there's a zero byte among that number of bytes, then we keep only up to that
// point.
//
// NOTE: We chose not to use os.Readlink() and then search on its result to
// avoid an extra overhead of converting back to []byte. The function to search
// for a byte over the string itself (strings.IndexByte()) is only available
// starting with Go 1.2. Also, we're not searching at every iteration to save
// some CPU time, even though that could mean extra iterations for systems
// affected with this bug. But it's wiser to optimize for the general case
// (i.e., those not affected).
func Readlink(name string) (string, error) {
for len := 128; ; len *= 2 {
b := make([]byte, len)
n, e := syscall.Readlink(name, b)
if e != nil {
return "", &os.PathError{"readlink", name, e}
}
if n < len {
if z := bytes.IndexByte(b[:n], 0); z >= 0 {
n = z
}
return string(b[:n]), nil
}
}
}
func open(_relative *cursor, _relativePath string) (*cursor, Error) {
var _path string
if _relative != nil {
_path = path.Join(_relative.entity.Path, _relativePath)
} else {
_path = _relativePath
}
var _descriptor, _errno int
var _stat syscall.Stat_t
var _link string
_descriptor = -1
_errno = syscall.Lstat(_path, &_stat)
if _errno == 0 {
var _flags int = syscall.O_NOCTTY | syscall.O_NOFOLLOW | syscall.O_CLOEXEC | syscall.O_LARGEFILE | syscall.O_NOATIME
var _mode uint32 = syscall.O_RDONLY
for {
if ((_stat.Mode & syscall.S_IFMT) != syscall.S_IFREG) && ((_stat.Mode & syscall.S_IFMT) != syscall.S_IFDIR) {
break
}
if _relative != nil {
_descriptor, _errno = syscall.Openat(_relative.entity.Descriptor, _relativePath, _flags, _mode)
} else {
_descriptor, _errno = syscall.Open(_relativePath, _flags, _mode)
}
if (_errno == syscall.EPERM) && ((_flags & syscall.O_NOATIME) == syscall.O_NOATIME) {
_flags &= ^syscall.O_NOATIME
continue
} else {
break
}
}
switch {
case _errno == 0:
_errno = syscall.Fstat(_descriptor, &_stat)
case _errno == syscall.EACCES:
_descriptor = -1
case _errno == syscall.ELOOP:
_descriptor = -1
case _errno == syscall.ENOENT:
return nil, newError("open", _path, -1, _errno)
case _errno != 0:
_descriptor = -1
}
if (_errno == 0) && ((_stat.Mode & syscall.S_IFMT) == syscall.S_IFLNK) {
var _linkBuffer [syscall.PathMax + 1]byte
var _linkLimit int
_linkLimit, _errno = syscall.Readlink(_path, _linkBuffer[:])
if _errno == 0 {
_link = string(_linkBuffer[:_linkLimit])
}
}
if (_errno != 0) && (_descriptor >= 0) {
syscall.Close(_descriptor)
_descriptor = -1
}
}
_entity := new(Entity)
_entity.Name = path.Base(_path)
_entity.Path = _path
_entity.Errno = _errno
_entity.Stat = _stat
_entity.Link = _link
_entity.Descriptor = _descriptor
_cursor := new(cursor)
_cursor.parent = _relative
_cursor.entity = _entity
return _cursor, nil
}
func ext۰syscall۰Readlink(fr *frame, args []value) value {
path := args[0].(string)
buf := valueToBytes(args[1])
n, err := syscall.Readlink(path, buf)
return tuple{n, wrapError(err)}
}