// application can only parse GNU formatted archives.
	//
	// Reference:
	//	https://www.gnu.org/software/tar/manual/html_node/Standard.html
	FormatGNU

	// Schily's tar format, which is incompatible with USTAR.
	// This does not cover STAR extensions to the PAX format; these fall under
	// the PAX format.
	formatSTAR

	formatMax
)

// Scanner reads more data and continues scanning; if there is no more
// data--if atEOF was true--the [Scanner] returns. If the data does not
// yet hold a complete token, for instance if it has no newline while
// scanning lines, a [SplitFunc] can return (0, nil, nil) to signal the
// [Scanner] to read more data into the slice and try again with a
// longer slice starting at the same point in the input.
//

	tw.pad = blockPadding(size)
	return nil
}

// AddFS adds the files from fs.FS to the archive.
// It walks the directory tree starting at the root of the filesystem
// adding each file to the tar archive while maintaining the directory structure.
func (tw *Writer) AddFS(fsys fs.FS) error {
	return fs.WalkDir(fsys, ".", func(name string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {

			b := got.AvailableBuffer()
			b = strconv.AppendInt(b, int64(i), 10)
			got.Write(b)
		}
	})
	if n > 0 {
		t.Errorf("allocations occurred while appending")
	}
}

func TestRuneIO(t *testing.T) {
	const NRune = 1000
	// Built a test slice while we write the data
	b := make([]byte, utf8.UTFMax*NRune)
	var buf Buffer
	n := 0
	for r := rune(0); r < NRune; r++ {
		size := utf8.EncodeRune(b[n:], r)

points to is pinned.

C code may not keep a copy of a Go pointer after the call returns,
unless the memory it points to is pinned with [runtime.Pinner] and the
Pinner is not unpinned while the Go pointer is stored in C memory.
This implies that C code may not keep a copy of a string, slice,
channel, and so forth, because they cannot be pinned with
[runtime.Pinner].

		{"☺☻☹", "日a本b語ç", "27 ☺☻☹=日a本b語ç\n", true},
		{"xhello", "\x00world", "17 xhello=\x00world\n", true},
		{"path", "null\x00", "", false},
		{"null\x00", "value", "", false},
		{paxSchilyXattr + "key", "null\x00", "26 SCHILY.xattr.key=null\x00\n", true},
	}

	for _, v := range vectors {
		got, err := formatPAXRecord(v.inKey, v.inVal)
		ok := (err == nil)
		if ok != v.ok {
			if v.ok {

	for i := 0; i < 100; i++ {
		// Obtain a buffer to append to.
		b := w.AvailableBuffer()
		if w.Available() != cap(b) {
			t.Fatalf("Available() = %v, want %v", w.Available(), cap(b))
		}

		// While not recommended, it is valid to append to a shifted buffer.
		// This forces Write to copy the input.
		if rn.Intn(8) == 0 && cap(b) > 0 {
			b = b[1:1:cap(b)]
		}

		// Append a random integer of varying width.

				"atime":                         "1389782991.41987522",
				"ctime":                         "1389782956.794414986",
				"SCHILY.xattr.user.key":         "value",
				"SCHILY.xattr.user.key2":        "value2",
				"SCHILY.xattr.security.selinux": "unconfined_u:object_r:default_t:s0\x00",
			},
			Format: FormatPAX,
		}, {
			Name:       "small2.txt",
			Mode:       0644,

	Devminor int64 // Minor device number (valid for TypeChar or TypeBlock)

	// Xattrs stores extended attributes as PAX records under the
	// "SCHILY.xattr." namespace.
	//
	// The following are semantically equivalent:
	//  h.Xattrs[key] = value
	//  h.PAXRecords["SCHILY.xattr."+key] = value
	//
	// When Writer.WriteHeader is called, the contents of Xattrs will take
	// precedence over those in PAXRecords.
	//

// #include <unistd.h>
// #include <sys/types.h>
//
// pthread_t *t = NULL;
// pthread_mutex_t mu;
// int nts = 0;
// int all_done = 0;
//
// static void *aFn(void *vargp) {
//   int done = 0;
//   while (!done) {
//     usleep(100);
//     pthread_mutex_lock(&mu);
//     done = all_done;
//     pthread_mutex_unlock(&mu);
//   }
//   return NULL;
// }
//
// void trial(int argc) {
//   int i;