const (
	// Type '0' indicates a regular file.
	TypeReg = '0'

	// Deprecated: Use TypeReg instead.
	TypeRegA = '\x00'

	// Type '1' to '6' are header-only flags and may not have a data body.
	TypeLink    = '1' // Hard link
	TypeSymlink = '2' // Symbolic link
	TypeChar    = '3' // Character device node
	TypeBlock   = '4' // Block device node
	TypeDir     = '5' // Directory
	TypeFifo    = '6' // FIFO node

	// Type '7' is reserved.

in an assembly source file within the math/rand package implementation,
the package's Int function can be referred to as <code>·Int</code>.
This convention avoids the need to hard-code a package's import path in its
own source code, making it easier to move the code from one location to another.
</p>

<h3 id="directives">Directives</h3>

<p>

			Name:     "sticky.txt",
			Mode:     0600 | c_ISVTX,
			Size:     7,
			ModTime:  time.Unix(1360602540, 0),
			Typeflag: TypeReg,
		},
		fm: 0600 | fs.ModeSticky,
	}, {
		// hard link.
		h: &Header{
			Name:     "hard.txt",
			Mode:     0644,
			Size:     0,
			Linkname: "file.txt",
			ModTime:  time.Unix(1360600916, 0),
			Typeflag: TypeLink,
		},
		fm: 0644,
	}, {
		// More information.

			testWrite{"hello\n", 6, nil},
			testClose{nil},
		},
	}, {
		// This file was produced using GNU tar v1.26:
		//	echo "Slartibartfast" > file.txt
		//	ln file.txt hard.txt
		//	tar -b 1 --format=ustar -c -f hardlink.tar file.txt hard.txt
		file: "testdata/hardlink.tar",
		tests: []testFnc{
			testHeader{Header{
				Typeflag: TypeReg,
				Name:     "file.txt",
				Size:     15,
				Mode:     0644,

}

var listCache sync.Map // map[string]listImports, keyed by contextName

// listSem is a semaphore restricting concurrent invocations of 'go list'. 'go
// list' has its own internal concurrency, so we use a hard-coded constant (to
// allow the I/O-intensive phases of 'go list' to overlap) instead of scaling
// all the way up to GOMAXPROCS.
var listSem = make(chan semToken, 2)

type semToken struct{}