ASCII text.  There are four ways to represent the integer value
as a numeric constant: <code>\x</code> followed by exactly two hexadecimal
digits; <code>\u</code> followed by exactly four hexadecimal digits;
<code>\U</code> followed by exactly eight hexadecimal digits, and a
plain backslash <code>\</code> followed by exactly three octal digits.
In each case the value of the literal is the value represented by
the digits in the corresponding base.

//   - Exactly 0 bytes are read and EOF is hit.
//   - Exactly 1 block of zeros is read and EOF is hit.
//   - At least 2 blocks of zeros are read.
func (tr *Reader) readHeader() (*Header, *block, error) {
	// Two blocks of zero bytes marks the end of the archive.
	if _, err := io.ReadFull(tr.r, tr.blk[:]); err != nil {
		return nil, nil, err // EOF is okay here; exactly 0 bytes read
	}

memory pinned using [runtime.Pinner]. This type may be used to manage
the duration of the memory's pinned status, potentially beyond the
duration of a C function call. Memory may be pinned more than once and
must be unpinned exactly the same number of times it has been pinned.

Go code may pass a Go pointer to C provided the memory to which it
points does not contain any Go pointers to memory that is unpinned. When

ASCII text.  There are four ways to represent the integer value
as a numeric constant: <code>\x</code> followed by exactly two hexadecimal
digits; <code>\u</code> followed by exactly four hexadecimal digits;
<code>\U</code> followed by exactly eight hexadecimal digits, and a
plain backslash <code>\</code> followed by exactly three octal digits.
In each case the value of the literal is the value represented by
the digits in the corresponding base.

<p>
Any implementation can, upon detecting a data race,
report the race and halt execution of the program.
Implementations using ThreadSanitizer
(accessed with “<code>go</code> <code>build</code> <code>-race</code>”)
do exactly this.
</p>

<p>
A read of an array, struct, or complex number
may by implemented as a read of each individual sub-value
(array element, struct field, or real/imaginary component),
in any order.

			t.Fatalf("Failed to read header: %s", err)
		}
		if header.Typeflag != TypeReg {
			t.Fatalf("Typeflag should've been %d, found %d", TypeReg, header.Typeflag)
		}
	}
}

// failOnceWriter fails exactly once and then always reports success.
type failOnceWriter bool

func (w *failOnceWriter) Write(b []byte) (int, error) {
	if !*w {
		return 0, io.ErrShortWrite
	}
	*w = true
	return len(b), nil
}