}},
	}}

	b.Run("Writer", func(b *testing.B) {
		for _, v := range vectors {
			b.Run(v.label, func(b *testing.B) {
				b.ReportAllocs()
				for i := 0; i < b.N; i++ {
					// Writing to io.Discard because we want to
					// test purely the writer code and not bring in disk performance into this.
					tw := NewWriter(io.Discard)
					for _, file := range v.files {
						if err := tw.WriteHeader(file.hdr); err != nil {

		if ok1 || ok2 {
			return ok1 && ok2
		}
		return x == y
	}
	for _, v := range vectors {
		t.Run(path.Base(v.file), func(t *testing.T) {
			const maxSize = 10 << 10 // 10KiB
			buf := new(bytes.Buffer)
			tw := NewWriter(iotest.TruncateWriter(buf, maxSize))

			for i, tf := range v.tests {
				switch tf := tf.(type) {
				case testHeader:
					err := tw.WriteHeader(&tf.hdr)

	}
	return readGNUSparseMap0x1(hdr.PAXRecords)
}

// mergePAX merges paxHdrs into hdr for all relevant fields of Header.
func mergePAX(hdr *Header, paxHdrs map[string]string) (err error) {
	for k, v := range paxHdrs {
		if v == "" {
			continue // Keep the original USTAR value
		}
		var id64 int64
		switch k {
		case paxPath:
			hdr.Name = v
		case paxLinkpath:
			hdr.Linkname = v
		case paxUname:

			return err
		}
		w.last = nil
	}
	if w.closed {
		return errors.New("zip: writer closed twice")
	}
	w.closed = true

	// write central directory
	start := w.cw.count
	for _, h := range w.dir {
		var buf [directoryHeaderLen]byte
		b := writeBuf(buf[:])
		b.uint32(uint32(directoryHeaderSignature))
		b.uint16(h.CreatorVersion)
		b.uint16(h.ReaderVersion)
		b.uint16(h.Flags)
		b.uint16(h.Method)

goroutines coordinate using the <code>limit</code> channel to ensure
that at most three are running work functions at a time.
</p>

<pre>
var limit = make(chan int, 3)

func main() {
	for _, w := range work {
		go func(w func()) {
			limit &lt;- 1
			w()
			&lt;-limit
		}(w)
	}
	select{}
}
</pre>

<h3 id="locks">Locks</h3>

<p>