//go:cgo_dynamic_linker "/lib64/ld-linux-x86-64.so.2"
	//go:cgo_import_dynamic puts puts#GLIBC_2.2.5 "libc.so.6"
	//go:cgo_import_dynamic __libc_start_main __libc_start_main#GLIBC_2.2.5 "libc.so.6"
	//go:cgo_import_dynamic stdout stdout#GLIBC_2.2.5 "libc.so.6"
	//go:cgo_import_dynamic fflush fflush#GLIBC_2.2.5 "libc.so.6"
	//go:cgo_import_dynamic _ _ "libpthread.so.0"
	//go:cgo_import_dynamic _ _ "libc.so.6"

	// Two different parses: once with comments, once without.
	// The printer is not good enough at printing comments in the
	// right place when we start editing the AST behind its back,
	// so we use ast1 to look for the doc comments on import "C"
	// and on exported functions, and we use ast2 for translating
	// and reprinting.
	// In cgo mode, we ignore ast2 and just apply edits directly

	var cap0 int
	for i := 0; i < 5<<10; i++ {
		b.Write(buf)
		b.Read(buf)
		if i == 0 {
			cap0 = b.Cap()
		}
	}
	cap1 := b.Cap()
	// (*Buffer).grow allows for 2x capacity slop before sliding,
	// so set our error threshold at 3x.
	if cap1 > cap0*3 {
		t.Errorf("buffer cap = %d; too big (grew from %d)", cap1, cap0)
	}
}

func BenchmarkWriteByte(b *testing.B) {
	const n = 4 << 10
	b.SetBytes(n)

	buf      []byte // contents are the bytes buf[off : len(buf)]
	off      int    // read at &buf[off], write at &buf[len(buf)]
	lastRead readOp // last read operation, so that Unread* can work correctly.
}

// The readOp constants describe the last action performed on
// the buffer, so that UnreadRune and UnreadByte can check for
// invalid usage. opReadRuneX constants are chosen such that
// converted to int they correspond to the rune size that was read.

used to refer to frame-local variables and the arguments being
prepared for function calls.
It points to the highest address within the local stack frame, so references should use negative offsets
in the range [−framesize, 0):
<code>x-8(SP)</code>, <code>y-4(SP)</code>, and so on.
</p>

<p>
On architectures with a hardware register named <code>SP</code>,
the name prefix distinguishes

enabling the HTTP/2 use by the HTTP client broke programs
connecting to servers with buggy HTTP/2 implementations.
These kinds of changes are unavoidable and
[permitted by the Go 1 compatibility rules](/doc/go1compat).
Even so, Go provides a mechanism called GODEBUG to
reduce the impact such changes have on Go developers
using newer toolchains to compile old code.

A GODEBUG setting is a `key=value` pair

		for _, f := range r.File {
			if f.Name == "" {
				// Zip permits an empty file name field.
				continue
			}
			// The zip specification states that names must use forward slashes,
			// so consider any backslashes in the name insecure.
			if !filepath.IsLocal(f.Name) || strings.Contains(f.Name, `\`) {
				zipinsecurepath.IncNonDefault()
				return ErrInsecurePath
			}
		}
	}
	return nil
}

	paxGNUSparseRealSize  = "GNU.sparse.realsize"
)

// basicKeys is a set of the PAX keys for which we have built-in support.
// This does not contain "charset" or "comment", which are both PAX-specific,
// so adding them as first-class features of Header is unlikely.
// Users can use the PAXRecords field to set it themselves.
var basicKeys = map[string]bool{
	paxPath: true, paxLinkpath: true, paxSize: true, paxUid: true, paxGid: true,

// output are interpreted as UTF-8-encoded code points.
func Map(mapping func(r rune) rune, s []byte) []byte {
	// In the worst case, the slice can grow when mapped, making
	// things unpleasant. But it's so rare we barge in assuming it's
	// fine. It could also shrink but that falls out naturally.
	b := make([]byte, 0, len(s))
	for i := 0; i < len(s); {
		wid := 1
		r := rune(s[i])
		if r >= utf8.RuneSelf {

		// or space is needed.
		if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
			copy(s.buf, s.buf[s.start:s.end])
			s.end -= s.start
			s.start = 0
		}
		// Is the buffer full? If so, resize.
		if s.end == len(s.buf) {
			// Guarantee no overflow in the multiplication below.
			const maxInt = int(^uint(0) >> 1)
			if len(s.buf) >= s.maxTokenSize || len(s.buf) > maxInt/2 {
				s.setErr(ErrTooLong)