<p class="rule">
For any call to <code>l.RLock</code> on a <code>sync.RWMutex</code> variable <code>l</code>,
there is an <i>n</i> such that the <i>n</i>th call to <code>l.Unlock</code>
is synchronized before the return from <code>l.RLock</code>,
and the matching call to <code>l.RUnlock</code> is synchronized before the return from call <i>n</i>+1 to <code>l.Lock</code>.
</p>

<p class="rule">

pkg syscall (linux-amd64-cgo), type Flock_t struct, Pad_cgo_0 [4]uint8
pkg syscall (linux-amd64-cgo), type Flock_t struct, Pad_cgo_1 [4]uint8
pkg syscall (linux-amd64-cgo), type Flock_t struct, Pid int32
pkg syscall (linux-amd64-cgo), type Flock_t struct, Start int64
pkg syscall (linux-amd64-cgo), type Flock_t struct, Type int16
pkg syscall (linux-amd64-cgo), type Flock_t struct, Whence int16

	    and ends at the end of the innermost containing block.</li>

	<li>The scope of a type identifier declared inside a function
	    begins at the identifier in the TypeSpec
	    and ends at the end of the innermost containing block.</li>
</ol>

<p>
An identifier declared in a block may be redeclared in an inner block.
While the identifier of the inner declaration is in scope, it denotes

pkg syscall (netbsd-arm64), const LOCK_EX = 2
pkg syscall (netbsd-arm64), const LOCK_EX ideal-int
pkg syscall (netbsd-arm64), const LOCK_NB = 4
pkg syscall (netbsd-arm64), const LOCK_NB ideal-int
pkg syscall (netbsd-arm64), const LOCK_SH = 1
pkg syscall (netbsd-arm64), const LOCK_SH ideal-int
pkg syscall (netbsd-arm64), const LOCK_UN = 8
pkg syscall (netbsd-arm64), const LOCK_UN ideal-int

			b.Write(buf[:1])
		}
	}
}

func BenchmarkBufferWriteBlock(b *testing.B) {
	block := make([]byte, 1024)
	for _, n := range []int{1 << 12, 1 << 16, 1 << 20} {
		b.Run(fmt.Sprintf("N%d", n), func(b *testing.B) {
			b.ReportAllocs()
			for i := 0; i < b.N; i++ {
				var bb Buffer
				for bb.Len() < n {
					bb.Write(block)
				}
			}
		})
	}
}

func BenchmarkBufferAppendNoCopy(b *testing.B) {

	// callback(x) calls goCallback(x)
	callbackMutex.Lock()
	callbackToken++
	i := callbackToken
	callbackFuncs[i] = f
	callbackMutex.Unlock()

	// Pass the address of i because the C function was written to
	// take a pointer.  We could pass an int if we felt like
	// rewriting the C code.
	C.callback(unsafe.Pointer(&i))

	callbackMutex.Lock()
	delete(callbackFuncs, i)
	callbackMutex.Unlock()
}

pkg crypto, type Decrypter interface, Public() PublicKey
pkg crypto, type DecrypterOpts interface {}
pkg crypto/cipher, func NewGCMWithNonceSize(Block, int) (AEAD, error)
pkg crypto/elliptic, type CurveParams struct, Name string
pkg crypto/rsa, method (*PrivateKey) Decrypt(io.Reader, []uint8, crypto.DecrypterOpts) ([]uint8, error)
pkg crypto/rsa, type OAEPOptions struct

pkg encoding/pem, func Decode([]uint8) (*Block, []uint8)
pkg encoding/pem, func Encode(io.Writer, *Block) error
pkg encoding/pem, func EncodeToMemory(*Block) []uint8
pkg encoding/pem, type Block struct
pkg encoding/pem, type Block struct, Bytes []uint8
pkg encoding/pem, type Block struct, Headers map[string]string
pkg encoding/pem, type Block struct, Type string
pkg encoding/xml, const Header ideal-string

pkg syscall (freebsd-arm64), const LOCK_EX = 2
pkg syscall (freebsd-arm64), const LOCK_EX ideal-int
pkg syscall (freebsd-arm64), const LOCK_NB = 4
pkg syscall (freebsd-arm64), const LOCK_NB ideal-int
pkg syscall (freebsd-arm64), const LOCK_SH = 1
pkg syscall (freebsd-arm64), const LOCK_SH ideal-int
pkg syscall (freebsd-arm64), const LOCK_UN = 8
pkg syscall (freebsd-arm64), const LOCK_UN ideal-int

		}
		pre = cur
	}
	return true
}

// alignSparseEntries mutates src and returns dst where each fragment's
// starting offset is aligned up to the nearest block edge, and each
// ending offset is aligned down to the nearest block edge.
//
// Even though the Go tar Reader and the BSD tar utility can handle entries
// with arbitrary offsets and lengths, the GNU tar utility can only handle