var errNegativeRead = errors.New("bytes.Buffer: reader returned negative count from Read")

const maxInt = int(^uint(0) >> 1)

// Bytes returns a slice of length b.Len() holding the unread portion of the buffer.
// The slice is valid for use only until the next buffer modification (that is,
// only until the next call to a method like [Buffer.Read], [Buffer.Write], [Buffer.Reset], or [Buffer.Truncate]).

The [RuneLen] function returns the number of 16-bit words in
the UTF-16 encoding of the rune. It returns -1 if the rune

	if len(record) != size {
		size = len(record)
		record = strconv.Itoa(size) + " " + k + "=" + v + "\n"
	}
	return record, nil
}

// validPAXRecord reports whether the key-value pair is valid where each
// record is formatted as:
//
//	"%d %s=%s\n" % (size, key, value)
//
// Keys and values should be UTF-8, but the number of bad writers out there
// forces us to be a more liberal.

pkg net, method (*UDPConn) WriteToUDPAddrPort([]uint8, netip.AddrPort) (int, error)
pkg net, type Error interface, Temporary //deprecated
pkg net/http, func MaxBytesHandler(Handler, int64) Handler
pkg net/http, method (*Cookie) Valid() error
pkg net/netip, func AddrFrom16([16]uint8) Addr
pkg net/netip, func AddrFrom4([4]uint8) Addr
pkg net/netip, func AddrFromSlice([]uint8) (Addr, bool)
pkg net/netip, func AddrPortFrom(Addr, uint16) AddrPort

pkg encoding/base32, const StdPadding = 61
pkg encoding/base32, const StdPadding int32
pkg encoding/base32, method (Encoding) WithPadding(int32) *Encoding
pkg encoding/csv, type Reader struct, ReuseRecord bool
pkg encoding/json, func Valid([]uint8) bool
pkg go/ast, type TypeSpec struct, Assign token.Pos
pkg go/types, func SizesFor(string, string) Sizes
pkg go/types, method (*TypeName) IsAlias() bool
pkg hash/fnv, func New128() hash.Hash

func (b *block) toUSTAR() *headerUSTAR { return (*headerUSTAR)(b) }
func (b *block) toSparse() sparseArray { return sparseArray(b[:]) }

// getFormat checks that the block is a valid tar header based on the checksum.
// It then attempts to guess the specific format based on magic values.
// If the checksum fails, then FormatUnknown is returned.
func (b *block) getFormat() Format {
	// Verify checksum.

	//
	// This flag should only be set if the user intends to encode a non-portable
	// ZIP file for a specific localized region. Otherwise, the Writer
	// automatically sets the ZIP format's UTF-8 flag for valid UTF-8 strings.
	NonUTF8 bool

	CreatorVersion uint16
	ReaderVersion  uint16
	Flags          uint16

	// Method is the compression method. If zero, Store is used.
	Method uint16

	// Fast path 1: ASCII.
	if data[0] < utf8.RuneSelf {
		return 1, data[0:1], nil
	}

	// Fast path 2: Correct UTF-8 decode without error.
	_, width := utf8.DecodeRune(data)
	if width > 1 {
		// It's a valid encoding. Width cannot be one for a correctly encoded
		// non-ASCII rune.
		return width, data[0:width], nil
	}

	// We know it's an error: we have width==1 and implicitly r==utf8.RuneError.

	vectors := []struct {
		input string // Input stream
		cnt   int    // Expected number of headers read
		err   error  // Expected error outcome
	}{
		{"", 0, io.EOF}, // Empty file is a "valid" tar file
		{data1[:511], 0, io.ErrUnexpectedEOF},
		{data1[:512], 1, io.ErrUnexpectedEOF},
		{data1[:1024], 1, io.EOF},
		{data1[:1536], 2, io.ErrUnexpectedEOF},
		{data1[:2048], 2, io.EOF},
		{data1, 2, io.EOF},

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This contains the majority of valid opcode combinations
// available in cmd/internal/obj/ppc64/asm9.go with
// their valid instruction encodings.

#include "../../../../../runtime/textflag.h"

// In case of index mode instructions, usage of
// (Rx)(R0) is equivalent to (Rx+R0)