Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 521 insertions, 0 deletions

diff --git a/src/encoding/ascii85/ascii85.go b/src/encoding/ascii85/ascii85.go
new file mode 100644
index 0000000..1f1fb00
--- /dev/null
+++ b/src/encoding/ascii85/ascii85.go
@@ -0,0 +1,307 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ascii85 implements the ascii85 data encoding
+// as used in the btoa tool and Adobe's PostScript and PDF document formats.
+package ascii85
+
+import (
+	"io"
+	"strconv"
+)
+
+/*
+ * Encoder
+ */
+
+// Encode encodes src into at most MaxEncodedLen(len(src))
+// bytes of dst, returning the actual number of bytes written.
+//
+// The encoding handles 4-byte chunks, using a special encoding
+// for the last fragment, so Encode is not appropriate for use on
+// individual blocks of a large data stream. Use NewEncoder() instead.
+//
+// Often, ascii85-encoded data is wrapped in <~ and ~> symbols.
+// Encode does not add these.
+func Encode(dst, src []byte) int {
+	if len(src) == 0 {
+		return 0
+	}
+
+	n := 0
+	for len(src) > 0 {
+		dst[0] = 0
+		dst[1] = 0
+		dst[2] = 0
+		dst[3] = 0
+		dst[4] = 0
+
+		// Unpack 4 bytes into uint32 to repack into base 85 5-byte.
+		var v uint32
+		switch len(src) {
+		default:
+			v |= uint32(src[3])
+			fallthrough
+		case 3:
+			v |= uint32(src[2]) << 8
+			fallthrough
+		case 2:
+			v |= uint32(src[1]) << 16
+			fallthrough
+		case 1:
+			v |= uint32(src[0]) << 24
+		}
+
+		// Special case: zero (!!!!!) shortens to z.
+		if v == 0 && len(src) >= 4 {
+			dst[0] = 'z'
+			dst = dst[1:]
+			src = src[4:]
+			n++
+			continue
+		}
+
+		// Otherwise, 5 base 85 digits starting at !.
+		for i := 4; i >= 0; i-- {
+			dst[i] = '!' + byte(v%85)
+			v /= 85
+		}
+
+		// If src was short, discard the low destination bytes.
+		m := 5
+		if len(src) < 4 {
+			m -= 4 - len(src)
+			src = nil
+		} else {
+			src = src[4:]
+		}
+		dst = dst[m:]
+		n += m
+	}
+	return n
+}
+
+// MaxEncodedLen returns the maximum length of an encoding of n source bytes.
+func MaxEncodedLen(n int) int { return (n + 3) / 4 * 5 }
+
+// NewEncoder returns a new ascii85 stream encoder. Data written to
+// the returned writer will be encoded and then written to w.
+// Ascii85 encodings operate in 32-bit blocks; when finished
+// writing, the caller must Close the returned encoder to flush any
+// trailing partial block.
+func NewEncoder(w io.Writer) io.WriteCloser { return &encoder{w: w} }
+
+type encoder struct {
+	err  error
+	w    io.Writer
+	buf  [4]byte    // buffered data waiting to be encoded
+	nbuf int        // number of bytes in buf
+	out  [1024]byte // output buffer
+}
+
+func (e *encoder) Write(p []byte) (n int, err error) {
+	if e.err != nil {
+		return 0, e.err
+	}
+
+	// Leading fringe.
+	if e.nbuf > 0 {
+		var i int
+		for i = 0; i < len(p) && e.nbuf < 4; i++ {
+			e.buf[e.nbuf] = p[i]
+			e.nbuf++
+		}
+		n += i
+		p = p[i:]
+		if e.nbuf < 4 {
+			return
+		}
+		nout := Encode(e.out[0:], e.buf[0:])
+		if _, e.err = e.w.Write(e.out[0:nout]); e.err != nil {
+			return n, e.err
+		}
+		e.nbuf = 0
+	}
+
+	// Large interior chunks.
+	for len(p) >= 4 {
+		nn := len(e.out) / 5 * 4
+		if nn > len(p) {
+			nn = len(p)
+		}
+		nn -= nn % 4
+		if nn > 0 {
+			nout := Encode(e.out[0:], p[0:nn])
+			if _, e.err = e.w.Write(e.out[0:nout]); e.err != nil {
+				return n, e.err
+			}
+		}
+		n += nn
+		p = p[nn:]
+	}
+
+	// Trailing fringe.
+	copy(e.buf[:], p)
+	e.nbuf = len(p)
+	n += len(p)
+	return
+}
+
+// Close flushes any pending output from the encoder.
+// It is an error to call Write after calling Close.
+func (e *encoder) Close() error {
+	// If there's anything left in the buffer, flush it out
+	if e.err == nil && e.nbuf > 0 {
+		nout := Encode(e.out[0:], e.buf[0:e.nbuf])
+		e.nbuf = 0
+		_, e.err = e.w.Write(e.out[0:nout])
+	}
+	return e.err
+}
+
+/*
+ * Decoder
+ */
+
+type CorruptInputError int64
+
+func (e CorruptInputError) Error() string {
+	return "illegal ascii85 data at input byte " + strconv.FormatInt(int64(e), 10)
+}
+
+// Decode decodes src into dst, returning both the number
+// of bytes written to dst and the number consumed from src.
+// If src contains invalid ascii85 data, Decode will return the
+// number of bytes successfully written and a CorruptInputError.
+// Decode ignores space and control characters in src.
+// Often, ascii85-encoded data is wrapped in <~ and ~> symbols.
+// Decode expects these to have been stripped by the caller.
+//
+// If flush is true, Decode assumes that src represents the
+// end of the input stream and processes it completely rather
+// than wait for the completion of another 32-bit block.
+//
+// NewDecoder wraps an io.Reader interface around Decode.
+func Decode(dst, src []byte, flush bool) (ndst, nsrc int, err error) {
+	var v uint32
+	var nb int
+	for i, b := range src {
+		if len(dst)-ndst < 4 {
+			return
+		}
+		switch {
+		case b <= ' ':
+			continue
+		case b == 'z' && nb == 0:
+			nb = 5
+			v = 0
+		case '!' <= b && b <= 'u':
+			v = v*85 + uint32(b-'!')
+			nb++
+		default:
+			return 0, 0, CorruptInputError(i)
+		}
+		if nb == 5 {
+			nsrc = i + 1
+			dst[ndst] = byte(v >> 24)
+			dst[ndst+1] = byte(v >> 16)
+			dst[ndst+2] = byte(v >> 8)
+			dst[ndst+3] = byte(v)
+			ndst += 4
+			nb = 0
+			v = 0
+		}
+	}
+	if flush {
+		nsrc = len(src)
+		if nb > 0 {
+			// The number of output bytes in the last fragment
+			// is the number of leftover input bytes - 1:
+			// the extra byte provides enough bits to cover
+			// the inefficiency of the encoding for the block.
+			if nb == 1 {
+				return 0, 0, CorruptInputError(len(src))
+			}
+			for i := nb; i < 5; i++ {
+				// The short encoding truncated the output value.
+				// We have to assume the worst case values (digit 84)
+				// in order to ensure that the top bits are correct.
+				v = v*85 + 84
+			}
+			for i := 0; i < nb-1; i++ {
+				dst[ndst] = byte(v >> 24)
+				v <<= 8
+				ndst++
+			}
+		}
+	}
+	return
+}
+
+// NewDecoder constructs a new ascii85 stream decoder.
+func NewDecoder(r io.Reader) io.Reader { return &decoder{r: r} }
+
+type decoder struct {
+	err     error
+	readErr error
+	r       io.Reader
+	buf     [1024]byte // leftover input
+	nbuf    int
+	out     []byte // leftover decoded output
+	outbuf  [1024]byte
+}
+
+func (d *decoder) Read(p []byte) (n int, err error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+	if d.err != nil {
+		return 0, d.err
+	}
+
+	for {
+		// Copy leftover output from last decode.
+		if len(d.out) > 0 {
+			n = copy(p, d.out)
+			d.out = d.out[n:]
+			return
+		}
+
+		// Decode leftover input from last read.
+		var nn, nsrc, ndst int
+		if d.nbuf > 0 {
+			ndst, nsrc, d.err = Decode(d.outbuf[0:], d.buf[0:d.nbuf], d.readErr != nil)
+			if ndst > 0 {
+				d.out = d.outbuf[0:ndst]
+				d.nbuf = copy(d.buf[0:], d.buf[nsrc:d.nbuf])
+				continue // copy out and return
+			}
+			if ndst == 0 && d.err == nil {
+				// Special case: input buffer is mostly filled with non-data bytes.
+				// Filter out such bytes to make room for more input.
+				off := 0
+				for i := 0; i < d.nbuf; i++ {
+					if d.buf[i] > ' ' {
+						d.buf[off] = d.buf[i]
+						off++
+					}
+				}
+				d.nbuf = off
+			}
+		}
+
+		// Out of input, out of decoded output. Check errors.
+		if d.err != nil {
+			return 0, d.err
+		}
+		if d.readErr != nil {
+			d.err = d.readErr
+			return 0, d.err
+		}
+
+		// Read more data.
+		nn, d.readErr = d.r.Read(d.buf[d.nbuf:])
+		d.nbuf += nn
+	}
+}
diff --git a/src/encoding/ascii85/ascii85_test.go b/src/encoding/ascii85/ascii85_test.go
new file mode 100644
index 0000000..578829e
--- /dev/null
+++ b/src/encoding/ascii85/ascii85_test.go
@@ -0,0 +1,214 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ascii85
+
+import (
+	"bytes"
+	"io"
+	"strings"
+	"testing"
+)
+
+type testpair struct {
+	decoded, encoded string
+}
+
+var bigtest = testpair{
+	"Man is distinguished, not only by his reason, but by this singular passion from " +
+		"other animals, which is a lust of the mind, that by a perseverance of delight in " +
+		"the continued and indefatigable generation of knowledge, exceeds the short " +
+		"vehemence of any carnal pleasure.",
+	"9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,\n" +
+		"O<DJ+*.@<*K0@<6L(Df-\\0Ec5e;DffZ(EZee.Bl.9pF\"AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKY\n" +
+		"i(DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIa\n" +
+		"l(DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs`8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G\n" +
+		">uD.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c\n",
+}
+
+var pairs = []testpair{
+	// Encode returns 0 when len(src) is 0
+	{
+		"",
+		"",
+	},
+	// Wikipedia example
+	bigtest,
+	// Special case when shortening !!!!! to z.
+	{
+		"\000\000\000\000",
+		"z",
+	},
+}
+
+func testEqual(t *testing.T, msg string, args ...any) bool {
+	t.Helper()
+	if args[len(args)-2] != args[len(args)-1] {
+		t.Errorf(msg, args...)
+		return false
+	}
+	return true
+}
+
+func strip85(s string) string {
+	t := make([]byte, len(s))
+	w := 0
+	for r := 0; r < len(s); r++ {
+		c := s[r]
+		if c > ' ' {
+			t[w] = c
+			w++
+		}
+	}
+	return string(t[0:w])
+}
+
+func TestEncode(t *testing.T) {
+	for _, p := range pairs {
+		buf := make([]byte, MaxEncodedLen(len(p.decoded)))
+		n := Encode(buf, []byte(p.decoded))
+		buf = buf[0:n]
+		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, strip85(string(buf)), strip85(p.encoded))
+	}
+}
+
+func TestEncoder(t *testing.T) {
+	for _, p := range pairs {
+		bb := &strings.Builder{}
+		encoder := NewEncoder(bb)
+		encoder.Write([]byte(p.decoded))
+		encoder.Close()
+		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, strip85(bb.String()), strip85(p.encoded))
+	}
+}
+
+func TestEncoderBuffering(t *testing.T) {
+	input := []byte(bigtest.decoded)
+	for bs := 1; bs <= 12; bs++ {
+		bb := &strings.Builder{}
+		encoder := NewEncoder(bb)
+		for pos := 0; pos < len(input); pos += bs {
+			end := pos + bs
+			if end > len(input) {
+				end = len(input)
+			}
+			n, err := encoder.Write(input[pos:end])
+			testEqual(t, "Write(%q) gave error %v, want %v", input[pos:end], err, error(nil))
+			testEqual(t, "Write(%q) gave length %v, want %v", input[pos:end], n, end-pos)
+		}
+		err := encoder.Close()
+		testEqual(t, "Close gave error %v, want %v", err, error(nil))
+		testEqual(t, "Encoding/%d of %q = %q, want %q", bs, bigtest.decoded, strip85(bb.String()), strip85(bigtest.encoded))
+	}
+}
+
+func TestDecode(t *testing.T) {
+	for _, p := range pairs {
+		dbuf := make([]byte, 4*len(p.encoded))
+		ndst, nsrc, err := Decode(dbuf, []byte(p.encoded), true)
+		testEqual(t, "Decode(%q) = error %v, want %v", p.encoded, err, error(nil))
+		testEqual(t, "Decode(%q) = nsrc %v, want %v", p.encoded, nsrc, len(p.encoded))
+		testEqual(t, "Decode(%q) = ndst %v, want %v", p.encoded, ndst, len(p.decoded))
+		testEqual(t, "Decode(%q) = %q, want %q", p.encoded, string(dbuf[0:ndst]), p.decoded)
+	}
+}
+
+func TestDecoder(t *testing.T) {
+	for _, p := range pairs {
+		decoder := NewDecoder(strings.NewReader(p.encoded))
+		dbuf, err := io.ReadAll(decoder)
+		if err != nil {
+			t.Fatal("Read failed", err)
+		}
+		testEqual(t, "Read from %q = length %v, want %v", p.encoded, len(dbuf), len(p.decoded))
+		testEqual(t, "Decoding of %q = %q, want %q", p.encoded, string(dbuf), p.decoded)
+		if err != nil {
+			testEqual(t, "Read from %q = %v, want %v", p.encoded, err, io.EOF)
+		}
+	}
+}
+
+func TestDecoderBuffering(t *testing.T) {
+	for bs := 1; bs <= 12; bs++ {
+		decoder := NewDecoder(strings.NewReader(bigtest.encoded))
+		buf := make([]byte, len(bigtest.decoded)+12)
+		var total int
+		var n int
+		var err error
+		for total = 0; total < len(bigtest.decoded) && err == nil; {
+			n, err = decoder.Read(buf[total : total+bs])
+			total += n
+		}
+		if err != nil && err != io.EOF {
+			t.Errorf("Read from %q at pos %d = %d, unexpected error %v", bigtest.encoded, total, n, err)
+		}
+		testEqual(t, "Decoding/%d of %q = %q, want %q", bs, bigtest.encoded, string(buf[0:total]), bigtest.decoded)
+	}
+}
+
+func TestDecodeCorrupt(t *testing.T) {
+	type corrupt struct {
+		e string
+		p int
+	}
+	examples := []corrupt{
+		{"v", 0},
+		{"!z!!!!!!!!!", 1},
+	}
+
+	for _, e := range examples {
+		dbuf := make([]byte, 4*len(e.e))
+		_, _, err := Decode(dbuf, []byte(e.e), true)
+		switch err := err.(type) {
+		case CorruptInputError:
+			testEqual(t, "Corruption in %q at offset %v, want %v", e.e, int(err), e.p)
+		default:
+			t.Error("Decoder failed to detect corruption in", e)
+		}
+	}
+}
+
+func TestBig(t *testing.T) {
+	n := 3*1000 + 1
+	raw := make([]byte, n)
+	const alpha = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	for i := 0; i < n; i++ {
+		raw[i] = alpha[i%len(alpha)]
+	}
+	encoded := new(bytes.Buffer)
+	w := NewEncoder(encoded)
+	nn, err := w.Write(raw)
+	if nn != n || err != nil {
+		t.Fatalf("Encoder.Write(raw) = %d, %v want %d, nil", nn, err, n)
+	}
+	err = w.Close()
+	if err != nil {
+		t.Fatalf("Encoder.Close() = %v want nil", err)
+	}
+	decoded, err := io.ReadAll(NewDecoder(encoded))
+	if err != nil {
+		t.Fatalf("io.ReadAll(NewDecoder(...)): %v", err)
+	}
+
+	if !bytes.Equal(raw, decoded) {
+		var i int
+		for i = 0; i < len(decoded) && i < len(raw); i++ {
+			if decoded[i] != raw[i] {
+				break
+			}
+		}
+		t.Errorf("Decode(Encode(%d-byte string)) failed at offset %d", n, i)
+	}
+}
+
+func TestDecoderInternalWhitespace(t *testing.T) {
+	s := strings.Repeat(" ", 2048) + "z"
+	decoded, err := io.ReadAll(NewDecoder(strings.NewReader(s)))
+	if err != nil {
+		t.Errorf("Decode gave error %v", err)
+	}
+	if want := []byte("\000\000\000\000"); !bytes.Equal(want, decoded) {
+		t.Errorf("Decode failed: got %v, want %v", decoded, want)
+	}
+}