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-rw-r--r--libgo/go/encoding/git85/git.go277
-rw-r--r--libgo/go/encoding/git85/git_test.go194
2 files changed, 471 insertions, 0 deletions
diff --git a/libgo/go/encoding/git85/git.go b/libgo/go/encoding/git85/git.go
new file mode 100644
index 000000000..09a45cd3c
--- /dev/null
+++ b/libgo/go/encoding/git85/git.go
@@ -0,0 +1,277 @@
+// 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 git85 implements the radix 85 data encoding
+// used in the Git version control system.
+package git85
+
+import (
+ "bytes"
+ "io"
+ "os"
+ "strconv"
+)
+
+type CorruptInputError int64
+
+func (e CorruptInputError) String() string {
+ return "illegal git85 data at input byte " + strconv.Itoa64(int64(e))
+}
+
+const encode = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"
+
+// The decodings are 1+ the actual value, so that the
+// default zero value can be used to mean "not valid".
+var decode = [256]uint8{
+ '0': 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
+ 'A': 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
+ 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
+ 'a': 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
+ 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62,
+ '!': 63,
+ '#': 64, 65, 66, 67,
+ '(': 68, 69, 70, 71,
+ '-': 72,
+ ';': 73,
+ '<': 74, 75, 76, 77,
+ '@': 78,
+ '^': 79, 80, 81,
+ '{': 82, 83, 84, 85,
+}
+
+// Encode encodes src into EncodedLen(len(src))
+// bytes of dst. As a convenience, it returns the number
+// of bytes written to dst, but this value is always EncodedLen(len(src)).
+// Encode implements the radix 85 encoding used in the
+// Git version control tool.
+//
+// The encoding splits src into chunks of at most 52 bytes
+// and encodes each chunk on its own line.
+func Encode(dst, src []byte) int {
+ ndst := 0
+ for len(src) > 0 {
+ n := len(src)
+ if n > 52 {
+ n = 52
+ }
+ if n <= 27 {
+ dst[ndst] = byte('A' + n - 1)
+ } else {
+ dst[ndst] = byte('a' + n - 26 - 1)
+ }
+ ndst++
+ for i := 0; i < n; i += 4 {
+ var v uint32
+ for j := 0; j < 4 && i+j < n; j++ {
+ v |= uint32(src[i+j]) << uint(24-j*8)
+ }
+ for j := 4; j >= 0; j-- {
+ dst[ndst+j] = encode[v%85]
+ v /= 85
+ }
+ ndst += 5
+ }
+ dst[ndst] = '\n'
+ ndst++
+ src = src[n:]
+ }
+ return ndst
+}
+
+// EncodedLen returns the length of an encoding of n source bytes.
+func EncodedLen(n int) int {
+ if n == 0 {
+ return 0
+ }
+ // 5 bytes per 4 bytes of input, rounded up.
+ // 2 extra bytes for each line of 52 src bytes, rounded up.
+ return (n+3)/4*5 + (n+51)/52*2
+}
+
+var newline = []byte{'\n'}
+
+// Decode decodes src into at most MaxDecodedLen(len(src))
+// bytes, returning the actual number of bytes written to dst.
+//
+// If Decode encounters invalid input, it returns a CorruptInputError.
+//
+func Decode(dst, src []byte) (n int, err os.Error) {
+ ndst := 0
+ nsrc := 0
+ for nsrc < len(src) {
+ var l int
+ switch ch := int(src[nsrc]); {
+ case 'A' <= ch && ch <= 'Z':
+ l = ch - 'A' + 1
+ case 'a' <= ch && ch <= 'z':
+ l = ch - 'a' + 26 + 1
+ default:
+ return ndst, CorruptInputError(nsrc)
+ }
+ if nsrc+1+l > len(src) {
+ return ndst, CorruptInputError(nsrc)
+ }
+ el := (l + 3) / 4 * 5 // encoded len
+ if nsrc+1+el+1 > len(src) || src[nsrc+1+el] != '\n' {
+ return ndst, CorruptInputError(nsrc)
+ }
+ line := src[nsrc+1 : nsrc+1+el]
+ for i := 0; i < el; i += 5 {
+ var v uint32
+ for j := 0; j < 5; j++ {
+ ch := decode[line[i+j]]
+ if ch == 0 {
+ return ndst, CorruptInputError(nsrc + 1 + i + j)
+ }
+ v = v*85 + uint32(ch-1)
+ }
+ for j := 0; j < 4; j++ {
+ dst[ndst] = byte(v >> 24)
+ v <<= 8
+ ndst++
+ }
+ }
+ // Last fragment may have run too far (but there was room in dst).
+ // Back up.
+ if l%4 != 0 {
+ ndst -= 4 - l%4
+ }
+ nsrc += 1 + el + 1
+ }
+ return ndst, nil
+}
+
+func MaxDecodedLen(n int) int { return n / 5 * 4 }
+
+// NewEncoder returns a new Git base85 stream encoder. Data written to
+// the returned writer will be encoded and then written to w.
+// The Git encoding operates on 52-byte blocks; when finished
+// writing, the caller must Close the returned encoder to flush any
+// partially written blocks.
+func NewEncoder(w io.Writer) io.WriteCloser { return &encoder{w: w} }
+
+type encoder struct {
+ w io.Writer
+ err os.Error
+ buf [52]byte
+ nbuf int
+ out [1024]byte
+ nout int
+}
+
+func (e *encoder) Write(p []byte) (n int, err os.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 < 52; i++ {
+ e.buf[e.nbuf] = p[i]
+ e.nbuf++
+ }
+ n += i
+ p = p[i:]
+ if e.nbuf < 52 {
+ 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) >= 52 {
+ nn := len(e.out) / (1 + 52/4*5 + 1) * 52
+ if nn > len(p) {
+ nn = len(p) / 52 * 52
+ }
+ 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.
+ for i := 0; i < len(p); i++ {
+ e.buf[i] = p[i]
+ }
+ e.nbuf = len(p)
+ n += len(p)
+ return
+}
+
+func (e *encoder) Close() os.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
+}
+
+// NewDecoder returns a new Git base85 stream decoder.
+func NewDecoder(r io.Reader) io.Reader { return &decoder{r: r} }
+
+type decoder struct {
+ r io.Reader
+ err os.Error
+ readErr os.Error
+ buf [1024]byte
+ nbuf int
+ out []byte
+ outbuf [1024]byte
+ off int64
+}
+
+func (d *decoder) Read(p []byte) (n int, err os.Error) {
+ if len(p) == 0 {
+ return 0, nil
+ }
+
+ for {
+ // Copy leftover output from last decode.
+ if len(d.out) > 0 {
+ n = copy(p, d.out)
+ d.out = d.out[n:]
+ return
+ }
+
+ // 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 and decode more input.
+ var nn int
+ nn, d.readErr = d.r.Read(d.buf[d.nbuf:])
+ d.nbuf += nn
+
+ // Send complete lines to Decode.
+ nl := bytes.LastIndex(d.buf[0:d.nbuf], newline)
+ if nl < 0 {
+ continue
+ }
+ nn, d.err = Decode(d.outbuf[0:], d.buf[0:nl+1])
+ if e, ok := d.err.(CorruptInputError); ok {
+ d.err = CorruptInputError(int64(e) + d.off)
+ }
+ d.out = d.outbuf[0:nn]
+ d.nbuf = copy(d.buf[0:], d.buf[nl+1:d.nbuf])
+ d.off += int64(nl + 1)
+ }
+ panic("unreacahable")
+}
diff --git a/libgo/go/encoding/git85/git_test.go b/libgo/go/encoding/git85/git_test.go
new file mode 100644
index 000000000..c76385c35
--- /dev/null
+++ b/libgo/go/encoding/git85/git_test.go
@@ -0,0 +1,194 @@
+// 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 git85
+
+import (
+ "bytes"
+ "io/ioutil"
+ "os"
+ "testing"
+)
+
+type testpair struct {
+ decoded, encoded string
+}
+
+func testEqual(t *testing.T, msg string, args ...interface{}) bool {
+ if args[len(args)-2] != args[len(args)-1] {
+ t.Errorf(msg, args...)
+ return false
+ }
+ return true
+}
+
+func TestGitTable(t *testing.T) {
+ var saw [256]bool
+ for i, c := range encode {
+ if decode[c] != uint8(i+1) {
+ t.Errorf("decode['%c'] = %d, want %d", c, decode[c], i+1)
+ }
+ saw[c] = true
+ }
+ for i, b := range saw {
+ if !b && decode[i] != 0 {
+ t.Errorf("decode[%d] = %d, want 0", i, decode[i])
+ }
+ }
+}
+
+var gitPairs = []testpair{
+ // Wikipedia example, adapted.
+ {
+ "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.",
+
+ "zO<`^zX>%ZCX>)XGZfA9Ab7*B`EFf-gbRchTY<VDJc_3(Mb0BhMVRLV8EFfZabRc4R\n" +
+ "zAarPHb0BkRZfA9DVR9gFVRLh7Z*CxFa&K)QZ**v7av))DX>DO_b1WctXlY|;AZc?T\n" +
+ "zVIXXEb95kYW*~HEWgu;7Ze%PVbZB98AYyqSVIXj2a&u*NWpZI|V`U(3W*}r`Y-wj`\n" +
+ "zbRcPNAarPDAY*TCbZKsNWn>^>Ze$>7Ze(R<VRUI{VPb4$AZKN6WpZJ3X>V>IZ)PBC\n" +
+ "zZf|#NWn^b%EFfigV`XJzb0BnRWgv5CZ*p`Xc4cT~ZDnp_Wgu^6AYpEKAY);2ZeeU7\n" +
+ "IaBO8^b9HiME&u=k\n",
+ },
+}
+
+var gitBigtest = gitPairs[len(gitPairs)-1]
+
+func TestEncode(t *testing.T) {
+ for _, p := range gitPairs {
+ buf := make([]byte, EncodedLen(len(p.decoded)))
+ n := Encode(buf, []byte(p.decoded))
+ if n != len(buf) {
+ t.Errorf("EncodedLen does not agree with Encode")
+ }
+ buf = buf[0:n]
+ testEqual(t, "Encode(%q) = %q, want %q", p.decoded, string(buf), p.encoded)
+ }
+}
+
+func TestEncoder(t *testing.T) {
+ for _, p := range gitPairs {
+ bb := &bytes.Buffer{}
+ encoder := NewEncoder(bb)
+ encoder.Write([]byte(p.decoded))
+ encoder.Close()
+ testEqual(t, "Encode(%q) = %q, want %q", p.decoded, bb.String(), p.encoded)
+ }
+}
+
+func TestEncoderBuffering(t *testing.T) {
+ input := []byte(gitBigtest.decoded)
+ for bs := 1; bs <= 12; bs++ {
+ bb := &bytes.Buffer{}
+ 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, os.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, os.Error(nil))
+ testEqual(t, "Encoding/%d of %q = %q, want %q", bs, gitBigtest.decoded, bb.String(), gitBigtest.encoded)
+ }
+}
+
+func TestDecode(t *testing.T) {
+ for _, p := range gitPairs {
+ dbuf := make([]byte, 4*len(p.encoded))
+ ndst, err := Decode(dbuf, []byte(p.encoded))
+ testEqual(t, "Decode(%q) = error %v, want %v", p.encoded, err, os.Error(nil))
+ 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 gitPairs {
+ decoder := NewDecoder(bytes.NewBufferString(p.encoded))
+ dbuf, err := ioutil.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, os.EOF)
+ }
+ }
+}
+
+func TestDecoderBuffering(t *testing.T) {
+ for bs := 1; bs <= 12; bs++ {
+ decoder := NewDecoder(bytes.NewBufferString(gitBigtest.encoded))
+ buf := make([]byte, len(gitBigtest.decoded)+12)
+ var total int
+ for total = 0; total < len(gitBigtest.decoded); {
+ n, err := decoder.Read(buf[total : total+bs])
+ testEqual(t, "Read from %q at pos %d = %d, %v, want _, %v", gitBigtest.encoded, total, n, err, os.Error(nil))
+ total += n
+ }
+ testEqual(t, "Decoding/%d of %q = %q, want %q", bs, gitBigtest.encoded, string(buf[0:total]), gitBigtest.decoded)
+ }
+}
+
+func TestDecodeCorrupt(t *testing.T) {
+ type corrupt struct {
+ e string
+ p int
+ }
+ examples := []corrupt{
+ {"v", 0},
+ {"!z!!!!!!!!!", 0},
+ }
+
+ for _, e := range examples {
+ dbuf := make([]byte, 2*len(e.e))
+ _, err := Decode(dbuf, []byte(e.e))
+ 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 TestGitBig(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 := ioutil.ReadAll(NewDecoder(encoded))
+ if err != nil {
+ t.Fatalf("ioutil.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)
+ }
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-26 08:15:25 +0000