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Diffstat (limited to 'libgo/go/encoding/git85/git.go')
-rw-r--r-- | libgo/go/encoding/git85/git.go | 276 |
1 files changed, 0 insertions, 276 deletions
diff --git a/libgo/go/encoding/git85/git.go b/libgo/go/encoding/git85/git.go deleted file mode 100644 index d383213..0000000 --- a/libgo/go/encoding/git85/git.go +++ /dev/null @@ -1,276 +0,0 @@ -// 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" - "strconv" -) - -type CorruptInputError int64 - -func (e CorruptInputError) Error() string { - return "illegal git85 data at input byte " + strconv.FormatInt(int64(e), 10) -} - -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 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 error - buf [52]byte - nbuf int - out [1024]byte - nout int -} - -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 < 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() 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 error - readErr error - buf [1024]byte - nbuf int - out []byte - outbuf [1024]byte - off int64 -} - -func (d *decoder) Read(p []byte) (n int, err 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("unreachable") -} |