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mirror of https://github.com/golang/go synced 2024-10-07 05:21:22 -06:00
go/src/pkg/patch/git.go
Robert Griesemer d65a5cce89 1) Change default gofmt default settings for
parsing and printing to new syntax.

   Use -oldparser to parse the old syntax,
   use -oldprinter to print the old syntax.

2) Change default gofmt formatting settings
   to use tabs for indentation only and to use
   spaces for alignment. This will make the code
   alignment insensitive to an editor's tabwidth.

   Use -spaces=false to use tabs for alignment.

3) Manually changed src/exp/parser/parser_test.go
   so that it doesn't try to parse the parser's
   source files using the old syntax (they have
   new syntax now).

4) gofmt -w src misc test/bench

4th set of files.

R=rsc
CC=golang-dev
https://golang.org/cl/180049
2009-12-15 15:40:16 -08:00

122 lines
2.7 KiB
Go

// 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 patch
import (
"bytes"
"compress/zlib"
"crypto/sha1"
"encoding/git85"
"fmt"
"io"
"os"
)
func gitSHA1(data []byte) []byte {
if len(data) == 0 {
// special case: 0 length is all zeros sum
return make([]byte, 20)
}
h := sha1.New()
fmt.Fprintf(h, "blob %d\x00", len(data))
h.Write(data)
return h.Sum()
}
// BUG(rsc): The Git binary delta format is not implemented, only Git binary literals.
// GitBinaryLiteral represents a Git binary literal diff.
type GitBinaryLiteral struct {
OldSHA1 []byte // if non-empty, the SHA1 hash of the original
New []byte // the new contents
}
// Apply implements the Diff interface's Apply method.
func (d *GitBinaryLiteral) Apply(old []byte) ([]byte, os.Error) {
if sum := gitSHA1(old); !bytes.HasPrefix(sum, d.OldSHA1) {
return nil, ErrPatchFailure
}
return d.New, nil
}
func unhex(c byte) uint8 {
switch {
case '0' <= c && c <= '9':
return c - '0'
case 'a' <= c && c <= 'f':
return c - 'a' + 10
case 'A' <= c && c <= 'F':
return c - 'A' + 10
}
return 255
}
func getHex(s []byte) (data []byte, rest []byte) {
n := 0
for n < len(s) && unhex(s[n]) != 255 {
n++
}
n &^= 1 // Only take an even number of hex digits.
data = make([]byte, n/2)
for i := range data {
data[i] = unhex(s[2*i])<<4 | unhex(s[2*i+1])
}
rest = s[n:]
return
}
// ParseGitBinary parses raw as a Git binary patch.
func ParseGitBinary(raw []byte) (Diff, os.Error) {
var oldSHA1, newSHA1 []byte
var sawBinary bool
for {
var first []byte
first, raw, _ = getLine(raw, 1)
first = bytes.TrimSpace(first)
if s, ok := skip(first, "index "); ok {
oldSHA1, s = getHex(s)
if s, ok = skip(s, ".."); !ok {
continue
}
newSHA1, s = getHex(s)
continue
}
if _, ok := skip(first, "GIT binary patch"); ok {
sawBinary = true
continue
}
if n, _, ok := atoi(first, "literal ", 10); ok && sawBinary {
data := make([]byte, n)
d := git85.NewDecoder(bytes.NewBuffer(raw))
z, err := zlib.NewInflater(d)
if err != nil {
return nil, err
}
defer z.Close()
if _, err = io.ReadFull(z, data); err != nil {
if err == os.EOF {
err = io.ErrUnexpectedEOF
}
return nil, err
}
var buf [1]byte
m, err := z.Read(&buf)
if m != 0 || err != os.EOF {
return nil, os.NewError("Git binary literal longer than expected")
}
if sum := gitSHA1(data); !bytes.HasPrefix(sum, newSHA1) {
return nil, os.NewError("Git binary literal SHA1 mismatch")
}
return &GitBinaryLiteral{oldSHA1, data}, nil
}
if !sawBinary {
return nil, os.NewError("unexpected Git patch header: " + string(first))
}
}
panic("unreachable")
}