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//go:build ignore
// bin.go is a helper CLI to manipulate binary diff data for testing purposes.
// It can decode patches generated by git using the standard parsing functions
// or it can encode binary data back into the format expected by Git. It
// operates on stdin writes results (possibly binary) to stdout.
package main
import (
"bytes"
"compress/zlib"
"encoding/binary"
"flag"
"io/ioutil"
"log"
"os"
"strings"
"github.com/bluekeyes/go-gitdiff/gitdiff"
)
var (
b85Powers = []uint32{52200625, 614125, 7225, 85, 1}
b85Alpha = []byte(
"0123456789" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "!#$%&()*+-;<=>?@^_`{|}~",
)
)
var mode string
func base85Encode(data []byte) []byte {
chunks, remaining := len(data)/4, len(data)%4
if remaining > 0 {
data = append(data, make([]byte, 4-remaining)...)
chunks++
}
var n int
out := make([]byte, 5*chunks)
for i := 0; i < len(data); i += 4 {
v := binary.BigEndian.Uint32(data[i : i+4])
for j := 0; j < 5; j++ {
p := v / b85Powers[j]
out[n+j] = b85Alpha[p]
v -= b85Powers[j] * p
}
n += 5
}
return out
}
func compress(data []byte) ([]byte, error) {
var b bytes.Buffer
w := zlib.NewWriter(&b)
if _, err := w.Write(data); err != nil {
return nil, err
}
if err := w.Close(); err != nil {
return nil, err
}
return b.Bytes(), nil
}
func wrap(data []byte) string {
var s strings.Builder
for i := 0; i < len(data); i += 52 {
c := 52
if c > len(data)-i {
c = len(data) - i
}
b := (c / 5) * 4
if b <= 26 {
s.WriteByte(byte('A' + b - 1))
} else {
s.WriteByte(byte('a' + b - 27))
}
s.Write(data[i : i+c])
s.WriteByte('\n')
}
return s.String()
}
func init() {
flag.StringVar(&mode, "mode", "parse", "operation mode, one of 'parse' or 'encode'")
}
func main() {
flag.Parse()
switch mode {
case "parse":
files, _, err := gitdiff.Parse(os.Stdin)
if err != nil {
log.Fatalf("failed to parse file: %v", err)
}
if len(files) != 1 {
log.Fatalf("patch contains more than one file: %d", len(files))
}
if files[0].BinaryFragment == nil {
log.Fatalf("patch file does not contain a binary fragment")
}
os.Stdout.Write(files[0].BinaryFragment.Data)
case "encode":
data, err := ioutil.ReadAll(os.Stdin)
if err != nil {
log.Fatalf("failed to read input: %v", err)
}
data, err = compress(data)
if err != nil {
log.Fatalf("failed to compress data: %v", err)
}
os.Stdout.WriteString(wrap(base85Encode(data)))
default:
log.Fatalf("unknown mode: %s", mode)
}
}
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