forked from git-lfs/git-lfs
/
pointer.go
164 lines (134 loc) · 3.32 KB
/
pointer.go
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package lfs
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"regexp"
"strconv"
"strings"
)
var (
v1Aliases = []string{
"http://git-media.io/v/2", // alpha
"https://hawser.github.com/spec/v1", // pre-release
"https://git-lfs.github.com/spec/v1", // public launch
}
latest = "https://git-lfs.github.com/spec/v1"
oidType = "sha256"
oidRE = regexp.MustCompile(`\A[0-9a-fA-F]{64}`)
template = `version %s
oid sha256:%s
size %d
`
matcherRE = regexp.MustCompile("git-media|hawser|git-lfs")
pointerKeys = []string{"version", "oid", "size"}
)
type Pointer struct {
Version string
Oid string
Size int64
OidType string
}
func NewPointer(oid string, size int64) *Pointer {
return &Pointer{latest, oid, size, oidType}
}
func (p *Pointer) Smudge(writer io.Writer, workingfile string, cb CopyCallback) error {
return PointerSmudge(writer, p, workingfile, cb)
}
func (p *Pointer) Encode(writer io.Writer) (int, error) {
return EncodePointer(writer, p)
}
func (p *Pointer) Encoded() string {
return fmt.Sprintf(template, latest, p.Oid, p.Size)
}
func EncodePointer(writer io.Writer, pointer *Pointer) (int, error) {
return writer.Write([]byte(pointer.Encoded()))
}
func DecodePointer(reader io.Reader) (*Pointer, error) {
_, p, err := DecodeFrom(reader)
return p, err
}
func DecodeFrom(reader io.Reader) ([]byte, *Pointer, error) {
buf := make([]byte, 512)
written, err := reader.Read(buf)
if err != nil {
return buf, nil, err
}
output := buf[0:written]
p, err := decodeKV(bytes.TrimSpace(output))
return output, p, err
}
func verifyVersion(version string) error {
if len(version) == 0 {
return errors.New("Missing version")
}
for _, v := range v1Aliases {
if v == version {
return nil
}
}
return errors.New("Invalid version: " + version)
}
func decodeKV(data []byte) (*Pointer, error) {
parsed, err := decodeKVData(data)
if err != nil {
return nil, err
}
if err := verifyVersion(parsed["version"]); err != nil {
return nil, err
}
oidValue, ok := parsed["oid"]
if !ok {
return nil, errors.New("Invalid Oid")
}
oidParts := strings.SplitN(oidValue, ":", 2)
if len(oidParts) != 2 {
return nil, errors.New("Invalid Oid type in" + oidValue)
}
if oidParts[0] != oidType {
return nil, errors.New("Invalid Oid type: " + oidParts[0])
}
oid := oidParts[1]
var size int64
sizeStr, ok := parsed["size"]
if !ok {
return nil, errors.New("Invalid Oid")
} else {
size, err = strconv.ParseInt(sizeStr, 10, 0)
if err != nil {
return nil, errors.New("Invalid size: " + sizeStr)
}
}
return NewPointer(oid, size), nil
}
func decodeKVData(data []byte) (map[string]string, error) {
m := make(map[string]string)
if !matcherRE.Match(data) {
return m, fmt.Errorf("Not a valid Git LFS pointer file.")
}
scanner := bufio.NewScanner(bytes.NewBuffer(data))
line := 0
numKeys := len(pointerKeys)
for scanner.Scan() {
text := scanner.Text()
if len(text) == 0 {
continue
}
parts := strings.SplitN(text, " ", 2)
key := parts[0]
if numKeys <= line {
return m, fmt.Errorf("Extra line: %s", text)
}
if expected := pointerKeys[line]; key != expected {
return m, fmt.Errorf("Expected key %s, got %s", expected, key)
}
line += 1
if len(parts) < 2 {
return m, fmt.Errorf("Error reading line %d: %s", line, text)
}
m[key] = parts[1]
}
return m, scanner.Err()
}