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