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package packp
import (
"fmt"
"sort"
"strings"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/protocol/packp/capability"
"github.com/go-git/go-git/v5/plumbing/storer"
"github.com/go-git/go-git/v5/storage/memory"
)
// AdvRefs values represent the information transmitted on an
// advertised-refs message. Values from this type are not zero-value
// safe, use the New function instead.
type AdvRefs struct {
// Prefix stores prefix payloads.
//
// When using this message over (smart) HTTP, you have to add a pktline
// before the whole thing with the following payload:
//
// '# service=$servicename" LF
//
// Moreover, some (all) git HTTP smart servers will send a flush-pkt
// just after the first pkt-line.
//
// To accommodate both situations, the Prefix field allow you to store
// any data you want to send before the actual pktlines. It will also
// be filled up with whatever is found on the line.
Prefix [][]byte
// Head stores the resolved HEAD reference if present.
// This can be present with git-upload-pack, not with git-receive-pack.
Head *plumbing.Hash
// Capabilities are the capabilities.
Capabilities *capability.List
// References are the hash references.
References map[string]plumbing.Hash
// Peeled are the peeled hash references.
Peeled map[string]plumbing.Hash
// Shallows are the shallow object ids.
Shallows []plumbing.Hash
}
// NewAdvRefs returns a pointer to a new AdvRefs value, ready to be used.
func NewAdvRefs() *AdvRefs {
return &AdvRefs{
Prefix: [][]byte{},
Capabilities: capability.NewList(),
References: make(map[string]plumbing.Hash),
Peeled: make(map[string]plumbing.Hash),
Shallows: []plumbing.Hash{},
}
}
func (a *AdvRefs) AddReference(r *plumbing.Reference) error {
switch r.Type() {
case plumbing.SymbolicReference:
v := fmt.Sprintf("%s:%s", r.Name().String(), r.Target().String())
a.Capabilities.Add(capability.SymRef, v)
case plumbing.HashReference:
a.References[r.Name().String()] = r.Hash()
default:
return plumbing.ErrInvalidType
}
return nil
}
func (a *AdvRefs) AllReferences() (memory.ReferenceStorage, error) {
s := memory.ReferenceStorage{}
if err := a.addRefs(s); err != nil {
return s, plumbing.NewUnexpectedError(err)
}
return s, nil
}
func (a *AdvRefs) addRefs(s storer.ReferenceStorer) error {
for name, hash := range a.References {
ref := plumbing.NewReferenceFromStrings(name, hash.String())
if err := s.SetReference(ref); err != nil {
return err
}
}
if a.supportSymrefs() {
return a.addSymbolicRefs(s)
}
return a.resolveHead(s)
}
// If the server does not support symrefs capability,
// we need to guess the reference where HEAD is pointing to.
//
// Git versions prior to 1.8.4.3 has an special procedure to get
// the reference where is pointing to HEAD:
// - Check if a reference called master exists. If exists and it
// has the same hash as HEAD hash, we can say that HEAD is pointing to master
// - If master does not exists or does not have the same hash as HEAD,
// order references and check in that order if that reference has the same
// hash than HEAD. If yes, set HEAD pointing to that branch hash
// - If no reference is found, throw an error
func (a *AdvRefs) resolveHead(s storer.ReferenceStorer) error {
if a.Head == nil {
return nil
}
ref, err := s.Reference(plumbing.Master)
// check first if HEAD is pointing to master
if err == nil {
ok, err := a.createHeadIfCorrectReference(ref, s)
if err != nil {
return err
}
if ok {
return nil
}
}
if err != nil && err != plumbing.ErrReferenceNotFound {
return err
}
// From here we are trying to guess the branch that HEAD is pointing
refIter, err := s.IterReferences()
if err != nil {
return err
}
var refNames []string
err = refIter.ForEach(func(r *plumbing.Reference) error {
refNames = append(refNames, string(r.Name()))
return nil
})
if err != nil {
return err
}
sort.Strings(refNames)
var headSet bool
for _, refName := range refNames {
ref, err := s.Reference(plumbing.ReferenceName(refName))
if err != nil {
return err
}
ok, err := a.createHeadIfCorrectReference(ref, s)
if err != nil {
return err
}
if ok {
headSet = true
break
}
}
if !headSet {
return plumbing.ErrReferenceNotFound
}
return nil
}
func (a *AdvRefs) createHeadIfCorrectReference(
reference *plumbing.Reference,
s storer.ReferenceStorer) (bool, error) {
if reference.Hash() == *a.Head {
headRef := plumbing.NewSymbolicReference(plumbing.HEAD, reference.Name())
if err := s.SetReference(headRef); err != nil {
return false, err
}
return true, nil
}
return false, nil
}
func (a *AdvRefs) addSymbolicRefs(s storer.ReferenceStorer) error {
for _, symref := range a.Capabilities.Get(capability.SymRef) {
chunks := strings.Split(symref, ":")
if len(chunks) != 2 {
err := fmt.Errorf("bad number of `:` in symref value (%q)", symref)
return plumbing.NewUnexpectedError(err)
}
name := plumbing.ReferenceName(chunks[0])
target := plumbing.ReferenceName(chunks[1])
ref := plumbing.NewSymbolicReference(name, target)
if err := s.SetReference(ref); err != nil {
return nil
}
}
return nil
}
func (a *AdvRefs) supportSymrefs() bool {
return a.Capabilities.Supports(capability.SymRef)
}
// IsEmpty returns true if doesn't contain any reference.
func (a *AdvRefs) IsEmpty() bool {
return a.Head == nil &&
len(a.References) == 0 &&
len(a.Peeled) == 0 &&
len(a.Shallows) == 0
}
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