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package furgit
import (
"bufio"
"bytes"
"errors"
"os"
"strings"
)
// ResolveRef resolves a fully qualified ref name to its object ID.
func (repo *Repository) ResolveRef(refname string) (Hash, error) {
id, err := repo.resolveLooseRef(refname)
if err == nil {
return id, nil
} else if !errors.Is(err, ErrNotFound) {
return Hash{}, err
}
return repo.resolvePackedRef(refname)
}
func (repo *Repository) resolveLooseRef(refname string) (Hash, error) {
data, err := os.ReadFile(repo.repoPath(refname))
if err != nil {
if os.IsNotExist(err) {
return Hash{}, ErrNotFound
}
return Hash{}, err
}
line := strings.TrimSpace(string(data))
id, err := repo.ParseHash(line)
if err != nil {
return Hash{}, err
}
return id, nil
}
func (repo *Repository) resolvePackedRef(refname string) (Hash, error) {
path := repo.repoPath("packed-refs")
f, err := os.Open(path)
if err != nil {
if os.IsNotExist(err) {
return Hash{}, ErrNotFound
}
return Hash{}, err
}
defer func() { _ = f.Close() }()
want := []byte(refname)
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := scanner.Bytes()
if len(line) == 0 || line[0] == '#' || line[0] == '^' {
continue
}
sp := bytes.IndexByte(line, ' ')
if sp != repo.hashSize*2 {
continue
}
name := line[sp+1:]
if bytes.Equal(name, want) {
hex := string(line[:sp])
id, err := repo.ParseHash(hex)
if err != nil {
return Hash{}, err
}
return id, nil
}
}
scanErr := scanner.Err()
if scanErr != nil {
return Hash{}, scanErr
}
return Hash{}, ErrNotFound
}
// HeadKind represents the kind of HEAD reference.
type HeadKind int
const (
// The HEAD reference is invalid.
HeadKindInvalid HeadKind = iota
// The HEAD reference points to a detached commit hash.
HeadKindDetached
// The HEAD reference points to a symbolic ref.
HeadKindSymbolic
)
// HeadRef represents a HEAD reference.
type HeadRef struct {
// Kind is the kind of HEAD reference.
Kind HeadKind
// When Kind is HeadSymbolic, Ref is the fully qualified ref name.
Ref string
// When Kind is HeadDetached, Hash is the commit hash.
Hash Hash
}
// ResolveHead reads HEAD into a HEAD reference.
func (repo *Repository) ResolveHead() (HeadRef, error) {
data, err := os.ReadFile(repo.repoPath("HEAD"))
if err != nil {
return HeadRef{Kind: HeadKindInvalid}, err
}
line := strings.TrimSuffix(string(data), "\n")
if strings.HasPrefix(line, "ref: ") {
refname := strings.TrimSpace(line[5:])
if !strings.HasPrefix(refname, "refs/") {
return HeadRef{Kind: HeadKindSymbolic, Ref: refname}, ErrInvalidRef
}
return HeadRef{Kind: HeadKindSymbolic, Ref: refname}, nil
}
id, err := repo.ParseHash(line)
if err != nil {
return HeadRef{Kind: HeadKindInvalid}, err
}
return HeadRef{Kind: HeadKindDetached, Hash: id}, nil
}
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