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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{}, ErrInvalidObject
}
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{}, ErrInvalidObject
}
// ResolveHEAD reads HEAD and returns the ref that HEAD points to.
func (repo *Repository) ResolveHEAD() (string, error) {
data, err := os.ReadFile(repo.repoPath("HEAD"))
if err != nil {
return "", err
}
line := strings.TrimSpace(string(data))
const prefix = "ref: "
if strings.HasPrefix(line, prefix) {
ref := strings.TrimSpace(line[len(prefix):])
if ref == "" {
return "", ErrInvalidRef
}
return ref, nil
}
return "", ErrInvalidRef
}
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