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package commit
import (
"bytes"
"errors"
"fmt"
"lindenii.org/go/furgit/object/id"
"lindenii.org/go/furgit/object/signature"
)
// ErrInvalidCommit indicates a malformed commit object.
var ErrInvalidCommit = errors.New("object/commit: invalid commit")
// Parse decodes a commit object body.
func Parse(body []byte, objectFormat id.ObjectFormat) (*Commit, error) {
c := new(Commit)
i := 0
state := parseStateTree
sawHeaderEnd := false
for i < len(body) {
lineStart := i
rel := bytes.IndexByte(body[i:], '\n')
if rel < 0 {
return nil, fmt.Errorf("%w: unterminated header line at offset %d", ErrInvalidCommit, lineStart)
}
line := body[i : i+rel]
i += rel + 1
if len(line) == 0 {
sawHeaderEnd = true
break
}
key, value, found := bytes.Cut(line, []byte{' '})
if !found {
return nil, fmt.Errorf("%w: header line at offset %d has no ' ' separator", ErrInvalidCommit, lineStart)
}
switch string(key) {
case "tree":
if state != parseStateTree {
return nil, fmt.Errorf("%w: unexpected tree header at offset %d", ErrInvalidCommit, lineStart)
}
id, err := objectFormat.FromString(string(value))
if err != nil {
return nil, fmt.Errorf("%w: tree: %w", ErrInvalidCommit, err)
}
c.Tree = id
state = parseStateParentOrAuthor
case "parent":
if state != parseStateParentOrAuthor {
return nil, fmt.Errorf("%w: unexpected parent header at offset %d", ErrInvalidCommit, lineStart)
}
id, err := objectFormat.FromString(string(value))
if err != nil {
return nil, fmt.Errorf("%w: parent: %w", ErrInvalidCommit, err)
}
c.Parents = append(c.Parents, id)
case "author":
if state != parseStateParentOrAuthor {
return nil, fmt.Errorf("%w: unexpected author header at offset %d", ErrInvalidCommit, lineStart)
}
idt, err := signature.Parse(value)
if err != nil {
return nil, fmt.Errorf("%w: author: %w", ErrInvalidCommit, err)
}
c.Author = *idt
state = parseStateCommitter
case "committer":
if state != parseStateCommitter {
return nil, fmt.Errorf("%w: unexpected committer header at offset %d", ErrInvalidCommit, lineStart)
}
idt, err := signature.Parse(value)
if err != nil {
return nil, fmt.Errorf("%w: committer: %w", ErrInvalidCommit, err)
}
c.Committer = *idt
state = parseStateExtra
case "change-id":
if state != parseStateExtra {
return nil, fmt.Errorf("%w: unexpected change-id header at offset %d", ErrInvalidCommit, lineStart)
}
c.ChangeID = string(value)
case "gpgsig", "gpgsig-sha256":
if state != parseStateExtra {
return nil, fmt.Errorf("%w: unexpected %s header at offset %d", ErrInvalidCommit, key, lineStart)
}
for i < len(body) {
nextRel := bytes.IndexByte(body[i:], '\n')
if nextRel < 0 {
return nil, fmt.Errorf("%w: unterminated signature header at offset %d", ErrInvalidCommit, i)
}
if body[i] != ' ' {
break
}
i += nextRel + 1
}
default:
if state != parseStateExtra {
return nil, fmt.Errorf("%w: unexpected %s header at offset %d", ErrInvalidCommit, key, lineStart)
}
c.ExtraHeaders = append(c.ExtraHeaders, ExtraHeader{
Key: string(key),
Value: append([]byte(nil), value...),
})
}
}
if !sawHeaderEnd {
return nil, fmt.Errorf("%w: missing blank line before message", ErrInvalidCommit)
}
switch state {
case parseStateTree:
return nil, fmt.Errorf("%w: missing tree header", ErrInvalidCommit)
case parseStateParentOrAuthor:
return nil, fmt.Errorf("%w: missing author header", ErrInvalidCommit)
case parseStateCommitter:
return nil, fmt.Errorf("%w: missing committer header", ErrInvalidCommit)
case parseStateExtra:
default:
panic("unreachable parse state")
}
c.Message = append([]byte(nil), body[i:]...)
return c, nil
}
type parseState uint8
const (
parseStateTree parseState = iota
parseStateParentOrAuthor
parseStateCommitter
parseStateExtra
)
|
