| 1 | package agent |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "encoding/json" |
| 6 | "fmt" |
| 7 | "io" |
| 8 | "os" |
| 9 | fileencoding "reasonix/internal/fileutil/encoding" |
| 10 | "reasonix/internal/historywork" |
| 11 | ) |
| 12 | |
| 13 | // LoadBranchMetaBounded is the content-free catalog reader. An oversized or |
| 14 | // damaged sidecar leaves an unknown metadata row; it never triggers replay. |
| 15 | func LoadBranchMetaBounded(ctx context.Context, sessionPath string) (BranchMeta, bool, error) { |
| 16 | f, err := os.Open(BranchMetaPath(sessionPath)) |
| 17 | if os.IsNotExist(err) { |
| 18 | return BranchMeta{}, false, nil |
| 19 | } |
| 20 | if err != nil { |
| 21 | return BranchMeta{}, false, err |
| 22 | } |
| 23 | defer f.Close() |
| 24 | r := &historywork.Reader{Context: ctx, Source: f} |
| 25 | b, err := io.ReadAll(io.LimitReader(r, historywork.ReadChunk+1)) |
| 26 | if err != nil { |
| 27 | return BranchMeta{}, false, err |
| 28 | } |
| 29 | if len(b) > historywork.ReadChunk { |
| 30 | return BranchMeta{}, false, fmt.Errorf("session metadata exceeds discovery budget") |
| 31 | } |
| 32 | kind, _ := fileencoding.Detect(b) |
| 33 | return decodeBranchMeta(sessionPath, fileencoding.Decode(b, kind)) |
| 34 | } |
| 35 | |
| 36 | func decodeBranchMeta(sessionPath string, b []byte) (BranchMeta, bool, error) { |
| 37 | var m BranchMeta |
| 38 | if err := json.Unmarshal(b, &m); err != nil { |
| 39 | // Treat an all-NUL/JSON-whitespace sidecar as a torn write so callers |
| 40 | // rebuild it; retain errors for partial JSON to avoid swallowing corruption. |
| 41 | if metaIsUnparseableAsAbsent(b) { |
| 42 | return BranchMeta{}, false, nil |
| 43 | } |
| 44 | return BranchMeta{}, false, fmt.Errorf("decode branch meta %s: %w", BranchMetaPath(sessionPath), err) |
| 45 | } |
| 46 | if m.ID == "" { |
| 47 | m.ID = BranchID(sessionPath) |
| 48 | } |
| 49 | m.sanitizeDisplayFields() |
| 50 | return m, true, nil |
| 51 | } |
| 52 |