lima-vm/lima · critical

reading omap child node: %w

Error message

reading omap child node: %w

What it means

During descent through an internal omap B-tree node, omapLookup reads the child node at the physical address stored in the child pointer. This error wraps the readBlock failure for that child, meaning an I/O-level failure (typically EOF because the address lies past the end of the image) occurred before checksum or type validation could run.

Source

Thrown at pkg/apfs/chown.go:373

			keyStart := keyAreaStart + kOff
			entryOID := le.Uint64(blk[keyStart:])
			entryXID := le.Uint64(blk[keyStart+8:])

			cmp := compareOmapKey(entryOID, entryXID, oid, maxXID)
			if cmp <= 0 {
				childIdx = i
			} else {
				break
			}
		}

		// Read child pointer (physical address, 8 bytes).
		_, vOff := c.readTocEntry(blk, tocStart, childIdx, isFixedKV)
		childAddr := le.Uint64(blk[valueAreaEnd-vOff:])

		blk, err = c.readBlock(childAddr)
		if err != nil {
			return 0, fmt.Errorf("reading omap child node: %w", err)
		}
	}
}

// readTocEntry reads the key and value offsets from a ToC entry.
// For fixed-KV nodes (kvoff_t): 4 bytes per entry (k_off u16, v_off u16).
// For variable-KV nodes (kvloc_t): 8 bytes per entry (k.off u16, k.len u16, v.off u16, v.len u16).
// Returns keyOffset and valueOffset (both relative to their respective areas).
func (c *container) readTocEntry(blk []byte, tocStart, index uint32, fixedKV bool) (keyOff, valOff uint32) {
	if fixedKV {
		off := tocStart + index*4
		return uint32(le.Uint16(blk[off:])), uint32(le.Uint16(blk[off+2:]))
	}
	off := tocStart + index*8
	return uint32(le.Uint16(blk[off:])), uint32(le.Uint16(blk[off+4:]))
}

// verifyBTreeNodeType checks that a block's object type indicates a

View on GitHub (pinned to dd909d0973)

Solutions

1. Verify the image file size matches the source disk; re-copy if truncated.
2. Run fsck_apfs on the image from a macOS host to repair B-tree structure.
3. Re-export the image from a cleanly shut-down VM.
4. Check host disk health if I/O errors persist.
5. Restore from backup if corruption is confirmed.

if err := apfs.Chown(diskPath, role, uid, gid, paths...); err != nil {
	if strings.Contains(err.Error(), "reading omap child node") {
		return fmt.Errorf("omap tree is inconsistent or the image is truncated: %w", err)
	}
	return err
}

When it happens

Trigger: A corrupt or dangling child pointer inside an internal omap node, an image truncated so the child block is missing, or I/O errors reading that region of the disk file.

Common situations: Truncated/partial disk copies, images from crashed or still-running VMs with inconsistent trees, bad host storage, or corrupted images after an interrupted file transfer.

Related errors

• reading container omap at %d: %w
• omap node: %w
• expected B-tree node type (2 or 3), got %#x
• resolving filesystem root tree OID %d: %w
• resolving path %#q: %w

AI-assisted analysis of lima-vm/lima@dd909d0973 (2026-09-01). Data as JSON: /api/errors/0f3ae1db11f64403. Report an issue: GitHub.