Function writeFileRangesSync

packages/dofs/src/fs/writeFile.ts:996–1070

(
  db: Database,
  path: string,
  bytes: Uint8Array,
  dirtyRanges: WriteFileRange[],
  options: WriteFileOptions,
  now: () => number,
)

}

export function writeFileRangesSync(
  db: Database,
  path: string,
  bytes: Uint8Array,
  dirtyRanges: WriteFileRange[],
  options: WriteFileOptions,
  now: () => number,
): void {
  const { parts, path: canonical } = canonicalizePath(path);
  if (parts.length === 0) {
    throw createWorkspaceError("EISDIR", "cannot write to the root directory", canonical);
  }
  assertNotReadOnly(db, canonical);
  const mode = (options.mode ?? 0o644) & 0o7777;
  const ranges = normalizeRanges(dirtyRanges, bytes.byteLength);
  const mtime = now();
  db.transactionSync(() => {
    const parentInode = resolveParent(db, parts, canonical);
    const leafName = parts[parts.length - 1];
    const existing = db.one<{ child_inode: number }>(
      "SELECT child_inode FROM vfs_dirents WHERE parent_inode = ? AND name = ?",
      parentInode,
      leafName,
    );

    let inode: number;
    let oldChunks: ChunkRef[] = [];
    if (existing !== undefined) {
      const node = db.one<{ type: "file" | "dir" }>(
        "SELECT type FROM vfs_nodes WHERE inode = ?",
        existing.child_inode,
      );
      if (node?.type === "dir") {
        throw createWorkspaceError("EISDIR", `path is a directory: ${canonical}`, canonical);
      }
      inode = existing.child_inode;
      oldChunks = existingChunkRefs(db, inode);
    } else {
      inode = insertFileNode(db, mode, mtime);
      insertFileDirent(db, parentInode, leafName, inode, canonical);
    }

    const rev = incrementRev(db);
    const nextChunks: ChunkRef[] = [];
    const chunkCount = Math.ceil(bytes.byteLength / CHUNK_SIZE);
    for (let idx = 0; idx < chunkCount; idx++) {
      const start = idx * CHUNK_SIZE;
      const end = Math.min(start + CHUNK_SIZE, bytes.byteLength);
      const size = end - start;
      const oldChunk = oldChunks[idx];
      if (oldChunk !== undefined && oldChunk.size === size && !rangesOverlap(start, end, ranges)) {
        nextChunks.push(oldChunk);
        continue;
      }
      const chunk = {
        hash: sha256(bytes.subarray(start, end)),
        bytes: bytes.subarray(start, end),
        size,