@struktoai/mirage-core/dist/core/tidb_filesystem/read.js

A Unified Virtual Filesystem For AI Agents

// ========= Copyright 2026 @ Strukto.AI All Rights Reserved. =========
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========= Copyright 2026 @ Strukto.AI All Rights Reserved. =========
import { eisdir, fsError } from "../../errors/fs.js";
import { record, startOp } from "../../observe/context.js";
import { VFSName } from "../../types.js";
import { ancestors, norm } from "../../utils/path.js";
import { windowFor } from "../../utils/ranges.js";
import { download } from "./client.js";
import { kindsOf, lookupError } from "./dest.js";
import { hasStatus } from "./errors.js";
import { backendPath } from "./path.js";
/**
 * The errno a failed download answers with, null for any other failure.
 * drive9 answers 404 for a directory as for a missing path, and 422 for a
 * file in the extent layout, whose blocks only its FUSE client reads.
 */
export async function readError(accessor, path, exc) {
    if (hasStatus(exc, 422))
        return fsError(path, 'ENOTSUP');
    if (!hasStatus(exc, 404))
        return null;
    const key = norm(path.mountPath);
    const kinds = await kindsOf(accessor, [...ancestors(key), key]);
    if (kinds.get(key)?.isDir === true)
        return eisdir(path);
    return lookupError(kinds, path, key);
}
export async function read(accessor, path, offset = 0, size = null) {
    const virtual = path.virtual;
    const remotePath = backendPath(accessor.config, path);
    const timer = startOp();
    if (size === 0) {
        record('read', virtual, VFSName.TIDB_FILESYSTEM, 0, timer);
        return new Uint8Array(0);
    }
    let data;
    try {
        data = await download(accessor, remotePath, windowFor(offset, size));
    }
    catch (exc) {
        throw (await readError(accessor, path, exc)) ?? exc;
    }
    record('read', virtual, VFSName.TIDB_FILESYSTEM, data.byteLength, timer);
    return data;
}
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