@azure/storage-file-datalake
Version:
Microsoft Azure Storage SDK for JavaScript - DataLake
85 lines • 3.11 kB
JavaScript
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
import fs from "node:fs";
import util from "node:util";
/**
* Reads a readable stream into buffer. Fill the buffer from offset to end.
*
* @param stream - A Node.js Readable stream
* @param buffer - Buffer to be filled, length must greater than or equal to offset
* @param offset - From which position in the buffer to be filled, inclusive
* @param end - To which position in the buffer to be filled, exclusive
* @param encoding - Encoding of the Readable stream
*/
export async function streamToBuffer(stream, buffer, offset, end, encoding) {
let pos = 0; // Position in stream
const count = end - offset; // Total amount of data needed in stream
return new Promise((resolve, reject) => {
stream.on("readable", () => {
if (pos >= count) {
resolve();
return;
}
let chunk = stream.read();
if (!chunk) {
return;
}
if (typeof chunk === "string") {
chunk = Buffer.from(chunk, encoding);
}
// How much data needed in this chunk
const chunkLength = pos + chunk.length > count ? count - pos : chunk.length;
buffer.fill(chunk.slice(0, chunkLength), offset + pos, offset + pos + chunkLength);
pos += chunkLength;
});
stream.on("end", () => {
if (pos < count) {
reject(new Error(`Stream drains before getting enough data needed. Data read: ${pos}, data need: ${count}`));
}
resolve();
});
stream.on("error", reject);
});
}
/**
* Reads a readable stream into buffer entirely.
*
* @param stream - A Node.js Readable stream
* @param buffer - Buffer to be filled, length must greater than or equal to offset
* @param encoding - Encoding of the Readable stream
* @returns with the count of bytes read.
* @throws `RangeError` If buffer size is not big enough.
*/
export async function streamToBuffer2(stream, buffer, encoding) {
let pos = 0; // Position in stream
const bufferSize = buffer.length;
return new Promise((resolve, reject) => {
stream.on("readable", () => {
let chunk = stream.read();
if (!chunk) {
return;
}
if (typeof chunk === "string") {
chunk = Buffer.from(chunk, encoding);
}
if (pos + chunk.length > bufferSize) {
reject(new Error(`Stream exceeds buffer size. Buffer size: ${bufferSize}`));
return;
}
buffer.fill(chunk, pos, pos + chunk.length);
pos += chunk.length;
});
stream.on("end", () => {
resolve(pos);
});
stream.on("error", reject);
});
}
/**
* ONLY AVAILABLE IN NODE.JS RUNTIME.
*
* Promisified version of fs.stat().
*/
export const fsStat = util.promisify(fs.stat);
export const fsCreateReadStream = fs.createReadStream;
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