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import { |
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fsWritePromise, |
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fillBufferAsync, |
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fillBufferSync, |
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processFileSync, |
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processFileAsync |
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} from "./util-file" |
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import * as fs from 'fs' |
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import { findId3TagPosition, getId3TagSize } from "./id3-tag" |
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import { WriteCallback } from "./types/write" |
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const FileBufferSize = 20 * 1024 * 1024 |
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export function writeId3TagToFileSync(filepath: string, id3Tag: Buffer) { |
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if (!fs.existsSync(filepath)) { |
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processFileSync(filepath, "w", (fileDescriptor) => |
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fs.writeSync(fileDescriptor, id3Tag) |
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) |
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return |
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} |
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const tempFilepath = makeTempFilepath(filepath) |
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processFileSync(filepath, 'r', (readFileDescriptor) => { |
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try { |
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processFileSync(tempFilepath, 'w', (writeFileDescriptor) => { |
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fs.writeSync(writeFileDescriptor, id3Tag) |
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copyFileWithoutId3TagSync(readFileDescriptor, writeFileDescriptor) |
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}) |
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} catch(error) { |
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fs.unlinkSync(tempFilepath) |
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throw error |
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} |
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}) |
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fs.renameSync(tempFilepath, filepath) |
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} |
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// TODO handle the case when there is no source file and create a new one. |
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export function writeId3TagToFileAsync( |
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filepath: string, |
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id3Tag: Buffer, |
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callback: WriteCallback |
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) { |
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const tempFilepath = makeTempFilepath(filepath) |
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processFileAsync(filepath, 'r', async (readFileDescriptor) => { |
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processFileAsync(tempFilepath, 'w', async (writeFileDescriptor) => { |
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await fsWritePromise(writeFileDescriptor, id3Tag) |
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await copyFileWithoutId3TagAsync(readFileDescriptor, writeFileDescriptor) |
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}).catch((error) => { |
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fs.unlink(tempFilepath, callback) |
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throw error |
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}) |
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}).then(() => { |
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fs.rename(tempFilepath, filepath, callback) |
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}).catch(callback) |
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} |
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function makeTempFilepath(filepath: string) { |
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return `${filepath}.tmp-${Date.now()}` |
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} |
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function copyFileWithoutId3TagSync( |
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readFileDescriptor: number, |
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writeFileDescriptor: number |
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) { |
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const buffer = Buffer.alloc(FileBufferSize) |
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let readData |
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while((readData = fillBufferSync(readFileDescriptor, buffer)).length) { |
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const { data, bytesToSkip } = removeId3TagIfFound(readData) |
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if (bytesToSkip) { |
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fillBufferSync(readFileDescriptor, Buffer.alloc(bytesToSkip)) |
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} |
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fs.writeSync(writeFileDescriptor, data, 0, data.length, null) |
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} |
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} |
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async function copyFileWithoutId3TagAsync( |
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readFileDescriptor: number, |
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writeFileDescriptor: number |
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) { |
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const buffer = Buffer.alloc(FileBufferSize) |
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let readData |
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while((readData = await fillBufferAsync(readFileDescriptor, buffer)).length) { |
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const { data, bytesToSkip } = removeId3TagIfFound(readData) |
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if (bytesToSkip) { |
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await fillBufferAsync(readFileDescriptor, Buffer.alloc(bytesToSkip)) |
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} |
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await fsWritePromise(writeFileDescriptor, data, 0, data.length, null) |
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} |
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} |
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function removeId3TagIfFound(data: Buffer) { |
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const id3TagPosition = findId3TagPosition(data) |
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if (id3TagPosition === -1) { |
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return { data } |
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} |
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const dataFromId3Start = data.subarray(id3TagPosition) |
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const id3TagSize = getId3TagSize(dataFromId3Start) |
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return { |
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data: Buffer.concat([ |
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data.subarray(0, id3TagPosition), |
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dataFromId3Start.subarray(Math.min(id3TagSize, dataFromId3Start.length)) |
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]), |
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bytesToSkip: Math.max(0, id3TagSize - dataFromId3Start.length) |
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} |
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} |
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