mime-detect/index.js

Detect mime type and encoding (aka Content-Type) from buffer, file content and filename.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.mimeToExt = exports.detectBufferMime = exports.detectFilenameMime = exports.detectFileMime = exports.enableTypescriptMime = void 0;
const mime_types_1 = require("./mime.types");
const mime_ext_1 = require("./mime.ext");
function enableTypescriptMime(mime = 'text/typescript') {
    mime_types_1.ext_to_mime.ts = mime;
}
exports.enableTypescriptMime = enableTypescriptMime;
let binarySuffix = '; charset=binary';
let plainTextPrefix = 'text/plain';
let binaryPrefix = 'application/octet-stream';
function detectFileMime(file, cb) {
    if (!cb) {
        return new Promise((resolve, reject) => detectFileMime(file, (error, mime) => error ? reject(error) : resolve(mime)));
    }
    let { spawn } = child_process();
    let child = spawn('file', ['-bE', '--mime', file]);
    let stdout = '';
    let stderr = '';
    child.stdout.on('data', chunk => (stdout += chunk));
    child.stderr.on('data', chunk => (stderr += chunk));
    child.on('close', code => {
        if (code !== 0) {
            let message = (stdout + ' ' + stderr).trim();
            if (message.includes('No such file or directory')) {
                cb(new Error('No such file or directory'));
                return;
            }
            cb(new Error(message));
            return;
        }
        let mime = stdout.trim();
        if (mime.endsWith(binarySuffix)) {
            mime = mime.slice(0, mime.length - binarySuffix.length);
        }
        mime = detectFilenameMime(file, mime);
        cb(null, mime);
    });
}
exports.detectFileMime = detectFileMime;
function detectFilenameMime(file, mime = binaryPrefix) {
    let prefix = mime.startsWith(plainTextPrefix)
        ? plainTextPrefix
        : mime.startsWith(binaryPrefix)
            ? binaryPrefix
            : undefined;
    if (prefix) {
        let ext = file.split('.').pop();
        let result = mime_types_1.ext_to_mime[ext];
        if (result) {
            mime = result + mime.slice(prefix.length);
        }
    }
    return mime;
}
exports.detectFilenameMime = detectFilenameMime;
function detectBufferMime(buffer, cb) {
    if (!cb) {
        return new Promise((resolve, reject) => detectBufferMime(buffer, (error, mime) => error ? reject(error) : resolve(mime)));
    }
    if (buffer.length === 0) {
        cb(null, binaryPrefix);
        return;
    }
    let { exec } = child_process();
    let childError;
    let child = exec(`file -bE --mime -`, {}, (error, stdout, stderr) => {
        if (childError)
            return;
        if (error) {
            let message = (stdout + ' ' + stderr).trim();
            cb(message ? new Error(message) : error);
            return;
        }
        let mime = stdout.trim();
        if (mime.endsWith(binarySuffix)) {
            mime = mime.slice(0, mime.length - binarySuffix.length);
        }
        cb(null, mime);
    });
    if (child.stdin) {
        child.stdin.write(buffer);
        child.stdin.on('error', (error) => {
            if (error.code === 'EPIPE') {
                // early terminate before the mime is already detected
                return;
            }
            childError = error;
            cb(error);
        });
    }
}
exports.detectBufferMime = detectBufferMime;
/**
 * @description return file extension name without dot
 * e.g. "audio/mp4" -> "m4a"
 * e.g. "video/x-matroska" -> "mkv"
 * e.g. "image/jpeg" -> "jpg"
 * e.g. "application/octet-stream" -> "bin"
 */
function mimeToExt(mime) {
    mime = mime.split(';')[0];
    let ext = mime_ext_1.mime_to_ext[mime];
    if (ext)
        return ext;
    let exts = Object.entries(mime_types_1.ext_to_mime)
        .filter(([key, value]) => value == mime)
        .map(([key]) => key);
    if (exts.length > 1) {
        console.warn(`multiple extensions matched:`, { mime, exts });
    }
    if (exts.length == 1) {
        return exts[0];
    }
    return mime.split('/').pop();
}
exports.mimeToExt = mimeToExt;
// using eval to avoid error when bundling with esbuild
// at least detectFilenameMime() is usable in browser
function child_process() {
    return eval('require("child_process")');
}