


node.js solves the problem of obtaining the real file type of images_node.js
Encountered a requirement: Suppose there is an image file, the real type is jpg, and someone is too lazy to copy the jpg directly and save it as a png file with the same name, so that there will be no problem when AS3 reads the file. But mobile phone C encountered problems when reading files - -!
Now you need to write a program to traverse the files in all folders and find files with "abnormal" file formats. Our resources are mainly gif, png, and jpg. At first, I found an article on the Internet: Obtain the file type mime-type based on the binary stream and file header, and then read the binary header information of the file to obtain its true file type. , compare with the file type obtained through the suffix name.
var fd = fs.openSync(new_file_path, 'r');
var buffer = new Buffer(8);
var mineType = mime.lookup(new_file_path);
var fileType = mime.extension(mineType);
fs.readSync(fd, buffer, 0, 8, 0);
var newBuf = buffer.slice(0, 4);
var head_1 = newBuf[0].toString(16);
var head_2 = newBuf[1].toString(16);
var head_3 = newBuf[2].toString(16);
var head_4 = newBuf[3].toString(16);
var head_iden = head_1 head_2;
var tempFileType = FILE_TYPE_CONFIG[head_iden];
if (!tempFileType) {
head_iden = head_3;
tempFileType = FILE_TYPE_CONFIG[head_iden];
if (!tempFileType) {
var msg = "Unknow fileType " new_file_path '-' fileType;
showLog(msg);
Continue;
}
}
if (tempFileType != fileType) {
var msg = "Error fileType" new_file_path '-' fileType '|' tempFileType '--correct image file format';
ShowLog(msg);
g_errorFileTypArr.push(msg);
}
Later, when I searched for information related to node image, I found this article: node.js module ranking>> (images)
Then I filtered out a module "node-imageinfo" and wrote an example for testing (deliberately directly changing the suffix of the jpg file to png):
If you are interested, you can study its source code:
function readUInt32(buffer, offset, bigEndian) {
if (buffer.readUInt32) {
return buffer.readUInt32(offset, bigEndian);
}
var value;
if (bigEndian) {
if (buffer.readUInt32BE) {
return buffer.readUInt32BE(offset);
}
value = (buffer[offset]
}
else {
if (buffer.readUInt32LE) {
return buffer.readUInt32LE(offset);
}
value = buffer[offset] (buffer[offset 1]
}
return value;
}
function readUInt16(buffer, offset, bigEndian) {
if (buffer.readUInt16) {
return buffer.readUInt16(offset, bigEndian);
}
var value;
if (bigEndian) {
if (buffer.readUInt16BE) {
return buffer.readUInt16BE(offset);
}
value = (buffer[offset]
}
else {
if (buffer.readUInt16LE) {
return buffer.readUInt16LE(offset);
}
value = buffer[offset] (buffer[offset 1]
}
return value;
}
function readBit(buffer, offset, bitOffset) {
if (bitOffset > 7) {
offset = Math.floor(bitOffset / 8);
bitOffset = bitOffset % 8;
}
var b = buffer[offset];
if (bitOffset
b >>>= (7 - bitOffset);
}
var val = b & 0x01;
return val;
}
function readBits(buffer, offset, bitOffset, bitLen, signed) {
var val = 0;
var neg = false;
if (signed) {
if (readBit(buffer, offset, bitOffset) > 0) {
neg = true;
}
bitLen--;
bitOffset ;
}
var bytes = [];
for (var i = 0; i
var b = readBit(buffer, offset, bitOffset i);
if (i>0 && (bitLen - i) % 8 == 0) {
bytes.push(val);
val = 0;
}
val
val |= b;
}
bytes.push(val);
val = new Buffer(bytes);
val.negative = neg?true:false;
return val;
}
function imageInfoPng(buffer) {
var imageHeader = [0x49, 0x48, 0x44, 0x52],
pos = 12;
if (!checkSig(buffer, pos, imageHeader)) {
return false;
}
pos = 4;
return {
type: 'image',
format: 'PNG',
mimeType: 'image/png',
width: readUInt32(buffer, pos, true),
height: readUInt32(buffer, pos 4, true),
};
}
function imageInfoJpg(buffer) {
var pos = 2,
len = buffer.length,
sizeSig = [0xff, [0xc0, 0xc2]];
while (pos
if (checkSig(buffer, pos, sizeSig)) {
pos = 5;
return {
type: 'image',
format: 'JPG',
mimeType: 'image/jpeg',
width: readUInt16(buffer, pos 2, true),
height: readUInt16(buffer, pos, true),
};
}
pos = 2;
var size = readUInt16(buffer, pos, true);
pos = size;
}
}
function imageInfoGif(buffer) {
var pos = 6;
return {
type: 'image',
format: 'GIF',
mimeType: 'image/gif',
width: readUInt16(buffer, pos, false),
height: readUInt16(buffer, pos 2, false),
};
}
function imageInfoSwf(buffer) {
var pos = 8,
bitPos = 0,
val;
if (buffer[0] === 0x43) {
try {
// If you have zlib available ( npm install zlib ) then we can read compressed flash files
buffer = require('zlib').inflate(buffer.slice(8, 100));
pos = 0;
}
catch (ex) {
// Can't get width/height of compressed flash files... yet (need zlib)
return {
type: 'flash',
format: 'SWF',
mimeType: 'application/x-shockwave-flash',
width: null,
height: null,
}
}
}
var numBits = readBits(buffer, pos, bitPos, 5)[0];
bitPos = 5;
val = readBits(buffer, pos, bitPos, numBits, true);
var xMin = (numBits > 9 ? readUInt16(val, 0, true) : val[0]) * (val.negative ? -1 : 1);
bitPos = numBits;
val = readBits(buffer, pos, bitPos, numBits, true);
var xMax = (numBits > 9 ? readUInt16(val, 0, true) : val[0]) * (val.negative ? -1 : 1);
bitPos = numBits;
val = readBits(buffer, pos, bitPos, numBits, true);
var yMin = (numBits > 9 ? readUInt16(val, 0, true) : val[0]) * (val.negative ? -1 : 1);
bitPos = numBits;
val = readBits(buffer, pos, bitPos, numBits, true);
var yMax = (numBits > 9 ? readUInt16(val, 0, true) : val[0]) * (val.negative ? -1 : 1);
return {
type: 'flash',
format: 'SWF',
mimeType: 'application/x-shockwave-flash',
width: Math.ceil((xMax - xMin) / 20),
height: Math.ceil((yMax - yMin) / 20),
};
}
function checkSig(buffer, offset, sig) {
var len = sig.length;
for (var i = 0; i
var b = buffer[i offset],
s = sig[i],
m = false;
if ('number' == typeof s) {
m = s === b;
}
else {
for (var k in s) {
var o = s[k];
if (o === b) {
m = true;
}
}
}
if (!m) {
return false;
}
}
return true;
}
module.exports = function imageInfo(buffer, path) {
var pngSig = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
var jpgSig = [0xff, 0xd8, 0xff];
var gifSig = [0x47, 0x49, 0x46, 0x38, [0x37, 0x39], 0x61];
var swfSig = [[0x46, 0x43], 0x57, 0x53];
if (checkSig(buffer, 0, pngSig)) return imageInfoPng(buffer);
if (checkSig(buffer, 0, jpgSig)) return imageInfoJpg(buffer);
if (checkSig(buffer, 0, gifSig)) return imageInfoGif(buffer);
if (checkSig(buffer, 0, swfSig)) return imageInfoSwf(buffer);
return false;
};

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

Dreamweaver CS6
Visual web development tools

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.