76 lines
No EOL
2.4 KiB
JavaScript
76 lines
No EOL
2.4 KiB
JavaScript
const CSHARP_HEADER = [0, 1, 0, 0, 0, 255, 255, 255, 255, 1, 0, 0, 0, 0, 0, 0, 0, 6, 1, 0, 0, 0];
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function ShowFile(input) {
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let inputFileObject = input.files[0];
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alert(`File name: ${inputFileObject.name}`);
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alert(`Last modified: ${inputFileObject.lastModified}`);
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}
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// main input tag file function
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function LoadSaveFile(input) {
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// Prepares a File object from the first file of the input files for reading as an Array Buffer
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let inputFileObject = input.files[0];
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// 1. read file
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// The ArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer.
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// It is an array of bytes, often referred to in other languages as a "byte array".
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// new FileReader()
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let inputReader = new FileReader();
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// readAsArrayBuffer(file)
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inputReader.readAsArrayBuffer(inputFileObject);
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// addEventListener("load", function) - to decode the file when loaded
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inputReader.addEventListener("load", FileObjectToArrayBuffer);
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// 2. Decode file
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// base64 Decoding (ArrayBuffer)
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// AES decryption (ECB) removes pkcs7 padding (ArrayBuffer)
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// Convert ArrayBuffer to string/text TextDecoder().decode(ArrayBuffer)
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// 3. Convert file to JSON string (optional?)
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// JSON.stringify(JSON.parse(decrypted), undefined, 2)
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// 4. Paste decoded string file to text area
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}
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// reads the File object as an Array Buffer
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function FileObjectToArrayBuffer() {
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let inputArrayBuffer = this.result;
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try {
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// Uint8Array(ArrayBuffer)
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inputArrayBuffer = new Uint8Array(inputArrayBuffer);
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// ArrayBuffer.slice()
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// The slice() method copies up to, but not including, the byte indicated by the end parameter.
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inputArrayBuffer.slice();
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// remove C# header (ArrayBuffer)
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alert(`File: ${inputArrayBuffer}`);
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} catch (error) {
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alert(`The file cannot be read. Error: ${error}`);
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}
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}
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// removes C# header, LengthPrefixedString header and byte 11 at the end of the Uint8 Array Buffer
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function RemoveCSharpHeader(buffer) {
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// Remove the fixed C# header and byte 11 at the end.
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buffer = buffer.subarray(CSHARP_HEADER.length, buffer.length - 1);
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// Remove LengthPrefixedString header
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let lengthCount = 0;
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for (let i = 0; i < 5; i++) {
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lengthCount++;
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if ((buffer[i] & 0x80) == 0) {
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break;
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}
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}
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let fixedArrayBuffer = buffer.subarray(lengthCount);
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return fixedArrayBuffer;
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} |