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@drawcode
Created February 12, 2014 01:32
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Compression utility for compressing strings with ToCompressed and ToDecompressed extensions.
using System;
using System.IO;
using System.IO.Compression;
using System.Text;
public static class CompressUtil {
public static string ToCompressed(this string val) {
if (!IsStringCompressed(val)) {
return CompressString(val);
}
return val;
}
public static string ToDecompressed(this string val) {
if (IsStringCompressed(val)) {
return DecompressString(val);
}
return val;
}
public static string CompressString(string text) {
byte[] buffer = Encoding.UTF8.GetBytes(text);
var memoryStream = new MemoryStream();
using (var gZipStream = new GZipStream(memoryStream, CompressionMode.Compress, true)) {
gZipStream.Write(buffer, 0, buffer.Length);
}
memoryStream.Position = 0;
var compressedData = new byte[memoryStream.Length];
memoryStream.Read(compressedData, 0, compressedData.Length);
var gZipBuffer = new byte[compressedData.Length + 4];
Buffer.BlockCopy(compressedData, 0, gZipBuffer, 4, compressedData.Length);
Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gZipBuffer, 0, 4);
return Convert.ToBase64String(gZipBuffer);
}
public static string DecompressString(string compressedText) {
byte[] gZipBuffer = Convert.FromBase64String(compressedText);
using (var memoryStream = new MemoryStream()) {
int dataLength = BitConverter.ToInt32(gZipBuffer, 0);
memoryStream.Write(gZipBuffer, 4, gZipBuffer.Length - 4);
var buffer = new byte[dataLength];
memoryStream.Position = 0;
using (var gZipStream = new GZipStream(memoryStream, CompressionMode.Decompress)) {
gZipStream.Read(buffer, 0, buffer.Length);
}
return Encoding.UTF8.GetString(buffer);
}
}
public static bool IsStringCompressed(string data) {
if (IsStringCompressedGZip(data) || IsStringCompressedPKZip(data)) {
return true;
}
return false;
}
public static bool IsStringCompressedGZip(string data) {
return CheckSignatureString(data, 3, "1F-8B-08");
}
public static bool IsStringCompressedPKZip(string data) {
return CheckSignatureString(data, 4, "50-4B-03-04");
}
public static bool CheckSignatureFile(string filepath, int signatureSize, string expectedSignature) {
if (String.IsNullOrEmpty(filepath))
throw new ArgumentException("Must specify a filepath");
if (String.IsNullOrEmpty(expectedSignature))
throw new ArgumentException("Must specify a value for the expected file signature");
using (FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)) {
if (fs.Length < signatureSize)
return false;
byte[] signature = new byte[signatureSize];
int bytesRequired = signatureSize;
int index = 0;
while (bytesRequired > 0) {
int bytesRead = fs.Read(signature, index, bytesRequired);
bytesRequired -= bytesRead;
index += bytesRead;
}
string actualSignature = BitConverter.ToString(signature);
if (actualSignature == expectedSignature)
return true;
else
return false;
}
}
public static bool CheckSignatureString(string data, int signatureSize, string expectedSignature) {
byte[] datas = Encoding.ASCII.GetBytes(data);
using (MemoryStream ms = new MemoryStream(datas)) {
if (ms.Length < signatureSize)
return false;
byte[] signature = new byte[signatureSize];
int bytesRequired = signatureSize;
int index = 0;
while (bytesRequired > 0) {
int bytesRead = ms.Read(signature, index, bytesRequired);
bytesRequired -= bytesRead;
index += bytesRead;
}
string actualSignature = BitConverter.ToString(signature);
if (actualSignature == expectedSignature)
return true;
else
return false;
}
}
}
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