//

// StreamHelper.cs

// This file is part of Ghostscript.NET library

//

// Author: Josip Habjan (habjan@gmail.com, http://www.linkedin.com/in/habjan)

// Copyright (c) 2013-2016 by Josip Habjan. All rights reserved.

//

// Permission is hereby granted, free of charge, to any person obtaining

// a copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to

// permit persons to whom the Software is furnished to do so, subject to

// the following conditions:

//

// The above copyright notice and this permission notice shall be

// included in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

using System;

using System.IO;

namespace Ghostscript.NET

{

internal class StreamHelper

{

#region GetStreamExtension

public static string GetStreamExtension(Stream stream)

{

// https://github.com/awslabs/aws-sdk-xamarin/blob/master/AWS.XamarinSDK/AWSSDK_Core/Amazon.Runtime/Internal/Util/HashStream.cs

// Amazon.Runtime.Internal.Util.HashStream.Position {set; get;} throw NotSupportedException. First check CanSeek and default to PDF file extension

if (!stream.CanSeek)

{

return ".pdf";

}

if (stream.Length < 4)

{

throw new InvalidDataException("Less than 4 bytes found in stream.");

}

stream.Position = 0;

byte[] test = new byte[4];

stream.Read(test, 0, 4);

stream.Position = 0;

string extension = string.Empty;

if (test[0] == 0x25 && test[1] == 0x21) // standard ps or eps signature

{

extension = ".ps";

if (stream.Length > 23)

{

test = new byte[23];

stream.Read(test, 0, 23);

stream.Position = 0;

string tmp = System.Text.Encoding.ASCII.GetString(test);

if (tmp.ToUpper().Contains("EPS"))

{

extension = ".eps";

}

}

}

else if (test[0] == 0xc5 && test[1] == 0xd0 && test[2] == 0xd3 && test[3] == 0xc6) // eps with preview header signature / magic number (always C5D0D3C6)

{

extension = ".eps";

}

else if (test[0] == 0x25 && test[1] == 0x50 && test[2] == 0x44 && test[3] == 0x46) // pdf signature

{

extension = ".pdf";

}

else

{

// try to search for pdf signature once again

// this time look into all first 32 bytes as I run into pdf's that has extra bytes

// at the beginning of the pdf file before the actual signature

stream.Position = 0;

if (stream.Length > 32)

{

test = new byte[32];

stream.Read(test, 0, 32);

stream.Position = 0;

if (BufferHelper.IndexOf(test, new byte[] { 0x25, 0x50, 0x44, 0x46}) > -1)

{

extension = ".pdf";

}

}

if(string.IsNullOrWhiteSpace(extension))

{

// we didn't find pdf marker within first 32 bytes, read whole stream and search for pdf marker anywhere

BinaryReader reader = new BinaryReader(stream);

test = reader.ReadBytes((int)stream.Length);

stream.Position = 0;

if (BufferHelper.IndexOf(test, new byte[] { 0x25, 0x50, 0x44, 0x46 }) > -1)

{

extension = ".pdf";

}

}

}

if (string.IsNullOrWhiteSpace(extension))

{

throw new FormatException("Stream format is not valid! Please make sure it's PDF, PS or EPS.");

}

return extension;

}

#endregion

#region WriteToTemporaryFile

public static string WriteToTemporaryFile(Stream stream)

{

string extension = GetStreamExtension(stream);

string path = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + extension);

// https://github.com/awslabs/aws-sdk-xamarin/blob/master/AWS.XamarinSDK/AWSSDK_Core/Amazon.Runtime/Internal/Util/HashStream.cs

// Amazon.Runtime.Internal.Util.HashStream.Position {set; get;} throw NotSupportedException.

if (stream.CanSeek)

{

stream.Position = 0;

}

using (FileStream fs = File.Create(path))

{

CopyStream(stream, fs);

}

return path;

}

#endregion

#region CopyStream

public static void CopyStream(Stream input, Stream output)

{

int size = (input.CanSeek) ? Math.Min((int)(input.Length - input.Position), 0x2000) : 0x2000;

byte[] buffer = new byte[size];

int n;

do

{

n = input.Read(buffer, 0, buffer.Length);

output.Write(buffer, 0, n);

} while (n != 0);

}

#endregion

}

}