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);
}
public static string GetStreamExtension(Stream stream)
{
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))
{
throw new FormatException("Stream format is not valid! Please make sure it's PDF, PS or EPS.");
}
return(extension);
}