Develop Reference

Using memory stream instead of filestream for AWS C# S3 SDK not returning full file

I have some code that is meant to retrieve a file from an S3 bucket and deserialize the file. When I use a file stream I get all the data no problem, but when I use a memory stream it seems like I am not getting all of the data:
It doesnt get the full XML:
Where it should look like:
Here is the code I am using:
internal object ReadDataContractFromFile(string filename, Type type)
{
GetObjectRequest getObjRequest = new GetObjectRequest();
MemoryStream memoryStream = new MemoryStream();
getObjRequest.BucketName = bucketName;
getObjRequest.Key = filename;
string path = #"C:\{PATH_TO_FILE}\requests\" + filename;
FileStream fileStream = new FileStream(path, FileMode.Create, FileAccess.ReadWrite);
using (GetObjectResponse getObjRespone = s3Client.GetObject(getObjRequest))
using (Stream responseStream = getObjRespone.ResponseStream)
{
responseStream.CopyTo(fileStream);
//memoryStream.Seek(0, 0);
XmlReaderSettings rs = new XmlReaderSettings
{
ConformanceLevel = ConformanceLevel.Fragment,
};
XmlReader r = XmlReader.Create(fileStream, rs);
return new DataContractSerializer(type).ReadObject(r);
}
}
If I use memoryStream in place of the fileStream variable, I get the incomplete XML I showed above. I tried to seek to the beginning of the stream incase the position was wrong but that didnt fix it. Any idea what Im doing wrong?

C# equivalent to zlib.decompress

What is the equivalent of the Python function zlib.decompress() in C#? I need to decompress some zlib files using C# and I don't know how to do it.
Python example:
import zlib
file = open("myfile", mode = "rb")
data = zlib.decompress(file.read())
uncompressed_output = open("output_file", mode = "wb")
uncompressed_output.write(data)
I tried using the System.IO.Compression.DeflateStream class, but for every file I try it gives me an exception that the file contains invalid data while decoding.
byte[] binary = new byte[1000000];
using (DeflateStream compressed_file = new DeflateStream(new FileStream(#"myfile", FileMode.Open, FileAccess.Read), CompressionMode.Decompress))
compressed_file.Read(binary, 0, 1000000); //exception here
using (BinaryWriter outputFile = new BinaryWriter(new FileStream(#"output_file", FileMode.Create, FileAccess.Write)))
outputFile.Write(binary);
//Reading the file like normal with a BinaryReader and then turning it into a MemoryStream also didn't work
I should probably mention that the files are ZLIB compressed files. They start with the 78 9C header.

So, luckily, I found this post: https://stackoverflow.com/a/33855097/10505778
Basically the file must be stripped of its 2 header bytes (78 9C). While the 9C is important in decompression (it specifies whether a preset dictionary has been used or not), I don't need it, but I am pretty sure it is not that difficult to modify this to accomodate it:
byte[] binary, decompressed;
using (BinaryReader file = new BinaryReader(new FileStream(#"myfile", FileMode.Open, FileAccess.Read, FileShare.Read))
binary = file.ReadBytes(int.MaxValue); //read the entire file
output = new byte[int.MaxValue];
int outputSize;
using (MemoryStream memory_stream = new MemoryStream(binary, false))
{
memory_stream.Read(decompressed, 0, 2); //discard 2 bytes
using (DeflateStream compressed_file = new DeflateStream(memory_stream, CompressionMode.Decompress)
outputSize = compressed_file.Read(decompressed, 0, int.MaxValue);
}
binary = new byte[outputSize];
Array.Copy(decompressed, 0, binary, 0, outputSize);
using (BinaryWriter outputFile = new BinaryWriter(new FileStream(#"output_file", FileMode.Create, FileAccess.Write)))
outputFile.Write(binary);

Convert a PDF to PDF/A using IText 7?

I need to convert a PDF file as a stream (1.7) to PDFA/3. The original file has the fonts and images already embedded.
So far I did:
var output = new MemoryStream();
var reader = new PdfReader(stream);
var writer = new PdfWriter(output);
Stream s = new FileStream("sRGB Color Space Profile.icm", FileMode.Open, FileAccess.Read);
var intent = new PdfOutputIntent("Custom", "", "http://www.color.org", "sRGB IEC61966-2.1", s);
var pdfA = new PdfADocument(writer, PdfAConformanceLevel.PDF_A_3A, intent);
//Setting some required parameters
pdfA.SetTagged();
pdfA.GetCatalog().SetLang(new PdfString("en-US"));
pdfA.GetCatalog().SetViewerPreferences(new PdfViewerPreferences().SetDisplayDocTitle(true));
PdfDocumentInfo info = pdfA.GetDocumentInfo();
info.SetTitle("test pdf/a");
However I got stuck on how to copy from the input stream to the writer and return the pdf/a as a stream.
Furthermore, can I use iText to perform a conformance text on the output?
Any ideas?

Read Excel using NPOI

I am trying to read excel[xls and xlsx] using NPOI,I am using following code, but it is giving 'Unable to Read entire header; 27 bytes Read; expected 512 bytes' while reading an 8KB xls file
byte[] byteArray = Encoding.UTF8.GetBytes(filepath);
MemoryStream stream = new MemoryStream(byteArray);
MemoryStream stream1 = new MemoryStream(Encoding.UTF8.GetBytes(filepath ?? ""));
NPOI.HSSF.UserModel.HSSFWorkbook hssfwb = default(HSSFWorkbook);
hssfwb = new NPOI.HSSF.UserModel.HSSFWorkbook(stream1);
Sheet sheet = hssfwb.GetSheetAt(0);
DataTable dtinputExcel = new DataTable();
I have tried every possible code available on net for this error. Please guide me what's the errorless method to read and excel[xls/xlsx] of any size.

The problem is that the constructor of HSSFWorkbook is expecting a stream containing the contents of the spreadsheet file, while you are passing it a MemoryStream containing the name of the file. You should be using a FileStream to read the file and passing that stream to the HSSFWorkbook constructor.
Try it like this:
IWorkbook hssfwb;
using (FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read))
{
hssfwb = new HSSFWorkbook(fs);
}
ISheet sheet = hssfwb.GetSheetAt(0);

DotNetZip Saving to Stream

I am using DotNetZip to add a file from a MemoryStream to a zip file and then to save that zip as a MemoryStream so that I can email it as an attachment. The code below does not err but the MemoryStream must not be done right because it is unreadable. When I save the zip to my hard drive everything works perfect, just not when I try to save it to a stream.
using (ZipFile zip = new ZipFile())
{
var memStream = new MemoryStream();
var streamWriter = new StreamWriter(memStream);
streamWriter.WriteLine(stringContent);
streamWriter.Flush();
memStream.Seek(0, SeekOrigin.Begin);
ZipEntry e = zip.AddEntry("test.txt", memStream);
e.Password = "123456!";
e.Encryption = EncryptionAlgorithm.WinZipAes256;
var ms = new MemoryStream();
ms.Seek(0, SeekOrigin.Begin);
zip.Save(ms);
//ms is what I want to use to send as an attachment in an email
}

Ok, I figured out my problem, pretty stupid actually. Thanks for everyone's help!
ZipEntry e = zip.AddEntry("test.txt", memStream);
e.Password = "123456!";
e.Encryption = EncryptionAlgorithm.WinZipAes256;
//zip.Save("C:\\Test\\Test.zip");
//Stream outStream;
var ms = new MemoryStream();
zip.Save(ms);
//--Needed to add the following 2 lines to make it work----
ms.Seek(0, SeekOrigin.Begin);
ms.Flush();

I've copied your code, and then saved your final memory steam to disk as data.txt. It was completely unreadable to me, but then I realized that it wasn't a text file, it was a zip file, so i saved it as data.zip and it worked as expected
the method I used to save ms to disk is the following(immediately after your zip.Save(ms); line)
ms.Position = 0;
byte[] data = ms.ToArray();
File.WriteAllBytes("data.zip", data);
So, I believe that your memory stream is what It is supposed to be, which is compressed text. It won't be readable until you decompress it.