Develop Reference

c# how to save IO.Stream to MemoryStream and save to PDF file on local folder

I am calling a third party service, which return a pdf file by IO.Stream. I need to change to MemoryStream, and save to a pdf file.

cRequestString = ".....";//You need to set up you own URL here.
//Make the API call
try
{
byte[] bHeaderBytes = System.Text.Encoding.UTF8.GetBytes(GetUserPasswordString()); //user and pa for third party call.
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(cRequestString);
request.Method = WebRequestMethods.Http.Get;
request.PreAuthenticate = true;
request.ContentType = "application/pdf";
request.Accept = "application/pdf";
request.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(bHeaderBytes));
MemoryStream memStream;
WebResponse response = request.GetResponse();
using (Stream stream = response.GetResponseStream())
using (StreamReader reader = new StreamReader(stream))
{
memStream = new MemoryStream();
//read small blocks to show correctly
byte[] buffer = new Byte[1023];
int byteCount;
do
{
byteCount = stream.Read(buffer, 0, buffer.Length);
memStream.Write(buffer, 0, byteCount);
} while (byteCount > 0);
}
memStream.Seek(0, SeekOrigin.Begin);//set position to beginning
return memStream;
}
catch
{
return null;
}
//save MemoryStream to local pdf file
private void SavePDFFile(string cReportName, MemoryStream pdfStream)
{
//Check file exists, delete
if (File.Exists(cReportName))
{
File.Delete(cReportName);
}
using (FileStream file = new FileStream(cReportName, FileMode.Create, FileAccess.Write))
{
byte[] bytes = new byte[pdfStream.Length];
pdfStream.Read(bytes, 0, (int)pdfStream.Length);
file.Write(bytes, 0, bytes.Length);
pdfStream.Close();
}
}

You could do the following.
using (Stream stream = response.GetResponseStream())
using(MemoryStream memStream = new MemoryStream())
{
memStream = new MemoryStream();
stream.CopyTo(memoryStream);
// TODO : Rest of your task
}
More details on Stream.CopyTo on MSDN

Downloading a torrent file with WebClient, results in corrupt file

I'm trying to download a .torrent file (not the contents of the torrent itself) in my .NET application.
Using the following code works for other files, but not .torrent. The resulting files is about 1-3kb smaller than if I download the file via a browser. When opening it in a torrent client, it says the torrent is corrupt.
WebClient web = new WebClient();
web.Headers.Add("Content-Type", "application/x-bittorrent");
web.DownloadFile("http://kat.ph/torrents/linux-mint-12-gnome-mate-dvd-64-bit-t6008958/", "test.torrent");
Opening the URL in a browser results in the file being downloaded correctly.
Any ideas as to why this would happen? Are there any good alternatives to WebClient that would download the file correctly?
EDIT: I've tried this as well as WebClient, and it results in the same thing:
private void DownloadFile(string url, string file)
{
byte[] result;
byte[] buffer = new byte[4096];
WebRequest wr = WebRequest.Create(url);
wr.ContentType = "application/x-bittorrent";
using (WebResponse response = wr.GetResponse())
{
using (Stream responseStream = response.GetResponseStream())
{
using (MemoryStream memoryStream = new MemoryStream())
{
int count = 0;
do
{
count = responseStream.Read(buffer, 0, buffer.Length);
memoryStream.Write(buffer, 0, count);
} while (count != 0);
result = memoryStream.ToArray();
using (BinaryWriter writer = new BinaryWriter(new FileStream(file, FileMode.Create)))
{
writer.Write(result);
}
}
}
}
}

The problem that server returns content compressed by gzip and you download this compressed content to file. For such cases you should check the "Content-Encoding" header and use proper stream reader to decompress the source.
I modified your function to handle gzipped content:
private void DownloadFile(string url, string file)
{
byte[] result;
byte[] buffer = new byte[4096];
WebRequest wr = WebRequest.Create(url);
wr.ContentType = "application/x-bittorrent";
using (WebResponse response = wr.GetResponse())
{
bool gzip = response.Headers["Content-Encoding"] == "gzip";
var responseStream = gzip
? new GZipStream(response.GetResponseStream(), CompressionMode.Decompress)
: response.GetResponseStream();
using (MemoryStream memoryStream = new MemoryStream())
{
int count = 0;
do
{
count = responseStream.Read(buffer, 0, buffer.Length);
memoryStream.Write(buffer, 0, count);
} while (count != 0);
result = memoryStream.ToArray();
using (BinaryWriter writer = new BinaryWriter(new FileStream(file, FileMode.Create)))
{
writer.Write(result);
}
}
}
}

Unzipping a Stream in C#

I'm working in C#, and I'm downloading for the internet a zip file with one XML file in it. and I wish to load this XML file. This is what I have so far:
byte[] data;
WebClient webClient = new WebClient();
try {
data = webClient.DownloadData(downloadUrl);
}
catch (Exception ex) {
Console.WriteLine("Error in DownloadData (Ex:{0})", ex.Message);
throw;
}
if (data == null) {
Console.WriteLine("Bulk data is null");
throw new Exception("Bulk data is null");
}
//Create the stream
MemoryStream stream = new MemoryStream(data);
XmlDocument document = new XmlDocument();
//Gzip
GZipStream gzipStream = new GZipStream(stream, CompressionMode.Decompress);
//Load report straight from the gzip stream
try {
document.Load(gzipStream);
}
catch (Exception ex) {
Console.WriteLine("Error in Load (Ex:{0})", ex.Message);
throw;
}
in document.Load I'm always getting the following exception:
The magic number in GZip header is not correct. Make sure you are passing in a GZip stream.
What I'm doing wrong?

Apparently SharpZipLib is now unmaintained and you probably want to avoid it:
https://stackoverflow.com/a/593030
In .NET 4.5 there is now built in support for zip files, so for your example it would be:
var data = new WebClient().DownloadData(downloadUrl);
//Create the stream
var stream = new MemoryStream(data);
var document = new XmlDocument();
//zip
var zipArchive = new ZipArchive(stream);
//Load report straight from the zip stream
document.Load(zipArchive.Entries[0].Open());

If you have a byte array that contains a zip archive with a single file, you can use the ZipArchive class to get an unzipped byte array with the file's data.
ZipArchive is contained in .NET 4.5, in the assembly System.IO.Compression.FileSystem (you need to reference it explicitly).
The following function, adapted from this answer, works for me:
public static byte[] UnzipSingleEntry(byte[] zipped)
{
using (var memoryStream = new MemoryStream(zipped))
{
using (var archive = new ZipArchive(memoryStream))
{
foreach (ZipArchiveEntry entry in archive.Entries)
{
using (var entryStream = entry.Open())
{
using (var reader = new BinaryReader(entryStream))
{
return reader.ReadBytes((int)entry.Length);
}
}
}
}
}
return null; // To quiet my compiler
}

I am using SharpZipLib and it's working great !
Below is a function that encapsulate the library
public static void Compress(FileInfo sourceFile, string destinationFileName,string destinationTempFileName)
{
Crc32 crc = new Crc32();
string zipFile = Path.Combine(sourceFile.Directory.FullName, destinationTempFileName);
zipFile = Path.ChangeExtension(zipFile, ZIP_EXTENSION);
using (FileStream fs = File.Create(zipFile))
{
using (ZipOutputStream zOut = new ZipOutputStream(fs))
{
zOut.SetLevel(9);
ZipEntry entry = new ZipEntry(ZipEntry.CleanName(destinationFileName));
entry.DateTime = DateTime.Now;
entry.ZipFileIndex = 1;
entry.Size = sourceFile.Length;
using (FileStream sourceStream = sourceFile.OpenRead())
{
crc.Reset();
long len = sourceFile.Length;
byte[] buffer = new byte[bufferSize];
while (len > 0)
{
int readSoFar = sourceStream.Read(buffer, 0, buffer.Length);
crc.Update(buffer, 0, readSoFar);
len -= readSoFar;
}
entry.Crc = crc.Value;
zOut.PutNextEntry(entry);
len = sourceStream.Length;
sourceStream.Seek(0, SeekOrigin.Begin);
while (len > 0)
{
int readSoFar = sourceStream.Read(buffer, 0, buffer.Length);
zOut.Write(buffer, 0, readSoFar);
len -= readSoFar;
}
}
zOut.Finish();
zOut.Close();
}
fs.Close();
}
}

As the others have mentioned GZip and Zip are not the same so you might need to use a zip library. I use a library called: DotNetZip - available from the below site:
http://dotnetzip.codeplex.com/

From GZipStream Class description:
Compressed GZipStream objects written to a file with an extension of .gz can be decompressed using many common compression tools; however, this class does not inherently provide functionality for adding files to or extracting files from .zip archives
So unless you control server-side files, I'd suggest looking for specific zip-targeted library (SharpZipLib for example).

Programmatic compression/decompression to MemoryStream with GZipStream

I built (based on a CodeProject article) a wrapper class (C#) to use a GZipStream to compress a MemoryStream. It compresses fine but doesn't decompress. I've looked at many other examples that have the same problem, and I feel like I'm following what's said but still am getting nothing when I decompress. Here's the compression and decompression methods:
public static byte[] Compress(byte[] bSource)
{
using (MemoryStream ms = new MemoryStream())
{
using (GZipStream gzip = new GZipStream(ms, CompressionMode.Compress, true))
{
gzip.Write(bSource, 0, bSource.Length);
gzip.Close();
}
return ms.ToArray();
}
}
public static byte[] Decompress(byte[] bSource)
{
try
{
using (MemoryStream ms = new MemoryStream())
{
using (GZipStream gzip = new GZipStream(ms, CompressionMode.Decompress, true))
{
gzip.Read(bSource, 0, bSource.Length);
gzip.Close();
}
return ms.ToArray();
}
}
catch (Exception ex)
{
throw new Exception("Error decompressing byte array", ex);
}
}
Here's an example of how I use it:
string sCompressed = Convert.ToBase64String(CompressionHelper.Compress("Some Text"));
// Other Processes
byte[] bReturned = CompressionHelper.Decompress(Convert.FromBase64String(sCompressed));
// bReturned has no elements after this line is executed

There is a bug in Decompress method.
The code does not read content of bSource. On the contrary, it overrides its content wile reading from empty gzip, created based on empty memory stream.
Basically what your version of code is doing:
//create empty memory
using (MemoryStream ms = new MemoryStream())
//create gzip stream over empty memory stream
using (GZipStream gzip = new GZipStream(ms, CompressionMode.Compress, true))
// write from empty stream to bSource
gzip.Write(bSource, 0, bSource.Length);
The fix could look like this:
public static byte[] Decompress(byte[] bSource)
{
using (var inStream = new MemoryStream(bSource))
using (var gzip = new GZipStream(inStream, CompressionMode.Decompress))
using (var outStream = new MemoryStream())
{
gzip.CopyTo(outStream);
return outStream.ToArray();
}
}

The OP said in an edit, now rolled back:
Thanks to Alex's explanation of what was going wrong, I was able to fix the Decompress method. Unfortunately, I'm using .Net 3.5, so I wasn't able to implement the Stream.CopyTo method he suggested. With his explanation, though, I was able to figure out a solution. I made the appropriate changes to the Decompress method below.
public static byte[] Decompress(byte[] bSource)
{
try
{
using (var instream = new MemoryStream(bSource))
{
using (var gzip = new GZipStream(instream, CompressionMode.Decompress))
{
using (var outstream = new MemoryStream())
{
byte[] buffer = new byte[4096];
while (true)
{
int delta = gzip.Read(buffer, 0, buffer.Length);
if (delta > 0)
outstream.Write(buffer, 0, delta);
if (delta < 4096)
break;
}
return outstream.ToArray();
}
}
}
}
catch (Exception ex)
{
throw new Exception("Error decompressing byte array", ex);
}
}

C# code to GZip and upload a string to Amazon S3

I currently use the following code to retrieve and decompress string data from Amazon C#:
GetObjectRequest getObjectRequest = new GetObjectRequest().WithBucketName(bucketName).WithKey(key);
using (S3Response getObjectResponse = client.GetObject(getObjectRequest))
{
using (Stream s = getObjectResponse.ResponseStream)
{
using (GZipStream gzipStream = new GZipStream(s, CompressionMode.Decompress))
{
StreamReader Reader = new StreamReader(gzipStream, Encoding.Default);
string Html = Reader.ReadToEnd();
parseFile(Html);
}
}
}
I want to reverse this code so that I can compress and upload string data to S3 without being written to disk. I tried the following, but I am getting an Exception:
using (AmazonS3 client = Amazon.AWSClientFactory.CreateAmazonS3Client(AWSAccessKeyID, AWSSecretAccessKeyID))
{
string awsPath = AWSS3PrefixPath + "/" + keyName+ ".htm.gz";
byte[] buffer = Encoding.UTF8.GetBytes(content);
using (MemoryStream ms = new MemoryStream())
{
using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress))
{
zip.Write(buffer, 0, buffer.Length);
PutObjectRequest request = new PutObjectRequest();
request.InputStream = ms;
request.Key = awsPath;
request.BucketName = AWSS3BuckenName;
using (S3Response putResponse = client.PutObject(request))
{
//process response
}
}
}
}
The exception I am getting is:
Cannot access a closed Stream.
What am I doing wrong?
EDIT:
The exception is occuring on the closing bracket of using (GZipStream zip
Stack trace:
at
System.IO.MemoryStream.Write(Byte[]
buffer, Int32 offset, Int32 count)
at
System.IO.Compression.DeflateStream.Dispose(Boolean
disposing) at
System.IO.Stream.Close() at
System.IO.Compression.GZipStream.Dispose(Boolean
disposing) at
System.IO.Stream.Close()

You need to flush and close the GZipStream and reset the Position of the MemoryStream to 0 before using it as input to the request:
MemoryStream ms = new MemoryStream();
using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true))
{
byte[] buffer = Encoding.UTF8.GetBytes(content);
zip.Write(buffer, 0, buffer.Length);
zip.Flush();
}
ms.Position = 0;
PutObjectRequest request = new PutObjectRequest();
request.InputStream = ms;
request.Key = AWSS3PrefixPath + "/" + keyName+ ".htm.gz";
request.BucketName = AWSS3BuckenName;
using (AmazonS3 client = Amazon.AWSClientFactory.CreateAmazonS3Client(
AWSAccessKeyID, AWSSecretAccessKeyID))
using (S3Response putResponse = client.PutObject(request))
{
//process response
}
It might also be possible to use the GZipStream as input if you first fill the MemoryStream with the data, but I've never tried this yet.