Could someone be kind enough to explain how I get my files the same size after copying it using a chunked stream? I presume it is because the last chunk still has a buffer size of 2048 so it is putting empty bytes at the end, but I am unsure how I would adjust the last read?
Original size: 15.1 MB (15,835,745 bytes) New size: 15.1 MB (15,837,184 bytes)
static FileStream incomingFile;
static void Main(string[] args)
{
incomingFile = new FileStream(
@"D:\temp\" + Guid.NewGuid().ToString() + ".png",
FileMode.Create,
FileAccess.Write);
FileCopy();
}
private static void FileCopy()
{
using (Stream source = File.OpenRead(@"D:\temp\test.png"))
{
byte[] buffer = new byte[2048];
var chunkCount = source.Length;
for (int i = 0; i < (chunkCount / 2048) + 1; i++)
{
source.Position = i * 2048;
source.Read(buffer, 0, 2048);
WriteFile(buffer);
}
incomingFile.Close();
}
}
private static void WriteFile(byte[] buffer)
{
incomingFile.Write(buffer, 0, buffer.Length);
}
The last buffer read does not necessary contain exactly 2048 bytes (it can well be incomplete). Imagine, we have a file of 5000 bytes; in this case will read 3 chunks: 2 complete and 1 incomplete
2048
2048
904 the last incomplete buffer
Code:
using (Stream source = File.OpenRead(@"D:\temp\test.png"))
{
byte[] buffer = new byte[2048];
var chunkCount = source.Length;
for (int i = 0; i < (chunkCount / 2048) + 1; i++)
{
source.Position = i * 2048;
// size - number of actually bytes read
int size = source.Read(buffer, 0, 2048);
// if we bytes to write, do it
if (size > 0)
WriteFile(buffer, size);
}
incomingFile.Close();
}
...
private static void WriteFile(byte[] buffer, int size = -1)
{
incomingFile.Write(buffer, 0, size < 0 ? buffer.Length : size);
}
In your case you write 15837184 == 7733 * 2048 bytes (7733 complete chunks) when you should write 15835745 == 7732 * 2048 + 609 bytes - 7732 complete chunks and the last incomplete one of 609 bytes