How to Upload Data to Azure Storage in chunks/blocks?

Shubham Tyagi 0
Viewed 33

I'm uploading images to Azure Storage, and need to implement chunking to upload heavy image. But I'm getting exception such as "Offset and length out of bound"

int fileSize = imageModel.ImageByteArray.Length;
int blockSize = 100*1024 , numberOfBlocks = 0;

if (fileSize < blockSize)
    blockSize = fileSize;

if (fileSize % blockSize == 0)
    numberOfBlocks = fileSize / blockSize;
else
    numberOfBlocks = fileSize / blockSize + 1;

byte[] blockArray = new byte[blockSize];

for (int i = 0; i < numberOfBlocks; i++)
{
    Array.Copy(imageModel.ImageByteArray, i * blockSize, blockArray, 0, blockSize);
    await blob.UploadFromByteArrayAsync(blockArray, i, imageModel.ImageByteArray.Length);
    Progress = (float)i / numberOfBlocks;
}

var ResponseURL = blob.Uri.OriginalString;

Can anyone help me with the issue?

azure-blob-storage .net c#
1 Answers

This code always copies blockSize bytes:

Array.Copy(imageModel.ImageByteArray, i * blockSize, blockArray, 0, blockSize);

However, the last block may not be a full blockSize:

if (fileSize % blockSize == 0)
    numberOfBlocks = fileSize / blockSize;
else
    numberOfBlocks = fileSize / blockSize + 1;

To fix this, you'll need to handle the last block specially. It may be a full blockSize bytes or it may be less.

Stephen Cleary0
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