Writes a chunk of bytes from a blob to the BLOB accessible through this, blob
is unchanged after this call.
If blob has an associated BlobOp (ie. if blob->op is not
null) then the data to be written using this is the data fetched using
blob->op.
| this |
a BlobOp |
| blob |
a Blob which contains the data to write |
| offset |
offset to write from the start of the blob (starts at 0) |
|
the number of bytes written. In case of error, -1 is returned and the provider should have added an error to the connection. |