File.Read, error 0x8000ffff

Help & Support
1

It seems I can't get File.Read(blob) or blob=File.Read(size) to work.
This doesn't seem to work:

var b=DOpus.NewBlob(5000);
var f=DOpus.FSUtil.OpenFile("D:\\tmp\\x\\account_actions_24.jpg","we");
if ((f)&&(f.error==0)){
	f.Seek(0,"b");
	f.Read(b,1059);
	f.Close();
}

I've also tried f.Read(b).
The error for both is "A method was called unexpectedly (0x8000ffff)" when calling f.Read.

I found this while experimenting with reading the width/height myself using js..which probably should
be possible after file and blob was added.

2

You can't read from a file that's opened for writing.

3

Ah, thats why.. I found it strange that all the items listed began with w, but I didn't really think much of it.
No wonder then.
The error could've been handled better though, such as by providing some errorcode in .error or something other
than a E_UNEXPECTED/unhandled exception.

4

At the point you test f.error, no error has occurred.

When you call Read on a write-only file, the Read call is unexpected, so E_UNEXPECTED makes sense. I'm not sure Win32 defines a more suitable error code for that situation. (Win32 wastes so many error codes on incredibly specific/esoteric meanings/messages, and leaves out some very common/generic cases. It's a pain.)

5

Obviously.. I meant when the error occured.
Yes I know the errorcodes aren't really that usable (by experience), but I'd assume that anything is better than a unhandled exception/catastrophic failure.

E_UNEXPECTED isn't that kind of unexpected, but more like "sorry, I can't deal with this and I don't know why..but it is a fatal/catastrophic failure."
I guess it is among the most severe messages available.

6

But it's an error that will happen every time the script runs. There's no point allowing the script to handle the error better since it's not a transitory thing that might work next time. It may as well abort so you can fix it.

7

I have no problem with aborting, although it seems win32 has an error for this situation.

I tried opening a file only for reading (in C), then did a ReadFile on it which caused no data to be read
and GetLastError returns 5 (ERROR_ACCESS_DENIED)..which kind of makes sense.

8

Correction, I meant only for writing.