[Poppler-bugs] [Bug 16770] support for digital signatures

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=16770

--- Comment #81 from Adam Reichold <adam.reichold at t-online.de> ---
(In reply to Adrian Johnson from comment #78)
> I agree that the two calls to doGetChars and updateHash should be merged but
> I don't think a for loop is the best way to process loops where the
> increment is not exactly the same on each iteration. Maybe something like
> this:
> 
>   void FormFieldSignature::hashSignedByteRange(SignatureHandler *handler,
>      Goffset start, Goffset len)
>   {
>     const int CHUNK_SIZE = 4096;
>     unsigned char buffer[CHUNK_SIZE];
>     Goffset i = 0;
>     int byte_count = CHUNK_SIZE;
> 
>     doc->getBaseStream()->setPos(start);
>     while (i < len)
>     {
>       if (i + CHUNK_SIZE > len)
>         byte_count = len - i;
> 
>       doc->getBaseStream()->doGetChars(byte_count, buffer);
>       handler->updateHash(buffer, byte_count);
>       i += byte_count;
>     }
>   }

I was thinking of something like

doc->getBaseStream()->setPos(start);
for (Goffset offset = 0; offset < len; offset += CHUNK_SIZE)
{
  const int byte_count = min(CHUNK_SIZE, len - offset);

  doc->getBaseStream()->doGetChars(byte_count, buffer);
  handler->updateHash(buffer, byte_count);
}

to make the loop more regular as we don't care if offset > len instead of
offset == len after the last iteration. (That code was not tested or even
compiled.)

> I don't mind if we fix all this later. It doesn't have to hold up the
> initial release.

Maybe if there is some external pressure to release this, but otherwise I'd
propose polishing it now, since there is a certain momentum not to touch
working code once it is released.

Best regards, Adam.

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