tree 743d39d5d3ed2195b7717be5438ec7c7c7700cb2
parent 52d8c65408b9c600d829156f7c46f8cc43e4f9c8
author Miklos Vajna <vmiklos@collabora.co.uk> 1600853884 +0000
committer Chromium commit bot <commit-bot@chromium.org> 1600853884 +0000

Add FPDF_GetTrailerEnds() API

This follows the same pattern as FPDFSignatureObj_GetTime(), so the
client has to call this function twice, but allocation of the buffer
happens outside pdfium.

The benefit of this API is that client code can learn about the initial
trailer and the trailer at the end of incremental updates for signature
verification purposes.

This information can be used to write client code that emits no warnings
when a document is signed multiple times, but still warn when there are
unsigned incremental updates between the signatures or after the last
one. This behavior matches what Acrobat does, but it does not seem to be
in the PDF reference. So it is reasonable to have an API that allows
doing this, but not hardcode this policy into pdfium.

Change-Id: Ic741b672821d7743df88cdf51af54e85251857e6
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/73370
Commit-Queue: Miklos V <vmiklos@collabora.co.uk>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>