While it is unclear in ISO 32000-1 whether such a PDF is invalid, we made it clear in 32000-2 that you can only have one copy of each page in the Pages tree. So personally, I wouldn’t waste much time on this particular file.
Leonard On 9/17/15, 1:04 AM, "poppler on behalf of Jason Crain" <[email protected] on behalf of [email protected]> wrote: >On Wed, Sep 16, 2015 at 09:05:58PM -0400, William Bader wrote: >> > > I don't know of a good way to validate the page count. Even >> > > going through the page tree might be hard to do right without >> > > leading to an infinite loop, in addition to being slow. >> > >> > Catalog::cachePageTree goes over the tree, but i agree doing that >> > to calculate the num of pages can be meh. >> >> If the number of pages is huge, the PDF might be intentionally >> corrupted to provoke a bug in a particular PDF viewer, and other >> data structures could be subtly corrupted as well. Any scan would >> have to proceed very cautiously. >> >> If there is a minimum number of objects required for a page, and if >> the total number of objects is easy to find, could poppler >> immediately reject files with (total num objects) / (min objects per >> page) < page count? > >The document at >https://drive.google.com/open?id=0ByTyiZeyQ4p9cTVBUllNRmI3bmM is what >I'm thinking of. It has 5 objects and a single page that is listed in >the /Kids array 10 times. Duplicating the page just means adding it >to the array again and incrementing /Count. If we want this document >to work then there's really no minimum number of objects required for >a page. Otherwise, each page would require at least a /Page object. > >FWIW Adobe Reader shows an error on the document after the first >duplicated page. Other viewers show it just fine. >_______________________________________________ >poppler mailing list >[email protected] >http://lists.freedesktop.org/mailman/listinfo/poppler _______________________________________________ poppler mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/poppler
