Hello, Am 24.03.2013 06:32, schrieb Thomas Freitag: > Am 23.03.2013 20:08, schrieb Albert Astals Cid: >> El Dissabte, 23 de març de 2013, a les 20:01:58, Thomas Freitag va >> escriure: >>> Am 23.03.2013 18:59, schrieb Ihar `Philips` Filipau: >>>> On 3/23/13, Ihar `Philips` Filipau <[email protected]> wrote: >>>>>> (i tried to find a way to duplicate a FILE* but failed) >>>>> How did you duplicate FILE*? >>>>> >>>>> How did the `fdopen( fileno(oldfile), mode )` failed? >>>> Nope. This is the right way: >>>> >>>> int new_fd = dup( fileno(oldfile) ); >>>> FILE *new_file = fdopen( new_fd, mode ); >>> Duplicating the FILE pointer in that way is not a solution: I tried it >>> that way when I began to implement thread safe feature: At least under >>> Ubuntu and gcc the duplicated file pointer uses the same underlying >>> buffer, and that corrupts the thread safe feature. >> Exactly, it is the documented behaviour >> >> "They refer to the same open file description and thus share file offset" >> >>> That's why I used the >>> fileName to create a complete new file pointer. >>> Of course we can do it in that way if we detect that the file is deleted >>> (and only then!), but a program which use threads to render different >>> pages the same time will then render garbage :-( >> No. We either write the file back to a temporary location as i >> suggested in my >> initial mail, or use the only fd with locking. I think i'm favoring >> the second >> use case since writing the file back might not even work if we run out >> of free >> space. > I think, You're second solution is quite easy to implement (I mean > really only easy to implement, it will take some time to change every > code snippet and deeply test the changed code): since FileStream already > use it's own buffer, there is no really need of the underlying system > file buffer. So implementing something like a sharable GooFile (or > extend gfile) which can be locked and remember the next read position in > FileStream and then do something like gfile->read(readposition, buf, > buflength) wouldn't really reduce the speed. But then I would prefer use > the low level file handles instead of the file pointer. And it's even > better than to write platform specific code and rely on Windows that the > open file is not deletable and search for a Mac solution. > Then the UniqueFileStream mechanism and the streamOwner instance > variable can be removed, too. > On the other hand: who deletes a just opened file and expects stability > of the application which just opens the file? Is it really worth the > effort?
Seems I am a bit to the party, but for what it's worth: I asked myself the same question as Thomas. Providing a file object that takes care of looking and per-thread offset seems like the best solution (ideally implementing using low-level I/O), but is it really that useful to be able to continue rendering unlinked files as long as Poppler fails gracefully, i.e. does not crash. Best regards, Adam. > Cheers, > Thomas >> >> Cheers, >> Albert >> >>> Cheers, >>> Thomas >>> >>>> It is OK to use *NIX function here - the dup() - since deleting open >>>> file can happen only on the *NIX-like OS, Mac OS X included. Windows >>>> doesn't allow that. Correct me if I'm wrong. Tested on Linux, HP-UX >>>> and Solaris for the safety sake: the fclose() would close the dup()ed >>>> file descriptor. >>>> >>>> Though I'm not sure how to integrate that with the rest of the portable >>>> code. :) >>>> >>>> FYI. >>>> _______________________________________________ >>>> poppler mailing list >>>> [email protected] >>>> http://lists.freedesktop.org/mailman/listinfo/poppler >>>> >>>> . >>> _______________________________________________ >>> poppler mailing list >>> [email protected] >>> http://lists.freedesktop.org/mailman/listinfo/poppler >> _______________________________________________ >> poppler mailing list >> [email protected] >> http://lists.freedesktop.org/mailman/listinfo/poppler >> >> . >> > > > _______________________________________________ > poppler mailing list > [email protected] > http://lists.freedesktop.org/mailman/listinfo/poppler > _______________________________________________ poppler mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/poppler
