Re: Able to write to read-only pdf files

[Adriano Vilela Barbosa <adriano.vilela@gmail.com>]

On Sat, 14 Aug 2021 at 16:49, bruno zanetti <bzanetti00@gmail.com> wrote:
>
> Il giorno sab 14 ago 2021 alle ore 20:20 Adriano Vilela Barbosa <adriano.vilela@gmail.com> ha scritto:
>>
>> On Sat, 14 Aug 2021 at 12:54, bruno zanetti <bzanetti00@gmail.com> wrote:
>> >
>> > Il giorno sab 14 ago 2021 alle ore 15:39 Adriano Vilela Barbosa <adriano.vilela@gmail.com> ha scritto:
>> >>
>> >> Hello,
>> >>
>> >> Yesterday I came across a very weird behavior while annotating a pdf
>> >> file in Okular. Long story short: I opened a read-only pdf file
>> >> (permissions: 400), inserted some comments and hit the save button. At
>> >> this point, I thought I had been working on a write-enabled copy of
>> >> the file. After a while, I realized that I was actually working on the
>> >> read-only version of the file, that somehow got saved to disk when I
>> >> hit the save icon. Okular was not only able to save the file to disk,
>> >> but the file permissions were changed to 644.
>> >>
>> >> I initially thought this was an Okular problem. However, after some
>> >> more testing, I was able to reproduce the problem with Xournal. This
>> >> makes me think that the problem is not with Okular or Xournal, but
>> >> with some common library used by both of these packages (maybe
>> >> libpoppler?).
>> >>
>> >> Has anybody had this problem? Can anybody reproduce it?
>> >>
>> >> I'm using Debian testing.
>> >>
>> >> Thanks a lot,
>> >>
>> >> Adriano
>> >
>> >
>> > Hi Adriano,
>> > the read-only permission on the pdf file just prevents it's contents to be changed. It still can be deleted if the directory it belongs to is not write protected.
>> > Editor programs usually do not directly change the contents of a file but rather save them to a temporary new one (with default permissions), delete the original and then rename the new file replacing the original one. I don't know if Okular works this way, but I think it quite likely does.
>> >
>> > Have a good release day!
>> >
>> > Bruno
>> >
>> >
>>
>> Hi Bruno,
>>
>> Thanks for your reply.
>>
>> Indeed, what you describe may be what's happening. If I change the
>> permissions of the directory where the file is to read-only, I get an
>> error message when trying to save the file. The error message says the
>> file could not be saved (error: access denied), and also says that it
>> could not write to file.pdf.part (this .part file must be temporary
>> file you mentioned).
>>
>> I understand this mechanism, but I think this is quite controversial
>> and problematic. I mean, as an end user I don't care what the editor
>> is doing behind the scenes; it just shouldn't be able to modify a file
>> marked as read-only.
>>
>> This is the first time I came across this behavior. No text editor I
>> ever used does this; LibreOffice doesn't do it either (rather, it
>> shows a message saying the document is open in read-only and shows an
>> "Edit Document" button, which allows you to edit the document and then
>> save it under a different name).
>>
>> The question is: should I file a bug report somewhere? I really don't
>> want editors overwriting my read-only documents...
>>
>> Thanks again,
>>
>> Adriano
>
>
> Well, some editors take care of not overwriting read-only files, some others (like kate, kwite) don't...
> But I second your reasoning, the right behaviour IMHO would be to respect the file permissions, regardless of the mechanism of the underlying filesystem.
> I'd suggest you report the issue on bugs.kde.org since it doesn't seem to be a debian specific issue.
>
> Best
>
> Bruno
>

Hi Bruno,

At least on my system (Debian Testing), I can't overwrite a read-only
file with either kwrite or kate.

I'm going to report a bug upstream and post the link here.

Adriano