Re: BUG #15827: Unable to connect on Windows using pg_services.conf using Python psycopg2

Hi Tom,

Às 21:44 de 19/06/19, Tom Lane escreveu:
> Jorge Gustavo Rocha <jgr(at)geomaster(dot)pt> writes:
>> The error I was facing in QGIS is because the application changes the
>> default fopen mode to binary mode. So, every file is opened in binary
>> mode and so is pg_services.conf.
> Ah-hah! That explains much. So a non-invasive fix would be to force
> parseServiceFile to open the file in text mode; I think this would
> work for that:
>
> - f = fopen(serviceFile, "r");
> + f = fopen(serviceFile, "rt");

I've wrote a small test program in Windows, using MSVS, and your fix
works as expected. Even if we set the global mode to binary, if the file
is opened with "rt", the file is opened in text mode and \r are
discarded. Good!

I've attached the C file and one pg_services.conf file with \r, just for
the record.

This fixes the problem in QGIS.

> I don't think that that's really a good solution, because it does little
> to prevent the same problem from reappearing elsewhere. But if we wanted
> the smallest possible fix that might do.
I agree with you. It is the smallest possible fix.
>> In my humble opinion, we could make pg_services.conf agnostic in terms
>> of \r, just by filtering them, if present.
> I think we should have it go further and ignore any trailing isspace()
> characters, so that trailing spaces don't cause problems either.
> But in any case, the real stumbling block here is to get a project-wide
> convention as to how to do it.

Probably this can be accomplish by using a common function to read all
these kind of files. The function handles the text tokenize/parsing and
provided the contents in higher level data structure.

For example, OpenSceneGraph provides wrappers for all functions related
to the file system and to read and write all kind of file formats [1].
Developers can use things like readImageFile, readShaderFile,
readXmlFile, etc, without caring about os type, character encoding, etc.

If you point me some more examples where we need to read such files in
Postgresql, I can think about a proposal to handle all these cases.

But since we are discussing just a small tiny fix, if you agree, we
could apply this fix and later think about a common approach to handle
all text parse needed in different parts of the code. Is this fair?

Regards,

Jorge Gustavo

[1]
http://public.vrac.iastate.edu/vancegroup/docs/OpenSceneGraphReferenceDocs-3.0/a01245.html#a27021fc08b8d4088a72e83b81d771481

>
> regards, tom lane
>
>
--
Logo*   Geomaster, LDA*
  *VENHA DESCOBRIR O CAMINHO DO OPEN SOURCE CONNOSC**O

*
 
Avenida Barros e Soares
N.º 423, 4715-214 Braga
VAT/NIF510 906 109
Phone  +351 253 680 323
Site       geomaster.pt <http://geomaster.pt>
GPS       41.53322, -8.41929

------------------------------------------------------------------------
 
Jorge Gustavo Rocha
CTO

Mobile  +351 910 333 888
Email    jgr(at)geomaster(dot)pt