How to retrieve the name of the file from a FILE *

[jacob navia]

Recently there was a discussion in this group about
how to retrieve the file name given a FILE *.

The question raised my curiosity, and after some
research I have come up with a good implementation.

The solution is in the tutorial for lcc-win32
(http://www.cs.virginia.edu/~lcc-win32) page
331.

jacob

[Joona I Palaste]

jacob navia <ja***@jacob.re mcomp.fr> scribbled the following:

Recently there was a discussion in this group about
how to retrieve the file name given a FILE *. The question raised my curiosity, and after some
research I have come up with a good implementation. The solution is in the tutorial for lcc-win32
(http://www.cs.virginia.edu/~lcc-win32) page
331.

This solution is non-portable as it makes use of the Win32 system APIs.
As usual... *sigh*... Jacob Navia failed to mention this fact.

--
/-- Joona Palaste (pa*****@cc.hel sinki.fi) ------------- Finland --------\
\-------------------------------------------------------- rules! --------/
"B-but Angus! You're a dragon!"
- Mickey Mouse

[jacob navia]

Joona I Palaste wrote:

jacob navia <ja***@jacob.re mcomp.fr> scribbled the following:

Recently there was a discussion in this group about
how to retrieve the file name given a FILE *.

The question raised my curiosity, and after some
research I have come up with a good implementation.

The solution is in the tutorial for lcc-win32
(http://www.cs.virginia.edu/~lcc-win32) page
331.

This solution is non-portable as it makes use of the Win32 system APIs.
As usual... *sigh*... Jacob Navia failed to mention this fact.

Yes, it is based on the win32 API. That is why I did not publish the
code here, just giving a pointer to the code

[Joona I Palaste]

jacob navia <ja***@jacob.re mcomp.fr> scribbled the following:

Joona I Palaste wrote:

jacob navia <ja***@jacob.re mcomp.fr> scribbled the following:

Recently there was a discussion in this group about
how to retrieve the file name given a FILE *.

The question raised my curiosity, and after some
research I have come up with a good implementation.

The solution is in the tutorial for lcc-win32
(http://www.cs.virginia.edu/~lcc-win32) page
331.

This solution is non-portable as it makes use of the Win32 system APIs.
As usual... *sigh*... Jacob Navia failed to mention this fact.

Yes, it is based on the win32 API. That is why I did not publish the
code here, just giving a pointer to the code

Why did you even give a pointer here? This newsgroup is not concerned
about system-specific code no matter where that code is written. Also,
having to download a 5-megabyte PDF file just to see two pages of C
code doesn't exactly appeal to me, and I don't think it appeals to
many other people either.

--
/-- Joona Palaste (pa*****@cc.hel sinki.fi) ------------- Finland --------\
\-------------------------------------------------------- rules! --------/
"Roses are red, violets are blue, I'm a schitzophrenic and so am I."
- Bob Wiley

[Dan Pop]

In <41************ **********@news .wanadoo.fr> jacob navia <ja***@jacob.re mcomp.fr> writes:

The question raised my curiosity, and after some
research I have come up with a good implementation.

If it's not portable, you're abusing this newsgroup by advertising it.
If it's portable, my congratulations !

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
Currently looking for a job in the European Union

[CBFalconer]

Dan Pop wrote:

jacob navia <ja***@jacob.re mcomp.fr> writes:

The question raised my curiosity, and after some
research I have come up with a good implementation.

If it's not portable, you're abusing this newsgroup by advertising
it. If it's portable, my congratulations !

I feel morally certain that M.Navias method is non-portable.
However, I can conceive of a portable method, if you are willing to
replace the fopen call with something else, say fnopen. Then it
only has to cache a copy of the file name in a hashtable, keyed by
the FILE* pointer returned, and retrieval is a simple O(1) lookup.

--
Chuck F (cb********@yah oo.com) (cb********@wor ldnet.att.net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net> USE worldnet address!

[Mark McIntyre]

On Wed, 13 Oct 2004 15:18:20 +0200, in comp.lang.c , jacob navia
<ja***@jacob.re mcomp.fr> wrote:

Recently there was a discussion in this group about
how to retrieve the file name given a FILE *.

The question raised my curiosity, and after some
research I have come up with a good implementation.

The solution is in the tutorial for lcc-win32
(http://www.cs.virginia.edu/~lcc-win32) page
331.

It doesn't work. Please try not to post broken code, even in links, under
the guise of "good implementations "

--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt >
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[jacob navia]

Mark McIntyre wrote:

It doesn't work. Please try not to post broken code, even in links, under
the guise of "good implementations "

Obviously I have just written it, so it is not well tested. Can you give
any examples for your assertion? In which circumstances it doesn't work?

[Keith Thompson]

jacob navia <ja***@jacob.re mcomp.fr> writes:

Mark McIntyre wrote:

It doesn't work. Please try not to post broken code, even in links,
under
the guise of "good implementations "

Obviously I have just written it, so it is not well tested. Can you
give any examples for your assertion? In which circumstances it
doesn't work?

It doesn't work on any system other than MS Windows. I can't say
whether it does work on MS Windows; that's why we have
Windows-specific newsgroups, where people can comment intelligently on
Windows-specific code.

(I also took a brief look at the code, and I noticed that it returns
the strings "stdin", "stdout", and "stderr" for the corresponding
arguments. Those are C identifiers, not file names.)

There is no portable way to retrieve a file name from a FILE* value.
The closest you can come is to remember the name when you open the
file. If you don't have control over the code that opens the file,
you'll have to either give up on getting the name or resort to
non-portable code.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[jacob navia]

Keith Thompson wrote:

jacob navia <ja***@jacob.re mcomp.fr> writes:

Mark McIntyre wrote:

It doesn't work. Please try not to post broken code, even in links,
under
the guise of "good implementations "
Obviously I have just written it, so it is not well tested. Can you
give any examples for your assertion? In which circumstances it
doesn't work?

It doesn't work on any system other than MS Windows. I can't say
whether it does work on MS Windows; that's why we have
Windows-specific newsgroups, where people can comment intelligently on
Windows-specific code.

Under unix it is possible to do that too, I am sure. Maybe
using the inode of the file, you can get into the name,
or similar.

There is no portable directory handling in C. This hole in the
language is quite incredible, and there are a lot of proposals
on how to fill it. The standards comitee has blocked all those
propositions, some of them quite advanced.

I can't change this. I did not want to discuss system specific
code in this group so I gave just a pointer to the code. I
do not understand why all this fuzz.
(I also took a brief look at the code, and I noticed that it returns
the strings "stdin", "stdout", and "stderr" for the corresponding
arguments. Those are C identifiers, not file names.)

Yes, but since there isn't any file associated with the terminal,
I thought it could work like that... Maybe I should return
$CONIN $CONOUT or similar. You have a point here.
There is no portable way to retrieve a file name from a FILE* value.
The closest you can come is to remember the name when you open the
file. If you don't have control over the code that opens the file,
you'll have to either give up on getting the name or resort to
non-portable code.

Yes, I do not discuss that. I proposed a system specific
way of doing this under a popular platform, that's all.

jacob