DOS/Win95 file names

DOS/Win95 file names

[fluffy_pop]

Hi,

I'm a student writing a program that must ask the user for a file name
to be either created for writing or opened for reading by the program.

I'm being asked to validate the name format so that it satisfies the
(8.3) DOS requirements (actually it's a hybrid because I'm accepting
characters illegal under DOS but legal under Windows).  It's a Ada
console program and I'm working on a Win95 machine.

As it is (my program), when the user enters a file name that contains
an accented character, my handling of the Name_Error Exception occurs
to produce a message that the file is not in the repertory.  The file
*is* there.  Also, when the file name contains a '?', my program
crashes (when what follows is a Create(F,Out_File,"name") ).  That's
because the sweep of the string containing the illegal characters, in
my validation procedure, is not working properly.  The name passes
through whithout the illegal character being detected.  Everything
else about the validation works fine.

So the value of each character entered in the file name by the user
does not match the value of the characters in the actual Windows/DOS
file names, or the value of my own program's string of illegal
characters (a constant).  That string is declared like this:
	ILLEGAL_CHAR : CONSTANT string := "*?|\/<>:""";

Now, I'm guessing that the character code that is actually put on my
Ada page ("my_prog.ada") in that string matches the code of the
characters of the real file names, since I'm working under Windows
when I write my program code and the files are created also under
Windows or DOS.  Also, I'm assuming that when the user enters let's
say '�', what is put in the string to hold the file name in my program
is determined by the active Windows character table/code.  I think
that it matches exactly or very closely the ISO 8859-1 standard, which
in turn fits with Ada.Characters.Latin_1.  For my DOS, currently, it's
850 Multilingual (Latin I).  I have these tables to look up.

Beyond that I don't know much.  I know how to use the DOS Alt+x[xx]
codes, and the Windows(?) Alt+0x[xx] codes for display, but I don't
know the character(s) produced that go just before the numerical code.
I don't know exactly what produces this/these special characters or
what their role is in terms of what part of the system uses them:
hardware and/or OS, and/or my program.  Anyway, this might have
nothing to do whith my problem, but I would still like to have some
hint.

Thanks

Marc Galipeau
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[Gautier]

It's Windows in all its glory: the console has one
character set (437, 850 or so); Windows itself uses
another one... There is a DOS upper case function
that upcases the filenames but with which character
set, the same way or not under plain DOS or under
Windows... A possibility is to have an explicit
translation table; the best one is to forbid
accents in filenames: you could add to your exception
handling such a warning.

-- 
Gautier

--------
http://members.xoom.com/gdemont/

Re: DOS/Win95 file names

[Pascal Obry]

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Gautier <Gautier.deMontmollin@Maths.UniNe.CH> a �crit dans le message :
3760B4CC.6E84F2F6@Maths.UniNe.CH...
> It's Windows in all its glory: the console has one
> character set (437, 850 or so); Windows itself uses
> another one... There is a DOS upper case function
> that upcases the filenames but with which character
> set, the same way or not under plain DOS or under
> Windows... A possibility is to have an explicit
> translation table; the best one is to forbid
> accents in filenames: you could add to your exception
> handling such a warning.
>

Well that's not so bad for a Microsoft product :-)

Pascal.

Re: DOS/Win95 file names

[fluffy_pop]

On Fri, 11 Jun 1999 09:03:41 +0200, in comp.lang.ada you wrote:

>...
>Windows... A possibility is to have an explicit
>translation table;

I guess this is what you mean:
     DOS			Windows
--------------	---------------
Alt+130 => '�'	Alt+0130 => '�'
Alt+233 => '_'	Alt+0233 => '�'

FUNCTION ISO ( p_car : character ) RETURN character IS
WITH Ada.Characters.Latin_1; USE Ada.Characters.Latin_1;
	ISO_Char : character;
BEGIN
	CASE character'pos(p_car) IS
		...
		WHEN 129 => ISO_Char := lc_u_diaeresis;
		WHEN 130 => ISO_Char := lc_e_acute;
		WHEN 131 => ISO_Char := lc_a_circumflex;
		...
	END CASE;
	RETURN ISO_Char; 
END;

>                    the best one is to forbid
>accents in filenames: you could add to your exception
>handling such a warning.

I don't want to forbid accents in filenames.  Why should I ?
Windows (in all it's glory) accepts accents in filenames, so
why not take advantage of it with my program ?  If I'm a user
of the program and I arleady have input filenames that have
accented characters on my HD I don't want to have to change
my files' names before using the program.

If the user is using my program in a DOS window, what he/she
enters (each character) will be the code from the Windows
code page, and if it's in DOS MODE (reboot) it will be from
the DOS 850 code page, right ?

If the above is true, then the function ISO will only have
an effect if the user is in DOS MODE, right ?

So if the two statements above are true, then how come
I have a problem (explained in my first post), since I've
been working in a DOS window all along when playing the
user part and when coding ?

For 0-127 (Ascii) the code is the same:
	Alt+63 (DOS) => '?' and Alt+063 (Windows) => '?'.

Is there a chance that something related to this topic
is causing the problem when there's a '?' in the filename ?
Of course it could be my code that is faulty, but I doubt
it since the other validations, in the same procedure,
are working fine (see my first post).

Thanks

Marc
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[dennison]

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In article <3762f569.682876310@news.dsuper.net>,
  fluffy_pop@dsuper.net wrote:
> On Fri, 11 Jun 1999 09:03:41 +0200, in comp.lang.ada you wrote:
>
> >...
> >Windows... A possibility is to have an explicit
> >translation table;
>
> I guess this is what you mean:
>      DOS			Windows
> --------------	---------------
> Alt+130 => '�'	Alt+0130 => '�'
> Alt+233 => '_'	Alt+0233 => '�'
>
> FUNCTION ISO ( p_car : character ) RETURN character IS
> WITH Ada.Characters.Latin_1; USE Ada.Characters.Latin_1;
> 	ISO_Char : character;
> BEGIN
> 	CASE character'pos(p_car) IS

Rather than writing this function manually, you should probably look
into using a character mapping from Ada.Strings.Maps.

--
T.E.D.


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Re: DOS/Win95 file names

[fluffy_pop]

On Fri, 11 Jun 1999 15:38:55 GMT, dennison@telepath.com wrote:

>Rather than writing this function manually, you should probably look
>into using a character mapping from Ada.Strings.Maps.

OK, thanks.  My questions are still unanswered though.  I need to know
what exactly is the code entered into a variable string(i), in my
specific case, when I'm the user working with Win95 and the program is
run in a DOS window.  I can't write this function or use Strings.Maps
if I don't know.  I have to know what I'm working with !

Thanks again.


Marc
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[Robert Dewar]

In article <7jraid$isb$1@nnrp1.deja.com>,
  dennison@telepath.com wrote:
> In article <3762f569.682876310@news.dsuper.net>,
> Rather than writing this function manually, you should
> probably look
> into using a character mapping from Ada.Strings.Maps.


I suspect this is wrong, Ada.Strings.Maps has mapping functions
for Latin-1, but you cannot assume your PC is configured to
use Latin-1. I suggest looking at the csets unit in the
Ada sources to learn about various character set mappings
that are likely to be relevant, including the two most commonly
used PC code pages.


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Re: DOS/Win95 file names

[Robert Dewar]

In article <37643673.699528550@news.dsuper.net>,
  fluffy_pop@dsuper.net wrote:
> I can't write this function or use Strings.Maps
> if I don't know.  I have to know what I'm working with !

Surely this depends on which code page is selected???


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Re: DOS/Win95 file names

[jerry]

fluffy_pop@dsuper.net wrote:

: I'm being asked to validate the name format so that it satisfies the
: (8.3) DOS requirements (actually it's a hybrid because I'm accepting
: characters illegal under DOS but legal under Windows).  It's a Ada
: console program and I'm working on a Win95 machine.

I do not quite follow this:

a) the filename has to be consistent with DOS requirements, in which case
you should not accept filenames that are illegal under DOS, or

b) you will be accepting Win32 filenames, but than there is not much sense
in restricting the name to 8.3. 

: As it is (my program), when the user enters a file name that contains
: an accented character, my handling of the Name_Error Exception occurs
: to produce a message that the file is not in the repertory.

If I understand this correctly, you are saying that if a filename contains
a character, with an ASCII code > 127, you get a Name_Error exception when
you try to create/open it ?

I presume you are not using UniCode or Wide_Character ?

: Also, when the file name contains a '?', my program
: crashes (when what follows is a Create(F,Out_File,"name") ).

Mmmm, would need to look this up, but in DOS terms, a '?' is a wildcard
character, and would cause problems when trying to create a file (or not
give you the file you expected when opening one).

If you follow DOS rules, you should not allow a '?' in a filename. I'm not
sure if it is allowed under Win32 rules.

: characters of the real file names, since I'm working under Windows
: when I write my program code and the files are created also under
: Windows or DOS.

If you want your files to work with both DOS and Windows, you have no
option but to stick to the DOS filename format, and not allow any
Win32 extensions.

-- 
-- Jerry van Dijk | Leiden, Holland
-- Team Ada       | jdijk@acm.org
-- see http://stad.dsl.nl/~jvandyk

Re: DOS/Win95 file names

[Mario Klebsch]

jerry@jvdsys.stuyts.nl writes:

>fluffy_pop@dsuper.net wrote:

>: I'm being asked to validate the name format so that it satisfies the
>: (8.3) DOS requirements (actually it's a hybrid because I'm accepting
>: characters illegal under DOS but legal under Windows).  It's a Ada
>: console program and I'm working on a Win95 machine.

>a) the filename has to be consistent with DOS requirements, in which case
>you should not accept filenames that are illegal under DOS, or

>b) you will be accepting Win32 filenames, but than there is not much sense
>in restricting the name to 8.3. 

Why to you want to biuld in the problems of tomorrow today? The OS knows
quit well, which filenames to accept and surely does have some rules,
what to do, when the filenames do not satisfy their constraints.

I far to often have had programs, that did this kind of checking,
and I hated them all, when I was using them an a newer system, where
the original contraints were gone. Those programs can make your live
like hell. :-(

73, Mario
--
Mario Klebsch		Mario.Klebsch@braunschweig.netsurf.de

Re: DOS/Win95 file names

[fluffy_pop]

On Sat, 12 Jun 1999 01:11:12 GMT, jerry@jvdsys.stuyts.nl wrote:

>I do not quite follow this:
>
>a) the filename has to be consistent with DOS requirements, in which case
>you should not accept filenames that are illegal under DOS, or
>
>b) you will be accepting Win32 filenames, but than there is not much sense
>in restricting the name to 8.3. 

1. more than 12 characters total => ERROR
2. more than 8 characters before the period => ERROR
3. more than one period => ERROR
4. no period => ERROR
5. illegal characters : those that are illegal under Windows only

So it validates the name following DOS rules except for the illegal
characters where it will allow '[', ']', '=', '+', ',', and ';'.

>: As it is (my program), when the user enters a file name that contains
>: an accented character, my handling of the Name_Error Exception occurs
>: to produce a message that the file is not in the repertory.
>
>If I understand this correctly, you are saying that if a filename contains
>a character, with an ASCII code > 127, you get a Name_Error exception when
>you try to create/open it ?
>
>I presume you are not using UniCode or Wide_Character ?

NO.

>: Also, when the file name contains a '?', my program
>: crashes (when what follows is a Create(F,Out_File,"name") ).
>
>Mmmm, would need to look this up, but in DOS terms, a '?' is a wildcard
>character, and would cause problems when trying to create a file (or not
>give you the file you expected when opening one).
>
>If you follow DOS rules, you should not allow a '?' in a filename. I'm not
>sure if it is allowed under Win32 rules.

'?' is not allowed under either DOS or Windows in a file name.  I have
a procedure that checks this.  That's my point.  My procedure doesn't
work right.  It validates correctly all the other conditions (those
I outlined above) except for the illegal charcter like '?'.  The point
of the validation is to prevent the program to reach the point where
it tries to create a file with a name that contains one or more
illegal characters.  In my validation procedure I sweep through a 
string containing the illegal characters, for each character of the
file name.  For some reason the '?' in the file name entered does
not get caught, as if it were not Alt+063.

I don't understand why because, like I said in one of my posts, '?'
is within the ASCII 0-127 range, where the code is the same for DOS
and for Windows.  I thought that maybe there's something else about
all this that I need to know.


Marc
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[fluffy_pop]

On Sat, 12 Jun 1999 11:36:49 +0200, Mario Klebsch
<Mario.Klebsch@braunschweig.netsurf.de> wrote:

>Why to you want to biuld in the problems of tomorrow today? The OS knows
>quit well, which filenames to accept and surely does have some rules,
>what to do, when the filenames do not satisfy their constraints.
>
>I far to often have had programs, that did this kind of checking,
>and I hated them all, when I was using them an a newer system, where
>the original contraints were gone. Those programs can make your live
>like hell. :-(
>
>73, Mario

I'm a student and I'm trying stuff to get better aquainted with
the DOS/Windows interactions, character representation in general,
in addition to simply doing what the teacher is asking.  He was
not very precise in his instuctions for the name validation, and
when I asked him he said he didn't find it important.  This is not
a program that anyone is ever going to use, even not I.  It's an
experiment.

Marc
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[jerry]

fluffy_pop@dsuper.net wrote:

: '?' is not allowed under either DOS or Windows in a file name.  I have
: a procedure that checks this.  That's my point.  My procedure doesn't
: work right.  It validates correctly all the other conditions (those
: I outlined above) except for the illegal charcter like '?'.  The point
: of the validation is to prevent the program to reach the point where
: it tries to create a file with a name that contains one or more
: illegal characters.  In my validation procedure I sweep through a 
: string containing the illegal characters, for each character of the
: file name.  For some reason the '?' in the file name entered does
: not get caught, as if it were not Alt+063.

Ok, so the problem is that the algorithm (or implementation) you
use for checking for invalid characters does not work as it is supposed
too. It is difficult to say what is wrong with it, without seeing some
actual code.

I guess you use something like:

   with Ada.Strings.Fixed; use Ada.Strings.Fixed;

   function Has_Invalid_Char (S : String) return Boolean is
      Illegal_Characters : constant String := "&?|\/:""";
   begin
      for I in S'Range loop
         if Index (Illegal_Characters, S(I .. I)) /= 0 then
            return True;
         end if;
      end loop;
      return False;
   end Has_Invalid_Char;

-- 
-- Jerry van Dijk | Leiden, Holland
-- Team Ada       | jdijk@acm.org
-- see http://stad.dsl.nl/~jvandyk

Re: DOS/Win95 file names

[fluffy_puff]

On Sat, 12 Jun 1999 23:16:43 GMT, fluffy_pop@dsuper.net wrote:

>4. no period => ERROR

Oops.  No, that would NOT generate an error from DOS, it's allowed.
An extension under DOS is not obligatory (but is certainly useful).
Anyway it doesn't relate to the questions I had.

Marc
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[fluffy_puff]

On Sun, 13 Jun 1999 10:45:05 GMT, jerry@jvdsys.stuyts.nl wrote:

>Ok, so the problem is that the algorithm (or implementation) you
>use for checking for invalid characters does not work as it is supposed
>too. It is difficult to say what is wrong with it, without seeing some
>actual code.
>
>I guess you use something like:
>
>   with Ada.Strings.Fixed; use Ada.Strings.Fixed;
>
>   function Has_Invalid_Char (S : String) return Boolean is
>      Illegal_Characters : constant String := "&?|\/:""";
>   begin
>      for I in S'Range loop
>         if Index (Illegal_Characters, S(I .. I)) /= 0 then
>            return True;
>         end if;
>      end loop;
>      return False;
>   end Has_Invalid_Char;

Exactly.  At least that's what I wanted.

I'll allow and even welcome you to call me stupid now.

I had an external WHILE (num_periods_good AND NOT illegal_char)
loop, with an EXIT (WHEN more_than_8) statement in it.  Within 
that loop I had a simple FOR loop that was supposed to do what 
you just wrote, *without an exit condition, since it's a FOR 
loop!*.  So as far as the  illegal_char goes, the value I would 
get when coming out of this procedure was true only if one of 
the characters of the name was equal to the *last* character in
Illegal_Characters: it would go: FALSE, FALSE, TRUE, FALSE, 
TRUE, ... and would simply leave the inner loop with the last 
one.

A WHILE loop is what I have to use for the inner loop, or make 
a separate procedure like yours.

I'm sorry for wasting your time.  At least now I know I have 
only one problem (the accented characters, or 128-255).  There's 
a world of difference between having two or three problems that 
may or may not be related, and having one single problem.

Thanks for trying to help.


Marc Galipeau
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[Matthew Heaney]

On 13 Jun 1999 20:34, fluffy_puff@dsuper.net wrote:

> I had an external WHILE (num_periods_good AND NOT illegal_char)
> loop, with an EXIT (WHEN more_than_8) statement in it.  Within 
> that loop I had a simple FOR loop that was supposed to do what 
> you just wrote, *without an exit condition, since it's a FOR 
> loop!*. 

Wrong.

Re: DOS/Win95 file names

[fluffy_puff]

On Sun, 13 Jun 1999 22:19:30 GMT, Matthew Heaney
<matthew_heaney@acm.org> wrote:


>Wrong.

Exactly.  I thought that's what I just said.  I guess I wasn't clear
enough.


Marc
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.

Re: DOS/Win95 file names

[fluffy_puff]

On Sun, 13 Jun 1999 22:19:30 GMT, Matthew Heaney
<matthew_heaney@acm.org> wrote:

>>..., *without an exit condition, since it's a FOR 
>> loop!*. 

>Wrong.

OK, I mean without an exit *statement* in the loop.
--
What I really am is "fluffy", no "_dong",
no "_puff", no "_woo", no  nothing, just plain fluffy.