Accessing Windows environment vairables in ObjectADA on windows

Accessing Windows environment vairables in ObjectADA on windows

[TARAN TRIPATHI]

Hi All,

This is what I have.

I have a win batch file which sets an environment variable say
"TEST_SOURCE_DIR"

setlocal
..
set TEST_SOURCE_DIR=%1
...
endlocal

For the purpose of seeing how to do it I used set TEST_SOURCE_DIR=C:\
on command prompt to set the variable.

I have to access this evironment variable in my ADA code.
This is test code I wrote:

with ADA.Text_IO,System.RTS.Win32;
procedure GetEnvVar is
    EnvVal:String(1..100):=(others=>' ');
    len:System.RTS.Win32.DWORD:=100;
begin
      Len:=System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Address,Len);
      Ada.Text_IO.Put_Line(EnvVal);
end GetEnvVar;

The GetEnvironmentVariable function is defined in System.RTS32.Win32
packages in Win32INT file.

The problem is that the GetEnvironmentVariable function returns null
for TEST_SOURCE_DIR but gives the correct value for all other Env
variables like HOME, ALLUSERSPROFILE,APPDATA, PROCESSOR_ARCHITECTURE
etc, but never for TEST_SOURCE_DIR.

Also the funnier thing is that if I donot catch the return value of
GetEnvironmentVariable funtion and use it as such
 System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Address,Len);
I get a compiler error
" Error: line 34 col 19 LRM:5.1(4), Procedure call, entry call, or
code statement expected, Continuing "
which relates to BNF for simple statement. I believe we need not
necessarily capture the return value of any function(?)

Does the variable being local or system variable make any difference?

I googled many a times for this but no help. I've looked around at
FAQ's and the
adahome reference pages, but I haven't found anything.
I an using ObjectAda 7.2 on Windows NT.

I'm not supposed to use florist package or POSIX/ADA interface. Even a
C library is not assured so that I can use #pragma
Interface(C,getenv).
I have to use the GetEnvironmentVariable function. 

Any help or pointers would be appreciated.
Thanx in advance.

Regards,
Taran.

Re: Accessing Windows environment vairables in ObjectADA on windows

[Marius Amado Alves]

> I believe we need not
> necessarily capture the return value of any function(?)

The return value of an Ada function must always be catched.
Ada is different from C in this respect. Ada has procedures and 
functions. They are colectively called "subprograms".

Re: Accessing Windows environment vairables in ObjectADA on windows

[Marius Amado Alves]

>       Len:=System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Address,Len);

This is terribly C-ish and unlike the Ada way.

A proper Ada subprogram for this will have a prototype like

    function GetEnvironmentVariable
      (Name : String) return String;

or

    procedure GetEnvironmentVariable
      (Name : String; Value : out Unbounded_String);

Re: Accessing Windows environment vairables in ObjectADA on windows

[Marius Amado Alves]

> The problem is that the GetEnvironmentVariable function returns null

Are you sure this function returns an access value?

> for TEST_SOURCE_DIR but gives the correct value for all other Env
> variables like HOME, ALLUSERSPROFILE,APPDATA, PROCESSOR_ARCHITECTURE
> etc, but never for TEST_SOURCE_DIR.

Have you tried:

- creating a global variable

- create the variable via control panel

Re: Accessing Windows environment vairables in ObjectADA on windows

[Jeffrey Carter]

jn wrote:

> try replacing EnvVal'Address with EnvVal(EnvVal'First)'Address
> which should yield the address to the first component of EnvVal.

This is not needed in Ada 95.

-- 
Jeff Carter
"I would never want to belong to any club that
would have someone like me for a member."
Annie Hall
41

Re: Accessing Windows environment vairables in ObjectADA on windows

[Steve]

Here is an example that works with ObjectAda 7.2.2:

with ADA.Text_IO;
with Win32;
with Win32.WinBase;
with Interfaces.C;
with Interfaces.C.Strings;

procedure GetEnvVar is
    use type interfaces.c.unsigned_long;
    use type interfaces.c.size_t;
    EnvVar : aliased Interfaces.C.Char_Array := Interfaces.C.To_C(
"TEST_SOURCE_DIR" );
    EnvVal : aliased Interfaces.C.Char_Array(0..99);
    len    : Win32.DWORD;
    last   : Interfaces.C.size_t;
begin
      Len:=100;
      Len:=Win32.WinBase.GetEnvironmentVariable(
              EnvVar(0)'unchecked_access,
              EnvVal(0)'unchecked_access,
              EnvVal'Length);
      if Len > 0 then
         last := Interfaces.C.size_t( Len - 1 );
         Ada.Text_IO.Put_Line( Interfaces.C.To_Ada( EnvVal(0..last) &
Interfaces.C.NUL ) );
      else
         Ada.Text_IO.Put_Line( "Env var not found" );
      end if;
end GetEnvVar;

You'll need to include:
  c:\program files\aonix\objectada\win32ada\binding\lib
In the "Normal" directory links, and:
  c:\program files\aonix\objectada\apilib
In the "Linker only" directory links for this example to work.

Steve
(The Duck)


"TARAN TRIPATHI" <tarantripathi@ieee.org> wrote in message
news:b949b6a7.0410142325.3a379563@posting.google.com...
> Hi All,
>
> This is what I have.
>
> I have a win batch file which sets an environment variable say
> "TEST_SOURCE_DIR"
>
> setlocal
> ..
> set TEST_SOURCE_DIR=%1
> ...
> endlocal
>
> For the purpose of seeing how to do it I used set TEST_SOURCE_DIR=C:\
> on command prompt to set the variable.
>
> I have to access this evironment variable in my ADA code.
> This is test code I wrote:
>
> with ADA.Text_IO,System.RTS.Win32;
> procedure GetEnvVar is
>     EnvVal:String(1..100):=(others=>' ');
>     len:System.RTS.Win32.DWORD:=100;
> begin
>
Len:=System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Addres
s,Len);
>       Ada.Text_IO.Put_Line(EnvVal);
> end GetEnvVar;
>
> The GetEnvironmentVariable function is defined in System.RTS32.Win32
> packages in Win32INT file.
>
> The problem is that the GetEnvironmentVariable function returns null
> for TEST_SOURCE_DIR but gives the correct value for all other Env
> variables like HOME, ALLUSERSPROFILE,APPDATA, PROCESSOR_ARCHITECTURE
> etc, but never for TEST_SOURCE_DIR.
>
> Also the funnier thing is that if I donot catch the return value of
> GetEnvironmentVariable funtion and use it as such
>
System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Address,Len
);
> I get a compiler error
> " Error: line 34 col 19 LRM:5.1(4), Procedure call, entry call, or
> code statement expected, Continuing "
> which relates to BNF for simple statement. I believe we need not
> necessarily capture the return value of any function(?)
>
> Does the variable being local or system variable make any difference?
>
> I googled many a times for this but no help. I've looked around at
> FAQ's and the
> adahome reference pages, but I haven't found anything.
> I an using ObjectAda 7.2 on Windows NT.
>
> I'm not supposed to use florist package or POSIX/ADA interface. Even a
> C library is not assured so that I can use #pragma
> Interface(C,getenv).
> I have to use the GetEnvironmentVariable function.
>
> Any help or pointers would be appreciated.
> Thanx in advance.
>
> Regards,
> Taran.

Re: Accessing Windows environment vairables in ObjectADA on windows

[Frank Beard]

You could look at Pascal Obry's POSIX Windows package
(http://perso.wanadoo.fr/pascal.obry/archive/w32posix.html).
 The link to download it is at the bottom of the page.
It is bascially the POSIX spec wrapped around the
Win32 calls.  

Look in
POSIX_Process_Environment.Environment_Value_Of.  I've
used it and it works.

Frank

--- TARAN TRIPATHI <tarantripathi@ieee.org> wrote:

> Hi All,
> 
> This is what I have.
> 
> I have a win batch file which sets an environment
> variable say
> "TEST_SOURCE_DIR"
> 
> setlocal
> ..
> set TEST_SOURCE_DIR=%1
> ...
> endlocal
> 
> For the purpose of seeing how to do it I used set
> TEST_SOURCE_DIR=C:\
> on command prompt to set the variable.
> 
> I have to access this evironment variable in my ADA
> code.
> This is test code I wrote:
> 
> with ADA.Text_IO,System.RTS.Win32;
> procedure GetEnvVar is
>     EnvVal:String(1..100):=(others=>' ');
>     len:System.RTS.Win32.DWORD:=100;
> begin
>      
>
Len:=System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Address,Len);
>       Ada.Text_IO.Put_Line(EnvVal);
> end GetEnvVar;
> 
> The GetEnvironmentVariable function is defined in
> System.RTS32.Win32
> packages in Win32INT file.
> 
> The problem is that the GetEnvironmentVariable
> function returns null
> for TEST_SOURCE_DIR but gives the correct value for
> all other Env
> variables like HOME, ALLUSERSPROFILE,APPDATA,
> PROCESSOR_ARCHITECTURE
> etc, but never for TEST_SOURCE_DIR.
> 
> Also the funnier thing is that if I donot catch the
> return value of
> GetEnvironmentVariable funtion and use it as such
> 
>
System.RTS.Win32.GetEnvironmentVariable("TEST_SOURCE_DIR",EnvVal'Address,Len);
> I get a compiler error
> " Error: line 34 col 19 LRM:5.1(4), Procedure call,
> entry call, or
> code statement expected, Continuing "
> which relates to BNF for simple statement. I believe
> we need not
> necessarily capture the return value of any
> function(?)
> 
> Does the variable being local or system variable
> make any difference?
> 
> I googled many a times for this but no help. I've
> looked around at
> FAQ's and the
> adahome reference pages, but I haven't found
> anything.
> I an using ObjectAda 7.2 on Windows NT.
> 
> I'm not supposed to use florist package or POSIX/ADA
> interface. Even a
> C library is not assured so that I can use #pragma
> Interface(C,getenv).
> I have to use the GetEnvironmentVariable function. 
> 
> Any help or pointers would be appreciated.
> Thanx in advance.
> 
> Regards,
> Taran.
> _______________________________________________
> comp.lang.ada mailing list
> comp.lang.ada@ada-france.org
>
http://www.ada-france.org/mailman/listinfo/comp.lang.ada
> 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com