[fpc-pascal] environmentstrings in windows

[Michael Van Canneyt]

On Thu, 14 Dec 2006, Vincent Snijders wrote:

> Michael Van Canneyt schreef:
> > 
> > On Thu, 14 Dec 2006, Vincent Snijders wrote:
> > 
> > > Consider the following program:
> > >
> > > {$mode objfpc}{$H+}
> > >
> > > uses
> > >   SysUtils;
> > >
> > > var
> > >   i: integer;
> > >   s: string;
> > >
> > > begin
> > >   i := GetEnvironmentVariableCount;
> > >   writeln('VariableCount: ',i);
> > >   s := GetEnvironmentString(1);
> > >   writeln('Variable 1: ', s);
> > >   s := GetEnvironmentString(2);
> > >   writeln('Variable 2: ', s);
> > >   s := GetEnvironmentVariable('=D:');
> > >   writeln('Variable 1: ', s);
> > > end.
> > >
> > > If I run this from a command prompt on my windows 2000 computer it gives
> > > the
> > > following output:
> > > VariableCount: 43
> > > Variable 1: =D:=D:\lazarus\bugs\7699
> > > Variable 2: =ExitCode=00000000
> > > Variable 1:
> > >
> > > The first two envrionment string are special, in the sense that their name
> > > start with a =.
> > >
> > > but if ask for the value of the environment variable '=D:', it returns the
> > > empty string.
> > >
> > > I am wrestling a bit with how to interprete this. Should I consider these
> > > variable as special and hidden and ignore them?
> > > Or should code parsing environmentstrings be able to handle variables with
> > > a
> > > '=' on the first position?
> > 
> > IMHO, you should not be allowed to have a = in the name of an environment
> > variable at all. Since obviously you can in Windows, this is a problem which
> > will need fixing somehow. I'm pretty sure you can't do this in Linux (I get
> > an illegal variable name error).
> 
> In windows it doesn't seem to be allowed either:
> C:\lazarus>set =test=p
> De syntaxis van de opdracht is onjuist.
> 
> > So code relying on this will not be cross-platform.
> 
> My problem is code relying in the fact that GetEnvironmentString(1) doesn't
> return strings that start with '='. Will you fix that? Or must code using
> GetEnvironmentString be aware that on some platforms these strings can start
> with =.

I added a note to the docs.

If you use GetEnvironmentStrings, I assume you do the parsing all by
yourself, and so you have been warned :-)

Michael.