TMP and TMPDIR mapping

TMP and TMPDIR mapping

[john daintree]

[-- Attachment #1: Type: text/plain, Size: 351 bytes --]

Hi

 

My understanding is that Cygwin maps $TMP and $TMPDIR (and probably others)
to a Windows form (/cygdrive/c/tmp  -> C:\tmp) when calling a WIN32 program
(e.g. cmd.exe). Is it possible, from bash or from Cygwin startup , to add
additional environment variable names so that they  are also automatically
mapped in the same way?

 

Thanks

/John

Re: TMP and TMPDIR mapping

[Andrey Repin]

Greetings, john daintree!

> My understanding is that Cygwin maps $TMP and $TMPDIR (and probably others)
> to a Windows form (/cygdrive/c/tmp  -> C:\tmp)

Nop. The actual mapping depends on your settings, but defaults to /tmp which
is inside Cygwin installation root.
Another option is to mount /tmp with 'usertemp' option, which would then
redirect it to the user's %TEMP%.

> when calling a WIN32 program
> (e.g. cmd.exe). Is it possible, from bash or from Cygwin startup , to add
> additional environment variable names so that they  are also automatically
> mapped in the same way?

What is your question, exactly?
What you want to achieve and what your actual observation compared to expected
behavior?


-- 
With best regards,
Andrey Repin
Friday, January 27, 2023 10:41:46

Sorry for my terrible english...

RE: TMP and TMPDIR mapping

[john daintree]

Hi Audrey.

Here's an example of what's going on:

>>: export TMPDIR=/cygdrive/c/tmp/jd
>>: export TMPDIR2=/cygdrive/c/tmp/jd2
>>: cmd.exe
Microsoft Windows [Version 10.0.22621.1105]
(c) Microsoft Corporation. All rights reserved.

C:\>echo %TMPDIR%
C:\tmp\jd

C:\>echo %TMPDIR2%
/cygdrive/c/tmp/jd2

So, if I set TMPDIR and TMPDIR2 in bash, and then call cmd.exe then TMPDIR
is changed to c:\tmp\jd but TMPDIR2 is left as /cygdrive/c/tmp/jd2

I was hoping that there's something I can do to get the following in
cmd.exe:

C:\>echo %TMPDIR2%
C:\tmp\jd2                                              # TMPDIR2 "mapped"
to c:\.... in the same way that TMPDIR is

I hope that's a clearer example.

Note that the actual use case is calling other Win32 programs, and the
environment variable name is different, but the above example is an attempt
to simplify the repro.
$PATH is mapped in  a similar way. So I assume that there is a list of names
which are mapped. I'd like to be able to add my own names to that list.

Thanks.
John.



-----Original Message-----
From: Andrey Repin <anrdaemon@yandex.ru> 
Sent: 27 January 2023 07:45
To: john daintree <johnd@dyalog.com>; cygwin@cygwin.com
Subject: Re: TMP and TMPDIR mapping

Greetings, john daintree!

> My understanding is that Cygwin maps $TMP and $TMPDIR (and probably
others)
> to a Windows form (/cygdrive/c/tmp  -> C:\tmp)

Nop. The actual mapping depends on your settings, but defaults to /tmp which
is inside Cygwin installation root.
Another option is to mount /tmp with 'usertemp' option, which would then
redirect it to the user's %TEMP%.

> when calling a WIN32 program
> (e.g. cmd.exe). Is it possible, from bash or from Cygwin startup , to
add
> additional environment variable names so that they  are also
automatically
> mapped in the same way?

What is your question, exactly?
What you want to achieve and what your actual observation compared to
expected behavior?


--
With best regards,
Andrey Repin
Friday, January 27, 2023 10:41:46

Sorry for my terrible english...

Re: TMP and TMPDIR mapping

[Corinna Vinschen]

On Jan 27 09:08, john daintree via Cygwin wrote:
> Hi Audrey.
> 
> Here's an example of what's going on:
> 
> >>: export TMPDIR=/cygdrive/c/tmp/jd
> >>: export TMPDIR2=/cygdrive/c/tmp/jd2
> >>: cmd.exe
> Microsoft Windows [Version 10.0.22621.1105]
> (c) Microsoft Corporation. All rights reserved.
> 
> C:\>echo %TMPDIR%
> C:\tmp\jd
> 
> C:\>echo %TMPDIR2%
> /cygdrive/c/tmp/jd2
> 
> So, if I set TMPDIR and TMPDIR2 in bash, and then call cmd.exe then TMPDIR
> is changed to c:\tmp\jd but TMPDIR2 is left as /cygdrive/c/tmp/jd2
> 
> I was hoping that there's something I can do to get the following in
> cmd.exe:
> 
> C:\>echo %TMPDIR2%
> C:\tmp\jd2                                              # TMPDIR2 "mapped"
> to c:\.... in the same way that TMPDIR is
> 
> I hope that's a clearer example.
> 
> Note that the actual use case is calling other Win32 programs, and the
> environment variable name is different, but the above example is an attempt
> to simplify the repro.
> $PATH is mapped in  a similar way. So I assume that there is a list of names
> which are mapped. I'd like to be able to add my own names to that list.

Easy: Don't call the affected Win32 executable directly.  Call it
through a child process.

Two scenarios:

- Starting the nativ executable from a shell or a Makefile:

  Create a wrapper script which calls

    TMPDIR2="$(cygpath -wa ${TMPDIR2})
      
  before calling your native app.

- Starting the nativ executable from your own process:

  After fork(), call

    const char *tmpdir2_old;
    char *tmpdir2_new;

    tmpdir2_old = getenv ("TMPDIR2");
    tmpdir2_new = (char *) cygwin_create_path (CCP_POSIX_TO_WIN_A,
                                               tmpdir2_old);
    setenv ("TMPDIR2", tmpdir2_new, 1);
    free (tmpdir2_new);

  Then call execve or friends.  Alternatively you can construct the
  new environment like the above for any exec call taking an
  environment as argument, i.e, execve, execle, execvpe.


Corinna