From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <junkio@cox.net>
Subject: Re: [PATCH] Add ability to specify environment extension to run_command
Date: Mon, 21 May 2007 23:33:44 -0700
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Cc: Alex Riesen <raa.lkml@gmail.com>, git@vger.kernel.org,
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To: Martin Waitz <tali@admingilde.org>
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Martin Waitz <tali@admingilde.org> writes:

> On Mon, May 21, 2007 at 04:02:42PM -0700, Junio C Hamano wrote:
>> I had a feeling that some callers needed to be able to unsetenv
>> some.  How would this patch help them, or are they outside of
>> the scope?
>
> At first I had the same objection but the putenv documentation
> told me that at least in glibc you can unsetenv by providing
> the variable name without a "=".

I recall SysV putenv() does not remove "ENVNAME" without '=', and
http://www.opengroup.org/onlinepubs/000095399/functions/putenv.html
seems to say that as well.

> But perhaps we should check for other systems?

Probably.

At least we have setenv/unsetenv calls already (with emulation
where they aren't available), we could do something like this:

	struct child_process {
        	...
                const struct {
                        const char *name;
                        const char *value; /* NULL to unsetenv */
                } *env;
		...
	};

and in start_command():

	if (cmd->env) {
		int i;
                for (i = 0; cmd->env[i].name; i++) {
			if (cmd->env[i].value)
				setenv(cmd->env[i].name, cmd->env[i].value, 1);
			else
				unsetenv(cmd->env[i].name);
                }
        }