Junio C Hamano, Wed, May 23, 2007 00:19:47 +0200:
> > Others already discussed the issue. Just to be sure, I reimplemented
> > that comfortable putenv with unsetenv: if an environment entry ends
> > with a "=" it will be unset.
>
> Although combination of putenv and unsetenv gives a somewhat
> queasy feeling for obvious reasons, I'll let it pass. As we
> are coming up with an interface that uses only one string per
> environment element, that is probably a sensible thing to do,
> rather than trying to do the "historically correct" pairing of
> setenv/unsetenv.
>
> However, I do not think "VAR=" to unset it is a good interface.
> Having an environment variable whose value happens to be an
> empty string and not having the variable at all are two
> different things.
Right
> Because you _scan_ the whole string in your patch to see if it
> ends with = anyway, a trivial improvement would be to do:
>
> if (strchr(cmd->env, '='))
> putenv(cmd->env);
> else
> unsetenv(cmd->env);
I like this one. The env field in struct child_process and run_command
will have to mention it in comments (in run-command.h), it's kind of
special.
> If you do not mind such a special syntax (e.g. "VAR="), I would
> suggest doing that as a prefix (e.g. "!VAR") and do:
Nah, !VAR is a _working_ environment variable name.
int main(int argc, char *argv[], char *envp[])
{
const char *argv1[] = {"/usr/bin/perl", "-e", "print $ENV{'!VAR'}", NULL};
const char *envp1[] = {"!VAR=value", NULL};
execve(*argv, (char**)argv1, (char**)envp1);
return 0;
}
$ gcc ... && ./a.out
value
Someone could want it. We surely could use "=", though :)
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