On Apr 6, 2008, at 17:54, Jeremy Chadwick wrote:
On Sun, Apr 06, 2008 at 03:05:18PM -0700, Doug Hardie wrote:
On Apr 6, 2008, at 14:52, Jeremy Chadwick wrote:
On Sun, Apr 06, 2008 at 02:45:24PM -0700, Jeremy Chadwick wrote:
On Sun, Apr 06, 2008 at 02:37:06PM -0700, Doug Hardie wrote:
Somewhere between FreeBSD 6.2 and 7.0 getenv has been changed to
return
a
null if an environment variable is set but has no value. I
don't find
anything anywhere in the documentation/man pages on this. As a
result,
you
cannot distinguish between a variable that is not set and one
that is
set
to a value of "". Is this a bug or a feature change?
I'd begin peeking here:
http://www.freebsd.org/cgi/cvsweb.cgi/src/lib/libc/stdlib/getenv.c
Follow-up: the manpages between 6.3-PRERELEASE and 7.0-STABLE do
document said change:
http://www.freebsd.org/cgi/man.cgi?query=getenv&apropos=0&sektion=3&manpath=FreeBSD+6.3-RELEASE&format=html
Says that if the environment variable is NOT IN THE ENVIRONMENT
then null
is returned. Setting the variable to "" does put it in the
environment.
env returns it properly.
http://www.freebsd.org/cgi/man.cgi?query=getenv&apropos=0&sektion=3&manpath=FreeBSD+7.0-stable&format=html
Same thing. I find nothing documented about this change.
I'm not sure where you're going with this. I see it clearly in the
ERRORS section.
I didn't think that having a defined variable with the value "" would
be an error. getenv does not return EINVAL but returns a zero. I
would have expected some notification in the description of getenv.
But besides that, just like Bakul Shah, I cannot reproduce this
problem:
$ uname -mr
7.0-STABLE amd64
$ gcc -o z z.c
$ ./z
getenv(FOO) = (null)
$ export FOO=yep
$ ./z
getenv(FOO) = yep
export FOO=
$ ./z
getenv(FOO) =
$ cat z.c
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
char *e = getenv("FOO");
printf("getenv(FOO) = %s\n", e);
return 0;
}
At this time, it does return a pointer to "". However, earlier today
it did not. It returned a zero. It was quite consistent for several
hours. I wonder if this is another issue with gdb. It seems to be
quite flakey on 7.0.
Finally, why did you take freebsd-stable off this mail
conversation? If
others have the same question in the future, they're not going to be
able to read what partook here. I'm re-adding the list.
Thought I did include it. Must have used reply instead of reply all.
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