Date: Mon, 30 Apr 2007 12:54:45 -0400 From: John Baldwin <jhb@freebsd.org> To: "Andrey A. Chernov" <ache@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/usr.sbin/sysinstall main.c Message-ID: <200704301254.45807.jhb@freebsd.org> In-Reply-To: <200704301229.21190.jhb@freebsd.org> References: <200704301516.l3UFGJbu019162@repoman.freebsd.org> <200704301229.21190.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday 30 April 2007 12:29:20 pm John Baldwin wrote:
> On Monday 30 April 2007 11:16:19 am Andrey A. Chernov wrote:
> > ache 2007-04-30 15:16:19 UTC
> >
> > FreeBSD src repository
> >
> > Modified files:
> > usr.sbin/sysinstall main.c
> > Log:
> > Preparing for upcoming POSIXed putenv() rewrite:
> > don't allow const as putenv() arg, dup it
>
> Have you coordinated at all with the guy on current@ who has patches to make
> setenv(3) not leak memory as bad? Also, given that we malloc a limited
space
> for the string values, I don't see how you can make it so that one can
always
> just overwrite the string pointed to by putenv(3)'s return value to change
> the value. If we malloc a buffer for length N and the user wants to set the
> length to M > N, we pretty much have to malloc a new buffer that will end up
> at a different address, so places holding onto the previous value returned
> from putenv(3) will stop seeing updates.
Hmm, I think I see that this is orthogonal to the setenv(3) fix, but still, if
one does this:
char *cp = strdup("FOO=bar");
putenv(cp);
...
setenv("FOO", "baz");
...
setenv("FOO", "really_long_string");
...
printf("FOO: %s\n", cp + 4);
You are going to get 'baz' in the printf output. Or if one does:
char *cp = strdup("FOO=bar");
putenv(cp);
...
setenv("FOO", "really_long_string");
...
strcpy(cp + 4, "baz");
...
printf("FOO: %s\n", getenv("FOO"));
You are going to get 'really_long_string' in the printf output, and not 'baz'.
--
John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200704301254.45807.jhb>