Re: lib/59599: libc looses environment updates made during .so initialization

["RVP via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR lib/59599; it has been noted by GNATS.

From: RVP <rvp%SDF.ORG@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: lib/59599: libc looses environment updates made during .so
 initialization
Date: Sat, 16 Aug 2025 08:10:33 +0000 (UTC)

 On Fri, 15 Aug 2025, alkondratenko%gmail.com@localhost wrote:
 
 > The fix involves updating environ variable. And things work (on GNU/Linux and FreeBSD, at least). Except on NetBSD tests failed. Debugging this I found that some dynamic linker facility is actually overwriting environ variable (presumably back to what the kernel set) after shared library initializers have run.
 >
 > Here is the disasm of the place that overwrites environ that I caught with some obvious gdb-ing:
 >
 
 Only tested on amd64:
 
 ```
 diff -urN a/src/lib/csu/common/crt0-common.c b/src/lib/csu/common/crt0-common.c
 --- a/src/lib/csu/common/crt0-common.c	2025-05-04 04:02:31.221385431 +0000
 +++ b/src/lib/csu/common/crt0-common.c	2025-08-16 08:02:02.485055492 +0000
 @@ -330,7 +330,8 @@
   		_FATAL("ps_strings missing\n");
   	__ps_strings = ps_strings;
 
 -	environ = ps_strings->ps_envstr;
 +	if (environ == NULL)
 +		environ = ps_strings->ps_envstr;
 
   	if (ps_strings->ps_argvstr[0] != NULL) {
   		char *c;
 ```
 
 -RVP