Hi Charles,

I'm afraid that this sounds very much like a known problem (PR 75606).
If I remember correctly, the problem is somewhat ameliorated by some
changes I made in 6.5 (it should return an error rather than corrupting
anything) but there is still a (relatively small) upper limit on the
environment.

In summary, you are correct: there is a smallish upper limit on the
environment size.  Unfortunately the only workaround I can think of is
to make the environment smaller.  Perhaps you can use hard links,
symlinks, or union mounts to coalesce all of your libraries into a
single directory (perhaps one used exclusively for this purpose)? 

Regards,
Neil

On Thu, 2010-08-05 at 10:50 -0400, Charles Auger wrote:
> Good day,
> 
> I have been experiencing issues when using posix_spawn. The behavior I'm
> seeing is that the argc argument list passed from the parent to the child
> somehow gets corrupted in some situations. 
> 
> So far, my understanding of the situation is that the problem occurs when
> the parent process' environment is "large". For example, if I run a simple
> test of a parent creating a child process using posix_spawn with the default
> LD_LIBRARY_PATH defined on QNX, it succeeds. Using the same test, it fails
> if I modify the LD_LIBRARY_PATH in the parent's environment to something
> quite large. For example, in my tests the default and the large
> LD_LIBRARY_PATH were:
> 
> Default (QNX 6.4 self hosted): 
> /proc/boot:/lib:/usr/lib:/lib/dll:/opt/lib:/usr/photon/lib:/usr/photon/dll:/
> usr/local/lib:/opt/X11R6/lib:/usr/X11R6/lib
> 
> Large: 
> /dir1a/dir2a/dir3a/dir4a/dir5a/dir6a/dir7a/dir8a/dir9a:/dir1b/dir2b/dir3b/di
> r4b/dir5b/dir6b/dir7b/dir8b/dir9b:/dir1c/dir2c/dir3c/dir4c/dir5c/dir6c/dir7c
> /dir8c/dir9c:/dir1d/dir2d/dir3d/dir4d/dir5d/dir6d/dir7d/dir8d/dir9d:/dir1e/d
> ir2e/dir3e/dir4e/dir5e/dir6e/dir7e/dir8e/dir9e:/proc/boot:/lib:/usr/lib:/lib
> /dll:/opt/lib:/usr/photon/lib:/usr/photon/dll:/usr/local/lib:/opt/X11R6/lib:
> /usr/X11R6/lib
> 
> The observable behavior of the issue is that the argc parameters received in
> the child process seem like they have been moved position. For example, the
> parent passes the following argc list:
> 
> char* childArgv[] =
> {"/root/PosixSpawnTest/Child","PARAM_1_NAME","PARAM_1_VALUE",  0};
> 
> 
> When the test succeeds (with the small environment), the child prints the
> argument list it received normally:
> 
> Child Param 0 is : /root/PosixSpawnTest/Child
> Child Param 1 is : PARAM_1_NAME
> Child Param 2 is : PARAM_1_VALUE
> Child Param 3 is NULL
> 
> When the test fails, the child prints the following:
> 
> Child Param 0 is : SpawnTest/Child
> Child Param 1 is : /root/PosixSpawnTest/Child
> Child Param 2 is : PARAM_1_NAME
> Child Param 3 is NULL
> Child Param 4 is : PARAM_1_VALUE
> 
> So it looks like an extra parameter (derived from the file name?) was added
> which shifted down the rest of the parameters, including the value which in
> now passed the terminating null.
> 
> I would appreciate your help in determining if I'm doing something wrong, or
> if I'm actually exceeding a limit on the size of the environment that can be
> passed via posix_spawn().
> 
> Thank you,
> Charles Auger
> 
> 
> 
> 
> 
> _______________________________________________
> 
> OSTech
> http://community.qnx.com/sf/go/post61756
>