Re: [Win32] putenv modifications not inherited by child processed (Was: Heap corruption in putenv)

[Bastien ROUCARIES]

On Fri, Feb 15, 2013 at 11:24 PM, Eric Blake <address@hidden> wrote:
> On 02/15/2013 08:10 AM, Michael Goffioul wrote:
>> The problem is that the "environ" variable is just a mirror of the
>> environment that is manipulated through GetEnvironmentVariable and
>> SetEnvironmentVariable. Manipulating the "environ" variable directly has no
>> effect at the OS level and will only affect the current process (only calls
>> to _putenv will actually propagate the changes through Win32 API). Child
>> processes will not see the modified environment. Moreover even in the
>> current process, I believe the values returned by GetEnvironmentVariable
>> and "environ" (or getenv) will not be in sync.
>
> How are you spawning your child processes?  Is it simple enough to wrap
> all calls that create child processes so that those call sites iterate
> through environ and shove it back into the OS level environment, so that
> the child inherits the right thing, while not worrying about the OS
> level environment for the rest of the process?


Yes ntcreateprocess is hotpatchable (something like ldpreload)

see for example blog post
http://ge0-it.blogspot.fr/2011/07/hot-patching-function-little-example.html

Bastien
>
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> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>