__env_lock, __env_unlock--lock environ variableSynopsis
#include "envlock.h" void __env_lock (void *reent); void __env_unlock (void *reent);
Description
The setenv family of routines call these functions when they need
to modify the environ variable. The version of these routines supplied
in the library does not do anything. If multiple threads of execution
can call setenv, or if setenv can be called reentrantly, then
you need to define your own versions of these functions in order to
safely lock the memory pool during a call. If you do not, the memory
pool may become corrupted.
A call to setenv may call __env_lock recursively; that is,
the sequence of calls may go __env_lock, __env_lock,
__env_unlock, __env_unlock. Any implementation of these
routines must be careful to avoid causing a thread to wait for a lock
that it already holds.
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