__ENV_LOCK(3)

NAME
2.16 `__env_lock', `__env_unlock'--lock environ variable

SYNOPSIS
     #include <envlock.h>
     void __env_lock (struct _reent *REENT);
     void __env_unlock (struct _reent *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 use the lock API defined in sys/lock.h. 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.

SEE ALSO
__env_lock is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.