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/*

FUNCTION

<<__env_lock>>, <<__env_unlock>>---lock environ variable

INDEX

        __env_lock

INDEX

        __env_unlock

ANSI_SYNOPSIS

        #include <envlock.h>

        void __env_lock (struct _reent *<[reent]>);

        void __env_unlock (struct _reent *<[reent]>);

TRAD_SYNOPSIS

        void __env_lock(<[reent]>)

        struct _reent *<[reent]>;

        void __env_unlock(<[reent]>)

        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.

*/

#include "envlock.h"

#include <sys/lock.h>

#ifndef __SINGLE_THREAD__

__LOCK_INIT_RECURSIVE(static, __env_lock_object);

#endif

void

__env_lock (ptr)

     struct _reent *ptr;

{

#ifndef __SINGLE_THREAD__

  __lock_acquire_recursive (__env_lock_object);

#endif

}

void

__env_unlock (ptr)

     struct _reent *ptr;

{

#ifndef __SINGLE_THREAD__

  __lock_release_recursive (__env_lock_object);

#endif

}