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/*
FUNCTION
<<__env_lock>>, <<__env_unlock>>---lock environ variable
INDEX
__env_lock
INDEX
__env_unlock
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.
*/
#include "envlock.h"
#include <sys/lock.h>
#ifndef __SINGLE_THREAD__
__LOCK_INIT_RECURSIVE(static, __env_recursive_mutex);
#endif
void
__env_lock (ptr)
struct _reent *ptr;
{
#ifndef __SINGLE_THREAD__
__lock_acquire_recursive (__env_recursive_mutex);
#endif
}
void
__env_unlock (ptr)
struct _reent *ptr;
{
#ifndef __SINGLE_THREAD__
__lock_release_recursive (__env_recursive_mutex);
#endif
}
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