62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*
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FUNCTION
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<<__env_lock>>, <<__env_unlock>>--lock environ variable
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INDEX
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__env_lock
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INDEX
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__env_unlock
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ANSI_SYNOPSIS
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#include "envlock.h"
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void __env_lock (struct _reent *<[reent]>);
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void __env_unlock (struct _reent *<[reent]>);
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TRAD_SYNOPSIS
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void __env_lock(<[reent]>)
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struct _reent *<[reent]>;
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void __env_unlock(<[reent]>)
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struct _reent *<[reent]>;
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DESCRIPTION
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The <<setenv>> family of routines call these functions when they need to
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modify the environ variable. The version of these routines supplied in the
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library use the lock API defined in sys/lock.h. If multiple threads of
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execution can call <<setenv>>, or if <<setenv>> can be called reentrantly,
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then you need to define your own versions of these functions in order to
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safely lock the memory pool during a call. If you do not, the memory pool
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may become corrupted.
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A call to <<setenv>> may call <<__env_lock>> recursively; that is,
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the sequence of calls may go <<__env_lock>>, <<__env_lock>>,
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<<__env_unlock>>, <<__env_unlock>>. Any implementation of these
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routines must be careful to avoid causing a thread to wait for a lock
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that it already holds.
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*/
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#include "envlock.h"
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#include <sys/lock.h>
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#ifndef __SINGLE_THREAD__
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__LOCK_INIT_RECURSIVE(static, __env_lock_object);
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#endif
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void
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__env_lock (ptr)
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struct _reent *ptr;
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{
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#ifndef __SINGLE_THREAD__
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__lock_acquire_recursive (__env_lock_object);
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#endif
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}
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void
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__env_unlock (ptr)
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struct _reent *ptr;
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{
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#ifndef __SINGLE_THREAD__
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__lock_release_recursive (__env_lock_object);
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#endif
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}
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