glibc/sysdeps/mach/libc-lock.h

/* libc-internal interface for mutex locks.  Mach cthreads version.
   Copyright (C) 1996-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef _LIBC_LOCK_H
#define _LIBC_LOCK_H 1

#ifdef _LIBC

#include <tls.h>
#include <lowlevellock.h>

/* The locking here is very inexpensive, even for inlining.  */
#define _IO_lock_inexpensive   1

typedef unsigned int __libc_lock_t;
typedef struct
{
  __libc_lock_t lock;
  int cnt;
  void *owner;
} __libc_lock_recursive_t;

typedef __libc_lock_recursive_t __rtld_lock_recursive_t;

extern char __libc_lock_self0[0];
#define __libc_lock_owner_self()   \
  (__LIBC_NO_TLS () ? (void *)&__libc_lock_self0 : THREAD_SELF)

#else
typedef struct __libc_lock_opaque__ __libc_lock_t;
typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
#endif

/* Define a lock variable NAME with storage class CLASS.  The lock must be
   initialized with __libc_lock_init before it can be used (or define it
   with __libc_lock_define_initialized, below).  Use `extern' for CLASS to
   declare a lock defined in another module.  In public structure
   definitions you must use a pointer to the lock structure (i.e., NAME
   begins with a `*'), because its storage size will not be known outside
   of libc.  */
#define __libc_lock_define(CLASS,NAME) \
  CLASS __libc_lock_t NAME;

/* Define an initialized lock variable NAME with storage class CLASS.  */
#define _LIBC_LOCK_INITIALIZER LLL_LOCK_INITIALIZER
#define __libc_lock_define_initialized(CLASS,NAME) \
  CLASS __libc_lock_t NAME = LLL_LOCK_INITIALIZER;

/* Initialize the named lock variable, leaving it in a consistent, unlocked
   state.  */
#define __libc_lock_init(NAME) (NAME) = LLL_LOCK_INITIALIZER

/* Finalize the named lock variable, which must be locked.  It cannot be
   used again until __libc_lock_init is called again on it.  This must be
   called on a lock variable before the containing storage is reused.  */
#define __libc_lock_fini             __libc_lock_unlock
#define __libc_lock_fini_recursive   __libc_lock_unlock_recursive
#define __rtld_lock_fini_recursive   __rtld_lock_unlock_recursive

/* Lock the named lock variable.  */
#define __libc_lock_lock(NAME)   \
  ({ lll_lock ((NAME), 0); 0; })

/* Lock the named lock variable.  */
#define __libc_lock_trylock(NAME) lll_trylock (NAME)

/* Unlock the named lock variable.  */
#define __libc_lock_unlock(NAME)   \
  ({ lll_unlock ((NAME), 0); 0; })

#define __libc_lock_define_recursive(CLASS,NAME) \
  CLASS __libc_lock_recursive_t NAME;

#define _LIBC_LOCK_RECURSIVE_INITIALIZER { LLL_LOCK_INITIALIZER, 0, 0 }

#define __libc_lock_define_initialized_recursive(CLASS,NAME) \
  CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;

#define __rtld_lock_define_recursive(CLASS,NAME) \
  __libc_lock_define_recursive (CLASS, NAME)
#define _RTLD_LOCK_RECURSIVE_INITIALIZER \
  _LIBC_LOCK_RECURSIVE_INITIALIZER
#define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
  __libc_lock_define_initialized_recursive (CLASS, NAME)

#define __libc_lock_init_recursive(NAME)   \
  ({   \
     (NAME) = (__libc_lock_recursive_t)_LIBC_LOCK_RECURSIVE_INITIALIZER;   \
     0;   \
  })

#define __libc_lock_trylock_recursive(NAME)   \
  ({   \
     __libc_lock_recursive_t *const __lock = &(NAME);   \
     void *__self = __libc_lock_owner_self ();   \
     int __r = 0;   \
     if (__self == __lock->owner)   \
       ++__lock->cnt;   \
     else if ((__r = lll_trylock (__lock->lock)) == 0)   \
       __lock->owner = __self, __lock->cnt = 1;   \
     __r;   \
   })

#define __libc_lock_lock_recursive(NAME)   \
  ({   \
     __libc_lock_recursive_t *const __lock = &(NAME);   \
     void *__self = __libc_lock_owner_self ();   \
     if (__self != __lock->owner)   \
       {   \
         lll_lock (__lock->lock, 0);   \
         __lock->owner = __self;   \
       }   \
     ++__lock->cnt;   \
     (void)0;   \
   })

#define __libc_lock_unlock_recursive(NAME)   \
  ({   \
     __libc_lock_recursive_t *const __lock = &(NAME);   \
     if (--__lock->cnt == 0)   \
       {   \
         __lock->owner = 0;   \
         lll_unlock (__lock->lock, 0);   \
       }   \
   })


#define __rtld_lock_initialize(NAME) \
  (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
#define __rtld_lock_trylock_recursive(NAME) \
  __libc_lock_trylock_recursive (NAME)
#define __rtld_lock_lock_recursive(NAME) \
  __libc_lock_lock_recursive(NAME)
#define __rtld_lock_unlock_recursive(NAME) \
  __libc_lock_unlock_recursive (NAME)

/* XXX for now */
#define __libc_rwlock_define		__libc_lock_define
#define __libc_rwlock_define_initialized __libc_lock_define_initialized
#define __libc_rwlock_init		__libc_lock_init
#define __libc_rwlock_fini		__libc_lock_fini
#define __libc_rwlock_rdlock		__libc_lock_lock
#define __libc_rwlock_wrlock		__libc_lock_lock
#define __libc_rwlock_tryrdlock		__libc_lock_trylock
#define __libc_rwlock_trywrlock		__libc_lock_trylock
#define __libc_rwlock_unlock		__libc_lock_unlock

struct __libc_cleanup_frame
{
  void (*__fct) (void *);
  void *__argp;
  int __doit;
};

__extern_inline void
__libc_cleanup_fct (struct __libc_cleanup_frame *framep)
{
  if (framep->__doit)
    framep->__fct (framep->__argp);
}

/* Start a critical region with a cleanup function */
#define __libc_cleanup_region_start(DOIT, FCT, ARG)   \
  do   \
    {   \
      struct __libc_cleanup_frame __cleanup   \
        __attribute__ ((__cleanup__ (__libc_cleanup_fct))) =   \
        { .__fct = (FCT), .__argp = (ARG), .__doit = (DOIT) };

/* This one closes the brace above.  */
#define __libc_cleanup_region_end(DOIT)   \
      __cleanup.__doit = (DOIT);   \
    }   \
  while (0)

#define __libc_cleanup_end(DOIT)   __cleanup.__doit = (DOIT);

#define __libc_cleanup_push(fct, arg) __libc_cleanup_region_start (1, fct, arg)
#define __libc_cleanup_pop(execute) __libc_cleanup_region_end (execute)

/* Use mutexes as once control variables.  */

struct __libc_once
  {
    __libc_lock_t lock;
    int done;
  };

#define __libc_once_define(CLASS,NAME) \
  CLASS struct __libc_once NAME = { _LIBC_LOCK_INITIALIZER, 0 }

/* Call handler iff the first call.  */
#define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
  do {									      \
    __libc_lock_lock (ONCE_CONTROL.lock);				      \
    if (!ONCE_CONTROL.done)						      \
      (INIT_FUNCTION) ();						      \
    ONCE_CONTROL.done = 1;						      \
    __libc_lock_unlock (ONCE_CONTROL.lock);				      \
  } while (0)

/* Get once control variable.  */
#define __libc_once_get(ONCE_CONTROL)	((ONCE_CONTROL).done != 0)

#ifdef _LIBC
/* We need portable names for some functions.  E.g., when they are
   used as argument to __libc_cleanup_region_start.  */
#define __libc_mutex_unlock __libc_lock_unlock

/* Hide the definitions which are only supposed to be used inside libc in
   a separate file.  This file is not present in the installation!  */
# include <libc-lockP.h>
#endif

#endif	/* libc-lock.h */