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/* Return the internal lock used by mbrtowc and mbrtoc32.
Copyright (C) 2019-2023 Free Software Foundation, Inc.
This file 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.
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2019-2020. */
#include <config.h>
/* When it is known that the gl_get_mbtowc_lock function is defined
by a dependency library, it should not be defined here. */
#if OMIT_MBTOWC_LOCK
/* This declaration is solely to ensure that after preprocessing
this file is never empty. */
typedef int dummy;
#else
/* This file defines the internal lock used by mbrtowc and mbrtoc32.
It is a separate compilation unit, so that only one copy of it is
present when linking statically. */
/* Prohibit renaming this symbol. */
# undef gl_get_mbtowc_lock
/* Macro for exporting a symbol (function, not variable) defined in this file,
when compiled into a shared library. */
# ifndef DLL_EXPORTED
# if HAVE_VISIBILITY
/* Override the effect of the compiler option '-fvisibility=hidden'. */
# define DLL_EXPORTED __attribute__((__visibility__("default")))
# elif defined _WIN32 || defined __CYGWIN__
# define DLL_EXPORTED __declspec(dllexport)
# else
# define DLL_EXPORTED
# endif
# endif
# if defined _WIN32 && !defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
# include "windows-initguard.h"
/* The return type is a 'CRITICAL_SECTION *', not a 'glwthread_mutex_t *',
because the latter is not guaranteed to be a stable ABI in the future. */
/* Make sure the function gets exported from DLLs. */
DLL_EXPORTED CRITICAL_SECTION *gl_get_mbtowc_lock (void);
static glwthread_initguard_t guard = GLWTHREAD_INITGUARD_INIT;
static CRITICAL_SECTION lock;
/* Returns the internal lock used by mbrtowc and mbrtoc32. */
CRITICAL_SECTION *
gl_get_mbtowc_lock (void)
{
if (!guard.done)
{
if (InterlockedIncrement (&guard.started) == 0)
{
/* This thread is the first one to need the lock. Initialize it. */
InitializeCriticalSection (&lock);
guard.done = 1;
}
else
{
/* Don't let guard.started grow and wrap around. */
InterlockedDecrement (&guard.started);
/* Yield the CPU while waiting for another thread to finish
initializing this mutex. */
while (!guard.done)
Sleep (0);
}
}
return &lock;
}
# elif HAVE_PTHREAD_API
# include <pthread.h>
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
/* Make sure the function gets exported from shared libraries. */
DLL_EXPORTED pthread_mutex_t *gl_get_mbtowc_lock (void);
/* Returns the internal lock used by mbrtowc and mbrtoc32. */
pthread_mutex_t *
gl_get_mbtowc_lock (void)
{
return &mutex;
}
# elif HAVE_THREADS_H
# include <threads.h>
# include <stdlib.h>
static int volatile init_needed = 1;
static once_flag init_once = ONCE_FLAG_INIT;
static mtx_t mutex;
static void
atomic_init (void)
{
if (mtx_init (&mutex, mtx_plain) != thrd_success)
abort ();
init_needed = 0;
}
/* Make sure the function gets exported from shared libraries. */
DLL_EXPORTED mtx_t *gl_get_mbtowc_lock (void);
/* Returns the internal lock used by mbrtowc and mbrtoc32. */
mtx_t *
gl_get_mbtowc_lock (void)
{
if (init_needed)
call_once (&init_once, atomic_init);
return &mutex;
}
# endif
# if (defined _WIN32 || defined __CYGWIN__) && !defined _MSC_VER
/* Make sure the '__declspec(dllimport)' in mbrtowc.c and mbrtoc32.c does not
cause a link failure when no DLLs are involved. */
# if defined _WIN64 || defined _LP64
# define IMP(x) __imp_##x
# else
# define IMP(x) _imp__##x
# endif
void * IMP(gl_get_mbtowc_lock) = &gl_get_mbtowc_lock;
# endif
#endif
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