150 lines
4.3 KiB
C
150 lines
4.3 KiB
C
/* Return the internal lock used by nl_langinfo.
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Copyright (C) 2019-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>, 2019-2020. */
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#include <config.h>
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/* When it is known that the gl_get_nl_langinfo_lock function is defined
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by a dependency library, it should not be defined here. */
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#if OMIT_NL_LANGINFO_LOCK
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/* This declaration is solely to ensure that after preprocessing
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this file is never empty. */
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typedef int dummy;
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#else
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/* This file defines the internal lock used by nl_langinfo.
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It is a separate compilation unit, so that only one copy of it is
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present when linking statically. */
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/* Prohibit renaming this symbol. */
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# undef gl_get_nl_langinfo_lock
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/* Macro for exporting a symbol (function, not variable) defined in this file,
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when compiled into a shared library. */
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# ifndef DLL_EXPORTED
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# if HAVE_VISIBILITY
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/* Override the effect of the compiler option '-fvisibility=hidden'. */
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# define DLL_EXPORTED __attribute__((__visibility__("default")))
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# elif defined _WIN32 || defined __CYGWIN__
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# define DLL_EXPORTED __declspec(dllexport)
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# else
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# define DLL_EXPORTED
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# endif
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# endif
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# if defined _WIN32 && !defined __CYGWIN__
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# define WIN32_LEAN_AND_MEAN /* avoid including junk */
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# include <windows.h>
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# include "windows-initguard.h"
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/* The return type is a 'CRITICAL_SECTION *', not a 'glwthread_mutex_t *',
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because the latter is not guaranteed to be a stable ABI in the future. */
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/* Make sure the function gets exported from DLLs. */
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DLL_EXPORTED CRITICAL_SECTION *gl_get_nl_langinfo_lock (void);
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static glwthread_initguard_t guard = GLWTHREAD_INITGUARD_INIT;
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static CRITICAL_SECTION lock;
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/* Returns the internal lock used by nl_langinfo. */
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CRITICAL_SECTION *
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gl_get_nl_langinfo_lock (void)
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{
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if (!guard.done)
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{
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if (InterlockedIncrement (&guard.started) == 0)
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{
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/* This thread is the first one to need the lock. Initialize it. */
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InitializeCriticalSection (&lock);
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guard.done = 1;
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}
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else
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{
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/* Don't let guard.started grow and wrap around. */
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InterlockedDecrement (&guard.started);
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/* Yield the CPU while waiting for another thread to finish
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initializing this mutex. */
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while (!guard.done)
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Sleep (0);
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}
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}
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return &lock;
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}
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# elif HAVE_PTHREAD_API
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# include <pthread.h>
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static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
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/* Make sure the function gets exported from shared libraries. */
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DLL_EXPORTED pthread_mutex_t *gl_get_nl_langinfo_lock (void);
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/* Returns the internal lock used by nl_langinfo. */
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pthread_mutex_t *
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gl_get_nl_langinfo_lock (void)
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{
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return &mutex;
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}
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# elif HAVE_THREADS_H
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# include <threads.h>
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# include <stdlib.h>
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static int volatile init_needed = 1;
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static once_flag init_once = ONCE_FLAG_INIT;
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static mtx_t mutex;
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static void
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atomic_init (void)
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{
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if (mtx_init (&mutex, mtx_plain) != thrd_success)
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abort ();
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init_needed = 0;
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}
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/* Make sure the function gets exported from shared libraries. */
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DLL_EXPORTED mtx_t *gl_get_nl_langinfo_lock (void);
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/* Returns the internal lock used by nl_langinfo. */
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mtx_t *
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gl_get_nl_langinfo_lock (void)
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{
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if (init_needed)
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call_once (&init_once, atomic_init);
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return &mutex;
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}
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# endif
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# if (defined _WIN32 || defined __CYGWIN__) && !defined _MSC_VER
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/* Make sure the '__declspec(dllimport)' in nl_langinfo.c does not cause
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a link failure when no DLLs are involved. */
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# if defined _WIN64 || defined _LP64
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# define IMP(x) __imp_##x
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# else
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# define IMP(x) _imp__##x
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# endif
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void * IMP(gl_get_nl_langinfo_lock) = &gl_get_nl_langinfo_lock;
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# endif
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#endif
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