1/* Return the internal lock used by mbrtowc and mbrtoc32. 2 Copyright (C) 2019-2020 Free Software Foundation, Inc. 3 4 This program is free software: you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17/* Written by Bruno Haible <bruno@clisp.org>, 2019-2020. */ 18 19#include <config.h> 20 21/* When it is known that the gl_get_mbtowc_lock function is defined 22 by a dependency library, it should not be defined here. */ 23#if OMIT_MBTOWC_LOCK 24 25/* This declaration is solely to ensure that after preprocessing 26 this file is never empty. */ 27typedef int dummy; 28 29#else 30 31/* This file defines the internal lock used by mbrtowc and mbrtoc32. 32 It is a separate compilation unit, so that only one copy of it is 33 present when linking statically. */ 34 35/* Prohibit renaming this symbol. */ 36# undef gl_get_mbtowc_lock 37 38/* Macro for exporting a symbol (function, not variable) defined in this file, 39 when compiled into a shared library. */ 40# ifndef DLL_EXPORTED 41# if HAVE_VISIBILITY 42 /* Override the effect of the compiler option '-fvisibility=hidden'. */ 43# define DLL_EXPORTED __attribute__((__visibility__("default"))) 44# elif defined _WIN32 || defined __CYGWIN__ 45# define DLL_EXPORTED __declspec(dllexport) 46# else 47# define DLL_EXPORTED 48# endif 49# endif 50 51# if defined _WIN32 && !defined __CYGWIN__ 52 53# define WIN32_LEAN_AND_MEAN /* avoid including junk */ 54# include <windows.h> 55 56# include "windows-initguard.h" 57 58/* The return type is a 'CRITICAL_SECTION *', not a 'glwthread_mutex_t *', 59 because the latter is not guaranteed to be a stable ABI in the future. */ 60 61/* Make sure the function gets exported from DLLs. */ 62DLL_EXPORTED CRITICAL_SECTION *gl_get_mbtowc_lock (void); 63 64static glwthread_initguard_t guard = GLWTHREAD_INITGUARD_INIT; 65static CRITICAL_SECTION lock; 66 67/* Returns the internal lock used by mbrtowc and mbrtoc32. */ 68CRITICAL_SECTION * 69gl_get_mbtowc_lock (void) 70{ 71 if (!guard.done) 72 { 73 if (InterlockedIncrement (&guard.started) == 0) 74 { 75 /* This thread is the first one to need the lock. Initialize it. */ 76 InitializeCriticalSection (&lock); 77 guard.done = 1; 78 } 79 else 80 { 81 /* Don't let guard.started grow and wrap around. */ 82 InterlockedDecrement (&guard.started); 83 /* Yield the CPU while waiting for another thread to finish 84 initializing this mutex. */ 85 while (!guard.done) 86 Sleep (0); 87 } 88 } 89 return &lock; 90} 91 92# elif HAVE_PTHREAD_API 93 94# include <pthread.h> 95 96static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; 97 98/* Make sure the function gets exported from shared libraries. */ 99DLL_EXPORTED pthread_mutex_t *gl_get_mbtowc_lock (void); 100 101/* Returns the internal lock used by mbrtowc and mbrtoc32. */ 102pthread_mutex_t * 103gl_get_mbtowc_lock (void) 104{ 105 return &mutex; 106} 107 108# elif HAVE_THREADS_H 109 110# include <threads.h> 111# include <stdlib.h> 112 113static int volatile init_needed = 1; 114static once_flag init_once = ONCE_FLAG_INIT; 115static mtx_t mutex; 116 117static void 118atomic_init (void) 119{ 120 if (mtx_init (&mutex, mtx_plain) != thrd_success) 121 abort (); 122 init_needed = 0; 123} 124 125/* Make sure the function gets exported from shared libraries. */ 126DLL_EXPORTED mtx_t *gl_get_mbtowc_lock (void); 127 128/* Returns the internal lock used by mbrtowc and mbrtoc32. */ 129mtx_t * 130gl_get_mbtowc_lock (void) 131{ 132 if (init_needed) 133 call_once (&init_once, atomic_init); 134 return &mutex; 135} 136 137# endif 138 139# if (defined _WIN32 || defined __CYGWIN__) && !defined _MSC_VER 140/* Make sure the '__declspec(dllimport)' in mbrtowc.c and mbrtoc32.c does not 141 cause a link failure when no DLLs are involved. */ 142# if defined _WIN64 || defined _LP64 143# define IMP(x) __imp_##x 144# else 145# define IMP(x) _imp__##x 146# endif 147void * IMP(gl_get_mbtowc_lock) = &gl_get_mbtowc_lock; 148# endif 149 150#endif 151