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-rw-r--r--gl/setlocale-lock.c150
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diff --git a/gl/setlocale-lock.c b/gl/setlocale-lock.c
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1/* Return the internal lock used by setlocale_null_r.
2 Copyright (C) 2019-2023 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 This file 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 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser 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. */
18
19#include <config.h>
20
21/* When it is known that the gl_get_setlocale_null_lock function is defined
22 by a dependency library, it should not be defined here. */
23#if OMIT_SETLOCALE_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 setlocale_null_r.
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_setlocale_null_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_setlocale_null_lock (void);
63
64static glwthread_initguard_t guard = GLWTHREAD_INITGUARD_INIT;
65static CRITICAL_SECTION lock;
66
67/* Returns the internal lock used by setlocale_null_r. */
68CRITICAL_SECTION *
69gl_get_setlocale_null_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_setlocale_null_lock (void);
100
101/* Returns the internal lock used by setlocale_null_r. */
102pthread_mutex_t *
103gl_get_setlocale_null_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_setlocale_null_lock (void);
127
128/* Returns the internal lock used by setlocale_null_r. */
129mtx_t *
130gl_get_setlocale_null_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 setlocale_null.c does not cause
141 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_setlocale_null_lock) = &gl_get_setlocale_null_lock;
148# endif
149
150#endif