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-rw-r--r--lib/mbtowc-lock.c150
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diff --git a/lib/mbtowc-lock.c b/lib/mbtowc-lock.c
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+/* Return the internal lock used by mbrtowc and mbrtoc32.
+ Copyright (C) 2019-2022 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