1 files changed, 150 insertions, 0 deletions
diff --git a/lib/mbtowc-lock.c b/lib/mbtowc-lock.c
new file mode 100644
index 00000000..06d32246
--- /dev/null
+++ b/lib/mbtowc-lock.c
@@ -0,0 +1,150 @@
+/* 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