setlocale-null: New module.

* lib/locale.in.h (SETLOCALE_NULL_MAX, SETLOCALE_NULL_ALL_MAX,
setlocale_null): New declarations.
* lib/setlocale_null.c: New file.
* lib/setlocale-lock.c: New file.
* m4/threadlib.m4 (gl_PTHREADLIB_BODY): Define C macro HAVE_PTHREAD_API.
* m4/setlocale_null.m4: New file.
* m4/locale_h.m4 (gl_LOCALE_H_DEFAULTS): Initialize
GNULIB_SETLOCALE_NULL.
* modules/locale (Makefile.am): Substitute GNULIB_SETLOCALE_NULL.
* modules/setlocale-null: New file.
* doc/posix-functions/setlocale.texi: Mention the new module.

1 files changed, 204 insertions, 0 deletions

diff --git a/lib/setlocale_null.c b/lib/setlocale_null.c
new file mode 100644
index 0000000000..b0506b9a12
--- /dev/null
+++ b/lib/setlocale_null.c
@@ -0,0 +1,204 @@
+/* Query the name of the current global locale.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2019.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <locale.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#if defined _WIN32 && !defined __CYGWIN__
+# include <wchar.h>
+#endif
+
+#if !(SETLOCALE_NULL_ALL_MTSAFE && SETLOCALE_NULL_ONE_MTSAFE)
+# if defined _WIN32 && !defined __CYGWIN__
+#  define WIN32_LEAN_AND_MEAN  /* avoid including junk */
+#  include <windows.h>
+# elif HAVE_PTHREAD_API
+#  include <pthread.h>
+# elif HAVE_THREADS_H
+#  include <threads.h>
+# endif
+#endif
+
+/* Use the system's setlocale() function, not the gnulib override, here.  */
+#undef setlocale
+
+static int
+setlocale_null_unlocked (int category, char *buf, size_t bufsize)
+{
+#if defined _WIN32 && !defined __CYGWIN__ && defined _MSC_VER
+  /* On native Windows, nowadays, the setlocale() implementation is based
+     on _wsetlocale() and uses malloc() for the result.  We are better off
+     using _wsetlocale() directly.  */
+  const wchar_t *result = _wsetlocale (category, NULL);
+  size_t length = wcslen (result);
+  if (length < bufsize)
+    {
+      size_t i;
+
+      /* Convert wchar_t[] -> char[], assuming plain ASCII.  */
+      for (i = 0; i <= length; i++)
+        buf[i] = result[i];
+
+      return 0;
+    }
+  else
+    {
+      if (bufsize > 0)
+        {
+          /* Return a truncated result in BUF.
+             This is a convenience for callers that don't want to write
+             explicit code for handling ERANGE.  */
+          size_t i;
+
+          /* Convert wchar_t[] -> char[], assuming plain ASCII.  */
+          for (i = 0; i < bufsize; i++)
+            buf[i] = result[i];
+          buf[bufsize - 1] = '\0';
+        }
+      return ERANGE;
+    }
+#else
+  const char *result = setlocale (category, NULL);
+  size_t length = strlen (result);
+  if (length < bufsize)
+    {
+      memcpy (buf, result, length + 1);
+      return 0;
+    }
+  else
+    {
+      if (bufsize > 0)
+        {
+          /* Return a truncated result in BUF.
+             This is a convenience for callers that don't want to write
+             explicit code for handling ERANGE.  */
+          memcpy (buf, result, bufsize - 1);
+          buf[bufsize - 1] = '\0';
+        }
+      return ERANGE;
+    }
+#endif
+}
+
+#if !(SETLOCALE_NULL_ALL_MTSAFE && SETLOCALE_NULL_ONE_MTSAFE)
+
+/* Use a lock, so that no two threads can invoke setlocale_null_unlocked
+   at the same time.  */
+
+/* Prohibit renaming this symbol.  */
+# undef gl_get_setlocale_null_lock
+
+# if defined _WIN32 && !defined __CYGWIN__
+
+extern __declspec(dllimport) CRITICAL_SECTION *gl_get_setlocale_null_lock (void);
+
+static int
+setlocale_null_with_lock (int category, char *buf, size_t bufsize)
+{
+  CRITICAL_SECTION *lock = gl_get_setlocale_null_lock ();
+  int ret;
+
+  EnterCriticalSection (lock);
+  ret = setlocale_null_unlocked (category, buf, bufsize);
+  LeaveCriticalSection (lock);
+
+  return ret;
+}
+
+# elif HAVE_PTHREAD_API
+
+extern
+#  if defined _WIN32 || defined __CYGWIN__
+  __declspec(dllimport)
+#  endif
+  pthread_mutex_t *gl_get_setlocale_null_lock (void);
+
+static int
+setlocale_null_with_lock (int category, char *buf, size_t bufsize)
+{
+  pthread_mutex_t *lock = gl_get_setlocale_null_lock ();
+  int ret;
+
+  if (pthread_mutex_lock (lock))
+    abort ();
+  ret = setlocale_null_unlocked (category, buf, bufsize);
+  if (pthread_mutex_unlock (lock))
+    abort ();
+
+  return ret;
+}
+
+# elif HAVE_THREADS_H
+
+extern mtx_t *gl_get_setlocale_null_lock (void);
+
+static int
+setlocale_null_with_lock (int category, char *buf, size_t bufsize)
+{
+  mtx_t *lock = gl_get_setlocale_null_lock ();
+  int ret;
+
+  if (mtx_lock (lock) != thrd_success)
+    abort ();
+  ret = setlocale_null_unlocked (category, buf, bufsize);
+  if (mtx_unlock (lock) != thrd_success)
+    abort ();
+
+  return ret;
+}
+
+# endif
+
+#endif
+
+int
+setlocale_null (int category, char *buf, size_t bufsize)
+{
+#if SETLOCALE_NULL_ALL_MTSAFE
+# if SETLOCALE_NULL_ONE_MTSAFE
+
+  return setlocale_null_unlocked (category, buf, bufsize);
+
+# else
+
+  if (category == LC_ALL)
+    return setlocale_null_unlocked (category, buf, bufsize);
+  else
+    return setlocale_null_with_lock (category, buf, bufsize);
+
+# endif
+#else
+# if SETLOCALE_NULL_ONE_MTSAFE
+
+  if (category == LC_ALL)
+    return setlocale_null_with_lock (category, buf, bufsize);
+  else
+    return setlocale_null_unlocked (category, buf, bufsize);
+
+# else
+
+  return setlocale_null_with_lock (category, buf, bufsize);
+
+# endif
+#endif
+}