gnulib/import/mbtowc-lock.h

   1 /* Use the internal lock used by mbrtowc and mbrtoc32.
   2    Copyright (C) 2019-2022 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>, 2019-2020.  */
  18
  19 /* Use a lock, so that no two threads can invoke mbtowc at the same time.  */
  20
  21 static inline int
  22 mbtowc_unlocked (wchar_t *pwc, const char *p, size_t m)
  23 {
  24   /* Put the hidden internal state of mbtowc into its initial state.
  25      This is needed at least with glibc, uClibc, and MSVC CRT.
  26      See <https://sourceware.org/bugzilla/show_bug.cgi?id=9674>.  */
  27   mbtowc (NULL, NULL, 0);
  28
  29   return mbtowc (pwc, p, m);
  30 }
  31
  32 /* Prohibit renaming this symbol.  */
  33 #undef gl_get_mbtowc_lock
  34
  35 #if GNULIB_MBRTOWC_SINGLE_THREAD
  36
  37 /* All uses of this function are in a single thread.  No locking needed.  */
  38
  39 static int
  40 mbtowc_with_lock (wchar_t *pwc, const char *p, size_t m)
  41 {
  42   return mbtowc_unlocked (pwc, p, m);
  43 }
  44
  45 #elif defined _WIN32 && !defined __CYGWIN__
  46
  47 extern __declspec(dllimport) CRITICAL_SECTION *gl_get_mbtowc_lock (void);
  48
  49 static int
  50 mbtowc_with_lock (wchar_t *pwc, const char *p, size_t m)
  51 {
  52   CRITICAL_SECTION *lock = gl_get_mbtowc_lock ();
  53   int ret;
  54
  55   EnterCriticalSection (lock);
  56   ret = mbtowc_unlocked (pwc, p, m);
  57   LeaveCriticalSection (lock);
  58
  59   return ret;
  60 }
  61
  62 #elif HAVE_PTHREAD_API /* AIX, IRIX, Cygwin */
  63
  64 extern
  65 # if defined _WIN32 || defined __CYGWIN__
  66   __declspec(dllimport)
  67 # endif
  68   pthread_mutex_t *gl_get_mbtowc_lock (void);
  69
  70 # if HAVE_WEAK_SYMBOLS /* IRIX */
  71
  72    /* Avoid the need to link with '-lpthread'.  */
  73 #  pragma weak pthread_mutex_lock
  74 #  pragma weak pthread_mutex_unlock
  75
  76    /* Determine whether libpthread is in use.  */
  77 #  pragma weak pthread_mutexattr_gettype
  78    /* See the comments in lock.h.  */
  79 #  define pthread_in_use() \
  80      (pthread_mutexattr_gettype != NULL || c11_threads_in_use ())
  81
  82 # else
  83 #  define pthread_in_use() 1
  84 # endif
  85
  86 static int
  87 mbtowc_with_lock (wchar_t *pwc, const char *p, size_t m)
  88 {
  89   if (pthread_in_use())
  90     {
  91       pthread_mutex_t *lock = gl_get_mbtowc_lock ();
  92       int ret;
  93
  94       if (pthread_mutex_lock (lock))
  95         abort ();
  96       ret = mbtowc_unlocked (pwc, p, m);
  97       if (pthread_mutex_unlock (lock))
  98         abort ();
  99
 100       return ret;
 101     }
 102   else
 103     return mbtowc_unlocked (pwc, p, m);
 104 }
 105
 106 #elif HAVE_THREADS_H
 107
 108 extern mtx_t *gl_get_mbtowc_lock (void);
 109
 110 static int
 111 mbtowc_with_lock (wchar_t *pwc, const char *p, size_t m)
 112 {
 113   mtx_t *lock = gl_get_mbtowc_lock ();
 114   int ret;
 115
 116   if (mtx_lock (lock) != thrd_success)
 117     abort ();
 118   ret = mbtowc_unlocked (pwc, p, m);
 119   if (mtx_unlock (lock) != thrd_success)
 120     abort ();
 121
 122   return ret;
 123 }
 124
 125 #endif