Towards fixing AU preset invalidation

[ardour.git] / libs / pbd / locale_guard.cc

diff --git a/libs/pbd/locale_guard.cc b/libs/pbd/locale_guard.cc
index aa5a57552188b3a38f74b53367cee3d4a6eb5512..dc2657c239896ae6423fc87b42503827b0dcfa0e 100644 (file)
--- a/libs/pbd/locale_guard.cc
+++ b/libs/pbd/locale_guard.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012 Paul Davis 
+    Copyright (C) 2012 Paul Davis
 
     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
@@ -19,36 +19,87 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <assert.h>
 #include <locale.h>
 
+#include "pbd/compose.h"
+#include "pbd/debug.h"
+#include "pbd/error.h"
 #include "pbd/locale_guard.h"
 
 using namespace PBD;
 
-// try to avoid calling setlocale() recursively.  this is not thread-safe.
-std::string PBD::LocaleGuard::current;
+/* Neither C nor C++ pick up a user's preferred locale choice without the
+ * application actively taking steps to make this happen.
+ *
+ * For C: setlocale (LC_ALL, "");
+ * For C++ (assuming that the C version was called):
+ *      std::locale::global (std::locale (setlocale (LC_ALL, 0)));
+ *
+ * The application needs to make these calls, probably in main().
+ *
+ * Setting the C++ locale will change the C locale, but not the other way 'round.
+ * and some plugin may change either behind our back.
+ */
 
-LocaleGuard::LocaleGuard (const char* str)
-       : old(0)
+LocaleGuard::LocaleGuard ()
+       : old_c_locale (0)
 {
-       if (current != str) {
-               old = strdup (setlocale (LC_NUMERIC, NULL));
-               if (strcmp (old, str)) {
-                       if (setlocale (LC_NUMERIC, str)) {
-                               current = str;
-                       }
-               }
+       /* A LocaleGuard object ensures that the
+        * LC_NUMERIC/std::locale::numeric aspect of the C and C++ locales are
+        * set to "C" during its lifetime, so that printf/iostreams use a
+        * portable format for numeric output (i.e. 1234.5 is always 1234.5 and
+        * not sometimes 1234,5, as it would be in fr or de locales)
+        */
+
+       char const * const current_c_locale = setlocale (LC_NUMERIC, 0);
+
+       if (strcmp ("C", current_c_locale) != 0) {
+               old_c_locale = strdup (current_c_locale);
+               setlocale (LC_NUMERIC, "C");
+               pre_cpp_locale = std::locale();
+               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: change C locale from '%1' => 'C' (C++ locale is %2)\n", old_c_locale, pre_cpp_locale.name()));
        }
 }
 
 LocaleGuard::~LocaleGuard ()
 {
-       if (old) {
-               if (setlocale (LC_NUMERIC, old)) {
-                       current = old;
+       char const * current_c_locale = setlocale (LC_NUMERIC, 0);
+       std::locale current_cpp_locale;
+
+       if (current_cpp_locale != pre_cpp_locale) {
+
+               PBD::warning << string_compose ("LocaleGuard: someone (a plugin) changed the C++ locale from\n\t%1\nto\n\t%2\n, expect non-portable session files. Decimal OK ? %3",
+                                             old_cpp_locale.name(), current_cpp_locale.name(),
+                                             (std::use_facet<std::numpunct<char> >(std::locale()).decimal_point() == '.'))
+                          << endmsg;
+
+               try {
+                       /* this resets C & C++ locales */
+                       std::locale::global (old_cpp_locale);
+                       DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C & C++ locale: '%1'\n", std::locale().name()));
+               } catch (...) {
+                       /* see comments in the constructor regarding the
+                        * exception.
+                        *
+                        * This should restore restore numeric handling back to
+                        * the default (which may reflect user
+                        * preferences). This probably can't fail, because
+                        * old_c_locale was already in use during the
+                        * constructor for this object.
+                        *
+                        * Still ... Apple ... locale support ... just sayin' ....
+                        */
+                       setlocale (LC_NUMERIC, old_c_locale);
+                       DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: C++ locale API failed, restore C locale from %1 to\n'%2'\n(C++ is '%3')\n", current_c_locale, old_c_locale, std::locale().name()));
                }
 
-               free (old);
        }
-}
+       if (old_c_locale && (strcmp (current_c_locale, old_c_locale) != 0)) {
+               /* reset only the C locale */
+               setlocale (LC_NUMERIC, old_c_locale);
+               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C locale from %1 to\n'%2'\n(C++ is '%3')\n", current_c_locale, old_c_locale, std::locale().name()));
+       }
 
+       free (const_cast<char*> (old_c_locale));
+}