duplocale: protect use of global locale (bug 23970)

Protect the global locale from being modified while we compute the size of
the locale category names.  That allows the use of the global locale in a
single thread, while all other threads use the thread safe locale
functions.

1 files changed, 8 insertions, 6 deletions

diff --git a/locale/duplocale.c b/locale/duplocale.c
index a755ac5c36..bad476700f 100644
--- a/locale/duplocale.c
+++ b/locale/duplocale.c
@@ -43,6 +43,11 @@ __duplocale (locale_t dataset)
   int cnt;
   size_t names_len = 0;
 
+  /* If dataset points to _nl_global_locale, we need to prevent other
+     threads from modifying it.  We also modify global data below (the
+     usage counts).  */
+  __libc_rwlock_wrlock (__libc_setlocale_lock);
+
   /* Calculate the total space we need to store all the names.  */
   for (cnt = 0; cnt < __LC_LAST; ++cnt)
     if (cnt != LC_ALL && dataset->__names[cnt] != _nl_C_name)
@@ -55,9 +60,6 @@ __duplocale (locale_t dataset)
     {
       char *namep = (char *) (result + 1);
 
-      /* We modify global data (the usage counts).  */
-      __libc_rwlock_wrlock (__libc_setlocale_lock);
-
       for (cnt = 0; cnt < __LC_LAST; ++cnt)
 	if (cnt != LC_ALL)
 	  {
@@ -78,11 +80,11 @@ __duplocale (locale_t dataset)
       result->__ctype_b = dataset->__ctype_b;
       result->__ctype_tolower = dataset->__ctype_tolower;
       result->__ctype_toupper = dataset->__ctype_toupper;
-
-      /* It's done.  */
-      __libc_rwlock_unlock (__libc_setlocale_lock);
     }
 
+  /* It's done.  */
+  __libc_rwlock_unlock (__libc_setlocale_lock);
+
   return result;
 }
 weak_alias (__duplocale, duplocale)