PR 47007 and 61847 Locale failures in libgfortran.

2014-11-10  Janne Blomqvist  <jb@gcc.gnu.org>

	PR libfortran/47007
	PR libfortran/61847
	* config.h.in: Regenerated.
	* configure: Regenerated.
	* configure.ac (AC_CHECK_HEADERS_ONCE): Check for xlocale.h.
	(AC_CHECK_FUNCS_ONCE): Check for newlocale, freelocale, uselocale,
	strerror_l.
	* io/io.h (locale.h): Include.
	(xlocale.h): Include if present.
	(c_locale): New variable.
	(old_locale): New variable.
	(old_locale_ctr): New variable.
	(old_locale_lock): New variable.
	(st_parameter_dt): Add old_locale member.
	* io/transfer.c (data_transfer_init): Set locale to "C" if doing
	formatted transfer.
	(finalize_transfer): Reset locale to previous.
	* io/unit.c (c_locale): New variable.
	(old_locale): New variable.
	(old_locale_ctr): New variable.
	(old_locale_lock): New variable.
	(init_units): Init c_locale, init old_locale_lock.
	(close_units): Free c_locale.
	* runtime/error.c (locale.h): Include.
	(xlocale.h): Include if present.
	(gf_strerror): Use strerror_l if available. Reset locale to
	LC_GLOBAL_LOCALE for strerror_r branch.

2014-11-10  Janne Blomqvist  <jb@gcc.gnu.org>

	PR libfortran/47007
	PR libfortran/61847
	* gfortran.texi: Add note about locale issues to thread-safety
	section.

From-SVN: r217273

2 files changed, 27 insertions, 4 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 3a8e658ee86..576e69407f1 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,10 @@
+2014-11-10  Janne Blomqvist  <jb@gcc.gnu.org>
+
+	PR libfortran/47007
+	PR libfortran/61847
+	* gfortran.texi: Add note about locale issues to thread-safety
+	section.
+
 2014-11-04  Bernd Schmidt  <bernds@codesourcery.com>
 
 	* f95-lang.c (gfc_init_builtin_functions): Use type index 2 for
diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi
index 41d6559fab0..0d19e7a2b3a 100644
--- a/gcc/fortran/gfortran.texi
+++ b/gcc/fortran/gfortran.texi
@@ -1223,10 +1223,26 @@ implemented with the @code{system} function, which need not be
 thread-safe.  It is the responsibility of the user to ensure that
 @code{system} is not called concurrently.
 
-Finally, for platforms not supporting thread-safe POSIX functions,
-further functionality might not be thread-safe.  For details, please
-consult the documentation for your operating system.
-
+For platforms not supporting thread-safe POSIX functions, further
+functionality might not be thread-safe.  For details, please consult
+the documentation for your operating system.
+
+The GNU Fortran runtime library uses various C library functions that
+depend on the locale, such as @code{strtod} and @code{snprintf}.  In
+order to work correctly in locale-aware programs that set the locale
+using @code{setlocale}, the locale is reset to the default ``C''
+locale while executing a formatted @code{READ} or @code{WRITE}
+statement.  On targets supporting the POSIX 2008 per-thread locale
+functions (e.g. @code{newlocale}, @code{uselocale},
+@code{freelocale}), these are used and thus the global locale set
+using @code{setlocale} or the per-thread locales in other threads are
+not affected.  However, on targets lacking this functionality, the
+global LC_NUMERIC locale is set to ``C'' during the formatted I/O.
+Thus, on such targets it's not safe to call @code{setlocale}
+concurrently from another thread while a Fortran formatted I/O
+operation is in progress.  Also, other threads doing something
+dependent on the LC_NUMERIC locale might not work correctly if a
+formatted I/O operation is in progress in another thread.
 
 @node Data consistency and durability
 @section Data consistency and durability