Stop c32rtomb and mbrtoc32 aliasing wcrtomb and mbrtowc (bug 23793)

[Joseph Myers <joseph at codesourcery dot com>]

glibc does:

/* There should be no difference between the UTF-32 handling required
   by c32rtomb and the wchar_t handling which has long since been
   implemented in wcrtomb.  */
weak_alias (__wcrtomb, c32rtomb)

/* There should be no difference between the UTF-32 handling required
   by mbrtoc32 and the wchar_t handling which has long since been
   implemented in mbrtowc.  */
weak_alias (__mbrtowc, mbrtoc32)

The reasoning in those comments to justify those aliases is incorrect:
ISO C requires that, for the case of a NULL mbstate_t* being passed,
each function has its *own* internal static mbstate_t.  Thus a program
must be able to use both wcrtomb and c32rtomb at the same time with
each keeping its own separate state, and likewise for mbrtowc and
mbrtoc32.

This patch duly sets up separarate char32_t function that wrap the
wchar_t ones.  Note that the included test only covers the mbrtoc32 /
mbrtowc pair.  While I think the change made is logically correct for
c32rtomb / wcrtomb as well, I'm not sure we have a locale with a
suitable state-dependent multibyte encoding for testing that part of
the change.

Tested for x86_64.

2018-10-19  Joseph Myers  <joseph@codesourcery.com>

	[BZ #23793]
	* wcsmbs/c32rtomb.c: New file.
	* wcsmbs/mbrtoc32.c: Likewise.
	* wcsmbs/tst-c32-state.c: Likewise.
	* wcsmbs/mbrtowc.c (mbrtoc32): Do not define as alias.
	* wcsmbs/wcrtomb.c (c32rtomb): Likewise.
	* wcsmbs/Makefile (routines): Add mbrtoc32 and c32rtomb.
	(tests): Add tst-c32-state.
	[$(run-built-tests) = yes] ($(objpfx)tst-c32-state.out): Depend on
	$(gen-locales).

diff --git a/wcsmbs/Makefile b/wcsmbs/Makefile
index a58d36ff8f..cdd8dd5c50 100644
--- a/wcsmbs/Makefile
+++ b/wcsmbs/Makefile
@@ -42,7 +42,7 @@ routines := wcscat wcschr wcscmp wcscpy wcscspn wcsdup wcslen wcsncat \
 	    wcsmbsload mbsrtowcs_l \
 	    isoc99_wscanf isoc99_vwscanf isoc99_fwscanf isoc99_vfwscanf \
 	    isoc99_swscanf isoc99_vswscanf \
-	    mbrtoc16 c16rtomb
+	    mbrtoc16 c16rtomb mbrtoc32 c32rtomb
 
 strop-tests :=  wcscmp wcsncmp wmemcmp wcslen wcschr wcsrchr wcscpy wcsnlen \
 		wcpcpy wcsncpy wcpncpy wcscat wcsncat wcschrnul wcsspn wcspbrk \
@@ -51,7 +51,7 @@ tests := tst-wcstof wcsmbs-tst1 tst-wcsnlen tst-btowc tst-mbrtowc \
 	 tst-wcrtomb tst-wcpncpy tst-mbsrtowcs tst-wchar-h tst-mbrtowc2 \
 	 tst-c16c32-1 wcsatcliff tst-wcstol-locale tst-wcstod-nan-locale \
 	 tst-wcstod-round test-char-types tst-fgetwc-after-eof \
-	 tst-wcstod-nan-sign tst-c16-surrogate \
+	 tst-wcstod-nan-sign tst-c16-surrogate tst-c32-state \
 	 $(addprefix test-,$(strop-tests))
 
 include ../Rules
@@ -70,6 +70,7 @@ $(objpfx)wcsmbs-tst1.out: $(gen-locales)
 $(objpfx)tst-wcstol-locale.out: $(gen-locales)
 $(objpfx)tst-wcstod-nan-locale.out: $(gen-locales)
 $(objpfx)tst-c16-surrogate.out: $(gen-locales)
+$(objpfx)tst-c32-state.out: $(gen-locales)
 endif
 
 $(objpfx)tst-wcstod-round: $(libm)
diff --git a/wcsmbs/c32rtomb.c b/wcsmbs/c32rtomb.c
new file mode 100644
index 0000000000..f370ae28ad
--- /dev/null
+++ b/wcsmbs/c32rtomb.c
@@ -0,0 +1,32 @@
+/* Convert char32_t to multibyte.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <uchar.h>
+#include <wchar.h>
+
+
+/* This is the private state used if PS is NULL.  */
+static mbstate_t state;
+
+size_t
+c32rtomb (char *s, char32_t c32, mbstate_t *ps)
+{
+  if (ps == NULL)
+    ps = &state;
+  return wcrtomb (s, c32, ps);
+}
diff --git a/wcsmbs/mbrtoc32.c b/wcsmbs/mbrtoc32.c
new file mode 100644
index 0000000000..d3f6ef8e5d
--- /dev/null
+++ b/wcsmbs/mbrtoc32.c
@@ -0,0 +1,32 @@
+/* Convert multibyte to char32_t.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <uchar.h>
+#include <wchar.h>
+
+
+/* This is the private state used if PS is NULL.  */
+static mbstate_t state;
+
+size_t
+mbrtoc32 (char32_t *pc32, const char *s, size_t n, mbstate_t *ps)
+{
+  if (ps == NULL)
+    ps = &state;
+  return mbrtowc ((wchar_t *) pc32, s, n, ps);
+}
diff --git a/wcsmbs/mbrtowc.c b/wcsmbs/mbrtowc.c
index 954933d068..410f6855cd 100644
--- a/wcsmbs/mbrtowc.c
+++ b/wcsmbs/mbrtowc.c
@@ -122,8 +122,3 @@ __mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps)
 libc_hidden_def (__mbrtowc)
 weak_alias (__mbrtowc, mbrtowc)
 libc_hidden_weak (mbrtowc)
-
-/* There should be no difference between the UTF-32 handling required
-   by mbrtoc32 and the wchar_t handling which has long since been
-   implemented in mbrtowc.  */
-weak_alias (__mbrtowc, mbrtoc32)
diff --git a/wcsmbs/tst-c32-state.c b/wcsmbs/tst-c32-state.c
new file mode 100644
index 0000000000..68f646c801
--- /dev/null
+++ b/wcsmbs/tst-c32-state.c
@@ -0,0 +1,44 @@
+/* Test mbrtowc and mbrtoc32 do not share state (bug 23793).
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <locale.h>
+#include <uchar.h>
+#include <wchar.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  TEST_VERIFY_EXIT (setlocale (LC_ALL, "de_DE.UTF-8") != NULL);
+  const char buf[] = "\u00ff";
+  wchar_t wc = 0;
+  char32_t c32 = 0;
+  size_t ret = mbrtowc (&wc, buf, 1, NULL);
+  TEST_COMPARE (ret, (size_t) -2);
+  ret = mbrtoc32 (&c32, buf, 1, NULL);
+  TEST_COMPARE (ret, (size_t) -2);
+  ret = mbrtowc (&wc, buf + 1, 1, NULL);
+  TEST_COMPARE (ret, 1);
+  TEST_COMPARE (wc, 0xff);
+  ret = mbrtoc32 (&c32, buf + 1, 1, NULL);
+  TEST_COMPARE (ret, 1);
+  TEST_COMPARE (c32, 0xff);
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/wcsmbs/wcrtomb.c b/wcsmbs/wcrtomb.c
index 23f122599a..b10295e939 100644
--- a/wcsmbs/wcrtomb.c
+++ b/wcsmbs/wcrtomb.c
@@ -113,8 +113,3 @@ __wcrtomb (char *s, wchar_t wc, mbstate_t *ps)
 }
 weak_alias (__wcrtomb, wcrtomb)
 libc_hidden_weak (wcrtomb)
-
-/* There should be no difference between the UTF-32 handling required
-   by c32rtomb and the wchar_t handling which has long since been
-   implemented in wcrtomb.  */
-weak_alias (__wcrtomb, c32rtomb)

-- 
Joseph S. Myers
joseph@codesourcery.com