mbrtoc32: Use the system's mbrtoc32 if it exists and basically works.

* m4/mbrtoc32.m4 (gl_MBRTOC32_SANITYCHECK): New macro.
(gl_FUNC_MBRTOC32): Require it. Set REPLACE_MBRTOC32 if mbrtoc32 exists
but is not working.
* lib/mbrtoc32.c: Include hard-locale.h, <locale.h>.
(mbrtoc32): If the char32_t encoding and the wchar_t encoding may
differ, use the system's mbrtoc32, adding workarounds.
* modules/mbrtoc32 (Depends-on): Add hard-locale.
* doc/posix-functions/mbrtoc32.texi: Mention the Solaris and native
Windows problem.
* lib/btoc32.c: Include <stdio.h>, <string.h>.
(btoc32): If the char32_t encoding and the wchar_t encoding may differ,
use mbrtoc32, not btowc.
* modules/btoc32 (Depends-on): Add mbrtoc32.
* lib/mbsrtoc32s.c (mbsrtoc32s): If the char32_t encoding and the
wchar_t encoding may differ, use mbrtoc32, not mbsrtowcs.
* modules/mbsrtoc32s (Depends-on): Update conditions.
(configure.ac): Compile mbsrtoc32s-state.c unconditionally.
* lib/mbsnrtoc32s.c (mbsnrtoc32s): If the char32_t encoding and the
wchar_t encoding may differ, use mbrtoc32, not mbsnrtowcs.
* modules/mbsnrtoc32s (Depends-on): Update conditions.
(configure.ac): Compile mbsrtoc32s-state.c unconditionally.

1 files changed, 39 insertions, 14 deletions

diff --git a/lib/mbrtoc32.c b/lib/mbrtoc32.c
index f2cf71ec11..facf28bc54 100644
--- a/lib/mbrtoc32.c
+++ b/lib/mbrtoc32.c
@@ -24,13 +24,13 @@
 #include <errno.h>
 #include <stdlib.h>
 
-# ifndef FALLTHROUGH
-#  if __GNUC__ < 7
-#   define FALLTHROUGH ((void) 0)
-#  else
-#   define FALLTHROUGH __attribute__ ((__fallthrough__))
-#  endif
+#ifndef FALLTHROUGH
+# if __GNUC__ < 7
+#  define FALLTHROUGH ((void) 0)
+# else
+#  define FALLTHROUGH __attribute__ ((__fallthrough__))
 # endif
+#endif
 
 #if GNULIB_defined_mbstate_t /* AIX, IRIX */
 /* Implement mbrtoc32() on top of mbtowc() for the non-UTF-8 locales
@@ -74,17 +74,23 @@ mbrtoc32 (char32_t *pwc, const char *s, size_t n, mbstate_t *ps)
 
 #else /* glibc, macOS, FreeBSD, NetBSD, OpenBSD, HP-UX, Solaris, Cygwin, mingw, MSVC, Minix, Android */
 
-/* Implement mbrtoc32() based on mbrtowc().  */
+/* Implement mbrtoc32() based on the original mbrtoc32() or on mbrtowc().  */
 
 # include <wchar.h>
 
 # include "localcharset.h"
 # include "streq.h"
 
+# if MBRTOC32_IN_C_LOCALE_MAYBE_EILSEQ
+#  include "hard-locale.h"
+#  include <locale.h>
+# endif
+
 static mbstate_t internal_state;
 
 size_t
 mbrtoc32 (char32_t *pwc, const char *s, size_t n, mbstate_t *ps)
+# undef mbrtoc32
 {
   /* It's simpler to handle the case s == NULL upfront, than to worry about
      this case later, before every test of pwc and n.  */
@@ -103,7 +109,31 @@ mbrtoc32 (char32_t *pwc, const char *s, size_t n, mbstate_t *ps)
   if (ps == NULL)
     ps = &internal_state;
 
-# if _GL_LARGE_CHAR32_T
+# if HAVE_WORKING_MBRTOC32
+  /* mbrtoc32() may produce different values for wc than mbrtowc().  Therefore
+     use mbrtoc32().  */
+
+#  if defined _WIN32 && !defined __CYGWIN__
+  char32_t wc;
+  size_t ret = mbrtoc32 (&wc, s, n, ps);
+  if (ret < (size_t) -2 && pwc != NULL)
+    *pwc = wc;
+#  else
+  size_t ret = mbrtoc32 (pwc, s, n, ps);
+#  endif
+
+#  if MBRTOC32_IN_C_LOCALE_MAYBE_EILSEQ
+  if ((size_t) -2 <= ret && n != 0 && ! hard_locale (LC_CTYPE))
+    {
+      if (pwc != NULL)
+        *pwc = (unsigned char) *s;
+      return 1;
+    }
+#  endif
+
+  return ret;
+
+# elif _GL_LARGE_CHAR32_T
 
   /* Special-case all encodings that may produce wide character values
      > WCHAR_MAX.  */
@@ -209,12 +239,7 @@ mbrtoc32 (char32_t *pwc, const char *s, size_t n, mbstate_t *ps)
 
 # else
 
-  /* char32_t and wchar_t are equivalent.
-     Two implementations are possible:
-       - We can call the original mbrtoc32 (if it exists) and handle
-         MBRTOC32_IN_C_LOCALE_MAYBE_EILSEQ.
-       - We can call mbrtowc.
-     The latter is simpler.   */
+  /* char32_t and wchar_t are equivalent.  Use mbrtowc().  */
   wchar_t wc;
   size_t ret = mbrtowc (&wc, s, n, ps);
   if (ret < (size_t) -2 && pwc != NULL)