libc: Move MB_LEN_MAX from lib_wctob.c to limits.h

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: I3a5addac99adb02f57aba05aa9fe2e6aaf31071d

include/limits.h

@@ -49,7 +49,9 @@
 /********************************************************************************
  * Pre-processor Definitions
  ********************************************************************************/
+
 /* Default values for user configurable limits **********************************/
+
 /* Maximum number of bytes in a filename (not including terminating null). */
 
 #ifndef CONFIG_NAME_MAX
@@ -68,6 +70,13 @@
 #  endif
 #endif
 
+/* Maximum length of any multibyte character in any locale.
+ * We define this value here since the gcc header does not define
+ * the correct value.
+ */
+
+#define MB_LEN_MAX            1
+
 /* Configurable limits required by POSIX ****************************************
  *
  * Required for all implementations:
@@ -303,6 +312,7 @@
 #define SEM_VALUE_MAX  _POSIX_SEM_VALUE_MAX
 
 /* Required for readv() and writev() */
+
 /* There really is no upper limit on the number of vectors */
 
 #define IOV_MAX        INT_MAX

libs/libc/wchar/lib_wcrtomb.c

@@ -55,14 +55,14 @@
  *
  ****************************************************************************/
 
-size_t wcrtomb(FAR char *s, wchar_t wc, FAR mbstate_t * ps)
+size_t wcrtomb(FAR char *s, wchar_t wc, FAR mbstate_t *ps)
 {
   int retval = 0;
-  char buf[10];
+  char buf[MB_LEN_MAX];
 
   if (s == NULL)
     {
-      retval = wctomb((char *)buf, L'\0');
+      retval = wctomb(buf, L'\0');
     }
   else
     {
@@ -71,11 +71,11 @@ size_t wcrtomb(FAR char *s, wchar_t wc, FAR mbstate_t * ps)
 
   if (retval == -1)
     {
-      return (size_t) (-1);
+      return (size_t)(-1);
     }
   else
     {
-      return (size_t) retval;
+      return (size_t)retval;
     }
 }
 #endif

libs/libc/wchar/lib_wctob.c

@@ -44,27 +44,19 @@
 
 #ifdef CONFIG_LIBC_WCHAR
 
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-#ifndef MB_LEN_MAX
-#  define MB_LEN_MAX 8
-#endif
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
 int wctob(wint_t wc)
 {
-  unsigned char pmb[MB_LEN_MAX];
+  char pmb[MB_LEN_MAX];
 
   if (wc == WEOF)
     {
       return EOF;
     }
 
-  return wctomb((char *)pmb, wc) == 1 ? (int)pmb[0] : EOF;
+  return wctomb(pmb, wc) == 1 ? (int)pmb[0] : EOF;
 }
 #endif