ctype: Always allow negative _ctype_ indices

Compilers now provide build-time options controlling whether 'char'
means 'signed char' or 'unsigned char'. This means we cannot assume
the same mode will be used when building picolibc as when building the
application.

To avoid having the ABI shift with compiler flags, remove support for
the smaller tables and always provide tables which allow for signed
char indexing as this provides the safest possible implementation.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

newlib/libc/ctype/ctype_.c

@@ -34,30 +34,16 @@
 #include "locale_private.h"
 #include "../stdlib/local.h"
 
-#if defined(_ALLOW_NEGATIVE_CTYPE_INDEX)
-
 const char _ctype_b[128 + 256] = {
 	_CTYPE_DATA_128_255,
 	_CTYPE_DATA_0_127,
 	_CTYPE_DATA_128_255
 };
 
-#else	/* !_ALLOW_NEGATIVE_CTYPE_INDEX */
-
-const char _ctype_[1 + 256] = {
-	0,
-	_CTYPE_DATA_0_127,
-	_CTYPE_DATA_128_255
-};
-
-#endif	/* !_ALLOW_NEGATIVE_CTYPE_INDEX */
-
 #ifdef _MB_EXTENDED_CHARSETS_NON_UNICODE
 
 #include "ctype_extended.h"
 
-#if defined(_ALLOW_NEGATIVE_CTYPE_INDEX)
-
 #define __CTYPE(base) [locale_ ## base - locale_EXTENDED_BASE] = { \
         _CTYPE_ ## base ## _128_254,        \
         0,                                  \
@@ -66,17 +52,6 @@ const char _ctype_[1 + 256] = {
         _CTYPE_ ## base ## _255             \
         }
 
-#else
-
-#define __CTYPE(base) [locale_ ## base - locale_EXTENDED_BASE] = { \
-        0,                                  \
-        _CTYPE_DATA_0_127,                  \
-        _CTYPE_ ## base ## _128_254,        \
-        _CTYPE_ ## base ## _255             \
-        }
-
-#endif
-
 const char __ctype[locale_END - locale_EXTENDED_BASE][_CTYPE_OFFSET + 1 + 256] = {
 #ifdef _MB_EXTENDED_CHARSETS_ISO
     __CTYPE(ISO_8859_1),

newlib/libc/include/ctype.h

@@ -218,20 +218,12 @@ __declare_extern_inline(int) toupper_l (int c, locale_t l) { (void) l; return to
 
 #else  /* _PICOLIBC_CTYPE_SMALL */
 
-#ifndef __CHAR_UNSIGNED__
-#define _ALLOW_NEGATIVE_CTYPE_INDEX
-#endif
-
-#if defined(_ALLOW_NEGATIVE_CTYPE_INDEX)
-extern const char	_ctype_b[];
 #define _CTYPE_OFFSET   127
-#define _ctype_ (_ctype_b + _CTYPE_OFFSET)
-#else
-#define _CTYPE_OFFSET   0
-extern const char	_ctype_[];
-#endif
 
-extern const short _ctype_wide[];
+extern const char       _ctype_b[];
+extern const short      _ctype_wide[];
+
+#define _ctype_ (_ctype_b + _CTYPE_OFFSET)
 
 #ifndef __cplusplus