libc/string: prevent libc in the kernel/userspace optionally

Add the `LIBC_PREVENT_STRING_KERNEL` and `LIBC_PREVENT_STRING_USER`
that are meant to be selected by the chip if no libc implementation
is going to be built. If selected, neither NuttX's software version
of the libc nor any architecture-specific implementation will be
built in the kernel or in the userspace, respectively. In this
case, the linker may provide a ROM-defined version of the libc
functions instead.

libs/libc/string/Make.defs

@@ -32,61 +32,15 @@ CSRCS += lib_strsep.c lib_strerrorr.c lib_explicit_bzero.c lib_strsignal.c
 CSRCS += lib_index.c lib_rindex.c lib_timingsafe_bcmp.c lib_strverscmp.c
 CSRCS += lib_mempcpy.c lib_rawmemchr.c lib_bzero.c
 
-ifneq ($(CONFIG_LIBC_ARCH_MEMCHR),y)
-CSRCS += lib_memchr.c
-endif
+CSRCS += lib_memchr.c lib_memcmp.c lib_memmove.c lib_memset.c
+CSRCS += lib_strchr.c lib_strcmp.c lib_strcpy.c lib_strlcat.c
+CSRCS += lib_strlcpy.c lib_strlen.c lib_strncpy.c lib_strnlen.c
 
-ifneq ($(CONFIG_LIBC_ARCH_MEMCMP),y)
-CSRCS += lib_memcmp.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_MEMCPY),y)
 ifeq ($(CONFIG_MEMCPY_VIK),y)
 CSRCS += lib_vikmemcpy.c
 else
 CSRCS += lib_memcpy.c
 endif
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_MEMMOVE),y)
-CSRCS += lib_memmove.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_MEMSET),y)
-CSRCS += lib_memset.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRCHR),y)
-CSRCS += lib_strchr.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRCMP),y)
-CSRCS += lib_strcmp.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRCPY),y)
-CSRCS += lib_strcpy.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRLCAT),y)
-CSRCS += lib_strlcat.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRLCPY),y)
-CSRCS += lib_strlcpy.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRLEN),y)
-CSRCS += lib_strlen.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRNCPY),y)
-CSRCS += lib_strncpy.c
-endif
-
-ifneq ($(CONFIG_LIBC_ARCH_STRNLEN),y)
-CSRCS += lib_strnlen.c
-endif
 
 ifeq ($(CONFIG_LIBC_LOCALE),y)
 CSRCS += lib_strcoll.c lib_strxfrm.c

libs/libc/string/lib_memchr.c

@@ -26,6 +26,8 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -44,6 +46,7 @@
  *
  ****************************************************************************/
 
+#if !defined(CONFIG_LIBC_ARCH_MEMCHR) && defined(LIBC_BUILD_STRING)
 #undef memchr /* See mm/README.txt */
 FAR void *memchr(FAR const void *s, int c, size_t n)
 {
@@ -61,3 +64,4 @@ FAR void *memchr(FAR const void *s, int c, size_t n)
 
   return NULL;
 }
+#endif

libs/libc/string/lib_memcmp.c

@@ -26,11 +26,13 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_MEMCMP
+#if !defined(CONFIG_LIBC_ARCH_MEMCMP) && defined(LIBC_BUILD_STRING)
 #undef memcmp /* See mm/README.txt */
 no_builtin("memcmp")
 int memcmp(FAR const void *s1, FAR const void *s2, size_t n)

libs/libc/string/lib_memcpy.c

@@ -26,6 +26,8 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -34,7 +36,7 @@
  * Name: memcpy
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_MEMCPY
+#if !defined(CONFIG_LIBC_ARCH_MEMCPY) && defined(LIBC_BUILD_STRING)
 #undef memcpy /* See mm/README.txt */
 no_builtin("memcpy")
 FAR void *memcpy(FAR void *dest, FAR const void *src, size_t n)

libs/libc/string/lib_memmove.c

@@ -26,11 +26,13 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_MEMMOVE
+#if !defined(CONFIG_LIBC_ARCH_MEMMOVE) && defined(LIBC_BUILD_STRING)
 #undef memmove /* See mm/README.txt */
 no_builtin("memmove")
 FAR void *memmove(FAR void *dest, FAR const void *src, size_t count)

libs/libc/string/lib_memset.c

@@ -30,6 +30,8 @@
 #include <string.h>
 #include <assert.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -46,7 +48,7 @@
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_MEMSET
+#if !defined(CONFIG_LIBC_ARCH_MEMSET) && defined(LIBC_BUILD_STRING)
 #undef memset /* See mm/README.txt */
 no_builtin("memset")
 FAR void *memset(FAR void *s, int c, size_t n)

libs/libc/string/lib_strcasecmp.c

@@ -27,11 +27,13 @@
 #include <strings.h>
 #include <ctype.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRCASECMP
+#if !defined(CONFIG_LIBC_ARCH_STRCASECMP) && defined(LIBC_BUILD_STRING)
 #undef strcasecmp /* See mm/README.txt */
 int strcasecmp(FAR const char *cs, FAR const char *ct)
 {

libs/libc/string/lib_strcat.c

@@ -26,11 +26,13 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRCAT
+#if !defined(CONFIG_LIBC_ARCH_STRCAT) && defined(LIBC_BUILD_STRING)
 #undef strcat /* See mm/README.txt */
 FAR char *strcat(FAR char *dest, FAR const char *src)
 {

libs/libc/string/lib_strchr.c

@@ -26,6 +26,8 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -44,7 +46,7 @@
  *
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRCHR
+#if !defined(CONFIG_LIBC_ARCH_STRCHR) && defined(LIBC_BUILD_STRING)
 #undef strchr /* See mm/README.txt */
 FAR char *strchr(FAR const char *s, int c)
 {

libs/libc/string/lib_strchrnul.c

@@ -26,6 +26,8 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -44,7 +46,7 @@
  *
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRCHRNUL
+#if !defined(CONFIG_LIBC_ARCH_STRCHRNUL) && defined(LIBC_BUILD_STRING)
 FAR char *strchrnul(FAR const char *s, int c)
 {
   if (s)

libs/libc/string/lib_strcmp.c

@@ -26,11 +26,13 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRCMP
+#if !defined(CONFIG_LIBC_ARCH_STRCMP) && defined(LIBC_BUILD_STRING)
 #undef strcmp /* See mm/README.txt */
 int strcmp(FAR const char *cs, FAR const char *ct)
 {

libs/libc/string/lib_strcpy.c

@@ -26,6 +26,8 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -42,7 +44,7 @@
  *
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRCPY
+#if !defined(CONFIG_LIBC_ARCH_STRCPY) && defined(LIBC_BUILD_STRING)
 #undef strcpy /* See mm/README.txt */
 FAR char *strcpy(FAR char *dest, FAR const char *src)
 {

libs/libc/string/lib_strlcat.c

@@ -27,6 +27,8 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -44,7 +46,7 @@
  *
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRLCAT
+#if !defined(CONFIG_LIBC_ARCH_STRLCAT) && defined(LIBC_BUILD_STRING)
 size_t strlcat(FAR char *dst, FAR const char *src, size_t dsize)
 {
   FAR const char *odst = dst;

libs/libc/string/lib_strlcpy.c

@@ -27,6 +27,8 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -43,7 +45,7 @@
  *
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRLCPY
+#if !defined(CONFIG_LIBC_ARCH_STRLCPY) && defined(LIBC_BUILD_STRING)
 size_t strlcpy(FAR char *dst, FAR const char *src, size_t dsize)
 {
   FAR const char *osrc = src;

libs/libc/string/lib_strlen.c

@@ -26,11 +26,13 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRLEN
+#if !defined(CONFIG_LIBC_ARCH_STRLEN) && defined(LIBC_BUILD_STRING)
 #undef strlen /* See mm/README.txt */
 size_t strlen(const char *s)
 {

libs/libc/string/lib_strncasecmp.c

@@ -28,11 +28,13 @@
 #include <strings.h>
 #include <ctype.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRNCASECMP
+#if !defined(CONFIG_LIBC_ARCH_STRNCASECMP) && defined(LIBC_BUILD_STRING)
 #undef strncasecmp /* See mm/README.txt */
 int strncasecmp(FAR const char *cs, FAR const char *ct, size_t nb)
 {

libs/libc/string/lib_strncat.c

@@ -26,11 +26,13 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRNCAT
+#if !defined(CONFIG_LIBC_ARCH_STRNCAT) && defined(LIBC_BUILD_STRING)
 #undef strncat /* See mm/README.txt */
 FAR char *strncat(FAR char *dest, FAR const char *src, size_t n)
 {

libs/libc/string/lib_strncmp.c

@@ -26,11 +26,13 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRNCMP
+#if !defined(CONFIG_LIBC_ARCH_STRNCMP) && defined(LIBC_BUILD_STRING)
 #undef strncmp /* See mm/README.txt */
 int strncmp(FAR const char *cs, FAR const char *ct, size_t nb)
 {

libs/libc/string/lib_strncpy.c

@@ -26,6 +26,8 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -51,7 +53,7 @@
  *
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRNCPY
+#if !defined(CONFIG_LIBC_ARCH_STRNCPY) && defined(LIBC_BUILD_STRING)
 #undef strncpy /* See mm/README.txt */
 FAR char *strncpy(FAR char *dest, FAR const char *src, size_t n)
 {

libs/libc/string/lib_strnlen.c

@@ -26,11 +26,13 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
 
-#ifndef CONFIG_LIBC_ARCH_STRNLEN
+#if !defined(CONFIG_LIBC_ARCH_STRNLEN) && defined(LIBC_BUILD_STRING)
 size_t strnlen(const char *s, size_t maxlen)
 {
   const char *sc;

libs/libc/string/lib_strrchr.c

@@ -26,6 +26,8 @@
 
 #include <string.h>
 
+#include "libc.h"
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -34,7 +36,7 @@
  * occurrence of the character c in the string s.
  */
 
-#ifndef CONFIG_LIBC_ARCH_STRRCHR
+#if !defined(CONFIG_LIBC_ARCH_STRRCHR) && defined(LIBC_BUILD_STRING)
 #undef strrchr /* See mm/README.txt */
 FAR char *strrchr(FAR const char *s, int c)
 {

libs/libc/string/lib_vikmemcpy.c

@@ -62,6 +62,10 @@
 #include <stdint.h>
 #include <string.h>
 
+#include "libc.h"
+
+#if !defined(CONFIG_LIBC_ARCH_MEMCPY) && defined(LIBC_BUILD_STRING)
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -342,3 +346,5 @@ FAR void *memcpy(FAR void *dest, FAR const void *src, size_t count)
 
   return dest;
 }
+
+#endif