Detect 'isascii' at configuration stage

[redbaron]

Description

Detect 'isascii' at configuration stage

Previously platforms without isascii had to manually
indicate it's absence with NO_STDLIB_ISASCII define.

It is trivial to detect function availability, so do that.

Testing

Built on platform with no isascii available

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[wolfSSL-Bot]

Can one of the admins verify this patch?

[redbaron]

It just occurred to me, that HAVE_ISASCII is stored in config.h which is optional. Maybe this define should stay as is?

[embhorn]

@redbaron is approved as a wolfSSL contributor

[douzzer]

This seems like an improvement to me, but you do need to accommodate autotools too:

diff --git a/configure.ac b/configure.ac
index 16af3bb24..7b0e35912 100644
--- a/configure.ac
+++ b/configure.ac
@@ -119,7 +119,7 @@ then
     AM_CCASFLAGS="$AM_CCASFLAGS -DWOLFSSL_EXPERIMENTAL_SETTINGS"
 fi
 
-AC_CHECK_HEADERS([arpa/inet.h fcntl.h limits.h netdb.h netinet/in.h stddef.h time.h sys/ioctl.h sys/socket.h sys/time.h errno.h sys/un.h])
+AC_CHECK_HEADERS([arpa/inet.h fcntl.h limits.h netdb.h netinet/in.h stddef.h time.h sys/ioctl.h sys/socket.h sys/time.h errno.h sys/un.h ctype.h])
 AC_CHECK_LIB([network],[socket])
 AC_C_BIGENDIAN
 AC_C___ATOMIC
@@ -128,8 +128,8 @@ AC_CHECK_HEADER(stdatomic.h, [AM_CPPFLAGS="$AM_CPPFLAGS -DWOLFSSL_HAVE_ATOMIC_H"
 # check if functions of interest are linkable, but also check if
 # they're declared by the expected headers, and if not, supersede the
 # unusable positive from AC_CHECK_FUNCS().
-AC_CHECK_FUNCS([gethostbyname getaddrinfo gettimeofday gmtime_r gmtime_s inet_ntoa memset socket strftime atexit])
-AC_CHECK_DECLS([gethostbyname, getaddrinfo, gettimeofday, gmtime_r, gmtime_s, inet_ntoa, memset, socket, strftime, atexit], [], [
+AC_CHECK_FUNCS([gethostbyname getaddrinfo gettimeofday gmtime_r gmtime_s inet_ntoa memset socket strftime atexit isascii])
+AC_CHECK_DECLS([gethostbyname, getaddrinfo, gettimeofday, gmtime_r, gmtime_s, inet_ntoa, memset, socket, strftime, atexit, isascii], [], [
 if test "$(eval echo \$"$(eval 'echo ac_cv_func_${as_decl_name}')")" = "yes"
 then
     AC_MSG_NOTICE([    note: earlier check for $(eval 'echo ${as_decl_name}') superseded.])
@@ -159,6 +159,9 @@ fi
 #ifdef HAVE_STDLIB_H
     #include <stdlib.h>
 #endif
+#ifdef HAVE_CTYPE_H
+    #include <ctype.h>
+#endif
 ]])
 
 AC_PROG_INSTALL