Returns MP_VAL if not supported

Author: czurnieden

doc/bn.tex

@@ -2447,8 +2447,8 @@ \subsection{To ASCII}
 printf("In hex: %kN and in decimal: %N\textbackslash{}n", &a, &a);
 printf("In bin: %bN and in base 64: %@N\textbackslash{}n", &a, &a);
 printf("And finally octal: %oN \textbackslash{}n", &a);
-
 \end{alltt}
+Returns \texttt{MP\_VAL} if that function is not supported.
 
 \subsection{From ASCII}
 \index{mp\_read\_radix}

mp_printf_extension.c

@@ -4,17 +4,12 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-#ifdef _MSC_VER
-mp_err mp_printf_extension(void)
-{
-   return MP_VAL;
-}
 
-#else
-
-/* TODO: find min version of glibc. Seems to be >2.9, check */
-#if (!(defined MP_NO_FILE) && (defined __GLIBC__))
+#if ((defined(__GLIBC__)) && (defined(__GLIBC_MINOR__)) )
+#define GLIBC_VERSION (__GLIBC__ * 1000  + __GLIBC_MINOR__)
+#endif
 
+#if (!(defined(_MSC_VER)) &&  !(defined(MP_NO_FILE)) && (defined(GLIBC_VERSION)) && (GLIBC_VERSION > 2009) )
 /* The functions in printf.h are not threadsafe to begin with */
 static int mp_hexmod = 0;
 static int mp_octmod = 0;
@@ -27,12 +22,9 @@ static int s_mp_print_mp_int(FILE *stream,  const struct printf_info *info,  con
    mp_err err = MP_OKAY;
    const mp_int *a;
    char *buf, *start_buf;
-   int base;
-   size_t size, written;
-   int len;
-   size_t extra_len = 0u;
-   int idx = 0;
    char *prefixed_zero = "";
+   int base, len, idx = 0;
+   size_t size, written, extra_len = 0u;
 
    /* Fiddle our bigint out of the argument list */
    a = *((const mp_int * const *)(args[0]));
@@ -178,6 +170,10 @@ mp_err mp_printf_extension(void)
 
    return err;
 }
-#endif
+#else
+mp_err mp_printf_extension(void)
+{
+   return MP_VAL;
+}
 #endif
 #endif