--- a/libtommath/bn_mp_fwrite.c	Tue May 26 23:27:26 2020 +0800
+++ b/libtommath/bn_mp_fwrite.c	Tue May 26 17:36:47 2020 +0200
@@ -1,51 +1,45 @@
 #include "tommath_private.h"
 #ifdef BN_MP_FWRITE_C
-/* LibTomMath, multiple-precision integer library -- Tom St Denis
- *
- * LibTomMath is a library that provides multiple-precision
- * integer arithmetic as well as number theoretic functionality.
- *
- * The library was designed directly after the MPI library by
- * Michael Fromberger but has been written from scratch with
- * additional optimizations in place.
- *
- * SPDX-License-Identifier: Unlicense
- */
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
 
-#ifndef LTM_NO_FILE
-int mp_fwrite(const mp_int *a, int radix, FILE *stream)
+#ifndef MP_NO_FILE
+mp_err mp_fwrite(const mp_int *a, int radix, FILE *stream)
 {
    char *buf;
-   int err, len, x;
+   mp_err err;
+   int len;
+   size_t written;
 
-   if ((err = mp_radix_size(a, radix, &len)) != MP_OKAY) {
-      return err;
+   /* TODO: this function is not in this PR */
+   if (MP_HAS(MP_RADIX_SIZE_OVERESTIMATE)) {
+      /* if ((err = mp_radix_size_overestimate(&t, base, &len)) != MP_OKAY)      goto LBL_ERR; */
+   } else {
+      if ((err = mp_radix_size(a, radix, &len)) != MP_OKAY) {
+         return err;
+      }
    }
 
-   buf = OPT_CAST(char) XMALLOC((size_t)len);
+   buf = (char *) MP_MALLOC((size_t)len);
    if (buf == NULL) {
       return MP_MEM;
    }
 
-   if ((err = mp_toradix(a, buf, radix)) != MP_OKAY) {
-      XFREE(buf);
-      return err;
+   if ((err = mp_to_radix(a, buf, (size_t)len, &written, radix)) != MP_OKAY) {
+      goto LBL_ERR;
    }
 
-   for (x = 0; x < len; x++) {
-      if (fputc((int)buf[x], stream) == EOF) {
-         XFREE(buf);
-         return MP_VAL;
-      }
+   if (fwrite(buf, written, 1uL, stream) != 1uL) {
+      err = MP_ERR;
+      goto LBL_ERR;
    }
+   err = MP_OKAY;
 
-   XFREE(buf);
-   return MP_OKAY;
+
+LBL_ERR:
+   MP_FREE_BUFFER(buf, (size_t)len);
+   return err;
 }
 #endif
 
 #endif
-
-/* ref:         HEAD -> master, tag: v1.1.0 */
-/* git commit:  08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
-/* commit time: 2019-01-28 20:32:32 +0100 */