From c8bcfe476360b73bebb22d743617c199782472d9 Mon Sep 17 00:00:00 2001
From: TakayukiMatsuo <62984531+TakayukiMatsuo@users.noreply.github.com>
Date: Tue, 14 Sep 2021 09:08:55 +0900
Subject: [PATCH] Add implementation to make wolfSSL_BIO_flush work for
 WOLFSSL_BIO_FILE (#4395)

---
 src/bio.c                   | 15 ++++++++++++---
 wolfssl/wolfcrypt/wc_port.h |  1 +
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/bio.c b/src/bio.c
index 2ce59d2fc..fbdcdfd08 100644
--- a/src/bio.c
+++ b/src/bio.c
@@ -1842,9 +1842,18 @@ int wolfSSL_BIO_pending(WOLFSSL_BIO* bio)
 
 int wolfSSL_BIO_flush(WOLFSSL_BIO* bio)
 {
-    /* for wolfSSL no flushing needed */
     WOLFSSL_ENTER("BIO_flush");
-    (void)bio;
-    return 1;
+
+    if (bio == NULL)
+        return WOLFSSL_FAILURE;
+
+    if (bio->type == WOLFSSL_BIO_FILE) {
+#if !defined(NO_FILESYSTEM) && defined(XFFLUSH)
+        if (XFFLUSH((FILE *)bio->ptr) != 0)
+            return WOLFSSL_FAILURE;
+
+#endif /* !NO_FILESYSTEM && XFFLUSH */
+    }
+    return WOLFSSL_SUCCESS;
 }
 #endif /* WOLFSSL_BIO_INCLUDED */
diff --git a/wolfssl/wolfcrypt/wc_port.h b/wolfssl/wolfcrypt/wc_port.h
index d579679bf..1e615a86c 100644
--- a/wolfssl/wolfcrypt/wc_port.h
+++ b/wolfssl/wolfcrypt/wc_port.h
@@ -972,6 +972,7 @@ WOLFSSL_API int wolfCrypt_Cleanup(void);
     #define XBADFILE   NULL
     #define XFGETS     fgets
     #define XFPRINTF   fprintf
+    #define XFFLUSH    fflush
 
     #if !defined(NO_WOLFSSL_DIR)\
         && !defined(WOLFSSL_NUCLEUS) && !defined(WOLFSSL_NUCLEUS_1_2)