Fix for using uninitialised value in decision

Detail:
  It isn't possible to read FIONBIO using socketioctl, the Internet module returns -1 before writing the output variable, leaving it uninitialised.
  Track the FIONBIO state using an extra member in the mbedtls_net_context structure, so it can be read when needed.
Admin:
  Submission for TCP/IP bounty.

Version 2.12. Tagged as 'mbedTLS-2_12'

VersionNum

-/* (2.11)
+/* (2.12)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        2.11
+#define Module_MajorVersion_CMHG        2.12
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                28 Dec 2018
+#define Module_Date_CMHG                27 Jan 2019
 
-#define Module_MajorVersion             "2.11"
-#define Module_Version                  211
+#define Module_MajorVersion             "2.12"
+#define Module_Version                  212
 #define Module_MinorVersion             ""
-#define Module_Date                     "28 Dec 2018"
+#define Module_Date                     "27 Jan 2019"
 
-#define Module_ApplicationDate          "28-Dec-18"
+#define Module_ApplicationDate          "27-Jan-19"
 
 #define Module_ComponentName            "mbedTLS"
 #define Module_ComponentPath            "apache/RiscOS/Sources/Lib/mbedTLS"
 
-#define Module_FullVersion              "2.11"
-#define Module_HelpVersion              "2.11 (28 Dec 2018)"
-#define Module_LibraryVersionInfo       "2:11"
+#define Module_FullVersion              "2.12"
+#define Module_HelpVersion              "2.12 (27 Jan 2019)"
+#define Module_LibraryVersionInfo       "2:12"

c/net_sockets

@@ -291,15 +291,10 @@ int mbedtls_net_bind(mbedtls_net_context *ctx,
  */
 static int net_would_block(const mbedtls_net_context *ctx)
 {
-	int nbio, olderrno;
-
 	/*
 	 * Never return 'WOULD BLOCK' on a non-blocking socket
 	 */
-	olderrno = errno;
-	socketioctl(ctx->fd, _IOR('f', 126, int) /* Read FIONBIO */, &nbio);
-	errno = olderrno;
-	if (!nbio)
+	if (!ctx->nbio)
 	{
 		return 0;
 	}
@@ -425,6 +420,7 @@ int mbedtls_net_set_block(mbedtls_net_context *ctx)
 {
 	int on = 0;
 
+	ctx->nbio = on;
 	return socketioctl(ctx->fd, FIONBIO, &on);
 }
 
@@ -432,6 +428,7 @@ int mbedtls_net_set_nonblock(mbedtls_net_context *ctx)
 {
 	int on = 1;
 
+	ctx->nbio = on;
 	return socketioctl(ctx->fd, FIONBIO, &on);
 }
 

mbedtls/h/net_sockets

@@ -87,6 +87,9 @@ extern "C" {
 typedef struct mbedtls_net_context
 {
     int fd;             /**< The underlying file descriptor                 */
+#ifdef __riscos
+    int nbio;           /**< Flag to remember write only FIONBIO state      */
+#endif
 }
 mbedtls_net_context;