Import mbedtls-2.27.0

Imports Mbed TLS 2.27.0 from https://github.com/ARMmbed/mbedtls.git
commit f71e28780841 ("Merge pull request #843 from
paul-elliott-arm/mbedtls-2.27.0rc0-pr") (tag mbedtls-2.27.0, v2.27.0).

Files that are not needed are removed.

 cd lib/libmbedtls
 rm -rf mbedtls
 cp -R path/to/mbedtls-2.27.0/mbedtls .
 cd mbedtls
 rm CMakeLists.txt DartConfiguration.tcl Makefile
 rm .gitignore .travis.yml .pylintrc .globalrc .mypy.ini BRANCHES.md
 rm include/.gitignore include/CMakeLists.txt library/.gitignore
 rm library/CMakeLists.txt library/Makefile
 rm -rf .git .github doxygen configs programs scripts tests visualc yotta
 rm -rf 3rdparty ChangeLog.d docs
 rm -rf include/mbedtls/config_psa.h include/psa
 rm library/psa_* library/mps_*
 cd ..
 git add mbedtls

This is a complete overwrite of previous code so earlier changes in the
previous branch import/mbedtls-2.22.0 will be added on top of this commit.

Signed-off-by: Jerome Forissier <jerome@forissier.org>
diff --git a/lib/libmbedtls/mbedtls/library/entropy_poll.c b/lib/libmbedtls/mbedtls/library/entropy_poll.c
index 8148aff..2c1e093 100644
--- a/lib/libmbedtls/mbedtls/library/entropy_poll.c
+++ b/lib/libmbedtls/mbedtls/library/entropy_poll.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  *  Platform-specific and custom entropy polling functions
  *
- *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  *  not use this file except in compliance with the License.
@@ -15,20 +15,14 @@
  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
-#if defined(__linux__)
+#if defined(__linux__) && !defined(_GNU_SOURCE)
 /* Ensure that syscall() is available even when compiling with -std=c99 */
 #define _GNU_SOURCE
 #endif
 
-#if !defined(MBEDTLS_CONFIG_FILE)
-#include "mbedtls/config.h"
-#else
-#include MBEDTLS_CONFIG_FILE
-#endif
+#include "common.h"
 
 #include <string.h>
 
@@ -52,7 +46,7 @@
 
 #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
     !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
-    !defined(__HAIKU__)
+    !defined(__HAIKU__) && !defined(__midipix__)
 #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
 #endif
 
@@ -95,7 +89,7 @@
  * Since there is no wrapper in the libc yet, use the generic syscall wrapper
  * available in GNU libc and compatible libc's (eg uClibc).
  */
-#if defined(__linux__) && defined(__GLIBC__)
+#if ((defined(__linux__) && defined(__GLIBC__)) || defined(__midipix__))
 #include <unistd.h>
 #include <sys/syscall.h>
 #if defined(SYS_getrandom)
@@ -113,7 +107,57 @@
     return( syscall( SYS_getrandom, buf, buflen, flags ) );
 }
 #endif /* SYS_getrandom */
-#endif /* __linux__ */
+#endif /* __linux__ || __midipix__ */
+
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+#include <sys/param.h>
+#if (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || \
+    (defined(__DragonFly__) && __DragonFly_version >= 500700)
+#include <errno.h>
+#include <sys/random.h>
+#define HAVE_GETRANDOM
+static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
+{
+    return getrandom( buf, buflen, flags );
+}
+#endif /* (__FreeBSD__ && __FreeBSD_version >= 1200000) ||
+          (__DragonFly__ && __DragonFly_version >= 500700) */
+#endif /* __FreeBSD__ || __DragonFly__ */
+
+/*
+ * Some BSD systems provide KERN_ARND.
+ * This is equivalent to reading from /dev/urandom, only it doesn't require an
+ * open file descriptor, and provides up to 256 bytes per call (basically the
+ * same as getentropy(), but with a longer history).
+ *
+ * Documentation: https://netbsd.gw.com/cgi-bin/man-cgi?sysctl+7
+ */
+#if (defined(__FreeBSD__) || defined(__NetBSD__)) && !defined(HAVE_GETRANDOM)
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#if defined(KERN_ARND)
+#define HAVE_SYSCTL_ARND
+
+static int sysctl_arnd_wrapper( unsigned char *buf, size_t buflen )
+{
+    int name[2];
+    size_t len;
+
+    name[0] = CTL_KERN;
+    name[1] = KERN_ARND;
+
+    while( buflen > 0 )
+    {
+        len = buflen > 256 ? 256 : buflen;
+        if( sysctl(name, 2, buf, &len, NULL, 0) == -1 )
+            return( -1 );
+        buflen -= len;
+        buf += len;
+    }
+    return( 0 );
+}
+#endif /* KERN_ARND */
+#endif /* __FreeBSD__ || __NetBSD__ */
 
 #include <stdio.h>
 
@@ -139,6 +183,15 @@
     ((void) ret);
 #endif /* HAVE_GETRANDOM */
 
+#if defined(HAVE_SYSCTL_ARND)
+    ((void) file);
+    ((void) read_len);
+    if( sysctl_arnd_wrapper( output, len ) == -1 )
+        return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
+    *olen = len;
+    return( 0 );
+#else
+
     *olen = 0;
 
     file = fopen( "/dev/urandom", "rb" );
@@ -156,6 +209,7 @@
     *olen = len;
 
     return( 0 );
+#endif /* HAVE_SYSCTL_ARND */
 }
 #endif /* _WIN32 && !EFIX64 && !EFI32 */
 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
@@ -166,13 +220,13 @@
 {
     ((void) data);
     ((void) output);
-    *olen = 0;
 
+    *olen = 0;
     if( len < sizeof(unsigned char) )
         return( 0 );
 
+    output[0] = 0;
     *olen = sizeof(unsigned char);
-
     return( 0 );
 }
 #endif