Add support for MBEDTLS_USER_CONFIG_FILE

ChangeLog

@@ -2,6 +2,9 @@ mbed TLS ChangeLog (Sorted per branch, date)
 
 = mbed TLS 2 branch
 
+Features
+   * Added support for yotta as a build system
+
 Bugfix
    * Fix segfault in the benchmark program when benchmarking DHM.
    * Fix build error with CMake and pre-4.5 versions of GCC (found by Hugo
@@ -20,6 +23,9 @@ Bugfix
 
 Changes
    * The PEM parser now accepts a trailing space at end of lines (#226).
+   * It is now possible to #include a user-provided configuration file at the
+     end of the default config.h by defining MBEDTLS_USER_CONFIG_FILE on the
+     compiler's command line.
 
 = mbed TLS 2.0.0 released 2015-07-13
 

include/mbedtls/config.h

@@ -2425,6 +2425,19 @@
 #include "mbedtls/target_config.h"
 #endif
 
+/*
+ * Allow user to override any previous default.
+ *
+ * Use two macro names for that, as:
+ * - with yotta the prefix YOTTA_CFG_ is forced
+ * - without yotta is looks weird to have a YOTTA prefix.
+ */
+#if defined(YOTTA_CFG_MBEDTLS_USER_CONFIG_FILE)
+#include YOTTA_CFG_MBEDTLS_USER_CONFIG_FILE
+#elif defined(MBEDTLS_USER_CONFIG_FILE)
+#include MBEDTLS_USER_CONFIG_FILE
+#endif
+
 #include "check_config.h"
 
 #endif /* MBEDTLS_CONFIG_H */

tests/scripts/check-names.sh

@@ -56,7 +56,7 @@ sed -n 's/MBED..._[A-Z0-9_]*/\'"$NL"'&\'"$NL"/gp \
     $HEADERS library/*.c \
     | grep MBEDTLS | sort -u > _MBEDTLS_XXX
 TYPOS=$( diff _caps _MBEDTLS_XXX | sed -n 's/^> //p' \
-            | egrep -v 'XXX|__|_$|^MBEDTLS_CONFIG_FILE$' || true )
+            | egrep -v 'XXX|__|_$|^MBEDTLS_.*CONFIG_FILE$' || true )
 rm _MBEDTLS_XXX _caps
 if [ "x$TYPOS" = "x" ]; then
     echo "PASS"

yotta/data/README.md

@@ -20,6 +20,22 @@ These examples are integrated as yotta tests so that they are build automaticall
 
 Please follow the instructions in the [TLS client sample](https://github.com/ARMmbed/mbedtls/tree/master/yotta/data/example-tls-client). These include a list of prerequisites and an explanation of building mbed TLS with yotta.
 
+## Configuring mbed TLS features
+
+**Warning:** This is only a preview of a future feature that will require support from yotta; as of yotta 0.5.2 this is not supported yet.
+
+mbed TLS makes it easy to disable during the compilation any feature that is not needed for a particular project. The default configuration enables all modern and widely-used features, which should meet the need of any new project; it disables all features that are either older or less mainstrem, in order to keep the footprint low. The list of available compile flags is available in the fully documented [config.h file](https://github.com/ARMmbed/mbedtls/blob/master/include/mbedtls/config.h), present in the `mbedtls` directory of the yotta module.
+
+Should you need to adjust those flags, you can provide your own configuration file with the suitable `#define` and `#undef` statements, to be included between the default definitions and the sanity checks. This file should be in your application's include directory and can be named freely; you just need to let mbed TLS know the name of the file, by using yotta's [configuration system](http://docs.yottabuild.org/reference/config.html). This name should go in your `config.json`, under mbedtls, as the key `user-config-file`, for example:
+
+    {
+       "mbedtls": {
+          "user-config-file": "\"myapp/my_mbedtls_config_changes.h\""
+       }
+    }
+
+Please note you need to provide the exact name that will be used in the `#include` directive, including the `<>` or quotes around the name.
+
 ## Contributing
 
 We graciously accept bugs and contributions from the community. There are some requirements we need to fulfil in order to be able to integrate contributions in the main code: