Add redirect support to toolchains

We create an API for generating the linker flags needed to redirect
functions in an application

tools/toolchains/__init__.py

@@ -1345,6 +1345,51 @@ class mbedToolchain:
         """
         raise NotImplemented
 
+    @staticmethod
+    @abstractmethod
+    def name_mangle(name):
+        """Mangle a name based on the conventional name mangling of this toolchain
+
+        Positional arguments:
+        name -- the name to mangle
+
+        Return:
+        the mangled name as a string
+        """
+        raise NotImplemented
+
+    @staticmethod
+    @abstractmethod
+    def make_ld_define(name, value):
+        """Create an argument to the linker that would define a symbol
+
+        Positional arguments:
+        name -- the symbol to define
+        value -- the value to give the symbol
+
+        Return:
+        The linker flag as a string
+        """
+        raise NotImplemented
+
+    @staticmethod
+    @abstractmethod
+    def redirect_symbol(source, sync, build_dir):
+        """Redirect a symbol at link time to point at somewhere else
+
+        Positional arguments:
+        source -- the symbol doing the pointing
+        sync -- the symbol being pointed to
+        build_dir -- the directory to put "response files" if needed by the toolchain
+
+        Side Effects:
+        Possibly create a file in the build directory
+
+        Return:
+        The linker flag to redirect the symbol, as a string
+        """
+        raise NotImplemented
+
     # Return the list of macros geenrated by the build system
     def get_config_macros(self):
         return Config.config_to_macros(self.config_data) if self.config_data else []

tools/toolchains/arm.py

@@ -15,7 +15,9 @@ See the License for the specific language governing permissions and
 limitations under the License.
 """
 import re
-from os.path import join, dirname, splitext, basename
+from os.path import join, dirname, splitext, basename, exists
+from os import makedirs, write
+from tempfile import mkstemp
 
 from tools.toolchains import mbedToolchain, TOOLCHAIN_PATHS
 from tools.hooks import hook_tool
@@ -222,6 +224,22 @@ class ARM(mbedToolchain):
         self.cc_verbose("FromELF: %s" % ' '.join(cmd))
         self.default_cmd(cmd)
 
+    @staticmethod
+    def name_mangle(name):
+        return "_Z%i%sv" % (len(name), name)
+
+    @staticmethod
+    def make_ld_define(name, value):
+        return "--predefine=\"-D%s=0x%x\"" % (name, value)
+
+    @staticmethod
+    def redirect_symbol(source, sync, build_dir):
+        if not exists(build_dir):
+            makedirs(build_dir)
+        handle, filename = mkstemp(prefix=".redirect-symbol.", dir=build_dir)
+        write(handle, "RESOLVE %s AS %s\n" % (source, sync))
+        return "--edit=%s" % filename
+
 
 class ARM_STD(ARM):
     pass

tools/toolchains/gcc.py

@@ -258,6 +258,18 @@ class GCC(mbedToolchain):
         self.cc_verbose("FromELF: %s" % ' '.join(cmd))
         self.default_cmd(cmd)
 
+    @staticmethod
+    def name_mangle(name):
+        return "_Z%i%sv" % (len(name), name)
+
+    @staticmethod
+    def make_ld_define(name, value):
+        return "-D%s=0x%x" % (name, value)
+
+    @staticmethod
+    def redirect_symbol(source, sync, build_dir):
+        return "-Wl,--defsym=%s=%s" % (source, sync)
+
 
 class GCC_ARM(GCC):
     @staticmethod

tools/toolchains/iar.py

@@ -231,3 +231,15 @@ class IAR(mbedToolchain):
         # Exec command
         self.cc_verbose("FromELF: %s" % ' '.join(cmd))
         self.default_cmd(cmd)
+
+    @staticmethod
+    def name_mangle(name):
+        return "_Z%i%sv" % (len(name), name)
+
+    @staticmethod
+    def make_ld_define(name, value):
+        return "--config_def %s=0x%x" % (name, value)
+
+    @staticmethod
+    def redirect_symbol(source, sync, build_dir):
+        return "--redirect %s=%s" % (source, sync)