qmi-codegen: avoid breaking API when defining strings in public structs

Commit b9c3701e337198 introduced an API break, where we would change a pointer
to a heap allocated string and instead use a fixed size char array. This commit
will instead recover the pointer to the string when used in a public struct, so
that API isn't broken w.r.t. previous stable libqmi versions.

The string is now properly allocated before reading and deallocated as part of
the struct deallocation.

3 files changed, 53 insertions, 6 deletions

diff --git a/build-aux/qmi-codegen/Variable.py b/build-aux/qmi-codegen/Variable.py
index d3691a3..6b534d7 100644
--- a/build-aux/qmi-codegen/Variable.py
+++ b/build-aux/qmi-codegen/Variable.py
@@ -16,6 +16,7 @@
 # Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 #
 # Copyright (C) 2012 Lanedo GmbH
+# Copyright (C) 2012-2015 Aleksander Morgado <aleksander@aleksander.es>
 #
 
 import string
@@ -54,6 +55,11 @@ class Variable:
             else:
                 raise ValueError("Invalid endian value %s" % endian)
 
+        """
+        Initially all variables are flagged as not being public
+        """
+        self.public = False
+
     """
     Emits the code to declare specific new types required by the variable.
     """
@@ -150,3 +156,9 @@ class Variable:
     """
     def add_sections(self, sections):
         pass
+
+    """
+    Flag as being public
+    """
+    def flag_public(self):
+        self.public = True
diff --git a/build-aux/qmi-codegen/VariableString.py b/build-aux/qmi-codegen/VariableString.py
index b58a7d2..01452f5 100644
--- a/build-aux/qmi-codegen/VariableString.py
+++ b/build-aux/qmi-codegen/VariableString.py
@@ -16,6 +16,7 @@
 # Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 #
 # Copyright (C) 2012 Lanedo GmbH
+# Copyright (C) 2012-2015 Aleksander Morgado <aleksander@aleksander.es>
 #
 
 import string
@@ -83,10 +84,24 @@ class VariableString(Variable):
 
         if self.is_fixed_size:
             translations['fixed_size'] = self.fixed_size
-            template = (
-                '${lp}if (!qmi_message_tlv_read_fixed_size_string (message, init_offset, &offset, ${fixed_size}, &${variable_name}[0], ${error}))\n'
-                '${lp}    goto ${tlv_out};\n'
-                '${lp}${variable_name}[${fixed_size}] = \'\\0\';\n')
+
+            # Fixed sized strings exposed in public fields will need to be
+            # explicitly allocated in heap
+            if self.public:
+                translations['fixed_size_plus_one'] = int(self.fixed_size) + 1
+                template = (
+                    '${lp}${variable_name} = g_malloc (${fixed_size_plus_one});\n'
+                    '${lp}if (!qmi_message_tlv_read_fixed_size_string (message, init_offset, &offset, ${fixed_size}, &${variable_name}[0], ${error})) {\n'
+                    '${lp}    g_free (${variable_name});\n'
+                    '${lp}    ${variable_name} = NULL;\n'
+                    '${lp}    goto ${tlv_out};\n'
+                    '${lp}}\n'
+                    '${lp}${variable_name}[${fixed_size}] = \'\\0\';\n')
+            else:
+                template = (
+                    '${lp}if (!qmi_message_tlv_read_fixed_size_string (message, init_offset, &offset, ${fixed_size}, &${variable_name}[0], ${error}))\n'
+                    '${lp}    goto ${tlv_out};\n'
+                    '${lp}${variable_name}[${fixed_size}] = \'\\0\';\n')
         else:
             translations['n_size_prefix_bytes'] = self.n_size_prefix_bytes
             translations['max_size'] = self.max_size if self.max_size != '' else '0'
@@ -158,7 +173,13 @@ class VariableString(Variable):
         translations = { 'lp'   : line_prefix,
                          'name' : variable_name }
 
-        if self.is_fixed_size:
+        if public:
+            # Fixed sized strings given in public structs are given as pointers,
+            # instead of as fixed-sized arrays directly in the struct.
+            template = (
+                '${lp}gchar *${name};\n')
+            self.is_public = True
+        elif self.is_fixed_size:
             translations['fixed_size_plus_one'] = int(self.fixed_size) + 1
             template = (
                 '${lp}gchar ${name}[${fixed_size_plus_one}];\n')
@@ -309,7 +330,7 @@ class VariableString(Variable):
     """
     def build_dispose(self, line_prefix, variable_name):
         # Fixed-size strings don't need dispose
-        if self.is_fixed_size:
+        if self.is_fixed_size and not self.public:
             return ''
 
         translations = { 'lp'            : line_prefix,
@@ -318,3 +339,14 @@ class VariableString(Variable):
         template = (
             '${lp}g_free (${variable_name});\n')
         return string.Template(template).substitute(translations)
+
+
+    """
+    Flag as being public
+    """
+    def flag_public(self):
+        # Call the parent method
+        Variable.flag_public(self)
+        # Fixed-sized strings will need dispose if they are in the public header
+        if self.is_fixed_size:
+            self.needs_dispose = True
diff --git a/build-aux/qmi-codegen/VariableStruct.py b/build-aux/qmi-codegen/VariableStruct.py
index 445af71..78e6752 100644
--- a/build-aux/qmi-codegen/VariableStruct.py
+++ b/build-aux/qmi-codegen/VariableStruct.py
@@ -16,6 +16,7 @@
 # Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 #
 # Copyright (C) 2012 Lanedo GmbH
+# Copyright (C) 2012-2015 Aleksander Morgado <aleksander@aleksander.es>
 #
 
 import string
@@ -48,6 +49,8 @@ class VariableStruct(Variable):
             member = {}
             member['name'] = utils.build_underscore_name(member_dictionary['name'])
             member['object'] = VariableFactory.create_variable(member_dictionary, struct_type_name + ' ' + member['name'], self.container_type)
+            # Specify that the variable will be defined in the public header
+            member['object'].flag_public()
             self.members.append(member)
 
         # We'll need to dispose if at least one of the members needs it