libxl: generate destructors for each libxl defined type

I chose the name "_destroy" rather than "_free" because the destructor
functions will free only the members of a type recursively but will
not free the actual type structure itself. The allocation of the type
is typically done by the caller and may not be a single allocation,
e.g. lists/arrays of types or embedded in other structures etc.

The exceptions to this rule are libxl_string_list_destroy and
libxl_key_value_list_destroy but I'm not 100% convinced they are
exceptions (since they are kind-of opaque) and I couldn't see a
cleanerway to express this concept. I have made a best effort attempt
to implement these functions sanely but since as far as I can tell
nothing in the current code base ever sets
libxl_domain_create_info.{xsdata,platformdata} I'm flying somewhat
blind.

[PATCH 05 of 16 of
 libxl: autogenerate type definitions and destructor functions]

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 73 insertions, 5 deletions

diff --git a/tools/libxl/gentypes.py b/tools/libxl/gentypes.py
index 5053d8dea7..e4762d3767 100644
--- a/tools/libxl/gentypes.py
+++ b/tools/libxl/gentypes.py
@@ -59,16 +59,53 @@ def libxl_C_type_define(ty, indent = ""):
         raise NotImplementedError("%s" % type(ty))
     return s.replace("\n", "\n%s" % indent)
 
+def libxl_C_type_destroy(ty, v, reference, indent = "    ", parent = None):
+    if reference:
+        deref = v + "->"
+    else:
+        deref = v + "."
+
+    s = ""
+    if isinstance(ty, libxltypes.KeyedUnion):
+        if parent is None:
+            raise Exception("KeyedUnion type must have a parent")
+        for f in ty.fields:
+            keyvar_expr = f.keyvar_expr % (parent + ty.keyvar_name)
+            s += "if (" + keyvar_expr + ") {\n"
+            s += libxl_C_type_destroy(f.type, deref + f.name, False, indent + "    ", deref)
+            s += "}\n"
+    elif isinstance(ty, libxltypes.Reference):
+        s += libxl_C_type_destroy(ty.ref_type, v, True, indent, v)
+    elif isinstance(ty, libxltypes.Struct) and (parent is None or ty.destructor_fn is None):
+        for f in [f for f in ty.fields if not f.const]:
+
+            if f.name is None: # Anonynous struct
+                s += libxl_C_type_destroy(f.type, deref, False, "", deref)
+            else:
+                s += libxl_C_type_destroy(f.type, deref + f.name, False, "", deref)
+    else:
+        if ty.passby == libxltypes.PASS_BY_REFERENCE and not reference:
+            makeref = "&"
+        else:
+            makeref = ""
+
+        if ty.destructor_fn is not None:
+            s += "%s(%s);\n" % (ty.destructor_fn, makeref + v)
+            
+    if s != "":
+        s = indent + s
+    return s.replace("\n", "\n%s" % indent).rstrip(indent)
+
 if __name__ == '__main__':
-    if len(sys.argv) < 3:
-        print >>sys.stderr, "Usage: gentypes.py <idl> <header>"
+    if len(sys.argv) < 4:
+        print >>sys.stderr, "Usage: gentypes.py <idl> <header> <implementation>"
         sys.exit(1)
 
     idl = sys.argv[1]
     (_,types) = libxltypes.parse(idl)
                     
     header = sys.argv[2]
-    print "outputting libxl types to %s" % header
+    print "outputting libxl type definitions to %s" % header
 
     f = open(header, "w")
     
@@ -84,8 +121,39 @@ if __name__ == '__main__':
  
 """ % " ".join(sys.argv))
         
-    for t in types:
-        f.write(libxl_C_type_define(t) + ";\n")
+    for ty in types:
+        f.write(libxl_C_type_define(ty) + ";\n")
+        if ty.destructor_fn is not None:
+            f.write("void %s(%s *p);\n" % (ty.destructor_fn, ty.typename))
         f.write("\n")
 
     f.write("""#endif /* __LIBXL_TYPES_H */\n""")
+    f.close()
+    
+    impl = sys.argv[3]
+    print "outputting libxl type implementations to %s" % impl
+
+    f = open(impl, "w")
+    f.write("""
+/* DO NOT EDIT.
+ *
+ * This file is autogenerated by
+ * "%s"
+ */
+
+#include "libxl_osdeps.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "libxl.h"
+
+""" % " ".join(sys.argv))
+
+    for ty in [t for t in types if t.autogenerate_destructor]:
+        f.write("void %s(%s *p)\n" % (ty.destructor_fn, ty.typename))
+        f.write("{\n")
+        f.write(libxl_C_type_destroy(ty, "p", True))
+        f.write("}\n")
+        f.write("\n")
+    f.close()