Initial import of spice protocol description and demarshall generator

The "spice.proto" file describes in detail the networking prototcol
that spice uses and spice_codegen.py can parse this and generate
demarshallers for such network messages.

1 files changed, 1033 insertions, 0 deletions

diff --git a/python_modules/demarshal.py b/python_modules/demarshal.py
new file mode 100644
index 00000000..fcd68508
--- /dev/null
+++ b/python_modules/demarshal.py
@@ -0,0 +1,1033 @@
+import ptypes
+import codegen
+
+
+def write_parser_helpers(writer):
+    if writer.is_generated("helper", "demarshaller"):
+        return
+
+    writer.set_is_generated("helper", "demarshaller")
+
+    writer = writer.function_helper()
+
+    writer.writeln("#ifdef WORDS_BIGENDIAN")
+    for size in [8, 16, 32, 64]:
+        for sign in ["", "u"]:
+            utype = "uint%d" % (size)
+            type = "%sint%d" % (sign, size)
+            swap = "SPICE_BYTESWAP%d" % size
+            if size == 8:
+                writer.macro("read_%s" % type, "ptr", "(*((%s_t *)(ptr)))" % type)
+            else:
+                writer.macro("read_%s" % type, "ptr", "((%s_t)%s(*((%s_t *)(ptr)))" % (type, swap, utype))
+    writer.writeln("#else")
+    for size in [8, 16, 32, 64]:
+        for sign in ["", "u"]:
+            type = "%sint%d" % (sign, size)
+            writer.macro("read_%s" % type, "ptr", "(*((%s_t *)(ptr)))" % type)
+    writer.writeln("#endif")
+
+    for size in [8, 16, 32, 64]:
+        for sign in ["", "u"]:
+            writer.newline()
+            type = "%sint%d" % (sign, size)
+            ctype = "%s_t" % type
+            scope = writer.function("SPICE_GNUC_UNUSED consume_%s" % type, ctype, "uint8_t **ptr", True)
+            scope.variable_def(ctype, "val")
+            writer.assign("val", "read_%s(*ptr)" % type)
+            writer.increment("*ptr", size / 8)
+            writer.statement("return val")
+            writer.end_block()
+
+    writer.newline()
+    writer.statement("typedef struct PointerInfo PointerInfo")
+    writer.statement("typedef uint8_t * (*parse_func_t)(uint8_t *message_start, uint8_t *message_end, uint8_t *struct_data, PointerInfo *ptr_info, int minor)")
+    writer.statement("typedef uint8_t * (*parse_msg_func_t)(uint8_t *message_start, uint8_t *message_end, int minor, size_t *size_out)")
+    writer.statement("typedef uint8_t * (*spice_parse_channel_func_t)(uint8_t *message_start, uint8_t *message_end, uint16_t message_type, int minor, size_t *size_out)")
+
+    writer.newline()
+    writer.begin_block("struct PointerInfo")
+    writer.variable_def("uint64_t", "offset")
+    writer.variable_def("parse_func_t", "parse")
+    writer.variable_def("SPICE_ADDRESS *", "dest")
+    writer.variable_def("uint32_t", "nelements")
+    writer.end_block(semicolon=True)
+
+def write_read_primitive(writer, start, container, name, scope):
+    m = container.lookup_member(name)
+    assert(m.is_primitive())
+    writer.assign("pos", start + " + " + container.get_nw_offset(m, "", "__nw_size"))
+    writer.error_check("pos + %s > message_end" % m.member_type.get_fixed_nw_size())
+
+    var = "%s__value" % (name)
+    scope.variable_def(m.member_type.c_type(), var)
+    writer.assign(var, "read_%s(pos)" % (m.member_type.primitive_type()))
+    return var
+
+def write_read_primitive_item(writer, item, scope):
+    assert(item.type.is_primitive())
+    writer.assign("pos", item.get_position())
+    writer.error_check("pos + %s > message_end" % item.type.get_fixed_nw_size())
+    var = "%s__value" % (item.subprefix)
+    scope.variable_def(item.type.c_type(), var)
+    writer.assign(var, "read_%s(pos)" % (item.type.primitive_type()))
+    return var
+
+class ItemInfo:
+    def __init__(self, type, prefix, position):
+        self.type = type
+        self.prefix = prefix
+        self.subprefix = prefix
+        self.position = position
+        self.non_null = False
+        self.member = None
+
+    def nw_size(self):
+        return self.prefix + "__nw_size"
+
+    def mem_size(self):
+        return self.prefix + "__mem_size"
+
+    def extra_size(self):
+        return self.prefix + "__extra_size"
+
+    def get_position(self):
+        return self.position
+
+class MemberItemInfo(ItemInfo):
+    def __init__(self, member, container, start):
+        if not member.is_switch():
+            self.type = member.member_type
+        self.prefix = member.name
+        self.subprefix = member.name
+        self.non_null = member.has_attr("nonnull")
+        self.position = "(%s + %s)" % (start, container.get_nw_offset(member, "", "__nw_size"))
+        self.member = member
+
+def write_validate_switch_member(writer, container, switch_member, scope, parent_scope, start,
+                                 want_nw_size, want_mem_size, want_extra_size):
+    var = container.lookup_member(switch_member.variable)
+    var_type = var.member_type
+
+    v = write_read_primitive(writer, start, container, switch_member.variable, parent_scope)
+
+    item = MemberItemInfo(switch_member, container, start)
+
+    first = True
+    for c in switch_member.cases:
+        check = c.get_check(v, var_type)
+        m = c.member
+        with writer.if_block(check, not first, False) as if_scope:
+            item.type = c.member.member_type
+            item.subprefix = item.prefix + "_" + m.name
+            item.non_null = c.member.has_attr("nonnull")
+            sub_want_extra_size = want_extra_size
+            if sub_want_extra_size and not m.contains_extra_size():
+                writer.assign(item.extra_size(), 0)
+                sub_want_extra_size = False
+
+            write_validate_item(writer, container, item, if_scope, scope, start,
+                                want_nw_size, want_mem_size, sub_want_extra_size)
+
+        first = False
+
+    with writer.block(" else"):
+        if want_nw_size:
+            writer.assign(item.nw_size(), 0)
+        if want_mem_size:
+            writer.assign(item.mem_size(), 0)
+        if want_extra_size:
+            writer.assign(item.extra_size(), 0)
+
+    writer.newline()
+
+def write_validate_struct_function(writer, struct):
+    validate_function = "validate_%s" % struct.c_type()
+    if writer.is_generated("validator", validate_function):
+        return validate_function
+
+    writer.set_is_generated("validator", validate_function)
+    writer = writer.function_helper()
+    scope = writer.function(validate_function, "intptr_t", "uint8_t *message_start, uint8_t *message_end, SPICE_ADDRESS offset, int minor")
+    scope.variable_def("uint8_t *", "start = message_start + offset")
+    scope.variable_def("SPICE_GNUC_UNUSED uint8_t *", "pos");
+    scope.variable_def("size_t", "mem_size", "nw_size");
+    num_pointers = struct.get_num_pointers()
+    if  num_pointers != 0:
+        scope.variable_def("SPICE_GNUC_UNUSED intptr_t", "ptr_size");
+
+    writer.newline()
+    with writer.if_block("offset == 0"):
+        writer.statement("return 0")
+
+    writer.newline()
+    writer.error_check("start >= message_end")
+
+    writer.newline()
+    write_validate_container(writer, None, struct, "start", scope, True, True, False)
+
+    writer.newline()
+    writer.comment("Check if struct fits in reported side").newline()
+    writer.error_check("start + nw_size > message_end")
+
+    writer.statement("return mem_size")
+
+    writer.newline()
+    writer.label("error")
+    writer.statement("return -1")
+
+    writer.end_block()
+
+    return validate_function
+
+def write_validate_pointer_item(writer, container, item, scope, parent_scope, start,
+                                want_nw_size, want_mem_size, want_extra_size):
+    if want_nw_size:
+        writer.assign(item.nw_size(), 8)
+
+    if want_mem_size or want_extra_size:
+        target_type = item.type.target_type
+
+        v = write_read_primitive_item(writer, item, scope)
+        if item.non_null:
+            writer.error_check("%s == 0" % v)
+
+        # pointer target is struct, or array of primitives
+        # if array, need no function check
+
+        if target_type.is_array():
+            writer.error_check("message_start + %s >= message_end" % v)
+
+
+            assert target_type.element_type.is_primitive()
+
+            array_item = ItemInfo(target_type, "%s__array" % item.prefix, start)
+            scope.variable_def("uint32_t", array_item.nw_size())
+            scope.variable_def("uint32_t", array_item.mem_size())
+            if target_type.is_cstring_length():
+                writer.assign(array_item.nw_size(), "spice_strnlen((char *)message_start + %s, message_end - (message_start + %s))" % (v, v))
+                writer.error_check("*(message_start + %s + %s) != 0" % (v, array_item.nw_size()))
+                writer.assign(array_item.mem_size(), array_item.nw_size())
+            else:
+                write_validate_array_item(writer, container, array_item, scope, parent_scope, start,
+                                          True, True, False)
+                writer.error_check("message_start + %s + %s > message_end" % (v, array_item.nw_size()))
+
+            if want_extra_size:
+                if item.member and item.member.has_attr("nocopy"):
+                    writer.comment("@nocopy, so no extra size").newline()
+                    writer.assign(item.extra_size(), 0)
+                elif target_type.element_type.get_fixed_nw_size == 1:
+                    writer.assign(item.extra_size(), array_item.mem_size())
+                # If not bytes or zero, add padding needed for alignment
+                else:
+                    writer.assign(item.extra_size(), "%s + /* for alignment */ 3" % array_item.mem_size())
+            if want_mem_size:
+                writer.assign(item.mem_size(), "sizeof(void *) + %s" % array_item.mem_size())
+
+        elif target_type.is_struct():
+            validate_function = write_validate_struct_function(writer, target_type)
+            writer.assign("ptr_size", "%s(message_start, message_end, %s, minor)" % (validate_function, v))
+            writer.error_check("ptr_size < 0")
+
+            if want_extra_size:
+                writer.assign(item.extra_size(), "ptr_size + /* for alignment */ 3")
+            if want_mem_size:
+                writer.assign(item.mem_size(), "sizeof(void *) + ptr_size")
+        else:
+            raise NotImplementedError("pointer to unsupported type %s" % target_type)
+
+
+def write_validate_array_item(writer, container, item, scope, parent_scope, start,
+                              want_nw_size, want_mem_size, want_extra_size):
+    array = item.type
+    is_byte_size = False
+    element_type = array.element_type
+    if array.is_bytes_length():
+        nelements = "%s__nbytes" %(item.prefix)
+    else:
+        nelements = "%s__nelements" %(item.prefix)
+    if not parent_scope.variable_defined(nelements):
+        parent_scope.variable_def("uint32_t", nelements)
+
+    if array.is_constant_length():
+        writer.assign(nelements, array.size)
+    elif array.is_remaining_length():
+        if element_type.is_fixed_nw_size():
+            if element_type.get_fixed_nw_size() == 1:
+                writer.assign(nelements, "message_end - %s" % item.get_position())
+            else:
+                writer.assign(nelements, "(message_end - %s) / (%s)" %(item.get_position(), element_type.get_fixed_nw_size()))
+        else:
+            raise NotImplementedError("TODO array[] of dynamic element size not done yet")
+    elif array.is_identifier_length():
+        v = write_read_primitive(writer, start, container, array.size, scope)
+        writer.assign(nelements, v)
+    elif array.is_image_size_length():
+        bpp = array.size[1]
+        width = array.size[2]
+        rows = array.size[3]
+        width_v = write_read_primitive(writer, start, container, width, scope)
+        rows_v = write_read_primitive(writer, start, container, rows, scope)
+        # TODO: Handle multiplication overflow
+        if bpp == 8:
+            writer.assign(nelements, "%s * %s" % (width_v, rows_v))
+        elif bpp == 1:
+            writer.assign(nelements, "((%s + 7) / 8 ) * %s" % (width_v, rows_v))
+        else:
+            writer.assign(nelements, "((%s * %s + 7) / 8 ) * %s" % (bpp, width_v, rows_v))
+    elif array.is_bytes_length():
+        is_byte_size = True
+        v = write_read_primitive(writer, start, container, array.size[1], scope)
+        writer.assign(nelements, v)
+    elif array.is_cstring_length():
+        writer.todo("cstring array size type not handled yet")
+    else:
+        writer.todo("array size type not handled yet")
+
+    writer.newline()
+
+    nw_size = item.nw_size()
+    mem_size = item.mem_size()
+    extra_size = item.extra_size()
+
+    if is_byte_size and want_nw_size:
+        writer.assign(nw_size, nelements)
+        want_nw_size = False
+
+    if element_type.is_fixed_nw_size() and want_nw_size:
+        element_size = element_type.get_fixed_nw_size()
+        # TODO: Overflow check the multiplication
+        if element_size == 1:
+            writer.assign(nw_size, nelements)
+        else:
+            writer.assign(nw_size, "(%s) * %s" % (element_size, nelements))
+        want_nw_size = False
+
+    if element_type.is_fixed_sizeof() and want_mem_size and not is_byte_size:
+        # TODO: Overflow check the multiplication
+        writer.assign(mem_size, "%s * %s" % (element_type.sizeof(), nelements))
+        want_mem_size = False
+
+    if not element_type.contains_extra_size() and want_extra_size:
+        writer.assign(extra_size, 0)
+        want_extra_size = False
+
+    if not (want_mem_size or want_nw_size or want_extra_size):
+        return
+
+    start2 = codegen.increment_identifier(start)
+    scope.variable_def("uint8_t *", "%s = %s" % (start2, item.get_position()))
+    if is_byte_size:
+        start2_end = "%s_array_end" % start2
+        scope.variable_def("uint8_t *", start2_end)
+
+    element_item = ItemInfo(element_type, "%s__element" % item.prefix, start2)
+
+    element_nw_size = element_item.nw_size()
+    element_mem_size = element_item.mem_size()
+    scope.variable_def("uint32_t", element_nw_size)
+    scope.variable_def("uint32_t", element_mem_size)
+
+    if want_nw_size:
+        writer.assign(nw_size, 0)
+    if want_mem_size:
+        writer.assign(mem_size, 0)
+    if want_extra_size:
+        writer.assign(extra_size, 0)
+
+    want_element_nw_size = want_nw_size
+    if element_type.is_fixed_nw_size():
+        start_increment = element_type.get_fixed_nw_size()
+    else:
+        want_element_nw_size = True
+        start_increment = element_nw_size
+
+    if is_byte_size:
+        writer.assign(start2_end, "%s + %s" % (start2, nelements))
+
+    with writer.index(no_block = is_byte_size) as index:
+        with writer.while_loop("%s < %s" % (start2, start2_end) ) if is_byte_size else writer.for_loop(index, nelements) as scope:
+            write_validate_item(writer, container, element_item, scope, parent_scope, start2,
+                                want_element_nw_size, want_mem_size, want_extra_size)
+
+            if want_nw_size:
+                writer.increment(nw_size, element_nw_size)
+            if want_mem_size:
+                writer.increment(mem_size, element_mem_size)
+            if want_extra_size:
+                writer.increment(extra_size, element_extra_size)
+
+            writer.increment(start2, start_increment)
+    if is_byte_size:
+        writer.error_check("%s != %s" % (start2, start2_end))
+
+def write_validate_struct_item(writer, container, item, scope, parent_scope, start,
+                               want_nw_size, want_mem_size, want_extra_size):
+    struct = item.type
+    start2 = codegen.increment_identifier(start)
+    scope.variable_def("SPICE_GNUC_UNUSED uint8_t *", start2 + " = %s" % (item.get_position()))
+
+    write_validate_container(writer, item.prefix, struct, start2, scope, want_nw_size, want_mem_size, want_extra_size)
+
+def write_validate_primitive_item(writer, container, item, scope, parent_scope, start,
+                                  want_nw_size, want_mem_size, want_extra_size):
+    if want_nw_size:
+        nw_size = item.nw_size()
+        writer.assign(nw_size, item.type.get_fixed_nw_size())
+    if want_mem_size:
+        mem_size = item.mem_size()
+        writer.assign(mem_size, item.type.sizeof())
+    assert not want_extra_size
+
+def write_validate_item(writer, container, item, scope, parent_scope, start,
+                        want_nw_size, want_mem_size, want_extra_size):
+    if item.type.is_pointer():
+        write_validate_pointer_item(writer, container, item, scope, parent_scope, start,
+                                    want_nw_size, want_mem_size, want_extra_size)
+    elif item.type.is_array():
+        write_validate_array_item(writer, container, item, scope, parent_scope, start,
+                                  want_nw_size, want_mem_size, want_extra_size)
+    elif item.type.is_struct():
+        write_validate_struct_item(writer, container, item, scope, parent_scope, start,
+                                   want_nw_size, want_mem_size, want_extra_size)
+    elif item.type.is_primitive():
+        write_validate_primitive_item(writer, container, item, scope, parent_scope, start,
+                                      want_nw_size, want_mem_size, want_extra_size)
+    else:
+        writer.todo("Implement validation of %s" % item.type)
+
+def write_validate_member(writer, container, member, parent_scope, start,
+                          want_nw_size, want_mem_size, want_extra_size):
+    if member.has_minor_attr():
+        prefix = "if (minor >= %s)" % (member.get_minor_attr())
+        newline = False
+    else:
+        prefix = ""
+        newline = True
+    item = MemberItemInfo(member, container, start)
+    with writer.block(prefix, newline=newline, comment=member.name) as scope:
+        if member.is_switch():
+            write_validate_switch_member(writer, container, member, scope, parent_scope, start,
+                                         want_nw_size, want_mem_size, want_extra_size)
+        else:
+            write_validate_item(writer, container, item, scope, parent_scope, start,
+                                want_nw_size, want_mem_size, want_extra_size)
+
+    if member.has_minor_attr():
+        with writer.block(" else", comment = "minor < %s" % (member.get_minor_attr())):
+            if member.is_array():
+                nelements = "%s__nelements" %(item.prefix)
+                writer.assign(nelements, 0)
+            if want_nw_size:
+                writer.assign(item.nw_size(), 0)
+
+            if want_mem_size:
+                if member.is_fixed_sizeof():
+                    writer.assign(item.mem_size(), member.sizeof())
+                elif member.is_array():
+                    writer.assign(item.mem_size(), 0)
+                else:
+                    raise NotImplementedError("TODO minor check for non-constant items")
+
+            assert not want_extra_size
+
+def write_validate_container(writer, prefix, container, start, parent_scope, want_nw_size, want_mem_size, want_extra_size):
+    for m in container.members:
+        sub_want_nw_size = want_nw_size and not m.is_fixed_nw_size()
+        sub_want_mem_size = m.is_extra_size()
+        sub_want_extra_size = not m.is_extra_size() and m.contains_extra_size()
+
+        defs = ["size_t"]
+        if sub_want_nw_size:
+            defs.append (m.name + "__nw_size")
+        if sub_want_mem_size:
+            defs.append (m.name + "__mem_size")
+        if sub_want_extra_size:
+            defs.append (m.name + "__extra_size")
+
+        if sub_want_nw_size or sub_want_mem_size or sub_want_extra_size:
+            parent_scope.variable_def(*defs)
+            write_validate_member(writer, container, m, parent_scope, start,
+                                  sub_want_nw_size, sub_want_mem_size, sub_want_extra_size)
+            writer.newline()
+
+    if want_nw_size:
+        if prefix:
+            nw_size = prefix + "__nw_size"
+        else:
+            nw_size = "nw_size"
+
+        size = 0
+        for m in container.members:
+            if m.is_fixed_nw_size():
+                size = size + m.get_fixed_nw_size()
+
+        nm_sum = str(size)
+        for m in container.members:
+            if not m.is_fixed_nw_size():
+                nm_sum = nm_sum + " + " + m.name + "__nw_size"
+
+        writer.assign(nw_size, nm_sum)
+
+    if want_mem_size:
+        if prefix:
+            mem_size = prefix + "__mem_size"
+        else:
+            mem_size = "mem_size"
+
+        mem_sum = container.sizeof()
+        for m in container.members:
+            if m.is_extra_size():
+                mem_sum = mem_sum + " + " + m.name + "__mem_size"
+            elif m.contains_extra_size():
+                mem_sum = mem_sum + " + " + m.name + "__extra_size"
+
+        writer.assign(mem_size, mem_sum)
+
+    if want_extra_size:
+        if prefix:
+            extra_size = prefix + "__extra_size"
+        else:
+            extra_size = "extra_size"
+
+        extra_sum = []
+        for m in container.members:
+            if m.is_extra_size():
+                extra_sum.append(m.name + "__mem_size")
+            elif m.contains_extra_size():
+                extra_sum.append(m.name + "__extra_size")
+        writer.assign(extra_size, codegen.sum_array(extra_sum))
+
+class DemarshallingDestination:
+    def __init__(self):
+        pass
+
+    def child_at_end(self, writer, t):
+        return RootDemarshallingDestination(self, t.c_type(), t.sizeof())
+
+    def child_sub(self, member):
+        return SubDemarshallingDestination(self, member)
+
+    def declare(self, writer):
+        return writer.optional_block(self.reuse_scope)
+
+    def is_toplevel(self):
+        return self.parent_dest == None and not self.is_helper
+
+class RootDemarshallingDestination(DemarshallingDestination):
+    def __init__(self, parent_dest, c_type, sizeof, pointer = None):
+        self.is_helper = False
+        self.reuse_scope = None
+        self.parent_dest = parent_dest
+        if parent_dest:
+            self.base_var = codegen.increment_identifier(parent_dest.base_var)
+        else:
+            self.base_var = "out"
+        self.c_type = c_type
+        self.sizeof = sizeof
+        self.pointer = pointer # None == at "end"
+
+    def get_ref(self, member):
+        return self.base_var + "->" + member
+
+    def declare(self, writer):
+        if self.reuse_scope:
+            scope = self.reuse_scope
+        else:
+            writer.begin_block()
+            scope = writer.get_subwriter()
+
+        scope.variable_def(self.c_type + " *", self.base_var)
+        if not self.reuse_scope:
+            scope.newline()
+
+        if self.pointer:
+            writer.assign(self.base_var, "(%s *)%s" % (self.c_type, self.pointer))
+        else:
+            writer.assign(self.base_var, "(%s *)end" % (self.c_type))
+            writer.increment("end", self.sizeof)
+        writer.newline()
+
+        if self.reuse_scope:
+            return writer.no_block(self.reuse_scope)
+        else:
+            return writer.partial_block(scope)
+
+class SubDemarshallingDestination(DemarshallingDestination):
+    def __init__(self, parent_dest, member):
+        self.reuse_scope = None
+        self.parent_dest = parent_dest
+        self.base_var = parent_dest.base_var
+        self.member = member
+        self.is_helper = False
+
+    def get_ref(self, member):
+        return self.parent_dest.get_ref(self.member) + "." + member
+
+def read_array_len(writer, prefix, array, dest, scope, handles_bytes = False):
+    if array.is_bytes_length():
+        nelements = "%s__nbytes" % prefix
+    else:
+        nelements = "%s__nelements" % prefix
+    if dest.is_toplevel():
+        return nelements # Already there for toplevel, need not recalculate
+    element_type = array.element_type
+    scope.variable_def("uint32_t", nelements)
+    if array.is_constant_length():
+        writer.assign(nelements, array.size)
+    elif array.is_identifier_length():
+        writer.assign(nelements, dest.get_ref(array.size))
+    elif array.is_remaining_length():
+        if element_type.is_fixed_nw_size():
+            writer.assign(nelements, "(message_end - in) / (%s)" %(element_type.get_fixed_nw_size()))
+        else:
+            raise NotImplementedError("TODO array[] of dynamic element size not done yet")
+    elif array.is_image_size_length():
+        bpp = array.size[1]
+        width = array.size[2]
+        rows = array.size[3]
+        width_v = dest.get_ref(width)
+        rows_v = dest.get_ref(rows)
+        # TODO: Handle multiplication overflow
+        if bpp == 8:
+            writer.assign(nelements, "%s * %s" % (width_v, rows_v))
+        elif bpp == 1:
+            writer.assign(nelements, "((%s + 7) / 8 ) * %s" % (width_v, rows_v))
+        else:
+            writer.assign(nelements, "((%s * %s + 7) / 8 ) * %s" % (bpp, width_v, rows_v))
+    elif array.is_bytes_length():
+        if not handles_bytes:
+            raise NotImplementedError("handling of bytes() not supported here yet")
+        writer.assign(nelements, dest.get_ref(array.size[1]))
+    else:
+        raise NotImplementedError("TODO array size type not handled yet")
+    return nelements
+
+def write_switch_parser(writer, container, switch, dest, scope):
+    var = container.lookup_member(switch.variable)
+    var_type = var.member_type
+
+    if switch.has_attr("fixedsize"):
+        scope.variable_def("uint8_t *", "in_save")
+        writer.assign("in_save", "in")
+
+    first = True
+    for c in switch.cases:
+        check = c.get_check(dest.get_ref(switch.variable), var_type)
+        m = c.member
+        with writer.if_block(check, not first, False) as block:
+            t = m.member_type
+            if switch.has_end_attr():
+                dest2 = dest.child_at_end(writer, m.member_type)
+            elif switch.has_attr("anon"):
+                dest2 = dest
+            else:
+                if t.is_struct():
+                    dest2 = dest.child_sub(switch.name + "." + m.name)
+                else:
+                    dest2 = dest.child_sub(switch.name)
+            dest2.reuse_scope = block
+
+            if t.is_struct():
+                write_container_parser(writer, t, dest2)
+            elif t.is_pointer():
+                write_parse_pointer(writer, t, False, dest2, m.name, not m.has_attr("ptr32"), block)
+            elif t.is_primitive():
+                writer.assign(dest2.get_ref(m.name), "consume_%s(&in)" % (t.primitive_type()))
+                #TODO validate e.g. flags and enums
+            elif t.is_array():
+                nelements = read_array_len(writer, m.name, t, dest, block)
+                write_array_parser(writer, nelements, t, dest, block)
+            else:
+                writer.todo("Can't handle type %s" % m.member_type)
+
+        first = False
+
+    writer.newline()
+
+    if switch.has_attr("fixedsize"):
+        writer.assign("in", "in_save + %s" % switch.get_fixed_nw_size())
+
+def write_parse_ptr_function(writer, target_type):
+    if target_type.is_array():
+        parse_function = "parse_array_%s" % target_type.element_type.primitive_type()
+    else:
+        parse_function = "parse_struct_%s" % target_type.c_type()
+    if writer.is_generated("parser", parse_function):
+        return parse_function
+
+    writer.set_is_generated("parser", parse_function)
+
+    writer = writer.function_helper()
+    scope = writer.function(parse_function, "uint8_t *", "uint8_t *message_start, uint8_t *message_end, uint8_t *struct_data, PointerInfo *this_ptr_info, int minor")
+    scope.variable_def("uint8_t *", "in = message_start + this_ptr_info->offset")
+    scope.variable_def("uint8_t *", "end")
+
+    num_pointers = target_type.get_num_pointers()
+    if  num_pointers != 0:
+        scope.variable_def("SPICE_GNUC_UNUSED intptr_t", "ptr_size");
+        scope.variable_def("uint32_t", "n_ptr=0");
+        scope.variable_def("PointerInfo", "ptr_info[%s]" % num_pointers)
+
+    writer.newline()
+    if target_type.is_array():
+        writer.assign("end", "struct_data")
+    else:
+        writer.assign("end", "struct_data + %s" % (target_type.sizeof()))
+
+    dest = RootDemarshallingDestination(None, target_type.c_type(), target_type.sizeof(), "struct_data")
+    dest.is_helper = True
+    dest.reuse_scope = scope
+    if target_type.is_array():
+        write_array_parser(writer, "this_ptr_info->nelements", target_type, dest, scope)
+    else:
+        write_container_parser(writer, target_type, dest)
+
+    if num_pointers != 0:
+        write_ptr_info_check(writer)
+
+    writer.statement("return end")
+
+    if writer.has_error_check:
+        writer.newline()
+        writer.label("error")
+        writer.statement("return NULL")
+
+    writer.end_block()
+
+    return parse_function
+
+def write_array_parser(writer, nelements, array, dest, scope):
+    is_byte_size = array.is_bytes_length()
+
+    element_type = array.element_type
+    if element_type == ptypes.uint8 or element_type == ptypes.int8:
+        writer.statement("memcpy(end, in, %s)" % (nelements))
+        writer.increment("in", nelements)
+        writer.increment("end", nelements)
+    else:
+        if is_byte_size:
+            scope.variable_def("uint8_t *", "array_end")
+            writer.assign("array_end", "end + %s" % nelements)
+        with writer.index(no_block = is_byte_size) as index:
+            with writer.while_loop("end < array_end") if is_byte_size else writer.for_loop(index, nelements) as array_scope:
+                if element_type.is_primitive():
+                    writer.statement("*(%s *)end = consume_%s(&in)" % (element_type.c_type(), element_type.primitive_type()))
+                    writer.increment("end", element_type.sizeof())
+                else:
+                    dest2 = dest.child_at_end(writer, element_type)
+                    dest2.reuse_scope = array_scope
+                    write_container_parser(writer, element_type, dest2)
+
+def write_parse_pointer(writer, t, at_end, dest, member_name, is_64bit, scope):
+        target_type = t.target_type
+        if is_64bit:
+            writer.assign("ptr_info[n_ptr].offset", "consume_uint64(&in)")
+        else:
+            writer.assign("ptr_info[n_ptr].offset", "consume_uint32(&in)")
+        writer.assign("ptr_info[n_ptr].parse", write_parse_ptr_function(writer, target_type))
+        if at_end:
+            writer.assign("ptr_info[n_ptr].dest", "end")
+            writer.increment("end", "sizeof(SPICE_ADDRESS)");
+        else:
+            writer.assign("ptr_info[n_ptr].dest", "&%s" % dest.get_ref(member_name))
+        if target_type.is_array():
+            nelements = read_array_len(writer, member_name, target_type, dest, scope)
+            writer.assign("ptr_info[n_ptr].nelements", nelements)
+
+        writer.statement("n_ptr++")
+
+def write_member_parser(writer, container, member, dest, scope):
+    if member.is_switch():
+        write_switch_parser(writer, container, member, dest, scope)
+        return
+
+    t = member.member_type
+
+    if t.is_pointer():
+        if member.has_attr("nocopy"):
+            writer.comment("Reuse data from network message").newline()
+            writer.assign(dest.get_ref(member.name), "(size_t)(message_start + consume_uint64(&in))")
+        else:
+            write_parse_pointer(writer, t, member.has_end_attr(), dest, member.name, not member.has_attr("ptr32"), scope)
+    elif t.is_primitive():
+        if member.has_end_attr():
+            writer.statement("*(%s *)end = consume_%s(&in)" % (t.c_type(), t.primitive_type()))
+            writer.increment("end", t.sizeof())
+        else:
+            writer.assign(dest.get_ref(member.name), "consume_%s(&in)" % (t.primitive_type()))
+        #TODO validate e.g. flags and enums
+    elif t.is_array():
+        nelements = read_array_len(writer, member.name, t, dest, scope, handles_bytes = True)
+        write_array_parser(writer, nelements, t, dest, scope)
+    elif t.is_struct():
+        if member.has_end_attr():
+            dest2 = dest.child_at_end(writer, t)
+        else:
+            dest2 = dest.child_sub(member.name)
+        writer.comment(member.name)
+        write_container_parser(writer, t, dest2)
+    else:
+        raise NotImplementedError("TODO can't handle parsing of %s" % t)
+
+def write_container_parser(writer, container, dest):
+    with dest.declare(writer) as scope:
+        for m in container.members:
+            if m.has_minor_attr():
+                writer.begin_block("if (minor >= %s)" % m.get_minor_attr())
+            write_member_parser(writer, container, m, dest, scope)
+            if m.has_minor_attr():
+                # We need to zero out the fixed part of all optional fields
+                if not m.member_type.is_array():
+                    writer.end_block(newline=False)
+                    writer.begin_block(" else")
+                    # TODO: This is not right for fields that don't exist in the struct
+                    if m.member_type.is_primitive():
+                        writer.assign(dest.get_ref(m.name), "0")
+                    elif m.is_fixed_sizeof():
+                        writer.statement("memset ((char *)&%s, 0, %s)" % (dest.get_ref(m.name), m.sizeof()))
+                    else:
+                        raise NotImplementedError("TODO Clear optional dynamic fields")
+                writer.end_block()
+
+def write_ptr_info_check(writer):
+    writer.newline()
+    with writer.index() as index:
+        with writer.for_loop(index, "n_ptr") as scope:
+            offset = "ptr_info[%s].offset" % index
+            function = "ptr_info[%s].parse" % index
+            dest = "ptr_info[%s].dest" % index
+            with writer.if_block("%s == 0" % offset, newline=False):
+                writer.assign("*%s" % dest, "0")
+            with writer.block(" else"):
+                writer.comment("Align to 32 bit").newline()
+                writer.assign("end", "(uint8_t *)SPICE_ALIGN((size_t)end, 4)")
+                writer.assign("*%s" % dest, "(size_t)end")
+                writer.assign("end", "%s(message_start, message_end, end, &ptr_info[%s], minor)" % (function, index))
+                writer.error_check("end == NULL")
+    writer.newline()
+
+def write_msg_parser(writer, message):
+    msg_name = message.c_name()
+    function_name = "parse_%s" % msg_name
+    if writer.is_generated("demarshaller", function_name):
+        return function_name
+    writer.set_is_generated("demarshaller", function_name)
+
+    msg_type = message.c_type()
+    msg_sizeof = message.sizeof()
+
+    writer.newline()
+    parent_scope = writer.function(function_name,
+                                   "uint8_t *",
+                                   "uint8_t *message_start, uint8_t *message_end, int minor, size_t *size", True)
+    parent_scope.variable_def("SPICE_GNUC_UNUSED uint8_t *", "pos");
+    parent_scope.variable_def("uint8_t *", "start = message_start");
+    parent_scope.variable_def("uint8_t *", "data = NULL");
+    parent_scope.variable_def("size_t", "mem_size", "nw_size");
+    if not message.has_attr("nocopy"):
+        parent_scope.variable_def("uint8_t *", "in", "end");
+    num_pointers = message.get_num_pointers()
+    if  num_pointers != 0:
+        parent_scope.variable_def("SPICE_GNUC_UNUSED intptr_t", "ptr_size");
+        parent_scope.variable_def("uint32_t", "n_ptr=0");
+        parent_scope.variable_def("PointerInfo", "ptr_info[%s]" % num_pointers)
+    writer.newline()
+
+    write_parser_helpers(writer)
+
+    write_validate_container(writer, None, message, "start", parent_scope, True, True, False)
+
+    writer.newline()
+
+    writer.comment("Check if message fits in reported side").newline()
+    with writer.block("if (start + nw_size > message_end)"):
+        writer.statement("return NULL")
+
+    writer.newline().comment("Validated extents and calculated size").newline()
+
+    if message.has_attr("nocopy"):
+        writer.assign("data", "message_start")
+        writer.assign("*size", "message_end - message_start")
+    else:
+        writer.assign("data", "(uint8_t *)malloc(mem_size)")
+        writer.error_check("data == NULL")
+        writer.assign("end", "data + %s" % (msg_sizeof))
+        writer.assign("in", "start").newline()
+
+        dest = RootDemarshallingDestination(None, msg_type, msg_sizeof, "data")
+        dest.reuse_scope = parent_scope
+        write_container_parser(writer, message, dest)
+
+        writer.newline()
+        writer.statement("assert(in <= message_end)")
+
+        if num_pointers != 0:
+            write_ptr_info_check(writer)
+
+        writer.statement("assert(end <= data + mem_size)")
+
+        writer.newline()
+        writer.assign("*size", "end - data")
+
+    writer.statement("return data")
+    writer.newline()
+    if writer.has_error_check:
+        writer.label("error")
+        with writer.block("if (data != NULL)"):
+            writer.statement("free(data)")
+        writer.statement("return NULL")
+    writer.end_block()
+
+    return function_name
+
+def write_channel_parser(writer, channel, server):
+    writer.newline()
+    ids = {}
+    min_id = 1000000
+    if server:
+        messages = channel.server_messages
+    else:
+        messages = channel.client_messages
+    for m in messages:
+        ids[m.value] = m
+
+    ranges = []
+    ids2 = ids.copy()
+    while len(ids2) > 0:
+        end = start = min(ids2.keys())
+        while ids2.has_key(end):
+            del ids2[end]
+            end = end + 1
+
+        ranges.append( (start, end) )
+
+    if server:
+        function_name = "parse_%s_msg" % channel.name
+    else:
+        function_name = "parse_%s_msgc" % channel.name
+    writer.newline()
+    scope = writer.function(function_name,
+                            "uint8_t *",
+                            "uint8_t *message_start, uint8_t *message_end, uint16_t message_type, int minor, size_t *size_out")
+
+    helpers = writer.function_helper()
+
+    d = 0
+    for r in ranges:
+        d = d + 1
+        writer.write("static parse_msg_func_t funcs%d[%d] = " % (d, r[1] - r[0]));
+        writer.begin_block()
+        for i in range(r[0], r[1]):
+            func = write_msg_parser(helpers, ids[i].message_type)
+            writer.write(func)
+            if i != r[1] -1:
+                writer.write(",")
+            writer.newline()
+
+        writer.end_block(semicolon = True)
+
+    d = 0
+    for r in ranges:
+        d = d + 1
+        with writer.if_block("message_type >= %d && message_type < %d" % (r[0], r[1]), d > 1, False):
+            writer.statement("return funcs%d[message_type-%d](message_start, message_end, minor, size_out)" % (d, r[0]))
+    writer.newline()
+
+    writer.statement("return NULL")
+    writer.end_block()
+
+    return function_name
+
+def write_get_channel_parser(writer, channel_parsers, max_channel, is_server):
+    writer.newline()
+    if is_server:
+        function_name = "spice_get_server_channel_parser"
+    else:
+        function_name = "spice_get_client_channel_parser"
+
+    scope = writer.function(function_name,
+                            "spice_parse_channel_func_t",
+                            "uint32_t channel, unsigned int *max_message_type")
+
+    writer.write("static struct {spice_parse_channel_func_t func; unsigned int max_messages; } channels[%d] = " % (max_channel+1))
+    writer.begin_block()
+    for i in range(0, max_channel + 1):
+        writer.write("{ ")
+        if channel_parsers.has_key(i):
+            writer.write(channel_parsers[i][1])
+            writer.write(", ")
+
+            channel = channel_parsers[i][0]
+            max_msg = 0
+            if is_server:
+                messages = channel.server_messages
+            else:
+                messages = channel.client_messages
+            for m in messages:
+                max_msg = max(max_msg, m.value)
+            writer.write(max_msg)
+        else:
+            writer.write("NULL, 0")
+        writer.write("}")
+
+        if i != max_channel:
+            writer.write(",")
+        writer.newline()
+    writer.end_block(semicolon = True)
+
+    with writer.if_block("channel < %d" % (max_channel + 1)):
+        with writer.if_block("max_message_type != NULL"):
+            writer.assign("*max_message_type", "channels[channel].max_messages")
+        writer.statement("return channels[channel].func")
+
+    writer.statement("return NULL")
+    writer.end_block()
+
+
+def write_full_protocol_parser(writer, is_server):
+    writer.newline()
+    if is_server:
+        function_name = "spice_parse_msg"
+    else:
+        function_name = "spice_parse_reply"
+    scope = writer.function(function_name,
+                            "uint8_t *",
+                            "uint8_t *message_start, uint8_t *message_end, uint32_t channel, uint16_t message_type, int minor, size_t *size_out")
+    scope.variable_def("spice_parse_channel_func_t", "func" )
+
+    if is_server:
+        writer.assign("func", "spice_get_server_channel_parser(channel, NULL)")
+    else:
+        writer.assign("func", "spice_get_client_channel_parser(channel, NULL)")
+
+    with writer.if_block("func != NULL"):
+        writer.statement("return func(message_start, message_end, message_type, minor, size_out)")
+
+    writer.statement("return NULL")
+    writer.end_block()
+
+def write_protocol_parser(writer, proto, is_server):
+    max_channel = 0
+    parsers = {}
+
+    for channel in proto.channels:
+        max_channel = max(max_channel, channel.value)
+
+        parsers[channel.value] = (channel.channel_type, write_channel_parser(writer, channel.channel_type, is_server))
+
+    write_get_channel_parser(writer, parsers, max_channel, is_server)
+    write_full_protocol_parser(writer, is_server)
+
+def write_includes(writer):
+    writer.writeln("#include <string.h>")
+    writer.writeln("#include <assert.h>")
+    writer.writeln("#include <stdlib.h>")
+    writer.writeln("#include <stdio.h>")
+    writer.writeln("#include <spice/protocol.h>")
+    writer.writeln("#include <spice/macros.h>")
+    writer.newline()
+    writer.writeln("#ifdef _MSC_VER")
+    writer.writeln("#pragma warning(disable:4101)")
+    writer.writeln("#endif")