1 files changed, 239 insertions, 0 deletions
diff --git a/src/lib/confmgt/structvar.c b/src/lib/confmgt/structvar.c
new file mode 100644
index 0000000000..55deb4759c
--- /dev/null
+++ b/src/lib/confmgt/structvar.c
@@ -0,0 +1,239 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file structvar.c
+ * @brief Functions to manipulate named and typed elements of
+ *    a structure.
+ *
+ * These functions represent a low-level API for accessing a member of a
+ * structure.  They use typedvar.c to work, and they are used in turn by the
+ * configuration system to examine and set fields in configuration objects
+ * used by individual modules.
+ *
+ * Almost no code should call these directly.
+ **/
+
+#include "orconfig.h"
+#include "lib/confmgt/structvar.h"
+#include "lib/cc/compat_compiler.h"
+#include "lib/conf/conftypes.h"
+#include "lib/confmgt/type_defs.h"
+#include "lib/confmgt/typedvar.h"
+#include "lib/log/util_bug.h"
+
+#include "lib/confmgt/var_type_def_st.h"
+
+#include <stddef.h>
+
+/**
+ * Return true iff all fields on <b>decl</b> are NULL or 0, indicating that
+ * there is no object or no magic number to check.
+ **/
+static inline bool
+magic_is_null(const struct_magic_decl_t *decl)
+{
+  return decl->typename == NULL &&
+    decl->magic_offset == 0 &&
+    decl->magic_val == 0;
+}
+
+/**
+ * Set the 'magic number' on <b>object</b> to correspond to decl.
+ **/
+void
+struct_set_magic(void *object, const struct_magic_decl_t *decl)
+{
+  tor_assert(decl);
+  if (magic_is_null(decl))
+    return;
+
+  tor_assert(object);
+  uint32_t *ptr = STRUCT_VAR_P(object, decl->magic_offset);
+  *ptr = decl->magic_val;
+}
+
+/**
+ * Assert that the 'magic number' on <b>object</b> to corresponds to decl.
+ **/
+void
+struct_check_magic(const void *object, const struct_magic_decl_t *decl)
+{
+  tor_assert(decl);
+  if (magic_is_null(decl))
+    return;
+
+  tor_assert(object);
+
+  const uint32_t *ptr = STRUCT_VAR_P(object, decl->magic_offset);
+  tor_assertf(*ptr == decl->magic_val,
+              "Bad magic number on purported %s object. "
+              "Expected %"PRIu32"x but got %"PRIu32"x.",
+              decl->typename, decl->magic_val, *ptr);
+}
+
+/**
+ * Return a mutable pointer to the member of <b>object</b> described
+ * by <b>member</b>.
+ **/
+void *
+struct_get_mptr(void *object, const struct_member_t *member)
+{
+  tor_assert(object);
+  return STRUCT_VAR_P(object, member->offset);
+}
+
+/**
+ * Return a const pointer to the member of <b>object</b> described
+ * by <b>member</b>.
+ **/
+const void *
+struct_get_ptr(const void *object, const struct_member_t *member)
+{
+  tor_assert(object);
+  return STRUCT_VAR_P(object, member->offset);
+}
+
+/**
+ * Helper: given a struct_member_t, look up the type definition for its
+ * variable.
+ */
+static const var_type_def_t *
+get_type_def(const struct_member_t *member)
+{
+  if (member->type_def)
+    return member->type_def;
+
+  return lookup_type_def(member->type);
+}
+
+/**
+ * (As typed_var_free, but free and clear the member of <b>object</b> defined
+ * by <b>member</b>.)
+ **/
+void
+struct_var_free(void *object, const struct_member_t *member)
+{
+  void *p = struct_get_mptr(object, member);
+  const var_type_def_t *def = get_type_def(member);
+
+  typed_var_free(p, def);
+}
+
+/**
+ * (As typed_var_copy, but copy from <b>src</b> to <b>dest</b> the member
+ * defined by <b>member</b>.)
+ **/
+int
+struct_var_copy(void *dest, const void *src, const struct_member_t *member)
+{
+  void *p_dest = struct_get_mptr(dest, member);
+  const void *p_src = struct_get_ptr(src, member);
+  const var_type_def_t *def = get_type_def(member);
+
+  return typed_var_copy(p_dest, p_src, def);
+}
+
+/**
+ * (As typed_var_eq, but compare the members of <b>a</b> and <b>b</b>
+ * defined by <b>member</b>.)
+ **/
+bool
+struct_var_eq(const void *a, const void *b, const struct_member_t *member)
+{
+  const void *p_a = struct_get_ptr(a, member);
+  const void *p_b = struct_get_ptr(b, member);
+  const var_type_def_t *def = get_type_def(member);
+
+  return typed_var_eq(p_a, p_b, def);
+}
+
+/**
+ * (As typed_var_ok, but validate the member of <b>object</b> defined by
+ * <b>member</b>.)
+ **/
+bool
+struct_var_ok(const void *object, const struct_member_t *member)
+{
+  const void *p = struct_get_ptr(object, member);
+  const var_type_def_t *def = get_type_def(member);
+
+  return typed_var_ok(p, def);
+}
+
+/**
+ * (As typed_var_kvassign, but assign a value to the member of <b>object</b>
+ * defined by <b>member</b>.)
+ **/
+int
+struct_var_kvassign(void *object, const struct config_line_t *line,
+                    char **errmsg,
+                    const struct_member_t *member)
+{
+  void *p = struct_get_mptr(object, member);
+  const var_type_def_t *def = get_type_def(member);
+
+  return typed_var_kvassign(p, line, errmsg, def);
+}
+
+/**
+ * (As typed_var_kvencode, but encode the value of the member of <b>object</b>
+ * defined by <b>member</b>.)
+ **/
+struct config_line_t *
+struct_var_kvencode(const void *object, const struct_member_t *member)
+{
+  const void *p = struct_get_ptr(object, member);
+  const var_type_def_t *def = get_type_def(member);
+
+  return typed_var_kvencode(member->name, p, def);
+}
+
+/**
+ * Mark the field in <b>object</b> determined by <b>member</b> -- a variable
+ * that ordinarily would be extended by assignment -- as "fragile", so that it
+ * will get replaced by the next assignment instead.
+ */
+void
+struct_var_mark_fragile(void *object, const struct_member_t *member)
+{
+  void *p = struct_get_mptr(object, member);
+  const var_type_def_t *def = get_type_def(member);
+  return typed_var_mark_fragile(p, def);
+}
+
+/**
+ * Return the official name of this struct member.
+ **/
+const char *
+struct_var_get_name(const struct_member_t *member)
+{
+  return member->name;
+}
+
+/**
+ * Return the type name for this struct member.
+ *
+ * Do not use the output of this function to inspect a type within Tor.  It is
+ * suitable for debugging, informing the controller or user of a variable's
+ * type, etc.
+ **/
+const char *
+struct_var_get_typename(const struct_member_t *member)
+{
+  const var_type_def_t *def = get_type_def(member);
+
+  return def ? def->name : NULL;
+}
+
+/** Return all of the flags set for this struct member. */
+uint32_t
+struct_var_get_flags(const struct_member_t *member)
+{
+  const var_type_def_t *def = get_type_def(member);
+
+  return def ? def->flags : 0;
+}