Add new "struct_var_" functions to manipulate struct fields.

These functions exist one level higher than typed_var_t.  They
describe a type, a name, and an offset within a structure.
This commit is contained in:
Nick Mathewson 2019-06-18 20:40:11 -04:00
parent e16b90b88a
commit 2da188667d
4 changed files with 293 additions and 0 deletions

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@ -63,8 +63,48 @@ typedef enum config_type_t {
CONFIG_TYPE_ROUTERSET, /**< A list of router names, addrs, and fps,
* parsed into a routerset_t. */
CONFIG_TYPE_OBSOLETE, /**< Obsolete (ignored) option. */
CONFIG_TYPE_EXTENDED, /**< Extended type; definition will appear in
* pointer. */
} config_type_t;
/* Forward delcaration for var_type_def_t, for extended types. */
struct var_type_def_t;
/** Structure to specify a named, typed member within a structure. */
typedef struct struct_member_t {
/** Name of the field. */
const char *name;
/** Type of the field, according to the config_type_t enumeration.
*
* This value is CONFIG_TYPE_EXTENDED for any type not listed in
* config_type_t.
**/
config_type_t type;
/**
* Pointer to a type definition for the type of this field. Overrides
* <b>type</b> if not NULL.
**/
const struct var_type_def_t *type_def;
/**
* Offset of this field within the structure. Compute this with
* offsetof(structure, fieldname).
**/
int offset;
} struct_member_t;
/**
* Structure to describe the location and preferred value of a "magic number"
* field within a structure.
*
* These 'magic numbers' are 32-bit values used to tag objects to make sure
* that they have the correct type.
*/
typedef struct struct_magic_decl_t {
const char *typename;
uint32_t magic_val;
int magic_offset;
} struct_magic_decl_t;
#ifdef TOR_UNIT_TESTS
/**
* Union used when building in test mode typechecking the members of a type

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@ -6,6 +6,7 @@ endif
# ADD_C_FILE: INSERT SOURCES HERE.
src_lib_libtor_confmgt_a_SOURCES = \
src/lib/confmgt/structvar.c \
src/lib/confmgt/type_defs.c \
src/lib/confmgt/typedvar.c \
src/lib/confmgt/unitparse.c
@ -17,6 +18,7 @@ src_lib_libtor_confmgt_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
# ADD_C_FILE: INSERT HEADERS HERE.
noinst_HEADERS += \
src/lib/confmgt/structvar.h \
src/lib/confmgt/type_defs.h \
src/lib/confmgt/typedvar.h \
src/lib/confmgt/unitparse.h \

200
src/lib/confmgt/structvar.c Normal file
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@ -0,0 +1,200 @@
/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, 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 <stddef.h>
/**
* 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(object);
tor_assert(decl);
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(object);
tor_assert(decl);
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->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_assign, but assign a value to the member of <b>object</b>
* defined by <b>member</b>.)
**/
int
struct_var_assign(void *object, const char *value, 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_assign_ex(p, value, errmsg, def);
}
/**
* (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_ex(p, def);
}
/**
* (As typed_var_encode, but encode the member of <b>object</b> defined
* by <b>member</b>.)
**/
char *
struct_var_encode(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_encode_ex(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_ex(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_ex(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_ex(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_ex(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_ex(member->name, p, def);
}

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@ -0,0 +1,51 @@
/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* @file structvar.h
* @brief Header for lib/confmgt/structvar.c
**/
#ifndef TOR_LIB_CONFMGT_STRUCTVAR_H
#define TOR_LIB_CONFMGT_STRUCTVAR_H
struct struct_magic_decl_t;
struct struct_member_t;
struct config_line_t;
#include <stdbool.h>
void struct_set_magic(void *object,
const struct struct_magic_decl_t *decl);
void struct_check_magic(const void *object,
const struct struct_magic_decl_t *decl);
void *struct_get_mptr(void *object,
const struct struct_member_t *member);
const void *struct_get_ptr(const void *object,
const struct struct_member_t *member);
int struct_var_assign(void *object, const char *value, char **errmsg,
const struct struct_member_t *member);
void struct_var_free(void *object,
const struct struct_member_t *member);
char *struct_var_encode(const void *object,
const struct struct_member_t *member);
int struct_var_copy(void *dest, const void *src,
const struct struct_member_t *member);
bool struct_var_eq(const void *a, const void *b,
const struct struct_member_t *member);
bool struct_var_ok(const void *object,
const struct struct_member_t *member);
int struct_var_kvassign(void *object, const struct config_line_t *line,
char **errmsg,
const struct struct_member_t *member);
struct config_line_t *struct_var_kvencode(
const void *object,
const struct struct_member_t *member);
#endif /* !defined(TOR_LIB_CONFMGT_STRUCTVAR_H) */