-/* Placed into the public domain */
+/* CC0 (Public domain) - see LICENSE file for details */
#ifndef CCAN_TCON_H
#define CCAN_TCON_H
#include "config.h"
+#include <stddef.h>
+
/**
* TCON - declare a _tcon type containing canary variables.
* @decls: the semi-colon separated list of type canaries.
*
* This declares a _tcon member for a structure. It should be the
* last element in your structure; with sufficient compiler support it
- * will not use any actual storage. tcon_to_raw() will compare
+ * will not use any actual storage. tcon_check() will compare
* expressions with one of these "type canaries" to cause warnings if
* the container is misused.
*
- * A type of "void *" will allow tcon_to_raw() to pass on any (pointer) type.
+ * A type of "void *" will allow tcon_check() to pass on any (pointer) type.
*
* Example:
* // Simply typesafe linked list.
#define TCON(decls) struct { decls; } _tcon[1]
#endif
+/**
+ * TCON_WRAP - declare a wrapper type containing a base type and type canaries
+ * @basetype: the base type to wrap
+ * @decls: the semi-colon separated list of type canaries.
+ *
+ * This expands to a new type which includes the given base type, and
+ * also type canaries, similar to those created with TCON.
+ *
+ * The embedded base type value can be accessed using tcon_unwrap().
+ *
+ * Differences from using TCON()
+ * - The wrapper type will take either the size of the base type, or
+ * the size of a single pointer, whichever is greater (regardless of
+ * compiler)
+ * - A TCON_WRAP type may be included in another structure, and need
+ * not be the last element.
+ *
+ * A type of "void *" will allow tcon_check() to pass on any (pointer) type.
+ *
+ * Example:
+ * // Simply typesafe linked list.
+ * struct list_head {
+ * struct list_head *prev, *next;
+ * };
+ *
+ * typedef TCON_WRAP(struct list_head, char *canary) string_list_t;
+ *
+ * // More complex: mapping from one type to another.
+ * struct map {
+ * void *contents;
+ * };
+ *
+ * typedef TCON_WRAP(struct map, char *charp_canary; int int_canary)
+ * int_to_string_map_t;
+ */
+#define TCON_WRAP(basetype, decls) \
+ union { \
+ basetype _base; \
+ struct { \
+ decls; \
+ } *_tcon; \
+ }
+
+/**
+ * TCON_WRAP_INIT - an initializer for a variable declared with TCON_WRAP
+ * @...: Initializer for the base type (treated as variadic so commas
+ * can be included)
+ *
+ * Converts converts an initializer suitable for a base type into one
+ * suitable for that type wrapped with TCON_WRAP.
+ *
+ * Example:
+ * TCON_WRAP(int, char *canary) canaried_int = TCON_WRAP_INIT(17);
+ */
+#define TCON_WRAP_INIT(...) \
+ { ._base = __VA_ARGS__, }
+
+/**
+ * tcon_unwrap - Access the base type of a TCON_WRAP
+ * @ptr: pointer to an object declared with TCON_WRAP
+ *
+ * tcon_unwrap() returns a pointer to the base type of the TCON_WRAP()
+ * object pointer to by @ptr.
+ *
+ * Example:
+ * TCON_WRAP(int, char *canary) canaried_int;
+ *
+ * *tcon_unwrap(&canaried_int) = 17;
+ */
+#define tcon_unwrap(ptr) (&((ptr)->_base))
+
/**
* tcon_check - typecheck a typed container
* @x: the structure containing the TCON.
#define tcon_check(x, canary, expr) \
(sizeof((x)->_tcon[0].canary == (expr)) ? (x) : (x))
+/**
+ * tcon_check_ptr - typecheck a typed container
+ * @x: the structure containing the TCON.
+ * @canary: which canary to check against.
+ * @expr: the expression whose type must match &TCON (not evaluated)
+ *
+ * This macro is used to check that the expression is a pointer to the type
+ * expected for this structure (note the "useless" sizeof() argument
+ * which contains this comparison with the type canary), or NULL.
+ *
+ * It evaluates to @x so you can chain it.
+ */
+#define tcon_check_ptr(x, canary, expr) \
+ (sizeof((expr) ? (expr) : &(x)->_tcon[0].canary) ? (x) : (x))
+
+/**
+ * tcon_type - the type within a container (or void *)
+ * @x: the structure containing the TCON.
+ * @canary: which canary to check against.
+ */
+#if HAVE_TYPEOF
+#define tcon_type(x, canary) __typeof__((x)->_tcon[0].canary)
+#else
+#define tcon_type(x, canary) void *
+#endif
+
+/**
+ * tcon_sizeof - the size of type within a container
+ * @x: the structure containing the TCON.
+ * @canary: which canary to check against.
+ */
+#define tcon_sizeof(x, canary) sizeof((x)->_tcon[0].canary)
+
+/**
+ * TCON_VALUE - encode an integer value in a type canary
+ * @canary: name of the value canary
+ * @val: positive integer compile time constant value
+ *
+ * This macro can be included inside the declarations in a TCON() or
+ * TCON_WRAP(), constructing a special "type" canary which encodes the
+ * integer value @val (which must be a compile time constant, and a
+ * positive integer in the range of size_t).
+ */
+#define TCON_VALUE(canary, val) char _value_##canary[val]
+
+/**
+ * tcon_value - retrieve the value of a TCON_VALUE canary
+ * @x: the structure containing the TCON
+ * @canary: name of the value canary
+ *
+ * This macros expands to the value previously encoded into a TCON
+ * using TCON_VALUE().
+ */
+#define tcon_value(x, canary) tcon_sizeof(x, _value_##canary)
+
+/**
+ * tcon_ptr_type - pointer to the type within a container (or void *)
+ * @x: the structure containing the TCON.
+ * @canary: which canary to check against.
+ */
+#if HAVE_TYPEOF
+#define tcon_ptr_type(x, canary) __typeof__(&(x)->_tcon[0].canary)
+#else
+#define tcon_ptr_type(x, canary) void *
+#endif
/**
* tcon_cast - cast to a canary type for this container (or void *)
* platform doesn't HAVE_TYPEOF, then it casts to void * (which will
* cause a warning if the user doesn't expect a pointer type).
*/
+#define tcon_cast(x, canary, expr) ((tcon_type((x), canary))(expr))
+#define tcon_cast_ptr(x, canary, expr) ((tcon_ptr_type((x), canary))(expr))
+
+/**
+ * TCON_CONTAINER - encode information on a specific member of a
+ * containing structure into a "type" canary
+ * @canary: name of the container canary
+ * @container: type of the container structure
+ * @member: name of the member
+ *
+ * Used in the declarations in TCON() or TCON_WRAP(), encode a
+ * "container canary". This encodes the type of @container, the type
+ * of @member within it (with sufficient compiler support) and the
+ * offset of @member within @container.
+ */
#if HAVE_TYPEOF
-#define tcon_cast(x, canary, expr) ((__typeof__((x)->_tcon[0].canary))(expr))
+#define TCON_CONTAINER(canary, container, member) \
+ container _container_##canary; \
+ typeof(((container *)0)->member) _member_##canary; \
+ TCON_VALUE(_offset_##canary, offsetof(container, member))
#else
-#define tcon_cast(x, canary, expr) ((void *)(expr))
+#define TCON_CONTAINER(canary, container, member) \
+ container _container_##canary; \
+ TCON_VALUE(_offset_##canary, offsetof(container, member))
#endif
+/**
+ * tcon_container_check
+ * tcon_container_check_ptr
+ * tcon_container_type
+ * tcon_container_ptr_type
+ * tcon_container_sizeof
+ * tcon_container_cast
+ * tcon_container_cast_ptr
+ * @x: the structure containing the TCON.
+ * @canary: which container canary to check against.
+ *
+ * As tcon_check / tcon_check_ptr / tcon_type / tcon_ptr_type /
+ * tcon_sizeof / tcon_cast / tcon_cast_ptr, but use the type of the
+ * "container" type declared with TCON_CONTAINER, instead of a simple
+ * canary.
+ */
+#define tcon_container_check(x, canary, expr) \
+ tcon_check(x, _container_##canary, expr)
+#define tcon_container_check_ptr(x, canary, expr) \
+ tcon_check_ptr(x, _container_##canary, expr)
+#define tcon_container_type(x, canary) \
+ tcon_type(x, _container_##canary)
+#define tcon_container_ptr_type(x, canary) \
+ tcon_ptr_type(x, _container_##canary)
+#define tcon_container_sizeof(x, canary) \
+ tcon_sizeof(x, _container_##canary)
+#define tcon_container_cast(x, canary, expr) \
+ tcon_cast(x, _container_##canary, expr)
+#define tcon_container_cast_ptr(x, canary, expr) \
+ tcon_cast_ptr(x, _container_##canary, expr)
+
+/**
+ * tcon_member_check
+ * tcon_member_check_ptr
+ * tcon_member_type
+ * tcon_member_ptr_type
+ * tcon_member_sizeof
+ * tcon_member_cast
+ * tcon_member_cast_ptr
+ * @x: the structure containing the TCON.
+ * @canary: which container canary to check against.
+ *
+ * As tcon_check / tcon_check_ptr / tcon_type / tcon_ptr_type /
+ * tcon_sizeof / tcon_cast / tcon_cast_ptr, but use the type of the
+ * "member" type declared with TCON_CONTAINER, instead of a simple
+ * canary.
+ */
+#define tcon_member_check(x, canary, expr) \
+ tcon_check(x, _member_##canary, expr)
+#define tcon_member_check_ptr(x, canary, expr) \
+ tcon_check_ptr(x, _member_##canary, expr)
+#define tcon_member_type(x, canary) \
+ tcon_type(x, _member_##canary)
+#define tcon_member_ptr_type(x, canary) \
+ tcon_ptr_type(x, _member_##canary)
+#define tcon_member_sizeof(x, canary) \
+ tcon_sizeof(x, _member_##canary)
+#define tcon_member_cast(x, canary, expr) \
+ tcon_cast(x, _member_##canary, expr)
+#define tcon_member_cast_ptr(x, canary, expr) \
+ tcon_cast_ptr(x, _member_##canary, expr)
+
+/**
+ * tcon_offset - the offset of a member within a container, as
+ * declared with TCON_CONTAINER
+ * @x: the structure containing the TCON.
+ * @canary: which container canary to check against.
+ */
+#define tcon_offset(x, canary) \
+ tcon_value((x), _offset_##canary)
+
+/**
+ * tcon_container_of - get pointer to enclosing structure based on a
+ * container canary
+ * @x: the structure containing the TCON
+ * @canary: the name of the container canary
+ * @member_ptr: pointer to a member of the container
+ *
+ * @member_ptr must be a pointer to the member of a container
+ * structure previously recorded in @canary with TCON_CONTAINER.
+ *
+ * tcon_container_of() evaluates to a pointer to the container
+ * structure. With sufficient compiler support, the pointer will be
+ * correctly typed, and the type of @member_ptr will be verified.
+ * Note that const is discarded; a const @member_ptr still yields a
+ * non-const container (unless @canary is const).
+ *
+ * Returns NULL if @member_ptr is NULL.
+ */
+#define tcon_container_of(x, canary, member_ptr) \
+ tcon_container_cast_ptr( \
+ tcon_member_check_ptr((x), canary, (member_ptr)), \
+ canary, tcon_container_of_((member_ptr), \
+ tcon_offset((x), canary)))
+
+static inline void *tcon_container_of_(const void *member_ptr, size_t offset)
+{
+ return member_ptr ? (char *)member_ptr - offset : NULL;
+}
+
+
+/**
+ * tcon_member_of - get pointer to enclosed member structure based on a
+ * container canary
+ * @x: the structure containing the TCON
+ * @canary: the name of the container canary
+ * @container_ptr: pointer to a container
+ *
+ * @container_ptr must be a pointer to a container structure
+ * previously recorded in @canary with TCON_CONTAINER.
+ *
+ * tcon_member_of() evaluates to a pointer to the member of the
+ * container recorded in @canary. With sufficient compiler support,
+ * the pointer will be correctly typed, and the type of @container_ptr
+ * will be verified.
+ *
+ * Returns NULL if @container_ptr is NULL.
+ */
+#define tcon_member_of(x, canary, container_ptr) \
+ tcon_member_cast_ptr( \
+ tcon_container_check_ptr((x), canary, (container_ptr)), \
+ canary, tcon_member_of_((container_ptr), \
+ tcon_offset((x), canary)))
+static inline void *tcon_member_of_(void *container_ptr, size_t offset)
+{
+ return container_ptr ? (char *)container_ptr + offset : NULL;
+}
+
+
#endif /* CCAN_TCON_H */
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