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putty-source/defs.h
Simon Tatham 5129c40bea Modernise the Socket/Plug vtable system.
Now I've got FROMFIELD, I can rework it so that structures providing
an implementation of the Socket or Plug trait no longer have to have
the vtable pointer as the very first thing in the structure. In
particular, this means that the ProxySocket structure can now directly
implement _both_ the Socket and Plug traits, which is always
_logically_ how it's worked, but previously it had to be implemented
via two separate structs linked to each other.
2018-05-27 15:28:54 +01:00

67 lines
2.1 KiB
C

/*
* defs.h: initial definitions for PuTTY.
*
* The rule about this header file is that it can't depend on any
* other header file in this code base. This is where we define
* things, as much as we can, that other headers will want to refer
* to, such as opaque structure types and their associated typedefs,
* or macros that are used by other headers.
*/
#ifndef PUTTY_DEFS_H
#define PUTTY_DEFS_H
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
typedef struct conf_tag Conf;
typedef struct backend_tag Backend;
typedef struct terminal_tag Terminal;
typedef struct Filename Filename;
typedef struct FontSpec FontSpec;
typedef struct bufchain_tag bufchain;
typedef struct strbuf strbuf;
struct RSAKey;
#include <stdint.h>
typedef uint32_t uint32;
typedef struct BinarySink BinarySink;
typedef struct SockAddr_tag *SockAddr;
typedef struct Socket_vtable Socket_vtable;
typedef struct Plug_vtable Plug_vtable;
/* Note indirection: for historical reasons (it used to be closer to
* the OS socket type), the type that most code uses for a socket is
* 'Socket', not 'Socket *'. So an implementation of Socket or Plug
* has a 'const Socket *' field for the vtable pointer, and the
* 'Socket' type returned to client code is a pointer to _that_ in
* turn. */
typedef const Socket_vtable **Socket;
typedef const Plug_vtable **Plug;
/* Do a compile-time type-check of 'to_check' (without evaluating it),
* as a side effect of returning the value 'to_return'. Note that
* although this macro double-*expands* to_return, it always
* *evaluates* exactly one copy of it, so it's side-effect safe. */
#define TYPECHECK(to_check, to_return) \
(sizeof(to_check) ? (to_return) : (to_return))
/* Return a pointer to the object of structure type 'type' whose field
* with name 'field' is pointed at by 'object'. */
#define FROMFIELD(object, type, field) \
TYPECHECK(object == &((type *)0)->field, \
((type *)(((char *)(object)) - offsetof(type, field))))
#endif /* PUTTY_DEFS_H */