You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
83 lines
3.0 KiB
83 lines
3.0 KiB
#ifndef _COW_H
|
|
#define _COW_H
|
|
|
|
#ifdef __cplusplus
|
|
#define restrict __restrict__
|
|
extern "C" {
|
|
#endif
|
|
|
|
#include <stdlib.h>
|
|
|
|
enum cow_err_kind {
|
|
COW_ERR_UNKNOWN =0,
|
|
COW_ERR_NONE =1, // Success
|
|
|
|
/// `memfd_create()` failed.
|
|
COW_ERR_FDCREATE,
|
|
/// `ftruncate()` (set size) failed.
|
|
COW_ERR_SIZE,
|
|
/// `mmap()` failed.
|
|
COW_ERR_MAP,
|
|
/// Trying to use a poisoned cow
|
|
COW_ERR_POISONED,
|
|
|
|
_COW_ERR_SIZE,
|
|
};
|
|
// Message string corresponding to this error.
|
|
const char* const * cow_err_msg(enum cow_err_kind kind);
|
|
// The last error that `libcow` produced on this thread.
|
|
enum cow_err_kind cow_err();
|
|
|
|
// Copy-on-write mapped memory.
|
|
typedef struct cow_mapped_slice cow_t;
|
|
|
|
/// Create a new copy-on-write area of `size` bytes.
|
|
/// Writes to this instance pointer (`cow_ptr()`) are written to the allocated memory.
|
|
/// Writes to any cloned instances do not propagate to this instance.
|
|
cow_t* cow_create(size_t size);
|
|
/// Create a new copy-on-write area of `size` bytes from file `fd`.
|
|
/// Writes to this instance pointer (`cow_ptr()`) are written to the allocated memory.
|
|
/// Writes to any cloned instances do not propagate to this instance.
|
|
///
|
|
/// The resulting object does not own `fd`, but does own a duplicate of it.
|
|
cow_t* cow_create_fd(int fd, size_t size);
|
|
|
|
/// Free a cow area. This should be called on all clones before the parent of those clones is freed.
|
|
void cow_free(cow_t* restrict cow);
|
|
/// Create a clone of this instance. Any writes to the returned pointer will not be propagated to the input one.
|
|
cow_t* cow_clone(const cow_t* cow);
|
|
|
|
/// Returns 1 if this instance is a clone. 0 if it is not.
|
|
int cow_is_fake(const cow_t* cow);
|
|
/// Get the size of this cow area.
|
|
size_t cow_size(const cow_t* cow);
|
|
|
|
/// Get the size of this cow area by assuming layout. This should work assuming "cow_t.h"'s build assertions didn't fail and avoids an extra call.
|
|
/// XXX: Deprecated function unpon seeing preferable codegen for using `cow_size()` over this. Use `cow_size()` instead.
|
|
static inline
|
|
#ifdef _COW_NO_ASSUME_ABI
|
|
#define _cow_size_unsafe(v) cow_size(v)
|
|
#else
|
|
// XXX: This macro is *VERY* ABI sensitive. This shouldn't be used if the ABI has changed since the build of libcow's `cow_t.h` passed its stati assertions in *both* the C and C++ implementations.
|
|
// The C++ API uses this by default for its `Cow::size()` function.
|
|
#define _cow_size_unsafe(v) (*(((size_t*)(v))+1))
|
|
__attribute__((deprecated("size() is safer and offers better codegen.")))
|
|
#endif
|
|
size_t cow_size_unsafe(const cow_t* v) { return _cow_size_unsafe(v); }
|
|
|
|
/// Get the `void*` pointer to the start of the area.
|
|
#define cow_ptr(v) (*((void**)(v)))
|
|
/// Get the `T*` pointer to the start of the area.
|
|
#define cow_ptr_of(T, v) (*((T **)(v)))
|
|
///// Get the `cow_t*` back from a pointer created with cow_ptr.
|
|
///// NOTE: This pointer **MUST NOT** be a *copy* of a pointer created with `cow_ptr`, but the pointer returned from `cow_ptr` exactly.
|
|
//XXX: Too unsafe and not useful enough to warrant a function/macro.
|
|
//#define cow_from_ptr(p) (cow_t*)(&(p))
|
|
|
|
#ifdef __cplusplus
|
|
#undef restrict
|
|
}
|
|
#endif
|
|
|
|
#endif /* _COW_H */
|