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/*
* Copyright (c) 2018 Linaro Limited
*
* SPDX-License-Identifier: Apache-2.0
*/
#ifndef ZEPHYR_INCLUDE_SYS_FDTABLE_H_
#define ZEPHYR_INCLUDE_SYS_FDTABLE_H_
#include <stdarg.h>
#include <sys/types.h>
/* FIXME: For native_posix ssize_t, off_t. */
#include <fs/fs.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* File descriptor virtual method table.
* Currently all operations beyond read/write/close go thru ioctl method.
*/
struct fd_op_vtable {
ssize_t (*read)(void *obj, void *buf, size_t sz);
ssize_t (*write)(void *obj, const void *buf, size_t sz);
int (*close)(void *obj);
int (*ioctl)(void *obj, unsigned int request, va_list args);
};
/**
* @brief Reserve file descriptor.
*
* This function allows to reserve a space for file descriptor entry in
* the underlying table, and thus allows caller to fail fast if no free
* descriptor is available. If this function succeeds, z_finalize_fd()
* or z_free_fd() must be called mandatorily.
*
* @return Allocated file descriptor, or -1 in case of error (errno is set)
*/
int z_reserve_fd(void);
/**
* @brief Finalize creation of file descriptor.
*
* This function should be called exactly once after z_reserve_fd(), and
* should not be called in any other case.
*
* @param fd File descriptor previously returned by z_reserve_fd()
* @param obj pointer to I/O object structure
* @param vtable pointer to I/O operation implementations for the object
*/
void z_finalize_fd(int fd, void *obj, const struct fd_op_vtable *vtable);
/**
* @brief Allocate file descriptor for underlying I/O object.
*
* This function combines operations of z_reserve_fd() and z_finalize_fd()
* in one step, and provided for convenience.
*
* @param obj pointer to I/O object structure
* @param vtable pointer to I/O operation implementations for the object
*
* @return Allocated file descriptor, or -1 in case of error (errno is set)
*/
int z_alloc_fd(void *obj, const struct fd_op_vtable *vtable);
/**
* @brief Release reserved file descriptor.
*
* This function may be called once after z_reserve_fd(), and should
* not be called in any other case.
*
* @param fd File descriptor previously returned by z_reserve_fd()
*/
void z_free_fd(int fd);
/**
* @brief Get underlying object pointer from file descriptor.
*
* This function is useful for functions other than read/write/ioctl
* to look up underlying I/O object by fd, optionally checking its
* type (using vtable reference). If fd refers to invalid entry,
* NULL will be returned with errno set to EBADF. If fd is valid,
* but vtable param is not NULL and doesn't match object's vtable,
* NULL is returned and errno set to err param.
*
* @param fd File descriptor previously returned by z_reserve_fd()
* @param vtable Expected object vtable or NULL
* @param err errno value to set if object vtable doesn't match
*
* @return Object pointer or NULL, with errno set
*/
void *z_get_fd_obj(int fd, const struct fd_op_vtable *vtable, int err);
/**
* @brief Get underlying object pointer and vtable pointer from file descriptor.
*
* @param fd File descriptor previously returned by z_reserve_fd()
* @param vtable A pointer to a pointer variable to store the vtable
* @param lock An optional pointer to a pointer variable to store the mutex
* preventing concurrent descriptor access. The lock is not taken,
* it is just returned for the caller to use if necessary. Pass NULL
* if the lock is not needed by the caller.
*
* @return Object pointer or NULL, with errno set
*/
void *z_get_fd_obj_and_vtable(int fd, const struct fd_op_vtable **vtable,
struct k_mutex **lock);
/**
* @brief Call ioctl vmethod on an object using varargs.
*
* We need this helper function because ioctl vmethod is declared to
* take va_list and the only portable way to construct va_list is from
* function's ... parameters.
*
* @param vtable vtable containing ioctl function pointer
* @param obj Object to call ioctl on
* @param request ioctl request number
* @param ... Variadic arguments to ioctl
*/
static inline int z_fdtable_call_ioctl(const struct fd_op_vtable *vtable, void *obj,
unsigned long request, ...)
{
va_list args;
int res;
va_start(args, request);
res = vtable->ioctl(obj, request, args);
va_end(args);
return res;
}
/**
* Request codes for fd_op_vtable.ioctl().
*
* Note that these codes are internal Zephyr numbers, for internal
* Zephyr operations (and subject to change without notice, not part
* of "stable ABI"). These are however expected to co-exist with
* "well-known" POSIX/Linux ioctl numbers, and not clash with them.
*/
enum {
/* Codes below 0x100 are reserved for fcntl() codes. */
ZFD_IOCTL_FSYNC = 0x100,
ZFD_IOCTL_LSEEK,
ZFD_IOCTL_POLL_PREPARE,
ZFD_IOCTL_POLL_UPDATE,
ZFD_IOCTL_POLL_OFFLOAD,
ZFD_IOCTL_SET_LOCK,
};
#ifdef __cplusplus
}
#endif
#endif /* ZEPHYR_INCLUDE_SYS_FDTABLE_H_ */