root/include/linux/err.h

INCLUDED FROM

DEFINITIONS

1. ERR_PTR
2. PTR_ERR
3. IS_ERR
4. IS_ERR_OR_NULL
5. ERR_CAST
6. PTR_ERR_OR_ZERO

#ifndef _LINUX_ERR_H
#define _LINUX_ERR_H

#include <linux/compiler.h>
#include <linux/types.h>

#include <asm/errno.h>

/*
 * Kernel pointers have redundant information, so we can use a
 * scheme where we can return either an error code or a normal
 * pointer with the same return value.
 *
 * This should be a per-architecture thing, to allow different
 * error and pointer decisions.
 */
#define MAX_ERRNO       4095

#ifndef __ASSEMBLY__

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

static inline void * __must_check ERR_PTR(long error)
{
        return (void *) error;
}

static inline long __must_check PTR_ERR(__force const void *ptr)
{
        return (long) ptr;
}

static inline bool __must_check IS_ERR(__force const void *ptr)
{
        return IS_ERR_VALUE((unsigned long)ptr);
}

static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
{
        return !ptr || IS_ERR_VALUE((unsigned long)ptr);
}

/**
 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
 * @ptr: The pointer to cast.
 *
 * Explicitly cast an error-valued pointer to another pointer type in such a
 * way as to make it clear that's what's going on.
 */
static inline void * __must_check ERR_CAST(__force const void *ptr)
{
        /* cast away the const */
        return (void *) ptr;
}

static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
{
        if (IS_ERR(ptr))
                return PTR_ERR(ptr);
        else
                return 0;
}

/* Deprecated */
#define PTR_RET(p) PTR_ERR_OR_ZERO(p)

#endif

#endif /* _LINUX_ERR_H */