Quelle err.h Sprache: C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __TOOLS_LINUX_ERR_H
#define __TOOLS_LINUX_ERR_H

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

#include <asm/errno.h>

/*
* Original kernel header comment:
*
* 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.
*
* Userspace note:
* The same principle works for userspace, because 'error' pointers
* fall down to the unused hole far from user space, as described
* in Documentation/arch/x86/x86_64/mm.rst for x86_64 arch:
*
* 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension
* ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
*
* It should be the same case for other architectures, because
* this code is used in generic kernel code.
*/
#define MAX_ERRNO 4095

#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 unlikely(!ptr) || IS_ERR_VALUE((unsigned long)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;
}

/**
* 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;
}
#endif /* _LINUX_ERR_H */

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