LXR linux/tools/include/linux/err.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __TOOLS_LINUX_ERR_H
   3#define __TOOLS_LINUX_ERR_H
   4
   5#include <linux/compiler.h>
   6#include <linux/types.h>
   7
   8#include <asm/errno.h>
   9
  10/*
  11 * Original kernel header comment:
  12 *
  13 * Kernel pointers have redundant information, so we can use a
  14 * scheme where we can return either an error code or a normal
  15 * pointer with the same return value.
  16 *
  17 * This should be a per-architecture thing, to allow different
  18 * error and pointer decisions.
  19 *
  20 * Userspace note:
  21 * The same principle works for userspace, because 'error' pointers
  22 * fall down to the unused hole far from user space, as described
  23 * in Documentation/x86/x86_64/mm.rst for x86_64 arch:
  24 *
  25 * 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension
  26 * ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
  27 *
  28 * It should be the same case for other architectures, because
  29 * this code is used in generic kernel code.
  30 */
  31#define MAX_ERRNO       4095
  32
  33#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
  34
  35static inline void * __must_check ERR_PTR(long error_)
  36{
  37        return (void *) error_;
  38}
  39
  40static inline long __must_check PTR_ERR(__force const void *ptr)
  41{
  42        return (long) ptr;
  43}
  44
  45static inline bool __must_check IS_ERR(__force const void *ptr)
  46{
  47        return IS_ERR_VALUE((unsigned long)ptr);
  48}
  49
  50static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
  51{
  52        return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
  53}
  54
  55static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
  56{
  57        if (IS_ERR(ptr))
  58                return PTR_ERR(ptr);
  59        else
  60                return 0;
  61}
  62
  63/**
  64 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
  65 * @ptr: The pointer to cast.
  66 *
  67 * Explicitly cast an error-valued pointer to another pointer type in such a
  68 * way as to make it clear that's what's going on.
  69 */
  70static inline void * __must_check ERR_CAST(__force const void *ptr)
  71{
  72        /* cast away the const */
  73        return (void *) ptr;
  74}
  75#endif /* _LINUX_ERR_H */
  76