err.h 2.0 KB

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