include/err.h

   1 /* From linux kernle source code */
   2
   3 #ifndef _LINUX_ERR_H
   4 #define _LINUX_ERR_H
   5
   6 #include <errno.h>
   7
   8 /*
   9  * Kernel pointers have redundant information, so we can use a
  10  * scheme where we can return either an error code or a dentry
  11  * pointer with the same return value.
  12  *
  13  * This should be a per-architecture thing, to allow different
  14  * error and pointer decisions.
  15  */
  16 #define MAX_ERRNO       4095
  17
  18
  19 #define IS_ERR_VALUE(x) ((x) >= (unsigned long)-MAX_ERRNO)
  20
  21 static inline void *ERR_PTR(long error)
  22 {
  23         return (void *) error;
  24 }
  25
  26 static inline long PTR_ERR(const void *ptr)
  27 {
  28         return (long) ptr;
  29 }
  30
  31 static inline long IS_ERR(const void *ptr)
  32 {
  33         return IS_ERR_VALUE((unsigned long)ptr);
  34 }
  35
  36 static inline long IS_ERR_OR_NULL(const void *ptr)
  37 {
  38         return !ptr || IS_ERR_VALUE((unsigned long)ptr);
  39 }
  40
  41 /**
  42  * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
  43  * @ptr: The pointer to cast.
  44  *
  45  * Explicitly cast an error-valued pointer to another pointer type in such a
  46  * way as to make it clear that's what's going on.
  47  */
  48 static inline void *ERR_CAST(const void *ptr)
  49 {
  50         /* cast away the const */
  51         return (void *) ptr;
  52 }
  53
  54
  55 #endif /* _LINUX_ERR_H */