include/err.h

   1 /**
   2  * @file err.h
   3  *
   4  * @brief Handy error handling for userspace.
   5  *
   6  * @author Taken from Linux Kernel (GPL2)
   7  *
   8  * @date 09/07/2008
   9  */
  10 #ifndef _LINUX_ERR_H
  11 #define _LINUX_ERR_H
  12
  13 /*
  14  * Kernel pointers have redundant information, so we can use a
  15  * scheme where we can return either an error code or a dentry
  16  * pointer with the same return value.
  17  *
  18  * This should be a per-architecture thing, to allow different
  19  * error and pointer decisions.
  20  */
  21
  22 /* __builtin_expect(A, B) evaluates to A, but notifies the compiler that
  23    the most likely value of A is B.  This feature was added at some point
  24    between 2.95 and 3.0.  Let's use 3.0 as the lower bound for now.  */
  25 #define GCC_VERSION (__GNUC__ * 10000 \
  26                         + __GNUC_MINOR__ * 100 \
  27                         + __GNUC_PATCHLEVEL__)
  28 #if (GCC_VERSION < 30000)
  29 #define __builtin_expect(a, b) (a)
  30 #endif
  31
  32 //#define __builtin_expect(expr, val) (expr)
  33 #define likely(x)       __builtin_expect(!!(x), 1)
  34 #define unlikely(x)     __builtin_expect(!!(x), 0)
  35
  36 #define MAX_ERRNO       4095
  37
  38 #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
  39
  40 static inline void *ERR_PTR(long error)
  41 {
  42         return (void *) error;
  43 }
  44
  45 static inline long PTR_ERR(const void *ptr)
  46 {
  47         return (long) ptr;
  48 }
  49
  50 static inline long IS_ERR(const void *ptr)
  51 {
  52         return IS_ERR_VALUE((unsigned long)ptr);
  53 }
  54
  55 #endif /* _LINUX_ERR_H */