D28478: [FileProtocol] change statx stat_dev() to use device major + minor

[Stefan Brüns]

bruns added inline comments.

INLINE COMMENTS

> file_unix.cpp:286
>  inline static uint16_t stat_mode(struct statx &buf) { return buf.stx_mode; }
> -inline static uint32_t stat_dev(struct statx &buf) { return buf.stx_dev_major; }
> +inline static uint32_t stat_dev(struct statx &buf) { return (buf.stx_dev_major * 100) + buf.stx_dev_minor; }
>  inline static uint64_t stat_ino(struct statx &buf) { return buf.stx_ino; }

` * 100` is definitely wrong - maybe `* 0x100`, but ...

TLDR: use `makedev`, and change the return type to dev_t.

dev_t is defined as a 64bit type atleast on Linux, which matches the 32bit major/minor parts of buf.stx_dev_*.  Traditionally, major/minor are used as low/high bytes of a 16 bit type, but these can easily exhausted on a larger system. So this is was makedev does:

  #define __SYSMACROS_DEFINE_MAKEDEV(DECL_TEMPL)                  \
    __SYSMACROS_DECLARE_MAKEDEV (DECL_TEMPL)                      \
    {                                                             \
      __dev_t __dev;                                              \
      __dev  = (((__dev_t) (__major & 0x00000fffu)) <<  8);       \
      __dev |= (((__dev_t) (__major & 0xfffff000u)) << 32);       \
      __dev |= (((__dev_t) (__minor & 0x000000ffu)) <<  0);       \
      __dev |= (((__dev_t) (__minor & 0xffffff00u)) << 12);       \
      return __dev;                                               \
    }

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D28478

To: ahmadsamir, #frameworks, dfaure, meven
Cc: bruns, kde-frameworks-devel, LeGast00n, cblack, GB_2, michaelh, ngraham
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