Messages in this thread | | | Date | Mon, 14 May 2001 15:27:26 -0400 (EDT) | From | Chris Wing <> | Subject | Re: uid_t and gid_t vs. __kernel_uid_t and __kernel_gid_t |
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Vassilii:
__kernel_uid_t is my fault. The names are confusing, but uid_t and gid_t are NOT supposed to be different in kernel and user space.
They used to differ, and the junk in /include/linux/highuid.h is there to handle all old programs which used the smaller (16-bit) uid_t.
Kernel code should always use uid_t as a type, except when copying data between user and kernel space. In that case, just make sure that whatever data structure you use is big enough to contain a Linux uid_t. (as of 2.4, Linux uses 32-bit uid_t on all platforms) All new interfaces to user space should use 32-bit uids, i.e. type unsigned int.
Don't use __kernel_uid_t at all in new code. The name is basically there only because the older libc5 C library included the kernel headers and we have to preserve it so that programs still compile on these old systems.
if you look inside /include/linux/types.h, this is made explicit:
#ifdef __KERNEL__ typedef __kernel_uid32_t uid_t; typedef __kernel_gid32_t gid_t; ... ...
Thanks,
Chris Wing wingc@engin.umich.edu
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