Error checking with uname(2)?

Question

Is it necessary to check for errors after calling uname(2)?

According to the manual page:

On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

and under the ERRORS heading,

EFAULT buf is not valid.

is the only error listed.

Can I assume, therefore, that uname will never fail if given a valid struct utsname buffer?

Answer 1

No.

Just because EFAULT is the only errno listed, it doesn't mean uname will never fail as long as you pass a valid buffer. It could fail for any other reason. i.e. if uname's return code is -1, then it failed irrespective of the value of errno.

errno is only meaningful if the function/system call indicates failure; it doesn't, on its own, define the success/failure of a library function/syscall.