unix socket error 14: EFAULT (bad address)

c sockets udp sendto
aktungmak picture aktungmak · Feb 13, 2012 · Viewed 33.5k times · Source

I have a very simple question, but I have not managed to find any answers to it all weekend. I am using the sendto() function and it is returning error code 14: EFAULT. The man pages describe it as:

"An invalid user space address was specified for an argument."

I was convinced that this was talking about the IP address I was specifying, but now I suspect it may be the memory address of the message buffer that it is referring to - I can't find any clarification on this anywhere, can anyone clear this up?

Answer

Basile Starynkevitch picture Basile Starynkevitch · Feb 13, 2012

EFAULT It happen if the memory address of some argument passed to sendto (or more generally to any system call) is invalid. Think of it as a sort of SIGSEGV in kernel land regarding your syscall. For instance, if you pass a null or invalid buffer pointer (for reading, writing, sending, recieving...), you get that

See errno(3), sendto(2) etc... man pages.

EFAULT is not related to IP addresses at all.

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