musl/arch/x86_64/bits/socket.h

struct msghdr
{
	void *msg_name;
	socklen_t msg_namelen;
	struct iovec *msg_iov;
	int msg_iovlen, __pad1;
	void *msg_control;
	socklen_t msg_controllen, __pad2;
	int msg_flags;
};

struct cmsghdr
{
	socklen_t cmsg_len;
	int __pad1;
	int cmsg_level;
	int cmsg_type;
};
Port musl to x86-64. One giant commit! 2011-02-15 12:32:09 +00:00			`struct msghdr`
			`{`
			`void *msg_name;`
			`socklen_t msg_namelen;`
			`struct iovec *msg_iov;`
workaround broken msghdr struct on 64bit linux POSIX clearly specifies the type of msg_iovlen and msg_controllen, and Linux ignores it and makes them both size_t instead. to work around this we add padding (instead of just using the wrong types like glibc does), but we also need to patch-up the struct before passing it to the kernel in case the caller did not zero-fill it. if i could trust the kernel to just ignore the upper 32 bits, this would not be necessary, but i don't think it will ignore them... 2011-04-08 13:24:19 +00:00			`int msg_iovlen, __pad1;`
Port musl to x86-64. One giant commit! 2011-02-15 12:32:09 +00:00			`void *msg_control;`
workaround broken msghdr struct on 64bit linux POSIX clearly specifies the type of msg_iovlen and msg_controllen, and Linux ignores it and makes them both size_t instead. to work around this we add padding (instead of just using the wrong types like glibc does), but we also need to patch-up the struct before passing it to the kernel in case the caller did not zero-fill it. if i could trust the kernel to just ignore the upper 32 bits, this would not be necessary, but i don't think it will ignore them... 2011-04-08 13:24:19 +00:00			`socklen_t msg_controllen, __pad2;`
Port musl to x86-64. One giant commit! 2011-02-15 12:32:09 +00:00			`int msg_flags;`
			`};`
workaround another sendmsg kernel bug on 64-bit machines the kernel wrongly expects the cmsg length field to be size_t instead of socklen_t. in order to work around the issue, we have to impose a length limit and copy to a local buffer. the length limit should be more than sufficient for any real-world use; these headers are only used for passing file descriptors and permissions between processes over unix sockets. 2012-07-13 01:37:54 +00:00
			`struct cmsghdr`
			`{`
			`socklen_t cmsg_len;`
			`int __pad1;`
			`int cmsg_level;`
			`int cmsg_type;`
			`};`