[PATCH 02 of 14] chg: add connectat as a utility function

[Yuya Nishihara]

On Mon, 11 Apr 2016 00:57:19 +0100, Jun Wu wrote:
> # HG changeset patch
> # User Jun Wu <quark at fb.com>
> # Date 1460322456 -3600
> #      Sun Apr 10 22:07:36 2016 +0100
> # Node ID 97fbb23cf84c03ce59325e9de94902f40c68c8c8
> # Parent  cecc773636dcaeaf6d5130831f400a77fb065a96
> chg: add connectat as a utility function
> 
> We are going to use connectat and some platforms (namely FreeBSD) has it own
> native implementation. The signature is the same with FreeBSD's so we can
> switch to its native implementation easily with C macro later.

I'd rather give different function name than shadowing standard function
on some platforms.

> --- a/contrib/chg/util.c
> +++ b/contrib/chg/util.c
> @@ -8,6 +8,7 @@
>   */
>  
>  #include <errno.h>
> +#include <fcntl.h>
>  #include <signal.h>
>  #include <stdarg.h>
>  #include <stdio.h>
> @@ -178,3 +179,18 @@
>  		return -WTERMSIG(status);
>  	return 127;
>  }
> +
> +int connectat(int fd, int s, const struct sockaddr *addr, socklen_t addrlen)
> +{
> +	if (fd == AT_FDCWD)
> +		return connect(s, addr, addrlen);
> +	int cwdfd = open(".", O_DIRECTORY);
> +	if (cwdfd == -1)
> +		abortmsgerrno("cannot open cwd");
                ^^^^^^^^^^^^^
> +	fchdirx(fd);
        ^^^^^^^

Obviously this isn't compatible with the native implementation.