Re: [PATCH] tools/ocaml/libs/xs: Create FDs with the correct CLOEXEC status

[Andrii Sultanov <andriy.sultanov@xxxxxxxxxx>]

On 10/12/26 21:19, Andrew Cooper wrote:

> ... rather than editing them after the fact.
>
> This capability exists from Ocaml 4.05 which is also our minimum supported
> version.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Andrii Sultanov <andriy.sultanov@xxxxxxxxxx>
> CC: Guillaume Thouvenin <guillaume.thouvenin@xxxxxxxxxx>
>
> Found while reviewing the other FD handling patch.
> ---
>   tools/ocaml/libs/xs/xs.ml | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/tools/ocaml/libs/xs/xs.ml b/tools/ocaml/libs/xs/xs.ml
> index addccc80099b..a088d67a8cb6 100644
> --- a/tools/ocaml/libs/xs/xs.ml
> +++ b/tools/ocaml/libs/xs/xs.ml
> @@ -155,9 +155,8 @@ exception Failed_to_connect
>   let daemon_open () =
>     try
>       let sockaddr = Unix.ADDR_UNIX(daemon_socket) in
> -    let sock = Unix.socket Unix.PF_UNIX Unix.SOCK_STREAM 0 in
> +    let sock = Unix.socket ~cloexec:true Unix.PF_UNIX Unix.SOCK_STREAM 0 in
>       Unix.connect sock sockaddr;
> -    Unix.set_close_on_exec sock;
>       make sock
>     with _ -> raise Failed_to_connect
>   
> @@ -169,8 +168,7 @@ let domain_open () =
>       with Unix.Unix_error(_, _, _) ->
>         "/proc/xen/xenbus" in
>   
> -  let fd = Unix.openfile path [ Unix.O_RDWR ] 0o550 in
> -  Unix.set_close_on_exec fd;
> +  let fd = Unix.openfile path [ Unix.O_RDWR; Unix.O_CLOEXEC ] 0o550 in
>     make fd
>   
>   let close xsh = Xsraw.close xsh.con
> base-commit: 0d3bb3c98bc99ec1c84ebb3df71b6e18daebff4f
The change on its own is fine - there's no functional impact. But as far 
as I
can tell, these functions are not used anywhere (they haven't been used 
in xapi
in a long time), so there's limited utility in this cleanup.

Regarding your question from the original thread, if this patch was intended
as an answer to it:

> Where do these sockets come from?  What flags where they opened with?

The sockets that are dumped come from xenstored.ml:process_special_fds:

      let (cfd, _addr) = Unix.accept fd in

The default is keep-on-exec, so there shouldn't be any need to call
Unix.clear_close_on_exec in the patches suggested by Andrew Mbugua.

Acked-by: Andrii Sultanov <andriy.sultanov@xxxxxxxxxx>