podman: new option --preserve-fd

add a new option --preserve-fd that allows to specify a list of FDs to
pass down to the container.

It is similar to --preserve-fds but it allows to specify a list of FDs
instead of the maximum FD number to preserve.

--preserve-fd and --preserve-fds are mutually exclusive.

It requires crun since runc would complain if any fd below
--preserve-fds is not preserved.

Closes: https://github.com/containers/podman/issues/20844

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

libpod/options.go

@@ -1555,6 +1555,18 @@ func WithPreserveFDs(fd uint) CtrCreateOption {
 	}
 }
 
+// WithPreserveFD forwards from the process running Libpod into the container
+// the given list of extra FDs to the created container
+func WithPreserveFD(fds []uint) CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return define.ErrCtrFinalized
+		}
+		ctr.config.PreserveFD = fds
+		return nil
+	}
+}
+
 // WithCreateCommand adds the full command plus arguments of the current
 // process to the container config.
 func WithCreateCommand(cmd []string) CtrCreateOption {