Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > Unless I'm rather confused, you have two or possibly three ways to > pass in an open fd. Can you clarify what the difference is and/or > remove all but one of them? No, they're not equivalent. > > (*) fsconfig_set_path: A non-empty path is specified. The parameter must > > be expecting a path object. value points to a NUL-terminated string > > that is the path and aux is a file descriptor at which to start a > > relative lookup or AT_FDCWD. So, an example: fsconfig(fd, fsconfig_set_path, "source", "/dev/sda1", AT_FDCWD); I don't want to require that the caller open /dev/sda1 and pass in an fd as that might prevent the filesystem from "holding" it exclusively. > > (*) fsconfig_set_path_empty: As fsconfig_set_path, but with AT_EMPTY_PATH > > implied. You can't do: fsconfig(fd, fsconfig_set_path, "source", "", dir_fd); because AT_EMPTY_PATH cannot be specified directly[*]. What you do instead is: fsconfig(fd, fsconfig_set_path_empty, "source", "", dir_fd); [*] Not without a 6-arg syscall or some other way of passing it. I *could* require that the caller must call open(O_PATH) or openat(O_PATH) before calling fsconfig() - so you don't pass a string, but only a path-fd. > > (*) fsconfig_set_fd: An open file descriptor is specified. value must > > be NULL and aux indicates the file descriptor. See fd=%u on fuse. I think it's cleaner to do: fsconfig(fd, fsconfig_set_fd, "source", NULL, control_fd); saying explicitly that there's an open file to be passed rather than: fsconfig(fd, fsconfig_set_path, "source", NULL, control_fd); which indicates that you are actually providing a path. David
