| Message ID | 20170414102018.14853-3-wei.liu2@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Wei Liu writes ("[PATCH for-4.9 2/2] oxenstored: make it work on FreeBSD"):
> Call the uname syscall to determine sysname and return device names
> accordingly.
...
> -let xenstored_proc_kva = "/proc/xen/xsd_kva"
> -let xenstored_proc_port = "/proc/xen/xsd_port"
> +let xenstored_proc_kva =
> + let info = Unix_syscalls.uname () in
> + match info.sysname with
> + | "Linux" -> "/proc/xen/xsd_kva"
> + | "FreeBSD" -> "/dev/xen/xenstored"
> + | _ -> "nonexistent"
This isn't very good. If this code wants to fail, it returns a string
"nonexistent" which would then be used to construct pathnames, and
actually accessed.
In Haskell one could simply leave the default case off, which would
generate a runtime failure. Is that possible in ocaml ?
Ian.
> On 18. Apr 2017, at 11:16, Ian Jackson <ian.jackson@eu.citrix.com> wrote: > > Wei Liu writes ("[PATCH for-4.9 2/2] oxenstored: make it work on FreeBSD"): >> Call the uname syscall to determine sysname and return device names >> accordingly. > ... >> -let xenstored_proc_kva = "/proc/xen/xsd_kva" >> -let xenstored_proc_port = "/proc/xen/xsd_port" >> +let xenstored_proc_kva = >> + let info = Unix_syscalls.uname () in >> + match info.sysname with >> + | "Linux" -> "/proc/xen/xsd_kva" >> + | "FreeBSD" -> "/dev/xen/xenstored" >> + | _ -> "nonexistent" > > This isn't very good. If this code wants to fail, it returns a string > "nonexistent" which would then be used to construct pathnames, and > actually accessed. > > In Haskell one could simply leave the default case off, which would > generate a runtime failure. Is that possible in ocaml ? In Ocaml you would either use “assert false” or raise a dedicated exception for the catch-all case. You would get a run-time Match_failure exception without but this is nasty. The current solution has the problem you describe. — C
diff --git a/tools/ocaml/xenstored/define.ml b/tools/ocaml/xenstored/define.ml index 5a604d1bea..15b03e539f 100644 --- a/tools/ocaml/xenstored/define.ml +++ b/tools/ocaml/xenstored/define.ml @@ -14,11 +14,23 @@ * GNU Lesser General Public License for more details. *) +open Unix_syscalls + let xenstored_major = 1 let xenstored_minor = 0 -let xenstored_proc_kva = "/proc/xen/xsd_kva" -let xenstored_proc_port = "/proc/xen/xsd_port" +let xenstored_proc_kva = + let info = Unix_syscalls.uname () in + match info.sysname with + | "Linux" -> "/proc/xen/xsd_kva" + | "FreeBSD" -> "/dev/xen/xenstored" + | _ -> "nonexistent" +let xenstored_proc_port = + let info = Unix_syscalls.uname () in + match info.sysname with + | "Linux" -> "/proc/xen/xsd_port" + | "FreeBSD" -> "/dev/xen/xenstored" + | _ -> "nonexistent" let xs_daemon_socket = Paths.xen_run_stored ^ "/socket" let xs_daemon_socket_ro = Paths.xen_run_stored ^ "/socket_ro"
Call the uname syscall to determine sysname and return device names accordingly. Signed-off-by: Wei Liu <wei.liu2@citrix.com> --- Cc: Ian Jackson <ian.jackson@eu.citrix.com> Cc: dave@recoil.org Cc: christian.lindig@citrix.com Cc: jonathan.ludlam@citrix.com Cc: Roger Pau Monné <roger.pau@citrix.com> --- tools/ocaml/xenstored/define.ml | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)