* - The 'out' descriptor must be opened first
* - As soon as the backend script dies, the connection to the entry is
* closed.
+ * - To avoid user-inflicted pain, all entries are opened at the time
+ * that they are created. Reopening these entries is a little complicated
+ * but nevertheless sound:
+ * * When a script dies, its fd is reopened
+ * * If a script fails to execute, its fd is closed and reopened to
+ * beat a race that can happen when the user closes the connection
+ * before the script can be launched.
*)
open Inotify
open Printf
open Splice
-let backend_prefix = ref ""
-let direct_fifo_table: (string,(string*string) option) Hashtbl.t = Hashtbl.create 1024
+let close_if_open fd = (try (ignore(close fd);) with _ -> ())
-let rec list_check lst elt =
- match lst with
- | [] -> false
- | car::cdr -> if (car==elt) then true else list_check cdr elt
+type in_pathname = string
+type directory = string
+type base_pathname = string
+type slice_name = string
+
+let direct_fifo_table: (in_pathname,(directory*base_pathname*slice_name*Unix.file_descr) option) Hashtbl.t =
+ Hashtbl.create 1024
+
+let pidmap: (int,in_pathname * Unix.file_descr) Hashtbl.t = Hashtbl.create 1024
+
+let move_gate fname =
+ let tmpfname=String.concat "." [fname;"tmp"] in
+ Unix.rename fname tmpfname;
+ tmpfname
+
+let move_ungate fname restore =
+ Unix.rename restore fname
+
+let list_check lst elt _ =
+ let rec list_check_rec lst =
+ match lst with
+ | [] -> false
+ | car::cdr ->
+ if (car==elt) then
+ true
+ else
+ list_check_rec cdr
+ in
+ list_check_rec lst
+
+let openentry_int fifoin =
+ let fdin =
+ try openfile fifoin [O_RDONLY;O_NONBLOCK] 0o777 with
+ e->logprint "Error opening and connecting FIFO: %s,%o\n" fifoin 0o777;raise e
+ in
+ fdin
+
+(** Open entry safely, by first masking out the file to be opened *)
+let openentry_safe root_dir fqp_in backend_spec =
+ let restore = move_gate fqp_in in
+ let fd_in = openentry_int restore in
+ move_ungate fqp_in restore;
+ let (fqp,slice_name) = backend_spec in
+ Hashtbl.replace direct_fifo_table fqp_in (Some(root_dir,fqp,slice_name,fd_in))
+
+let openentry root_dir fqp backend_spec =
+ let fqp_in = String.concat "." [fqp;"in"] in
+ openentry_safe root_dir fqp_in backend_spec
+
+let reopenentry fifoin =
+ let entry = try Hashtbl.find direct_fifo_table fifoin with _ -> None in
+ match entry with
+ | Some(dir, fqp,slice_name,fd) -> close_if_open fd;openentry_safe dir fifoin (fqp,slice_name)
+ | None -> ()
(* vsys is activated when a client opens an in file *)
-let connect_file mask_events fqp_out =
+let connect_file fqp_in =
(* Do we care about this file? *)
let entry_info = try
- Hashtbl.find direct_fifo_table fqp_out with _ -> None in
+ Hashtbl.find direct_fifo_table fqp_in with _ -> None in
match entry_info with
- | Some(execpath,slice_name) ->
- fprintf logfd "Executing %s for slice %s\n" execpath slice_name;flush logfd;
+ | Some(_,execpath,slice_name,fifo_fdin) ->
begin
- let len = String.length fqp_out in
- let fqp = String.sub fqp_out 0 (len-4) in
- mask_events true;
- let fqp_in = String.concat "." [fqp;"in"] in
- let fifo_fdin =
- try openfile fqp_in [O_RDONLY;O_NONBLOCK] 0o777 with
- e->fprintf logfd "Error opening and connecting FIFO: %s\n" fqp_in;flush logfd;raise e
- in
+ let len = String.length fqp_in in
+ let fqp = String.sub fqp_in 0 (len-3) in
+ let fqp_out = String.concat "." [fqp;"out"] in
let fifo_fdout =
try openfile fqp_out [O_WRONLY;O_NONBLOCK] 0o777 with
- _->fprintf logfd "%s Output pipe not open, using stdout in place of %s\n" slice_name fqp_out;flush logfd;stdout
+ _-> (* The client is opening the descriptor too fast *)
+ sleep 1;try openfile fqp_out [O_WRONLY;O_NONBLOCK] 0o777 with
+ _->
+ logprint "%s Output pipe not open, using stdout in place of %s\n" slice_name fqp_out;stdout
in
- try ignore(create_process execpath [|execpath;slice_name|] fifo_fdin fifo_fdout fifo_fdout); with e -> begin fprintf logfd "Error executing service: %s\n" execpath;flush logfd end;
- close fifo_fdin;
- close fifo_fdout;
- mask_events false;
+ ignore(sigprocmask SIG_BLOCK [Sys.sigchld]);
+ (
+ clear_nonblock fifo_fdin;
+ let pid=try Some(create_process execpath [|execpath;slice_name|] fifo_fdin fifo_fdout fifo_fdout) with e -> None in
+ match pid with
+ | Some(pid) ->
+ if (fifo_fdout <> stdout) then close_if_open fifo_fdout;
+ Hashtbl.add pidmap pid (fqp_in,fifo_fdout)
+ | None ->logprint "Error executing service: %s\n" execpath;reopenentry fqp_in
+ );
+ ignore(sigprocmask SIG_UNBLOCK [Sys.sigchld]);
end
| None -> ()
(** Make a pair of fifo entries *)
let mkentry fqp abspath perm uname =
- fprintf logfd "Making entry %s->%s\n" fqp abspath;flush logfd;
+ logprint "Making entry %s->%s\n" fqp abspath;
let fifoin=sprintf "%s.in" fqp in
let fifoout=sprintf "%s.out" fqp in
(try Unix.unlink fifoin with _ -> ());
);
Success
with
- e->fprintf logfd "Error creating FIFO: %s->%s. May be something wrong at the frontend.\n" fqp fifoout;flush logfd;Failed)
+ e->logprint "Error creating FIFO: %s->%s. May be something wrong at the frontend.\n" fqp fifoout;Failed)
-(** Open fifos for a session. SHOULD NOt shutdown vsys if the fifos don't exist *)
-let openentry fqp backend_spec =
- let fqp_in = String.concat "." [fqp;"out"] in
- Hashtbl.replace direct_fifo_table fqp_in (Some(backend_spec))
(** Close fifos that just got removed *)
let closeentry fqp =
- let fqp_in = String.concat "." [fqp;"out"] in
- Hashtbl.remove direct_fifo_table fqp_in
+ let fqp_in = String.concat "." [fqp;"in"] in
+ let entry = try Hashtbl.find direct_fifo_table fqp_in with Not_found -> None in
+ match entry with
+ | None -> ()
+ | Some(_,_,_,fd) ->
+ close_if_open fd;
+ Hashtbl.remove direct_fifo_table fqp_in
-let direct_fifo_handler wd dirname evlist fname =
- let mask_events flag =
- if (flag) then Dirwatcher.mask_events wd else Dirwatcher.unmask_events wd
- in
- let is_event = list_check evlist in
- if (is_event Open) then
- let fqp_out = String.concat "/" [dirname;fname] in
- connect_file mask_events fqp_out
+let sigchld_handle s =
+ let pid,_=Unix.waitpid [Unix.WNOHANG] 0 in
+ try
+ let fqp_in,fd_out = Hashtbl.find pidmap pid in
+ begin
+ reopenentry fqp_in
+ end
+ with _ -> ()
-let add_dir_watch fqp =
+let rec add_dir_watch fqp =
Dirwatcher.add_watch fqp [S_Open] direct_fifo_handler
+and
+ direct_fifo_handler wd dirname evlist fname =
+ let is_event = list_check evlist in
+ if (is_event Open Attrib) then
+ let fqp_in = String.concat "/" [dirname;fname] in
+ connect_file fqp_in
let del_dir_watch fqp =
- (* XXX Dirwatcher.del_watch fqp *)
()
+
+let initialize () =
+ Sys.set_signal Sys.sigchld (Sys.Signal_handle sigchld_handle)
git://git.onelab.eu / vsys.git / blobdiff