X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=directfifowatcher.ml;h=4ebbe93768084108fd8bed1dee0dacfe6ccb322b;hb=c83cc6c663566b82531b670f8b492c6ff1e1f18f;hp=0ff74b3f35357e09cf80779d335fa8a88eaa3b17;hpb=47e86c6701f0bfe11a8a8784cd06db3283a57775;p=vsys.git diff --git a/directfifowatcher.ml b/directfifowatcher.ml index 0ff74b3..4ebbe93 100644 --- a/directfifowatcher.ml +++ b/directfifowatcher.ml @@ -3,6 +3,13 @@ * - 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 @@ -12,46 +19,101 @@ open Dirwatcher 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 + (* XXX add a check *) + Unix.rename fname tmpfname; + tmpfname + +let move_ungate fname restore = + (* XXX add a check *) + 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 fs_openentry 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 = fs_openentry 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 _ -> ()); @@ -59,40 +121,65 @@ let mkentry fqp abspath perm uname = (try let infname =(sprintf "%s.in" fqp) in let outfname =(sprintf "%s.out" fqp) in + (* XXX add checks *) Unix.mkfifo infname 0o666; Unix.mkfifo outfname 0o666; ( (* Make the user the owner of the pipes in a non-chroot environment *) if (!Globals.nochroot) then let pwentry = Unix.getpwnam uname in + (* XXX add checks *) Unix.chown infname pwentry.pw_uid pwentry.pw_gid; Unix.chown outfname pwentry.pw_uid pwentry.pw_gid ); 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 +let sigchld_handle s = + let rec reap_all_processes () = + let pid,_= try Unix.waitpid [Unix.WNOHANG] 0 with _ -> (-1,WEXITED(-1)) in + if (pid > 0) then + begin + begin + try + let fqp_in,fd_out = Hashtbl.find pidmap pid in + begin + reopenentry fqp_in + end + with _ -> () + end; + reap_all_processes () + end 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 add_dir_watch fqp = + reap_all_processes() + +(** The backendhandler class: defines event handlers for events in +the backend backend directory. + @param dir_root The location of the backend in the server context (eg. root context for vservers) + @param frontend_list List of frontends to serve with this backend + *) +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)