X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=backend.ml;h=4d243266598bc5a18bd130359612fb4a60657d9d;hb=refs%2Fheads%2Ftrellis;hp=1a3a432cecbe672f35dfe00257610f7940a98480;hpb=5648b4043b34c33111800aecba36f486627a30a0;p=vsys.git diff --git a/backend.ml b/backend.ml index 1a3a432..4d24326 100644 --- a/backend.ml +++ b/backend.ml @@ -1,3 +1,12 @@ +(** backend.ml: + Defines handlers for events related to the backend directory, where the + scripts are stored. Eg. a new script results in a new part of pipes in + the frontend etc. These handlers are defined in the backendHandler + class. + + @author Sapan Bhatia + *) + open Unix open Globals open Dirwatcher @@ -6,14 +15,20 @@ open Fifowatcher open Frontend open Printf +(** Helper functions: + +*) + +(** Turn an absolute path into a relative path. *) let delete_prefix prefix str = let len = String.length str in let plen = String.length prefix in if (String.sub str 0 plen <> prefix) then + (* XXX can a user make this happen? *) raise Bad_path else - Relpath(String.sub str (plen+1) (len-plen-1)) + Relpath(String.sub str (plen+1) (len-plen-1)) let rec list_check lst elt = match lst with @@ -21,99 +36,154 @@ let rec list_check lst elt = | car::cdr -> if (car==elt) then true else list_check cdr elt - (* - * One backendHandler class for each - * backend. Builds the initial - * tree for the frontend and - * watches for directory - * events. - *) - +(** 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 + *) class backendHandler dir_root (frontend_lst: frontendHandler list) = - let mk_rel_path = delete_prefix dir_root in object(this) - - val file_regexp = ref (Str.regexp "[a-zA-Z][a-zA-Z0-9_'.']*") - - method new_dir fqp func = - let s = Unix.stat fqp in - List.iter - (fun frontend-> - frontend#mkdir (mk_rel_path fqp) (s.st_perm); - Dirwatcher.add_watch fqp [S_Create;S_Delete] (Some(func))) - frontend_lst; - - method new_script fqp = - let s = Unix.stat fqp in - List.iter (fun frontend-> - frontend#mkentry (mk_rel_path fqp) fqp (s.st_perm)) frontend_lst - - val dir_regexp = Str.regexp "^dir_"; - - method handle_dir_event dirname evlist fname = - let fqp = String.concat "/" [dirname;fname] in - if (Str.string_match !file_regexp fname 0) then - begin - let is_event = list_check evlist in - if (is_event Create) then - begin - if (is_event Isdir) then - begin - this#new_dir fqp this#handle_dir_event - end - else - (* It's a new script *) - begin - (* - if (Str.string_match dir_regexp fname 0) then - let fqp = String.concat "/" [dirname;String.sub fname 4 ((String.length fname)-4+1)] in - let real_fqp = String.concat "/" [dirname;fname] in - this#new_dir fqp this#handle_spool_event; - Hashtbl.add spools fqp real_fqp - else*) - this#new_script fqp - end - end - else if (is_event Delete) then - begin - if (is_event Isdir) then - begin - (*this#rm_watch fqp;*) - List.iter (fun frontend-> - frontend#rmdir (mk_rel_path fqp)) frontend_lst - end - else List.iter (fun frontend -> - frontend#unlink (mk_rel_path fqp)) frontend_lst + let mk_rel_path = delete_prefix dir_root in object(this) + + (** Regular expression that defines a legal script name. Filter out + * temporary files using this *) + val file_regexp = Str.regexp "[a-zA-Z][a-zA-Z0-9_\.]*" + val acl_file_regexp = Str.regexp ".*acl$" + + val dir_regexp = Str.regexp "^dir_"; + val acl_regexp = Str.regexp ".*_.*"; + + (** Somebody created a new directory *) + (* XXX Race condition here *) + method private new_dir slice_list fqp func = + let s = Unix.stat fqp in + List.iter + (fun frontend-> + try begin + frontend#mkdir (mk_rel_path fqp) (s.st_perm); + Dirwatcher.add_watch fqp [S_Create;S_Delete] func end - end - else (* regex not matched *) - () - - initializer - let rec build_initial_tree dir = - let dir_handle = opendir dir in - let cont = ref true in - while (!cont) do - try - let curfile = readdir dir_handle in - let fqp = String.concat "/" [dir;curfile] in - if (Str.string_match !file_regexp curfile 0) then - let s = Unix.stat fqp in - begin - match s.st_kind with - | S_DIR -> - this#new_dir fqp this#handle_dir_event; - build_initial_tree fqp; - | S_REG -> - this#new_script fqp - | _ -> - printf "Don't know what to do with %s\n" curfile;flush Pervasives.stdout - end - with - _->cont:=false;() - done - in - begin - build_initial_tree dir_root; - Dirwatcher.add_watch dir_root [S_Create;S_Delete] (Some(this#handle_dir_event)); - end -end + with _ -> + fprintf logfd "Could not create %s. Looks like a slice shot itself in the foot\n" fqp;flush logfd; + ) + slice_list + + (** Somebody copied in a new script *) + (* XXX Race condition here *) + method private new_script slice_list fqp = + let s = Unix.stat fqp in + List.iter (fun frontend-> + frontend#mkentry (mk_rel_path fqp) fqp (s.st_perm)) slice_list + + method private make_filter acl_fqp = + let filter = Hashtbl.create 16 in + try + let acl_file = open_in acl_fqp in + let rec read_acl cur_filter = + let next_item = + try Some(input_line acl_file) + with _ -> None + in + match next_item with + | None -> close_in acl_file;cur_filter + | Some(item) -> + Hashtbl.add cur_filter item true; + read_acl cur_filter + in + Some(read_acl filter) + with _ -> + None + + method is_acl fname = Str.string_match acl_file_regexp fname 0 + + (** Gets called every time there's an inotify event at the backend + @param dirname Name of the backend directory + @param evlist Description of what happened + @param fname Name of the file that the event applies to + *) + method handle_dir_event _ dirname evlist fname = + let fqp = String.concat "/" [dirname;fname] in + if ((Str.string_match file_regexp fname 0) && not (Str.string_match acl_file_regexp fname 0)) then + begin + (* Filter frontend list based on acl *) + let acl_fqp = String.concat "." [fqp;"acl"] in + let acl_filter = this#make_filter acl_fqp in + let slice_list = + match acl_filter with + | None -> frontend_lst + | Some(filter) -> List.filter (fun fe->Hashtbl.mem filter (fe#get_slice_name ())) frontend_lst + in + let is_event = list_check evlist in + if (is_event Create) then + begin + if (is_event Isdir) then + begin + this#new_dir slice_list fqp this#handle_dir_event + end + else + (* It's a new script *) + begin + (* + if (Str.string_match dir_regexp fname 0) then + let fqp = String.concat "/" [dirname;String.sub fname 4 ((String.length fname)-4+1)] in + let real_fqp = String.concat "/" [dirname;fname] in + this#new_dir fqp this#handle_spool_event; + Hashtbl.add spools fqp real_fqp + else*) + this#new_script slice_list fqp + end + end + else if (is_event Delete) then + begin + if (is_event Isdir) then + begin + (*this#rm_watch fqp;*) + List.iter (fun frontend-> + frontend#rmdir (mk_rel_path fqp)) slice_list + end + else List.iter (fun frontend -> + frontend#unlink (mk_rel_path fqp)) slice_list + end + end + else (* regex not matched *) + () + + (** Initializer - build the initial tree based on the contents of /vsys *) + initializer + let rec build_initial_tree dir = + let dir_handle = opendir dir in + let cont = ref true in + while (!cont) do + try + let curfile = readdir dir_handle in + if (not (this#is_acl curfile)) then + begin + let fqp = String.concat "/" [dir;curfile] in + let acl_fqp = String.concat "." [fqp;"acl"] in + let acl_filter = this#make_filter acl_fqp in + let slice_list = + match acl_filter with + | None -> frontend_lst + | Some(filter) -> List.filter (fun fe->Hashtbl.mem filter (fe#get_slice_name ())) frontend_lst + in + if (Str.string_match file_regexp curfile 0) then + let s = Unix.stat fqp in + begin + match s.st_kind with + | S_DIR -> + this#new_dir slice_list fqp this#handle_dir_event; + build_initial_tree fqp; + | S_REG -> + this#new_script slice_list fqp + | _ -> + fprintf logfd "Don't know what to do with %s\n" curfile;flush logfd + end + end + with _ + ->cont:=false;() + done + in + begin + build_initial_tree dir_root; + Dirwatcher.add_watch dir_root [S_Create;S_Delete] (this#handle_dir_event); + end + end