Fix race condition in add_outbound_files() causing "Unable to open FLO file".

The directory list is catpured *before* the lock file is "taken", so it can
happen that another process (e.g. instance of binkit) has dealt with one or
more of the files by the time we take the lock and attempt to open the file.

Also, updated error log messages a bit.

exec/binkit.js

@@ -136,7 +136,7 @@ function lock_flow(file)
 		}
 		if (!f.open("wb")) {
 			f.date = orig_date;
-			log(LOG_WARNING, "Error " + f.error + " opening " + f.name);
+			log(LOG_WARNING, "Error " + f.error + " opening lock file: " + f.name);
 			return false;
 		}
 		f.date = now;
@@ -146,7 +146,7 @@ function lock_flow(file)
 	if(!mkpath(ret.bsy.name.slice(0, -file_getname(ret.bsy.name).length)))
 		log(LOG_WARNING, "MKPATH ERROR " + errno + " (" + errno_str + "): " + ret.bsy.name);
 	if (!ret.bsy.open("wb")) {	// Used to include 'e' mode flag (which never worked)
-		log(LOG_WARNING, "Error " + ret.bsy.error + " creating " + ret.bsy.name);
+		log(LOG_WARNING, "Error " + ret.bsy.error + " creating lock file: " + ret.bsy.name);
 		if (!take_lockfile(ret.bsy)) {
 			log(LOG_NOTICE, "Lock on "+ret.bsy.name+" failed.");
 			return undefined;
@@ -219,7 +219,7 @@ function add_outbound_files(addrs, bp)
 				var fnchars = '0123456789abcdefghijklmnopqrstuvwxyz';
 				var fname;
 
-				if(file_isdir(file))
+				if(file_isdir(file) || !file_exists(file))
 					return;
 				var ext = file_getext(file);
 				if (ext !== undefined)
@@ -233,7 +233,7 @@ function add_outbound_files(addrs, bp)
 					case '.ilo':
 						flo = new File(file);
 						if (!flo.open("r")) {
-							log(LOG_ERROR, "Unable to open FLO file '"+flo.name+"': " + flo.error);
+							log(LOG_ERROR, "Error " + flo.error + " opening FLO file: " + flo.name);
 							break;
 						}
 						if (bp.cb_data.binkit_flow_contents[flo.name] === undefined)
@@ -337,7 +337,7 @@ function remove_file(fname)
 	if (file_remove(fname))
 		log(LOG_INFO, "Deleted file: " + fname);
 	else
-		log(LOG_ERROR, "Unable to delete file: " + fname);
+		log(LOG_ERROR, "Error " + errno + " (" + errno_str + ") deleting file: " + fname);
 }
 
 
@@ -406,12 +406,12 @@ function rename_or_move(src, dst_dir, dst_fname)
 		return true;
 	sf = new File(src);
 	if (!sf.open("rb")) {
-		log(LOG_ERR, "Error " + sf.error + " opening " + sf.name);
+		log(LOG_ERR, "Error " + sf.error + " opening source file for move: " + sf.name);
 		return false;
 	}
 	df = new File(dst);
 	if (!df.open("wb")) {		// Used to include 'e' mode flag (which never worked)
-		log(LOG_ERR, "Error " + df.error + " opening " + df.name);
+		log(LOG_ERR, "Error " + df.error + " opening destination file for move: " + df.name);
 		sf.close();
 		return false;
 	}
@@ -554,7 +554,7 @@ function callout_done(bp)
 			// We have some unsent files in here... re-write the flo file...
 			f = new File(key);
 			if (!f.open("r+")) {
-				log(LOG_ERROR, "Unable to update flow file '"+key+"': " + f.error);
+				log(LOG_ERROR, "Error " + f.error + " opening flow file for update: " + key);
 				return;
 			}
 			lines = f.readAll(2048);
@@ -679,7 +679,7 @@ function check_held(addr, scfg, myaddr)
 	if (!f.exists)
 		return false;
 	if (!f.open("r")) {
-		log(LOG_ERROR, "Unable to open hold file '"+f.name+"': " + f.error);
+		log(LOG_ERROR, "Error " + f.error + " opening hold file: " + f.name);
 		return true;
 	}
 	until = f.readln();