Extract archive contents for files in a dir and save to each file's metadata

... only operates on a single directory currently. But this should be enough
of a proof of concept for echicken to work with for now.

Ideally, this would be a feature of addfiles.js and file-uploading via the
terminal server and FTP servers.

exec/inventory_archives.js

+// Extract the archive content listings of a directory and save them to each file's metadata property
+
+"use strict";
+
+var dir_code = argv[0];
+
+function inventory_archives(dir_code, filespec, hash) {
+	var filebase = new FileBase(dir_code);
+	if(!filebase.open()) {
+		alert(filebase.error);
+		return false;
+	}
+	
+	var list = filebase.get_list(filespec, FileBase.DETAIL.METADATA );
+	for(var i in list) {
+		var file = list[i];
+		if(file.metadata !== undefined) {
+			print(file.vpath + " already has metadata");
+			continue;
+		}
+		var metadata = {};
+		try {
+			metadata.archive_contents = Archive(filebase.get_path(file)).list(hash);
+		} catch(e) {
+			print(file.vpath + " is not a supported archive");
+			continue;
+		}
+		file.metadata = JSON.stringify(metadata);
+		if(!filebase.update(file.name, file, /* use_diz_always: */false, /* readd_always: */true))
+			alert("Error updating " + file.vpath);
+		print(file.vpath + " metadata updated");
+	}
+	filebase.close();
+	return true;
+}
+
+inventory_archives(dir_code, "*", argv.indexOf('-hash') >= 0);