Bug 1165162 - Introduce a helper for converting from origin strings t…

…o a principal. rpending=Yoshi

I didn't end up needing this in bug, but I think it's handy to have around.

caps/tests/unit/test_origin.js

@@ -3,9 +3,16 @@ const Ci = Components.interfaces;
 const Cu = Components.utils;
 
 Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/BrowserUtils.jsm");
 var ssm = Services.scriptSecurityManager;
 function makeURI(uri) { return Services.io.newURI(uri, null, null); }
 
+function checkThrows(f) {
+  var threw = false;
+  try { f(); } catch (e) { threw = true }
+  do_check_true(threw);
+}
+
 function checkCrossOrigin(a, b) {
   do_check_false(a.equals(b));
   do_check_false(a.equalsConsideringDomain(b));
@@ -22,6 +29,11 @@ function checkOriginAttributes(prin, appId, inBrowser, suffix) {
   do_check_eq(prin.originAttributes.appId, appId || 0);
   do_check_eq(prin.originAttributes.inBrowser, inBrowser || false);
   do_check_eq(prin.originSuffix, suffix || '');
+  if (!prin.isNullPrincipal && !prin.origin.startsWith('[')) {
+    do_check_true(BrowserUtils.principalFromOrigin(prin.origin).equals(prin));
+  } else {
+    checkThrows(() => BrowserUtils.principalFromOrigin(prin.origin));
+  }
 }
 
 function run_test() {

toolkit/modules/BrowserUtils.jsm

@@ -10,6 +10,7 @@ this.EXPORTED_SYMBOLS = [ "BrowserUtils" ];
 const {interfaces: Ci, utils: Cu, classes: Cc} = Components;
 
 Cu.import("resource://gre/modules/Services.jsm");
+Cu.importGlobalProperties(['URL']);
 
 this.BrowserUtils = {
 
@@ -93,6 +94,30 @@ this.BrowserUtils = {
     return Services.io.newURI(aCPOWURI.spec, aCPOWURI.originCharset, null);
   },
 
+  // Creates a codebase principal from a canonical origin string. This is the
+  // the inverse operation of .origin on a codebase principal.
+  principalFromOrigin: function(aOriginString) {
+    if (aOriginString.startsWith('[')) {
+      throw new Error("principalFromOrigin does not support System and Expanded principals");
+    }
+
+    if (aOriginString.startsWith("moz-nullprincipal:")) {
+      throw new Error("principalFromOrigin does not support nsNullPrincipal");
+    }
+
+    var parts = aOriginString.split('!');
+    if (parts.length > 2) {
+      throw new Error("bad origin string: " + aOriginString);
+    }
+
+    var uri = Services.io.newURI(parts[0], null, null);
+    var attrs = {};
+    // Parse the parameters string into a dictionary.
+    (parts[1] || "").split("&").map((x) => x.split('=')).forEach((x) => attrs[x[0]] = x[1]);
+
+    return Services.scriptSecurityManager.createCodebasePrincipal(uri, attrs);
+  },
+
   /**
    * For a given DOM element, returns its position in "screen"
    * coordinates. In a content process, the coordinates returned will