diff -r 000000000000 -r 6474c204b198 xpcom/build/Omnijar.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/build/Omnijar.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,169 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "Omnijar.h"
+
+#include "nsDirectoryService.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsIFile.h"
+#include "nsZipArchive.h"
+#include "nsNetUtil.h"
+
+namespace mozilla {
+
+nsIFile *Omnijar::sPath[2] = { nullptr, nullptr };
+nsZipArchive *Omnijar::sReader[2] = { nullptr, nullptr };
+bool Omnijar::sInitialized = false;
+static bool sIsUnified = false;
+static bool sIsNested[2] = { false, false };
+
+static const char *sProp[2] =
+    { NS_GRE_DIR, NS_XPCOM_CURRENT_PROCESS_DIR };
+
+#define SPROP(Type) ((Type == mozilla::Omnijar::GRE) ? sProp[GRE] : sProp[APP])
+
+void
+Omnijar::CleanUpOne(Type aType)
+{
+    if (sReader[aType]) {
+        sReader[aType]->CloseArchive();
+        NS_IF_RELEASE(sReader[aType]);
+    }
+    sReader[aType] = nullptr;
+    NS_IF_RELEASE(sPath[aType]);
+}
+
+void
+Omnijar::InitOne(nsIFile *aPath, Type aType)
+{
+    nsCOMPtr<nsIFile> file;
+    if (aPath) {
+        file = aPath;
+    } else {
+        nsCOMPtr<nsIFile> dir;
+        nsDirectoryService::gService->Get(SPROP(aType), NS_GET_IID(nsIFile), getter_AddRefs(dir));
+        NS_NAMED_LITERAL_CSTRING (kOmnijarName, NS_STRINGIFY(OMNIJAR_NAME));
+        if (NS_FAILED(dir->Clone(getter_AddRefs(file))) ||
+            NS_FAILED(file->AppendNative(kOmnijarName)))
+            return;
+    }
+    bool isFile;
+    if (NS_FAILED(file->IsFile(&isFile)) || !isFile) {
+        // If we're not using an omni.jar for GRE, and we don't have an
+        // omni.jar for APP, check if both directories are the same.
+        if ((aType == APP) && (!sPath[GRE])) {
+            nsCOMPtr<nsIFile> greDir, appDir;
+            bool equals;
+            nsDirectoryService::gService->Get(SPROP(GRE), NS_GET_IID(nsIFile), getter_AddRefs(greDir));
+            nsDirectoryService::gService->Get(SPROP(APP), NS_GET_IID(nsIFile), getter_AddRefs(appDir));
+            if (NS_SUCCEEDED(greDir->Equals(appDir, &equals)) && equals)
+                sIsUnified = true;
+        }
+        return;
+    }
+
+    bool equals;
+    if ((aType == APP) && (sPath[GRE]) &&
+        NS_SUCCEEDED(sPath[GRE]->Equals(file, &equals)) && equals) {
+        // If we're using omni.jar on both GRE and APP and their path
+        // is the same, we're in the unified case.
+        sIsUnified = true;
+        return;
+    }
+
+    nsRefPtr<nsZipArchive> zipReader = new nsZipArchive();
+    if (NS_FAILED(zipReader->OpenArchive(file))) {
+        return;
+    }
+
+    nsRefPtr<nsZipHandle> handle;
+    if (NS_SUCCEEDED(nsZipHandle::Init(zipReader, NS_STRINGIFY(OMNIJAR_NAME), getter_AddRefs(handle)))) {
+        zipReader = new nsZipArchive();
+        if (NS_FAILED(zipReader->OpenArchive(handle)))
+            return;
+        sIsNested[aType] = true;
+    }
+
+    CleanUpOne(aType);
+    sReader[aType] = zipReader;
+    NS_IF_ADDREF(sReader[aType]);
+    sPath[aType] = file;
+    NS_IF_ADDREF(sPath[aType]);
+}
+
+void
+Omnijar::Init(nsIFile *aGrePath, nsIFile *aAppPath)
+{
+    InitOne(aGrePath, GRE);
+    InitOne(aAppPath, APP);
+    sInitialized = true;
+}
+
+void
+Omnijar::CleanUp()
+{
+    CleanUpOne(GRE);
+    CleanUpOne(APP);
+    sInitialized = false;
+}
+
+already_AddRefed<nsZipArchive>
+Omnijar::GetReader(nsIFile *aPath)
+{
+    NS_ABORT_IF_FALSE(IsInitialized(), "Omnijar not initialized");
+
+    bool equals;
+    nsresult rv;
+
+    if (sPath[GRE] && !sIsNested[GRE]) {
+        rv = sPath[GRE]->Equals(aPath, &equals);
+        if (NS_SUCCEEDED(rv) && equals)
+            return GetReader(GRE);
+    }
+    if (sPath[APP] && !sIsNested[APP]) {
+        rv = sPath[APP]->Equals(aPath, &equals);
+        if (NS_SUCCEEDED(rv) && equals)
+            return GetReader(APP);
+    }
+    return nullptr;
+}
+
+nsresult
+Omnijar::GetURIString(Type aType, nsACString &result)
+{
+    NS_ABORT_IF_FALSE(IsInitialized(), "Omnijar not initialized");
+
+    result.Truncate();
+
+    // Return an empty string for APP in the unified case.
+    if ((aType == APP) && sIsUnified) {
+        return NS_OK;
+    }
+
+    nsAutoCString omniJarSpec;
+    if (sPath[aType]) {
+        nsresult rv = NS_GetURLSpecFromActualFile(sPath[aType], omniJarSpec);
+        if (NS_WARN_IF(NS_FAILED(rv)))
+            return rv;
+
+        result = "jar:";
+        if (sIsNested[aType])
+            result += "jar:";
+        result += omniJarSpec;
+        result += "!";
+        if (sIsNested[aType])
+            result += "/" NS_STRINGIFY(OMNIJAR_NAME) "!";
+    } else {
+        nsCOMPtr<nsIFile> dir;
+        nsDirectoryService::gService->Get(SPROP(aType), NS_GET_IID(nsIFile), getter_AddRefs(dir));
+        nsresult rv = NS_GetURLSpecFromActualFile(dir, result);
+        if (NS_WARN_IF(NS_FAILED(rv)))
+            return rv;
+    }
+    result += "/";
+    return NS_OK;
+}
+
+} /* namespace mozilla */