Library loading fallback.

base/android/linker/linker_jni.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This is the Android-specific Chromium linker, a tiny shared library
 // implementing a custom dynamic linker that can be used to load the
 // real Chromium libraries (e.g. libcontentshell.so).
 
 // The main point of this linker is to be able to share the RELRO
 // section of libcontentshell.so (or equivalent) between the browser and
@@ skipping 558 matching lines @@
       mmap(NULL, bytes, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   if (address == MAP_FAILED) {
     LOG_INFO("%s: Random base load address not determinable\n", __FUNCTION__);
     return 0;
   }
   munmap(address, bytes);
   LOG_INFO("%s: Random base load address is %p\n", __FUNCTION__, address);
   return static_cast<jlong>(reinterpret_cast<uintptr_t>(address));
 }
 
+// Maximum filename length of a file in a zip file.
+// Note(petrcermak): The same constant is defined in
+// crazy_linker_library_list.cpp.
+const size_t kMaxFilenameInZip = 256;

[rmcilroy, 2014/10/29 17:20:44]

Could we just export this in crazy_linker.h instead of duplicating it?

[petrcermak, 2014/10/30 19:55:07]

Done. I moved the constant to crazy_linker.h so crazy_linker_library_list.cpp
now includes "<crazy_linker.h>". If we wanted to avoid this, we would probably
need to add a new header file (e.g. "crazy_linker_constants.h").

+
+// Get the full filename of a library in the zip file
+// (lib/<abi>/crazy.<lib_name>).
+//
+// |env| is the current JNI environment handle.
+// |clazz| is the static class handle which is not used here.
+// |lib_name| is the library base name.
+// Returns the full filename (or empty string on failure).
+jstring GetLibraryFilenameInZipFile(JNIEnv* env,
+                                    jclass clazz,
+                                    jstring lib_name) {
+  String lib_name_str(env, lib_name);
+  const char* lib_name_c_str = lib_name_str.c_str();
+  char buffer[kMaxFilenameInZip + 1];
+  if (CRAZY_STATUS_SUCCESS != crazy_library_filename_in_zip_file(
+          lib_name_c_str, buffer, sizeof(buffer))) {

[picksi1, 2014/10/30 10:48:08]

Are the backwards <constant>!=<variable> part of the coding standards? They're
less intuitive to read.

Also != SUCCESS is confusing. Is this a binary enum, i.e. can we do == FAILURE
instead?

[petrcermak, 2014/10/30 19:55:07]

Done.

+    LOG_ERROR("%s: Failed to get full filename for library '%s'",
+              __FUNCTION__, lib_name_c_str);
+    buffer[0] = '\0';
+  }
+  return env->NewStringUTF(buffer);
+}
+
 // Check whether the device supports loading a library directly from the APK
 // file.
 //
 // |env| is the current JNI environment handle.
 // |clazz| is the static class handle which is not used here.
 // |apkfile_name| is the filename of the APK.
 // Returns true if supported.
 jboolean CheckLibraryLoadFromApkSupport(JNIEnv* env, jclass clazz,
                                         jstring apkfile_name) {
   String apkfile_name_str(env, apkfile_name);
@@ skipping 90 matching lines @@
      "("
      ")"
      "Z",
      reinterpret_cast<void*>(&CanUseSharedRelro)},
     {"nativeGetRandomBaseLoadAddress",
      "("
      "J"
      ")"
      "J",
      reinterpret_cast<void*>(&GetRandomBaseLoadAddress)},
-     {"nativeCheckLibraryLoadFromApkSupport",
-      "("
-      "Ljava/lang/String;"
-      ")"
-      "Z",
-      reinterpret_cast<void*>(&CheckLibraryLoadFromApkSupport)},
-     {"nativeCheckLibraryAlignedInApk",
-      "("
-      "Ljava/lang/String;"
-      "Ljava/lang/String;"
-      ")"
-      "Z",
-      reinterpret_cast<void*>(&CheckLibraryAlignedInApk)}, };
+    {"nativeGetLibraryFilenameInZipFile",
+     "("
+     "Ljava/lang/String;"
+     ")"
+     "Ljava/lang/String;",
+     reinterpret_cast<void*>(&GetLibraryFilenameInZipFile)},
+    {"nativeCheckLibraryLoadFromApkSupport",
+     "("
+     "Ljava/lang/String;"
+     ")"
+     "Z",
+     reinterpret_cast<void*>(&CheckLibraryLoadFromApkSupport)},
+    {"nativeCheckLibraryAlignedInApk",
+     "("
+     "Ljava/lang/String;"
+     "Ljava/lang/String;"
+     ")"
+     "Z",
+     reinterpret_cast<void*>(&CheckLibraryAlignedInApk)}, };
 
 }  // namespace
 
 // JNI_OnLoad() hook called when the linker library is loaded through
 // the regular System.LoadLibrary) API. This shall save the Java VM
 // handle and initialize LibInfo fields.
 jint JNI_OnLoad(JavaVM* vm, void* reserved) {
   LOG_INFO("%s: Entering", __FUNCTION__);
   // Get new JNIEnv
   JNIEnv* env;
@@ skipping 30 matching lines @@
   crazy_context_t* context = GetCrazyContext();
   crazy_context_set_java_vm(context, vm, JNI_VERSION_1_4);
 
   // Register the function that the crazy linker can call to post code
   // for later execution.
   crazy_context_set_callback_poster(context, &PostForLaterExecution, NULL);
 
   LOG_INFO("%s: Done", __FUNCTION__);
   return JNI_VERSION_1_4;
 }