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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/native_library.h"
      6 
      7 #include <dlfcn.h>
      8 #include <mach-o/getsect.h>
      9 
     10 #include "base/file_util.h"
     11 #include "base/files/file_path.h"
     12 #include "base/logging.h"
     13 #include "base/mac/scoped_cftyperef.h"
     14 #include "base/strings/string_util.h"
     15 #include "base/strings/utf_string_conversions.h"
     16 #include "base/threading/thread_restrictions.h"
     17 
     18 namespace base {
     19 
     20 static NativeLibraryObjCStatus GetObjCStatusForImage(
     21     const void* function_pointer) {
     22   Dl_info info;
     23   if (!dladdr(function_pointer, &info))
     24     return OBJC_UNKNOWN;
     25 
     26   // See if the the image contains an "ObjC image info" segment. This method
     27   // of testing is used in _CFBundleGrokObjcImageInfoFromFile in
     28   // CF-744/CFBundle.c, around lines 2447-2474.
     29   //
     30   // In 32-bit images, ObjC can be recognized in __OBJC,__image_info, whereas
     31   // in 64-bit, the data is in __DATA,__objc_imageinfo.
     32 #if __LP64__
     33   const section_64* section = getsectbynamefromheader_64(
     34       reinterpret_cast<const struct mach_header_64*>(info.dli_fbase),
     35       SEG_DATA, "__objc_imageinfo");
     36 #else
     37   const section* section = getsectbynamefromheader(
     38       reinterpret_cast<const struct mach_header*>(info.dli_fbase),
     39       SEG_OBJC, "__image_info");
     40 #endif
     41   return section == NULL ? OBJC_NOT_PRESENT : OBJC_PRESENT;
     42 }
     43 
     44 std::string NativeLibraryLoadError::ToString() const {
     45   return message;
     46 }
     47 
     48 // static
     49 // TODO(xhwang): Fill |error|. See http://crbug.com/353771
     50 NativeLibrary LoadNativeLibrary(const base::FilePath& library_path,
     51                                 NativeLibraryLoadError* /* error */) {
     52   // dlopen() etc. open the file off disk.
     53   if (library_path.Extension() == "dylib" || !DirectoryExists(library_path)) {
     54     void* dylib = dlopen(library_path.value().c_str(), RTLD_LAZY);
     55     if (!dylib)
     56       return NULL;
     57     NativeLibrary native_lib = new NativeLibraryStruct();
     58     native_lib->type = DYNAMIC_LIB;
     59     native_lib->dylib = dylib;
     60     native_lib->objc_status = OBJC_UNKNOWN;
     61     return native_lib;
     62   }
     63   base::ScopedCFTypeRef<CFURLRef> url(CFURLCreateFromFileSystemRepresentation(
     64       kCFAllocatorDefault,
     65       (const UInt8*)library_path.value().c_str(),
     66       library_path.value().length(),
     67       true));
     68   if (!url)
     69     return NULL;
     70   CFBundleRef bundle = CFBundleCreate(kCFAllocatorDefault, url.get());
     71   if (!bundle)
     72     return NULL;
     73 
     74   NativeLibrary native_lib = new NativeLibraryStruct();
     75   native_lib->type = BUNDLE;
     76   native_lib->bundle = bundle;
     77   native_lib->bundle_resource_ref = CFBundleOpenBundleResourceMap(bundle);
     78   native_lib->objc_status = OBJC_UNKNOWN;
     79   return native_lib;
     80 }
     81 
     82 // static
     83 void UnloadNativeLibrary(NativeLibrary library) {
     84   if (library->objc_status == OBJC_NOT_PRESENT) {
     85     if (library->type == BUNDLE) {
     86       CFBundleCloseBundleResourceMap(library->bundle,
     87                                      library->bundle_resource_ref);
     88       CFRelease(library->bundle);
     89     } else {
     90       dlclose(library->dylib);
     91     }
     92   } else {
     93     VLOG(2) << "Not unloading NativeLibrary because it may contain an ObjC "
     94                "segment. library->objc_status = " << library->objc_status;
     95     // Deliberately do not CFRelease the bundle or dlclose the dylib because
     96     // doing so can corrupt the ObjC runtime method caches. See
     97     // http://crbug.com/172319 for details.
     98   }
     99   delete library;
    100 }
    101 
    102 // static
    103 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
    104                                           const char* name) {
    105   void* function_pointer = NULL;
    106 
    107   // Get the function pointer using the right API for the type.
    108   if (library->type == BUNDLE) {
    109     base::ScopedCFTypeRef<CFStringRef> symbol_name(CFStringCreateWithCString(
    110         kCFAllocatorDefault, name, kCFStringEncodingUTF8));
    111     function_pointer = CFBundleGetFunctionPointerForName(library->bundle,
    112                                                          symbol_name);
    113   } else {
    114     function_pointer = dlsym(library->dylib, name);
    115   }
    116 
    117   // If this library hasn't been tested for having ObjC, use the function
    118   // pointer to look up the section information for the library.
    119   if (function_pointer && library->objc_status == OBJC_UNKNOWN)
    120     library->objc_status = GetObjCStatusForImage(function_pointer);
    121 
    122   return function_pointer;
    123 }
    124 
    125 // static
    126 string16 GetNativeLibraryName(const string16& name) {
    127   return name + ASCIIToUTF16(".dylib");
    128 }
    129 
    130 }  // namespace base
    131