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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/files/file_path.h"
     11 #include "base/files/file_util.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 NativeLibrary LoadNativeLibrary(const base::FilePath& library_path,
     50                                 NativeLibraryLoadError* error) {
     51   // dlopen() etc. open the file off disk.
     52   if (library_path.Extension() == "dylib" || !DirectoryExists(library_path)) {
     53     void* dylib = dlopen(library_path.value().c_str(), RTLD_LAZY);
     54     if (!dylib) {
     55       error->message = dlerror();
     56       return NULL;
     57     }
     58     NativeLibrary native_lib = new NativeLibraryStruct();
     59     native_lib->type = DYNAMIC_LIB;
     60     native_lib->dylib = dylib;
     61     native_lib->objc_status = OBJC_UNKNOWN;
     62     return native_lib;
     63   }
     64   base::ScopedCFTypeRef<CFURLRef> url(CFURLCreateFromFileSystemRepresentation(
     65       kCFAllocatorDefault,
     66       (const UInt8*)library_path.value().c_str(),
     67       library_path.value().length(),
     68       true));
     69   if (!url)
     70     return NULL;
     71   CFBundleRef bundle = CFBundleCreate(kCFAllocatorDefault, url.get());
     72   if (!bundle)
     73     return NULL;
     74 
     75   NativeLibrary native_lib = new NativeLibraryStruct();
     76   native_lib->type = BUNDLE;
     77   native_lib->bundle = bundle;
     78   native_lib->bundle_resource_ref = CFBundleOpenBundleResourceMap(bundle);
     79   native_lib->objc_status = OBJC_UNKNOWN;
     80   return native_lib;
     81 }
     82 
     83 // static
     84 void UnloadNativeLibrary(NativeLibrary library) {
     85   if (library->objc_status == OBJC_NOT_PRESENT) {
     86     if (library->type == BUNDLE) {
     87       CFBundleCloseBundleResourceMap(library->bundle,
     88                                      library->bundle_resource_ref);
     89       CFRelease(library->bundle);
     90     } else {
     91       dlclose(library->dylib);
     92     }
     93   } else {
     94     VLOG(2) << "Not unloading NativeLibrary because it may contain an ObjC "
     95                "segment. library->objc_status = " << library->objc_status;
     96     // Deliberately do not CFRelease the bundle or dlclose the dylib because
     97     // doing so can corrupt the ObjC runtime method caches. See
     98     // http://crbug.com/172319 for details.
     99   }
    100   delete library;
    101 }
    102 
    103 // static
    104 void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
    105                                           const char* name) {
    106   void* function_pointer = NULL;
    107 
    108   // Get the function pointer using the right API for the type.
    109   if (library->type == BUNDLE) {
    110     base::ScopedCFTypeRef<CFStringRef> symbol_name(CFStringCreateWithCString(
    111         kCFAllocatorDefault, name, kCFStringEncodingUTF8));
    112     function_pointer = CFBundleGetFunctionPointerForName(library->bundle,
    113                                                          symbol_name);
    114   } else {
    115     function_pointer = dlsym(library->dylib, name);
    116   }
    117 
    118   // If this library hasn't been tested for having ObjC, use the function
    119   // pointer to look up the section information for the library.
    120   if (function_pointer && library->objc_status == OBJC_UNKNOWN)
    121     library->objc_status = GetObjCStatusForImage(function_pointer);
    122 
    123   return function_pointer;
    124 }
    125 
    126 // static
    127 string16 GetNativeLibraryName(const string16& name) {
    128   return name + ASCIIToUTF16(".dylib");
    129 }
    130 
    131 }  // namespace base
    132