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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
18namespace base {
19
20static 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// static
45NativeLibrary LoadNativeLibrary(const base::FilePath& library_path,
46                                std::string* error) {
47  // dlopen() etc. open the file off disk.
48  if (library_path.Extension() == "dylib" || !DirectoryExists(library_path)) {
49    void* dylib = dlopen(library_path.value().c_str(), RTLD_LAZY);
50    if (!dylib)
51      return NULL;
52    NativeLibrary native_lib = new NativeLibraryStruct();
53    native_lib->type = DYNAMIC_LIB;
54    native_lib->dylib = dylib;
55    native_lib->objc_status = OBJC_UNKNOWN;
56    return native_lib;
57  }
58  base::ScopedCFTypeRef<CFURLRef> url(CFURLCreateFromFileSystemRepresentation(
59      kCFAllocatorDefault,
60      (const UInt8*)library_path.value().c_str(),
61      library_path.value().length(),
62      true));
63  if (!url)
64    return NULL;
65  CFBundleRef bundle = CFBundleCreate(kCFAllocatorDefault, url.get());
66  if (!bundle)
67    return NULL;
68
69  NativeLibrary native_lib = new NativeLibraryStruct();
70  native_lib->type = BUNDLE;
71  native_lib->bundle = bundle;
72  native_lib->bundle_resource_ref = CFBundleOpenBundleResourceMap(bundle);
73  native_lib->objc_status = OBJC_UNKNOWN;
74  return native_lib;
75}
76
77// static
78void UnloadNativeLibrary(NativeLibrary library) {
79  if (library->objc_status == OBJC_NOT_PRESENT) {
80    if (library->type == BUNDLE) {
81      CFBundleCloseBundleResourceMap(library->bundle,
82                                     library->bundle_resource_ref);
83      CFRelease(library->bundle);
84    } else {
85      dlclose(library->dylib);
86    }
87  } else {
88    VLOG(2) << "Not unloading NativeLibrary because it may contain an ObjC "
89               "segment. library->objc_status = " << library->objc_status;
90    // Deliberately do not CFRelease the bundle or dlclose the dylib because
91    // doing so can corrupt the ObjC runtime method caches. See
92    // http://crbug.com/172319 for details.
93  }
94  delete library;
95}
96
97// static
98void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
99                                          const char* name) {
100  void* function_pointer = NULL;
101
102  // Get the function pointer using the right API for the type.
103  if (library->type == BUNDLE) {
104    base::ScopedCFTypeRef<CFStringRef> symbol_name(CFStringCreateWithCString(
105        kCFAllocatorDefault, name, kCFStringEncodingUTF8));
106    function_pointer = CFBundleGetFunctionPointerForName(library->bundle,
107                                                         symbol_name);
108  } else {
109    function_pointer = dlsym(library->dylib, name);
110  }
111
112  // If this library hasn't been tested for having ObjC, use the function
113  // pointer to look up the section information for the library.
114  if (function_pointer && library->objc_status == OBJC_UNKNOWN)
115    library->objc_status = GetObjCStatusForImage(function_pointer);
116
117  return function_pointer;
118}
119
120// static
121string16 GetNativeLibraryName(const string16& name) {
122  return name + ASCIIToUTF16(".dylib");
123}
124
125}  // namespace base
126