| // Copyright 2014 The Crashpad Authors. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include <mach-o/getsect.h> |
| |
| // This is only necessary when building code that might run on systems earlier |
| // than 10.7. When building for 10.7 or later, getsectiondata() and |
| // getsegmentdata() are always present in libmacho and made available through |
| // libSystem. When building for earlier systems, custom definitions of |
| // these functions are needed. |
| // |
| // This file checks the deployment target instead of the SDK. The deployment |
| // target is correct because it identifies the earliest possible system that |
| // the code being compiled is expected to run on. |
| |
| #if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_7 |
| |
| #include <dlfcn.h> |
| #include <stddef.h> |
| |
| #include "third_party/apple_cctools/cctools/include/mach-o/getsect.h" |
| |
| namespace { |
| |
| // Returns a dlopen() handle to the same library that provides the |
| // getsectbyname() function. getsectbyname() is always present in libmacho. |
| // getsectiondata() and getsegmentdata() are not always present, but when they |
| // are, they’re in the same library as getsectbyname(). If the library cannot |
| // be found or a handle to it cannot be returned, returns nullptr. |
| void* SystemLibMachOHandle() { |
| Dl_info info; |
| if (!dladdr(reinterpret_cast<void*>(getsectbyname), &info)) { |
| return nullptr; |
| } |
| return dlopen(info.dli_fname, RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); |
| } |
| |
| // Returns a function pointer to a function in libmacho based on a lookup of |
| // that function by symbol name. Returns nullptr if libmacho cannot be found or |
| // opened, or if the named symbol cannot be found in libmacho. |
| void* LookUpSystemLibMachOSymbol(const char* symbol) { |
| static void* dl_handle = SystemLibMachOHandle(); |
| if (!dl_handle) { |
| return nullptr; |
| } |
| return dlsym(dl_handle, symbol); |
| } |
| |
| #ifndef __LP64__ |
| using MachHeader = mach_header; |
| #else |
| using MachHeader = mach_header_64; |
| #endif |
| |
| using GetSectionDataType = |
| uint8_t*(*)(const MachHeader*, const char*, const char*, unsigned long*); |
| using GetSegmentDataType = |
| uint8_t*(*)(const MachHeader*, const char*, unsigned long*); |
| |
| } // namespace |
| |
| extern "C" { |
| |
| // These implementations look up their functions in libmacho at run time. If the |
| // system libmacho provides these functions as it normally does on OS X 10.7 and |
| // later, the system’s versions are used directly. Otherwise, the versions in |
| // third_party/apple_cctools are used, which are actually just copies of the |
| // system’s functions. |
| |
| uint8_t* getsectiondata(const MachHeader* mhp, |
| const char* segname, |
| const char* sectname, |
| unsigned long* size) { |
| static GetSectionDataType system_getsectiondata = |
| reinterpret_cast<GetSectionDataType>( |
| LookUpSystemLibMachOSymbol("getsectiondata")); |
| if (system_getsectiondata) { |
| return system_getsectiondata(mhp, segname, sectname, size); |
| } |
| return crashpad_getsectiondata(mhp, segname, sectname, size); |
| } |
| |
| uint8_t* getsegmentdata( |
| const MachHeader* mhp, const char* segname, unsigned long* size) { |
| static GetSegmentDataType system_getsegmentdata = |
| reinterpret_cast<GetSegmentDataType>( |
| LookUpSystemLibMachOSymbol("getsegmentdata")); |
| if (system_getsegmentdata) { |
| return system_getsegmentdata(mhp, segname, size); |
| } |
| return crashpad_getsegmentdata(mhp, segname, size); |
| } |
| |
| } // extern "C" |
| |
| #endif // MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_7 |