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952f787f4a
Use “macOS” as the generic unversioned name of the operating system in comments. For version-specific references, use Mac OS X through 10.6, OS X from 10.7 through 10.11, and macOS for 10.12. Change-Id: I1ebee64fbf79200bc799d4a351725dd73257b54d Reviewed-on: https://chromium-review.googlesource.com/408269 Reviewed-by: Robert Sesek <rsesek@chromium.org>
108 lines
3.9 KiB
C++
108 lines
3.9 KiB
C++
// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <mach-o/getsect.h>
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// This is only necessary when building code that might run on systems earlier
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// than 10.7. When building for 10.7 or later, getsectiondata() and
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// getsegmentdata() are always present in libmacho and made available through
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// libSystem. When building for earlier systems, custom definitions of
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// these functions are needed.
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//
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// This file checks the deployment target instead of the SDK. The deployment
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// target is correct because it identifies the earliest possible system that
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// the code being compiled is expected to run on.
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#if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_7
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#include <dlfcn.h>
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#include <stddef.h>
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#include "third_party/apple_cctools/cctools/include/mach-o/getsect.h"
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namespace {
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// Returns a dlopen() handle to the same library that provides the
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// getsectbyname() function. getsectbyname() is always present in libmacho.
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// getsectiondata() and getsegmentdata() are not always present, but when they
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// are, they’re in the same library as getsectbyname(). If the library cannot
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// be found or a handle to it cannot be returned, returns nullptr.
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void* SystemLibMachOHandle() {
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Dl_info info;
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if (!dladdr(reinterpret_cast<void*>(getsectbyname), &info)) {
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return nullptr;
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}
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return dlopen(info.dli_fname, RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
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}
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// Returns a function pointer to a function in libmacho based on a lookup of
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// that function by symbol name. Returns nullptr if libmacho cannot be found or
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// opened, or if the named symbol cannot be found in libmacho.
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void* LookUpSystemLibMachOSymbol(const char* symbol) {
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static void* dl_handle = SystemLibMachOHandle();
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if (!dl_handle) {
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return nullptr;
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}
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return dlsym(dl_handle, symbol);
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}
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#ifndef __LP64__
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using MachHeader = mach_header;
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#else
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using MachHeader = mach_header_64;
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#endif
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using GetSectionDataType =
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uint8_t*(*)(const MachHeader*, const char*, const char*, unsigned long*);
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using GetSegmentDataType =
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uint8_t*(*)(const MachHeader*, const char*, unsigned long*);
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} // namespace
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extern "C" {
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// These implementations look up their functions in libmacho at run time. If the
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// system libmacho provides these functions as it normally does on OS X 10.7 and
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// later, the system’s versions are used directly. Otherwise, the versions in
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// third_party/apple_cctools are used, which are actually just copies of the
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// system’s functions.
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uint8_t* getsectiondata(const MachHeader* mhp,
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const char* segname,
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const char* sectname,
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unsigned long* size) {
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static GetSectionDataType system_getsectiondata =
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reinterpret_cast<GetSectionDataType>(
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LookUpSystemLibMachOSymbol("getsectiondata"));
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if (system_getsectiondata) {
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return system_getsectiondata(mhp, segname, sectname, size);
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}
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return crashpad_getsectiondata(mhp, segname, sectname, size);
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}
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uint8_t* getsegmentdata(
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const MachHeader* mhp, const char* segname, unsigned long* size) {
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static GetSegmentDataType system_getsegmentdata =
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reinterpret_cast<GetSegmentDataType>(
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LookUpSystemLibMachOSymbol("getsegmentdata"));
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if (system_getsegmentdata) {
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return system_getsegmentdata(mhp, segname, size);
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}
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return crashpad_getsegmentdata(mhp, segname, size);
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}
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} // extern "C"
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#endif // MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_7
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