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https://github.com/encounter/engine.git
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sjindel-google
104 lines
4.0 KiB
C++
104 lines
4.0 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// It is __imperative__ that the functions in this file are __not__ included in
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// release or profile builds.
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//
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// They call into the "private" ptrace() API to ensure that the current process
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// is being ptrace()-d. Only debug builds rely on ptrace(), and the ptrace() API
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// is not allowed for use in the App Store, so we must exclude it from profile-
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// and release-builds.
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//
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// When an app is launched from a host workstation (e.g. via Xcode or
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// "ios-deploy"), the process is already ptrace()-d by debugserver. However,
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// when an app is launched from the home screen, it is not, so for debug builds
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// we initialize the ptrace() relationship via PT_TRACE_ME if necessary.
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//
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// Please see the following documents for more details:
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// - go/decommissioning-dbc
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// - go/decommissioning-dbc-engine
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// - go/decommissioning-dbc-tools
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#include "flutter/common/settings.h"
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#include "flutter/fml/build_config.h" // For OS_IOS.
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#if OS_IOS && (FLUTTER_RUNTIME_MODE == FLUTTER_RUNTIME_MODE_DEBUG)
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// These headers should only be needed in debug mode.
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#include <sys/sysctl.h>
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#include <sys/types.h>
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#define PT_TRACE_ME 0
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#define PT_SIGEXC 12
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extern "C" int ptrace(int request, pid_t pid, caddr_t addr, int data);
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static bool DebuggedIOS(const flutter::Settings& vm_settings) {
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// Only the Flutter CLI passes "--enable-checked-mode". Therefore, if the flag
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// is present, we have been launched by "ios-deploy" via "debugserver".
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//
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// We choose this flag because it is always passed to launch debug builds.
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if (vm_settings.enable_checked_mode) {
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return true;
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}
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// Use "sysctl()" to check if we're currently being debugged (e.g. by Xcode).
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// We could also check "getppid() != 1" (launchd), but this is more direct.
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const pid_t self = getpid();
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int mib[5] = {CTL_KERN, KERN_PROC, KERN_PROC_PID, self, 0};
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auto proc = std::make_unique<struct kinfo_proc>();
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size_t proc_size = sizeof(struct kinfo_proc);
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if (sysctl(mib, 4, proc.get(), &proc_size, nullptr, 0) < 0) {
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FML_LOG(ERROR) << "Could not execute sysctl() to get current process info: "
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<< strerror(errno);
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return false;
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}
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return proc->kp_proc.p_flag & P_TRACED;
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}
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void EnsureDebuggedIOS(const flutter::Settings& vm_settings) {
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if (DebuggedIOS(vm_settings)) {
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return;
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}
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if (ptrace(PT_TRACE_ME, 0, nullptr, 0) == -1) {
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FML_LOG(ERROR) << "Could not call ptrace(PT_TRACE_ME): " << strerror(errno);
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// No use trying PT_SIGEXC -- it's only needed if PT_TRACE_ME succeeds.
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return;
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}
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if (ptrace(PT_SIGEXC, 0, nullptr, 0) == -1) {
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FML_LOG(ERROR) << "Could not call ptrace(PT_SIGEXC): " << strerror(errno);
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}
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// The previous operation causes this process to not be reaped after it
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// terminates (even if PT_SIGEXC fails). Issue a warning to the console every
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// (approximiately) maxproc/10 leaks. See the links above for an explanation
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// of this issue.
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size_t maxproc = 0;
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size_t maxproc_size = sizeof(size_t);
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const int sysctl_result =
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sysctlbyname("kern.maxproc", &maxproc, &maxproc_size, nullptr, 0);
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if (sysctl_result < 0) {
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FML_LOG(ERROR)
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<< "Could not execute sysctl() to determine process count limit: "
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<< strerror(errno);
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}
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const char* warning =
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"Launching a debug-mode app from the home screen may cause problems.\n"
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"Please compile a profile-/release-build, launch your app via \"flutter "
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"run\", or see https://github.com/flutter/flutter/wiki/"
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"PID-leak-in-iOS-debug-builds-launched-from-home-screen for details.";
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if (vm_settings.verbose_logging // used for testing and also informative
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|| sysctl_result < 0 // could not determine maximum process count
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|| maxproc / 10 == 0 // avoid division (%) by 0
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|| getpid() % (maxproc / 10) == 0) // warning every ~maxproc/10 leaks
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{
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FML_LOG(ERROR) << warning;
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}
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}
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#endif // OS_IOS && (FLUTTER_RUNTIME_MODE == FLUTTER_RUNTIME_MODE_DEBUG)
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