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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/debug/debugger.h"
- #include "base/build_config.h"
- #include <errno.h>
- #include <fcntl.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <sys/param.h>
- #include <sys/stat.h>
- #include <sys/types.h>
- #include <unistd.h>
- #include <vector>
- #if defined(__GLIBCXX__)
- #include <cxxabi.h>
- #endif
- #if defined(OS_MACOSX)
- #include <AvailabilityMacros.h>
- #endif
- #if defined(OS_MACOSX) || defined(OS_BSD)
- #include <sys/sysctl.h>
- #endif
- #if defined(OS_FREEBSD)
- #include <sys/user.h>
- #endif
- #include <ostream>
- #include "base/basictypes.h"
- #include "base/logging.h"
- #include "base/memory/scoped_ptr.h"
- #include "base/posix/eintr_wrapper.h"
- #include "base/safe_strerror_posix.h"
- #include "base/strings/string_piece.h"
- #if defined(USE_SYMBOLIZE)
- #include "base/third_party/symbolize/symbolize.h"
- #endif
- #if defined(OS_ANDROID)
- #include "base/threading/platform_thread.h"
- #endif
- namespace base {
- namespace debug {
- #if defined(OS_MACOSX) || defined(OS_BSD)
- // Based on Apple's recommended method as described in
- // http://developer.apple.com/qa/qa2004/qa1361.html
- bool BeingDebugged() {
- // NOTE: This code MUST be async-signal safe (it's used by in-process
- // stack dumping signal handler). NO malloc or stdio is allowed here.
- //
- // While some code used below may be async-signal unsafe, note how
- // the result is cached (see |is_set| and |being_debugged| static variables
- // right below). If this code is properly warmed-up early
- // in the start-up process, it should be safe to use later.
- // If the process is sandboxed then we can't use the sysctl, so cache the
- // value.
- static bool is_set = false;
- static bool being_debugged = false;
- if (is_set)
- return being_debugged;
- // Initialize mib, which tells sysctl what info we want. In this case,
- // we're looking for information about a specific process ID.
- int mib[] = {
- CTL_KERN,
- KERN_PROC,
- KERN_PROC_PID,
- getpid()
- #if defined(OS_OPENBSD)
- , sizeof(struct kinfo_proc),
- 0
- #endif
- };
- // Caution: struct kinfo_proc is marked __APPLE_API_UNSTABLE. The source and
- // binary interfaces may change.
- struct kinfo_proc info;
- size_t info_size = sizeof(info);
- #if defined(OS_OPENBSD)
- if (sysctl(mib, arraysize(mib), NULL, &info_size, NULL, 0) < 0)
- return -1;
- mib[5] = (info_size / sizeof(struct kinfo_proc));
- #endif
- int sysctl_result = sysctl(mib, arraysize(mib), &info, &info_size, NULL, 0);
- DCHECK_EQ(sysctl_result, 0);
- if (sysctl_result != 0) {
- is_set = true;
- being_debugged = false;
- return being_debugged;
- }
- // This process is being debugged if the P_TRACED flag is set.
- is_set = true;
- #if defined(OS_FREEBSD)
- being_debugged = (info.ki_flag & P_TRACED) != 0;
- #elif defined(OS_BSD)
- being_debugged = (info.p_flag & P_TRACED) != 0;
- #else
- being_debugged = (info.kp_proc.p_flag & P_TRACED) != 0;
- #endif
- return being_debugged;
- }
- #elif defined(OS_LINUX) || defined(OS_ANDROID)
- // We can look in /proc/self/status for TracerPid. We are likely used in crash
- // handling, so we are careful not to use the heap or have side effects.
- // Another option that is common is to try to ptrace yourself, but then we
- // can't detach without forking(), and that's not so great.
- // static
- bool BeingDebugged() {
- // NOTE: This code MUST be async-signal safe (it's used by in-process
- // stack dumping signal handler). NO malloc or stdio is allowed here.
- int status_fd = open("/proc/self/status", O_RDONLY);
- if (status_fd == -1)
- return false;
- // We assume our line will be in the first 1024 characters and that we can
- // read this much all at once. In practice this will generally be true.
- // This simplifies and speeds up things considerably.
- char buf[1024];
- ssize_t num_read = HANDLE_EINTR(read(status_fd, buf, sizeof(buf)));
- if (IGNORE_EINTR(close(status_fd)) < 0)
- return false;
- if (num_read <= 0)
- return false;
- StringPiece status(buf, num_read);
- StringPiece tracer("TracerPid:\t");
- StringPiece::size_type pid_index = status.find(tracer);
- if (pid_index == StringPiece::npos)
- return false;
- // Our pid is 0 without a debugger, assume this for any pid starting with 0.
- pid_index += tracer.size();
- return pid_index < status.size() && status[pid_index] != '0';
- }
- #else
- bool BeingDebugged() {
- NOTIMPLEMENTED();
- return false;
- }
- #endif
- // We want to break into the debugger in Debug mode, and cause a crash dump in
- // Release mode. Breakpad behaves as follows:
- //
- // +-------+-----------------+-----------------+
- // | OS | Dump on SIGTRAP | Dump on SIGABRT |
- // +-------+-----------------+-----------------+
- // | Linux | N | Y |
- // | Mac | Y | N |
- // +-------+-----------------+-----------------+
- //
- // Thus we do the following:
- // Linux: Debug mode if a debugger is attached, send SIGTRAP; otherwise send
- // SIGABRT
- // Mac: Always send SIGTRAP.
- #if defined(ARCH_CPU_ARMEL)
- #define DEBUG_BREAK_ASM() asm("bkpt 0")
- #elif defined(ARCH_CPU_ARM64)
- #define DEBUG_BREAK_ASM() asm("brk 0")
- #elif defined(ARCH_CPU_MIPS_FAMILY)
- #define DEBUG_BREAK_ASM() asm("break 2")
- #elif defined(ARCH_CPU_X86_FAMILY)
- #define DEBUG_BREAK_ASM() asm("int3")
- #endif
- #if defined(NDEBUG) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
- #define DEBUG_BREAK() abort()
- #elif defined(OS_NACL)
- // The NaCl verifier doesn't let use use int3. For now, we call abort(). We
- // should ask for advice from some NaCl experts about the optimum thing here.
- // http://code.google.com/p/nativeclient/issues/detail?id=645
- #define DEBUG_BREAK() abort()
- #elif !defined(OS_MACOSX)
- // Though Android has a "helpful" process called debuggerd to catch native
- // signals on the general assumption that they are fatal errors. If no debugger
- // is attached, we call abort since Breakpad needs SIGABRT to create a dump.
- // When debugger is attached, for ARM platform the bkpt instruction appears
- // to cause SIGBUS which is trapped by debuggerd, and we've had great
- // difficulty continuing in a debugger once we stop from SIG triggered by native
- // code, use GDB to set |go| to 1 to resume execution; for X86 platform, use
- // "int3" to setup breakpiont and raise SIGTRAP.
- //
- // On other POSIX architectures, except Mac OS X, we use the same logic to
- // ensure that breakpad creates a dump on crashes while it is still possible to
- // use a debugger.
- namespace {
- void DebugBreak() {
- if (!BeingDebugged()) {
- abort();
- } else {
- #if defined(DEBUG_BREAK_ASM)
- DEBUG_BREAK_ASM();
- #else
- volatile int go = 0;
- while (!go) {
- base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100));
- }
- #endif
- }
- }
- } // namespace
- #define DEBUG_BREAK() DebugBreak()
- #elif defined(DEBUG_BREAK_ASM)
- #define DEBUG_BREAK() DEBUG_BREAK_ASM()
- #else
- #error "Don't know how to debug break on this architecture/OS"
- #endif
- void BreakDebugger() {
- // NOTE: This code MUST be async-signal safe (it's used by in-process
- // stack dumping signal handler). NO malloc or stdio is allowed here.
- DEBUG_BREAK();
- #if defined(OS_ANDROID) && !defined(OFFICIAL_BUILD)
- // For Android development we always build release (debug builds are
- // unmanageably large), so the unofficial build is used for debugging. It is
- // helpful to be able to insert BreakDebugger() statements in the source,
- // attach the debugger, inspect the state of the program and then resume it by
- // setting the 'go' variable above.
- #elif defined(NDEBUG)
- // Terminate the program after signaling the debug break.
- _exit(1);
- #endif
- }
- } // namespace debug
- } // namespace base
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