debugger_posix.cc | Explore in Territory

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif

#include "base/debug/debugger.h"

#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <memory>
#include <string_view>

#include "base/check_op.h"
#include "base/notimplemented.h"
#include "base/strings/string_util.h"
#include "base/threading/platform_thread.h"
#include "base/time/time.h"
#include "build/build_config.h"

#if defined(__GLIBCXX__)
#include <cxxabi.h>
#endif

#if BUILDFLAG(IS_APPLE)
#include <AvailabilityMacros.h>
#endif

#if BUILDFLAG(IS_APPLE) || BUILDFLAG(IS_BSD)
#include <sys/sysctl.h>
#endif

#if BUILDFLAG(IS_FREEBSD)
#include <sys/user.h>
#endif

#include <ostream>

#include "base/check.h"
#include "base/debug/alias.h"
#include "base/debug/debugging_buildflags.h"
#include "base/environment.h"
#include "base/files/file_util.h"
#include "base/posix/eintr_wrapper.h"
#include "base/process/process.h"
#include "base/strings/string_number_conversions.h"

#if defined(USE_SYMBOLIZE)
#include "base/third_party/symbolize/symbolize.h"  // nogncheck
#endif

namespace base {
namespace debug {

#if BUILDFLAG(IS_APPLE) || BUILDFLAG(IS_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 BUILDFLAG(IS_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 BUILDFLAG(IS_OPENBSD)
  if (sysctl(mib, std::size(mib), NULL, &info_size, NULL, 0) < 0)
    return -1;

  mib[5] = (info_size / sizeof(struct kinfo_proc));
#endif

  int sysctl_result = sysctl(mib, std::size(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 BUILDFLAG(IS_FREEBSD)
  being_debugged = (info.ki_flag & P_TRACED) != 0;
#elif BUILDFLAG(IS_BSD)
  being_debugged = (info.p_flag & P_TRACED) != 0;
#else
  being_debugged = (info.kp_proc.p_flag & P_TRACED) != 0;
#endif
  return being_debugged;
}

void VerifyDebugger() {
#if BUILDFLAG(ENABLE_LLDBINIT_WARNING)
  if (Environment::Create()->HasVar("CHROMIUM_LLDBINIT_SOURCED"))
    return;
  if (!BeingDebugged())
    return;
  DCHECK(false)
      << "Detected lldb without sourcing //tools/lldb/lldbinit.py. lldb may "
         "not be able to find debug symbols. Please see debug instructions for "
         "using //tools/lldb/lldbinit.py:\n"
         "https://chromium.googlesource.com/chromium/src/+/main/docs/"
         "lldbinit.md\n"
         "To continue anyway, type 'continue' in lldb. To always skip this "
         "check, define an environment variable CHROMIUM_LLDBINIT_SOURCED=1";
#endif
}

#elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || \
    BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_AIX)

// 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
Process GetDebuggerProcess() { … }

bool BeingDebugged() { … }

void VerifyDebugger() { … }

#else

bool BeingDebugged() {
  NOTIMPLEMENTED();
  return false;
}

void VerifyDebugger() {}

#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 …
#elif defined(ARCH_CPU_ARM64)
#define DEBUG_BREAK_ASM …
#elif defined(ARCH_CPU_MIPS_FAMILY)
#define DEBUG_BREAK_ASM …
#elif defined(ARCH_CPU_X86_FAMILY)
#define DEBUG_BREAK_ASM() …
#endif

#if defined(NDEBUG) && !BUILDFLAG(IS_APPLE) && !BUILDFLAG(IS_ANDROID)
#define DEBUG_BREAK …
#elif BUILDFLAG(IS_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 …
#elif !BUILDFLAG(IS_APPLE)
// 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() { … }
}  // namespace
#define DEBUG_BREAK() …
#elif defined(DEBUG_BREAK_ASM)
#define DEBUG_BREAK …
#else
#error "Don't know how to debug break on this architecture/OS"
#endif

void BreakDebuggerAsyncSafe() { … }

}  // namespace debug
}  // namespace base
chromium/base/debug/debugger_posix.cc
