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// Copyright (c) 2011 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 "build/build_config.h"
#include <errno.h>
#include <execinfo.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/param.h>
#include <sys/stat.h>
#if !defined(OS_NACL)
#include <sys/sysctl.h>
#endif
#include <sys/types.h>
#include <unistd.h>
#include <string>
#include <vector>
#if defined(__GLIBCXX__)
#include <cxxabi.h>
#endif
#if defined(OS_MACOSX)
#include <AvailabilityMacros.h>
#endif
#include <iostream>
#include "base/basictypes.h"
#include "base/eintr_wrapper.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/safe_strerror_posix.h"
#include "base/string_piece.h"
#include "base/stringprintf.h"
#if defined(USE_SYMBOLIZE)
#include "base/third_party/symbolize/symbolize.h"
#endif
namespace base {
namespace debug {
bool SpawnDebuggerOnProcess(unsigned /* process_id */) {
NOTIMPLEMENTED();
return false;
}
#if defined(OS_MACOSX)
// Based on Apple's recommended method as described in
// http://developer.apple.com/qa/qa2004/qa1361.html
bool BeingDebugged() {
// 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()
};
// 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);
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;
being_debugged = (info.kp_proc.p_flag & P_TRACED) != 0;
return being_debugged;
}
#elif defined(OS_LINUX)
// 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() {
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 (HANDLE_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';
}
#elif defined(OS_NACL)
bool BeingDebugged() {
NOTIMPLEMENTED();
return false;
}
#elif defined(OS_FREEBSD)
bool BeingDebugged() {
// TODO(benl): can we determine this under FreeBSD?
NOTIMPLEMENTED();
return false;
}
#endif // defined(OS_FREEBSD)
// 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, send SIGTRAP; Release mode, send SIGABRT.
// Mac: Always send SIGTRAP.
#if defined(NDEBUG) && !defined(OS_MACOSX)
#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(ARCH_CPU_ARM_FAMILY)
#define DEBUG_BREAK() asm("bkpt 0")
#else
#define DEBUG_BREAK() asm("int3")
#endif
void BreakDebugger() {
DEBUG_BREAK();
#if defined(NDEBUG)
_exit(1);
#endif
}
} // namespace debug
} // namespace base
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