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// Copyright (c) 2006-2008 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 "build/build_config.h"
#include "base/debug_util.h"
#include <execinfo.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <unistd.h>
#include "base/basictypes.h"
#include "base/logging.h"
#include "base/string_piece.h"
// static
bool DebugUtil::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
// static
bool DebugUtil::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(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 DebugUtil::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 = read(status_fd, buf, sizeof(buf));
close(status_fd);
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';
}
#endif // OS_LINUX
// static
void DebugUtil::BreakDebugger() {
asm ("int3");
}
StackTrace::StackTrace() {
static const int kMaxCallers = 256;
void* callers[kMaxCallers];
int count = backtrace(callers, kMaxCallers);
trace_.resize(count);
memcpy(&trace_[0], callers, sizeof(void*) * count);
}
void StackTrace::PrintBacktrace() {
fflush(stderr);
backtrace_symbols_fd(&trace_[0], trace_.size(), STDERR_FILENO);
}
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