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// Copyright 2015 The Cobalt Authors. All Rights Reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include "starboard/system.h"
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include "starboard/common/log.h"
#include "starboard/shared/posix/file_internal.h"
#include "starboard/shared/posix/handle_eintr.h"
// Adapted from base/debug/
bool SbSystemIsDebuggerAttached() {
// 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.
// 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) - 1));
SB_DCHECK(num_read < sizeof(buf));
if (HANDLE_EINTR(close(status_fd)) < 0)
return false;
if (num_read <= 0)
return false;
buf[num_read] = '\0';
const char tracer[] = "TracerPid:\t";
char* pid_index = strstr(buf, tracer);
if (pid_index == NULL)
return false;
// Our pid is 0 without a debugger, assume this for any pid starting with 0.
pid_index += strlen(tracer);
return pid_index < (buf + num_read) && *pid_index != '0';