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 // Copyright (c) 2006-2009 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"

 #define MOZ_HAVE_EXECINFO_H (defined(OS_LINUX) && !defined(ANDROID))

 #include <errno.h>

 #include <fcntl.h>

 #include <stdio.h>

 #include <limits.h>

 #include <sys/stat.h>

 #include <sys/param.h>

 #include <sys/types.h>

 #include <unistd.h>

 #if MOZ_HAVE_EXECINFO_H

 #include <execinfo.h>

 #endif

 #if defined(OS_MACOSX) || defined(OS_BSD)

 #if defined(OS_OPENBSD)

 #include <sys/proc.h>

 #endif

 #include <sys/sysctl.h>

 #endif

 #if defined(OS_DRAGONFLY) || defined(OS_FREEBSD)

 #include <sys/user.h>

 #endif

 #include "base/basictypes.h"

 #include "base/eintr_wrapper.h"

 #include "base/logging.h"

 #include "base/scoped_ptr.h"

 #include "base/string_piece.h"

 #if defined(OS_NETBSD)

 #undef KERN_PROC

 #define KERN_PROC KERN_PROC2

 #define KINFO_PROC struct kinfo_proc2

 #else

 #define KINFO_PROC struct kinfo_proc

 #endif

 #if defined(OS_MACOSX)

 #define KP_FLAGS kp_proc.p_flag

 #elif defined(OS_DRAGONFLY)

 #define KP_FLAGS kp_flags

 #elif defined(OS_FREEBSD)

 #define KP_FLAGS ki_flag

 #elif defined(OS_OPENBSD) && !defined(_P_TRACED)

 #define KP_FLAGS p_psflags

 #define P_TRACED PS_TRACED

 #else

 #define KP_FLAGS p_flag

 #endif

 // static

 bool DebugUtil::SpawnDebuggerOnProcess(unsigned /* process_id */) {

   NOTIMPLEMENTED();

   return false;

 }

 #if defined(OS_MACOSX) || defined(OS_BSD)

 // 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(),

 #if defined(OS_NETBSD) || defined(OS_OPENBSD)

     sizeof(KINFO_PROC),

     1,

 #endif

   };

   // Caution: struct kinfo_proc is marked __APPLE_API_UNSTABLE.  The source and

   // binary interfaces may change.

   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_FLAGS & 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 = HANDLE_EINTR(read(status_fd, buf, sizeof(buf)));

   HANDLE_EINTR(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() {

 #if defined(ARCH_CPU_X86_FAMILY)

   asm ("int3");

 #endif

 }

 StackTrace::StackTrace() {

   const int kMaxCallers = 256;

   void* callers[kMaxCallers];

 #if MOZ_HAVE_EXECINFO_H

   int count = backtrace(callers, kMaxCallers);

 #else

   int count = 0;

 #endif

   // Though the backtrace API man page does not list any possible negative

   // return values, we still still exclude them because they would break the

   // memcpy code below.

   if (count > 0) {

     trace_.resize(count);

     memcpy(&trace_[0], callers, sizeof(callers[0]) * count);

   } else {

     trace_.resize(0);

   }

 }

 void StackTrace::PrintBacktrace() {

   fflush(stderr);

 #if MOZ_HAVE_EXECINFO_H

   backtrace_symbols_fd(&trace_[0], trace_.size(), STDERR_FILENO);

 #endif

 }

 void StackTrace::OutputToStream(std::ostream* os) {

   return;

 }