michael@0: // Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #include "build/build_config.h"
michael@0: #include "base/debug_util.h"
michael@0: 
michael@0: #define MOZ_HAVE_EXECINFO_H (defined(OS_LINUX) && !defined(ANDROID))
michael@0: 
michael@0: #include <errno.h>
michael@0: #include <fcntl.h>
michael@0: #include <stdio.h>
michael@0: #include <limits.h>
michael@0: #include <sys/stat.h>
michael@0: #include <sys/param.h>
michael@0: #include <sys/types.h>
michael@0: #include <unistd.h>
michael@0: #if MOZ_HAVE_EXECINFO_H
michael@0: #include <execinfo.h>
michael@0: #endif
michael@0: 
michael@0: #if defined(OS_MACOSX) || defined(OS_BSD)
michael@0: #if defined(OS_OPENBSD)
michael@0: #include <sys/proc.h>
michael@0: #endif
michael@0: #include <sys/sysctl.h>
michael@0: #endif
michael@0: 
michael@0: #if defined(OS_DRAGONFLY) || defined(OS_FREEBSD)
michael@0: #include <sys/user.h>
michael@0: #endif
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: #include "base/eintr_wrapper.h"
michael@0: #include "base/logging.h"
michael@0: #include "base/scoped_ptr.h"
michael@0: #include "base/string_piece.h"
michael@0: 
michael@0: #if defined(OS_NETBSD)
michael@0: #undef KERN_PROC
michael@0: #define KERN_PROC KERN_PROC2
michael@0: #define KINFO_PROC struct kinfo_proc2
michael@0: #else
michael@0: #define KINFO_PROC struct kinfo_proc
michael@0: #endif
michael@0: 
michael@0: #if defined(OS_MACOSX)
michael@0: #define KP_FLAGS kp_proc.p_flag
michael@0: #elif defined(OS_DRAGONFLY)
michael@0: #define KP_FLAGS kp_flags
michael@0: #elif defined(OS_FREEBSD)
michael@0: #define KP_FLAGS ki_flag
michael@0: #elif defined(OS_OPENBSD) && !defined(_P_TRACED)
michael@0: #define KP_FLAGS p_psflags
michael@0: #define P_TRACED PS_TRACED
michael@0: #else
michael@0: #define KP_FLAGS p_flag
michael@0: #endif
michael@0: 
michael@0: // static
michael@0: bool DebugUtil::SpawnDebuggerOnProcess(unsigned /* process_id */) {
michael@0:   NOTIMPLEMENTED();
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: #if defined(OS_MACOSX) || defined(OS_BSD)
michael@0: 
michael@0: // Based on Apple's recommended method as described in
michael@0: // http://developer.apple.com/qa/qa2004/qa1361.html
michael@0: // static
michael@0: bool DebugUtil::BeingDebugged() {
michael@0:   // If the process is sandboxed then we can't use the sysctl, so cache the
michael@0:   // value.
michael@0:   static bool is_set = false;
michael@0:   static bool being_debugged = false;
michael@0: 
michael@0:   if (is_set) {
michael@0:     return being_debugged;
michael@0:   }
michael@0: 
michael@0:   // Initialize mib, which tells sysctl what info we want.  In this case,
michael@0:   // we're looking for information about a specific process ID.
michael@0:   int mib[] = {
michael@0:     CTL_KERN,
michael@0:     KERN_PROC,
michael@0:     KERN_PROC_PID,
michael@0:     getpid(),
michael@0: #if defined(OS_NETBSD) || defined(OS_OPENBSD)
michael@0:     sizeof(KINFO_PROC),
michael@0:     1,
michael@0: #endif
michael@0:   };
michael@0: 
michael@0:   // Caution: struct kinfo_proc is marked __APPLE_API_UNSTABLE.  The source and
michael@0:   // binary interfaces may change.
michael@0:   KINFO_PROC info;
michael@0:   size_t info_size = sizeof(info);
michael@0: 
michael@0:   int sysctl_result = sysctl(mib, arraysize(mib), &info, &info_size, NULL, 0);
michael@0:   DCHECK(sysctl_result == 0);
michael@0:   if (sysctl_result != 0) {
michael@0:     is_set = true;
michael@0:     being_debugged = false;
michael@0:     return being_debugged;
michael@0:   }
michael@0: 
michael@0:   // This process is being debugged if the P_TRACED flag is set.
michael@0:   is_set = true;
michael@0:   being_debugged = (info.KP_FLAGS & P_TRACED) != 0;
michael@0:   return being_debugged;
michael@0: }
michael@0: 
michael@0: #elif defined(OS_LINUX)
michael@0: 
michael@0: // We can look in /proc/self/status for TracerPid.  We are likely used in crash
michael@0: // handling, so we are careful not to use the heap or have side effects.
michael@0: // Another option that is common is to try to ptrace yourself, but then we
michael@0: // can't detach without forking(), and that's not so great.
michael@0: // static
michael@0: bool DebugUtil::BeingDebugged() {
michael@0:   int status_fd = open("/proc/self/status", O_RDONLY);
michael@0:   if (status_fd == -1)
michael@0:     return false;
michael@0: 
michael@0:   // We assume our line will be in the first 1024 characters and that we can
michael@0:   // read this much all at once.  In practice this will generally be true.
michael@0:   // This simplifies and speeds up things considerably.
michael@0:   char buf[1024];
michael@0: 
michael@0:   ssize_t num_read = HANDLE_EINTR(read(status_fd, buf, sizeof(buf)));
michael@0:   HANDLE_EINTR(close(status_fd));
michael@0: 
michael@0:   if (num_read <= 0)
michael@0:     return false;
michael@0: 
michael@0:   StringPiece status(buf, num_read);
michael@0:   StringPiece tracer("TracerPid:\t");
michael@0: 
michael@0:   StringPiece::size_type pid_index = status.find(tracer);
michael@0:   if (pid_index == StringPiece::npos)
michael@0:     return false;
michael@0: 
michael@0:   // Our pid is 0 without a debugger, assume this for any pid starting with 0.
michael@0:   pid_index += tracer.size();
michael@0:   return pid_index < status.size() && status[pid_index] != '0';
michael@0: }
michael@0: 
michael@0: #endif  // OS_LINUX
michael@0: 
michael@0: // static
michael@0: void DebugUtil::BreakDebugger() {
michael@0: #if defined(ARCH_CPU_X86_FAMILY)
michael@0:   asm ("int3");
michael@0: #endif
michael@0: }
michael@0: 
michael@0: StackTrace::StackTrace() {
michael@0:   const int kMaxCallers = 256;
michael@0: 
michael@0:   void* callers[kMaxCallers];
michael@0: #if MOZ_HAVE_EXECINFO_H
michael@0:   int count = backtrace(callers, kMaxCallers);
michael@0: #else
michael@0:   int count = 0;
michael@0: #endif
michael@0: 
michael@0:   // Though the backtrace API man page does not list any possible negative
michael@0:   // return values, we still still exclude them because they would break the
michael@0:   // memcpy code below.
michael@0:   if (count > 0) {
michael@0:     trace_.resize(count);
michael@0:     memcpy(&trace_[0], callers, sizeof(callers[0]) * count);
michael@0:   } else {
michael@0:     trace_.resize(0);
michael@0:   }
michael@0: }
michael@0: 
michael@0: void StackTrace::PrintBacktrace() {
michael@0:   fflush(stderr);
michael@0: #if MOZ_HAVE_EXECINFO_H
michael@0:   backtrace_symbols_fd(&trace_[0], trace_.size(), STDERR_FILENO);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: void StackTrace::OutputToStream(std::ostream* os) {
michael@0:   return;
michael@0: }