Add Mac BeingDebugged implementation

Review URL: http://codereview.chromium.org/6582

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@3009 0039d316-1c4b-4281-b951-d872f2087c98

base/debug_util_posix.cc

@@ -4,32 +4,58 @@
 
 #include "base/debug_util.h"
 
-#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.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() {
-  NOTIMPLEMENTED();
-  return false;
+  // 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)
+    return false;
+
+  // This process is being debugged if the P_TRACED flag is set.
+  return (info.kp_proc.p_flag & P_TRACED) != 0;
 }
 
 #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)
@@ -57,10 +83,10 @@ bool DebugUtil::BeingDebugged() {
   pid_index += tracer.size();
   return pid_index < status.size() && status[pid_index] != '0';
 }
-#endif
+
+#endif  // OS_LINUX
 
 // static
 void DebugUtil::BreakDebugger() {
   asm ("int3");
 }
-