mono/utils/mono-utils-debug.c

   1 /* mono-utils-debug.c
   2  *
   3  * Copyright 2018 Microsoft
   4  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   5 */
   6
   7 #include <config.h>
   8 #include <glib.h>
   9 #include "mono-utils-debug.h"
  10
  11 #if defined (_WIN32)
  12
  13 #include <windows.h>
  14
  15 gboolean
  16 mono_is_usermode_native_debugger_present (void)
  17 {
  18         // This is just a few instructions and no syscall. It is very fast.
  19         // Kernel debugger is detected otherwise and is also useful for usermode debugging.
  20         // Mono managed debugger is detected otherwise.
  21         return IsDebuggerPresent () ? TRUE : FALSE;
  22 }
  23
  24 #else
  25
  26 #include <unistd.h>
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #if defined (__APPLE__)
  30 #include <sys/sysctl.h>
  31 #endif
  32 #if defined (__NetBSD__)
  33 #include <kvm.h>
  34 #endif
  35
  36 static gboolean
  37 mono_is_usermode_native_debugger_present_slow (void)
  38 // PAL_IsDebuggerPresent
  39 // based closely on with some local cleanup:
  40 //   https://github.com/dotnet/coreclr/blob/master/src/pal/src/init/pal.cpp
  41 //   https://raw.githubusercontent.com/dotnet/coreclr/f1c9dac3e2db2397e01cd2da3e8aaa4f81a80013/src/pal/src/init/pal.cpp
  42 {
  43 #if defined (__APPLE__)
  44
  45         struct kinfo_proc info;
  46         size_t size = sizeof (info);
  47         memset (&info, 0, size);
  48         int mib [4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID, getpid () };
  49         return sysctl (mib, sizeof (mib) / sizeof (*mib), &info, &size, NULL, 0) == 0
  50                 && (info.kp_proc.p_flag & P_TRACED) != 0;
  51
  52 #elif defined (__linux__)
  53
  54         int const status_fd = open ("/proc/self/status", O_RDONLY);
  55         if (status_fd == -1)
  56                 return FALSE;
  57
  58         char buf [4098];
  59         buf [0] = '\n'; // consider if the first line
  60         buf [1] = 0; // clear out garbage
  61         ssize_t const num_read = read (status_fd, &buf [1], sizeof(buf) - 2);
  62         close (status_fd);
  63         static const char TracerPid [ ] = "\nTracerPid:";
  64         if (num_read <= sizeof (TracerPid))
  65                 return FALSE;
  66
  67         buf [num_read + 1] = 0;
  68         char const * const tracer_pid = strstr (buf, TracerPid);
  69         return tracer_pid && atoi (tracer_pid + sizeof (TracerPid) - 1);
  70
  71 #elif defined (__NetBSD__)
  72
  73         kvm_t * const kd = kvm_open (NULL, NULL, NULL, KVM_NO_FILES, "kvm_open");
  74         if (!kd)
  75                 return FALSE;
  76         int count = 0;
  77         struct kinfo_proc const * const info = kvm_getprocs (kd, KERN_PROC_PID, getpid (), &count);
  78         gboolean const traced = info && count > 0 && (info->kp_proc.p_slflag & PSL_TRACED);
  79         kvm_close (kd);
  80         return traced;
  81
  82 #else
  83         return FALSE; // FIXME Other operating systems.
  84 #endif
  85 }
  86
  87 // Cache because it is slow.
  88 static gchar mono_is_usermode_native_debugger_present_cache; // 0:uninitialized 1:true 2:false
  89
  90 gboolean
  91 mono_is_usermode_native_debugger_present (void)
  92 {
  93         if (mono_is_usermode_native_debugger_present_cache == 0) {
  94                 int er = errno;
  95                 mono_is_usermode_native_debugger_present_cache = mono_is_usermode_native_debugger_present_slow () ? 1 : 2;
  96                 errno = er;
  97         }
  98         return mono_is_usermode_native_debugger_present_cache == 1;
  99 }
 100
 101 #endif // fast uncached Window vs. slow cached the rest
 102
 103 #if 0 // test
 104
 105 int
 106 #ifdef _MSC_VER
 107 __cdecl
 108 #endif
 109 main ()
 110 {
 111         printf ("mono_usermode_native_debugger_present:%d\n", mono_is_usermode_native_debugger_present ());
 112 }
 113
 114 #endif