toolchain/gdb/patches/730-debian_gdb-fix-tracefork-check.patch

   1 Status: submitted for comments
   2
   3 2004-11-12  Daniel Jacobowitz  <dan@debian.org>
   4
   5         * linux-nat.c (my_waitpid): New function.
   6         (linux_test_for_tracefork): Make more robust and verbose.  Take
   7         an ORIGINAL_PID argument and test for PTRACE_SETOPTIONS first.
   8         (linux_supports_tracefork, linux_supports_tracevforkdone): Take a PID
   9         argument.  Update calls to linux_test_for_tracefork.
  10         (linux_enable_event_reporting, child_follow_fork)
  11         (child_insert_fork_catchpoint, child_insert_vfork_catchpoint)
  12         (child_insert_exec_catchpoint): Update calls to
  13         linux_supports_tracefork and linux_supports_tracevforkdone.
  14
  15 Index: gdb-6.3/gdb/linux-nat.c
  16 ===================================================================
  17 --- gdb-6.3.orig/gdb/linux-nat.c        2004-10-08 16:29:47.000000000 -0400
  18 +++ gdb-6.3/gdb/linux-nat.c     2004-11-13 16:41:51.368720845 -0500
  19 @@ -150,18 +150,47 @@ linux_tracefork_child (void)
  20    exit (0);
  21  }
  22
  23 -/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events.  We
  24 +/* Wrapper function for waitpid which handles EINTR.  */
  25 +
  26 +static int
  27 +my_waitpid (int pid, int *status, int flags)
  28 +{
  29 +  int ret;
  30 +  do
  31 +    {
  32 +      ret = waitpid (pid, status, flags);
  33 +    }
  34 +  while (ret == -1 && errno == EINTR);
  35 +
  36 +  return ret;
  37 +}
  38 +
  39 +/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events.
  40 +
  41 +   First, we try to enable fork tracing on ORIGINAL_PID.  If this fails,
  42 +   we know that the feature is not available.  This may change the tracing
  43 +   options for ORIGINAL_PID, but we'll be setting them shortly anyway.
  44 +
  45 +   However, if it succeeds, we don't know for sure that the feature is
  46 +   available; old versions of PTRACE_SETOPTIONS ignored unknown options.  We
  47     create a child process, attach to it, use PTRACE_SETOPTIONS to enable
  48 -   fork tracing, and let it fork.  If the process exits, we assume that
  49 -   we can't use TRACEFORK; if we get the fork notification, and we can
  50 -   extract the new child's PID, then we assume that we can.  */
  51 +   fork tracing, and let it fork.  If the process exits, we assume that we
  52 +   can't use TRACEFORK; if we get the fork notification, and we can extract
  53 +   the new child's PID, then we assume that we can.  */
  54
  55  static void
  56 -linux_test_for_tracefork (void)
  57 +linux_test_for_tracefork (int original_pid)
  58  {
  59    int child_pid, ret, status;
  60    long second_pid;
  61
  62 +  linux_supports_tracefork_flag = 0;
  63 +  linux_supports_tracevforkdone_flag = 0;
  64 +
  65 +  ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACEFORK);
  66 +  if (ret != 0)
  67 +    return;
  68 +
  69    child_pid = fork ();
  70    if (child_pid == -1)
  71      perror_with_name ("linux_test_for_tracefork: fork");
  72 @@ -169,7 +198,7 @@ linux_test_for_tracefork (void)
  73    if (child_pid == 0)
  74      linux_tracefork_child ();
  75
  76 -  ret = waitpid (child_pid, &status, 0);
  77 +  ret = my_waitpid (child_pid, &status, 0);
  78    if (ret == -1)
  79      perror_with_name ("linux_test_for_tracefork: waitpid");
  80    else if (ret != child_pid)
  81 @@ -177,13 +206,23 @@ linux_test_for_tracefork (void)
  82    if (! WIFSTOPPED (status))
  83      error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
  84
  85 -  linux_supports_tracefork_flag = 0;
  86 -
  87    ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
  88    if (ret != 0)
  89      {
  90 -      ptrace (PTRACE_KILL, child_pid, 0, 0);
  91 -      waitpid (child_pid, &status, 0);
  92 +      ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
  93 +      if (ret != 0)
  94 +       {
  95 +         warning ("linux_test_for_tracefork: failed to kill child");
  96 +         return;
  97 +       }
  98 +
  99 +      ret = my_waitpid (child_pid, &status, 0);
 100 +      if (ret != child_pid)
 101 +       warning ("linux_test_for_tracefork: failed to wait for killed child");
 102 +      else if (!WIFSIGNALED (status))
 103 +       warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
 104 +                "killed child", status);
 105 +
 106        return;
 107      }
 108
 109 @@ -192,8 +231,12 @@ linux_test_for_tracefork (void)
 110                 PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORKDONE);
 111    linux_supports_tracevforkdone_flag = (ret == 0);
 112
 113 -  ptrace (PTRACE_CONT, child_pid, 0, 0);
 114 -  ret = waitpid (child_pid, &status, 0);
 115 +  ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
 116 +  if (ret != 0)
 117 +    warning ("linux_test_for_tracefork: failed to resume child");
 118 +
 119 +  ret = my_waitpid (child_pid, &status, 0);
 120 +
 121    if (ret == child_pid && WIFSTOPPED (status)
 122        && status >> 16 == PTRACE_EVENT_FORK)
 123      {
 124 @@ -204,34 +247,38 @@ linux_test_for_tracefork (void)
 125           int second_status;
 126
 127           linux_supports_tracefork_flag = 1;
 128 -         waitpid (second_pid, &second_status, 0);
 129 -         ptrace (PTRACE_DETACH, second_pid, 0, 0);
 130 +         my_waitpid (second_pid, &second_status, 0);
 131 +         ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
 132 +         if (ret != 0)
 133 +           warning ("linux_test_for_tracefork: failed to kill second child");
 134         }
 135      }
 136 +  else
 137 +    warning ("linux_test_for_tracefork: unexpected result from waitpid "
 138 +            "(%d, status 0x%x)", ret, status);
 139
 140 -  if (WIFSTOPPED (status))
 141 -    {
 142 -      ptrace (PTRACE_DETACH, child_pid, 0, 0);
 143 -      waitpid (child_pid, &status, 0);
 144 -    }
 145 +  ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
 146 +  if (ret != 0)
 147 +    warning ("linux_test_for_tracefork: failed to kill child");
 148 +  my_waitpid (child_pid, &status, 0);
 149  }
 150
 151  /* Return non-zero iff we have tracefork functionality available.
 152     This function also sets linux_supports_tracefork_flag.  */
 153
 154  static int
 155 -linux_supports_tracefork (void)
 156 +linux_supports_tracefork (int pid)
 157  {
 158    if (linux_supports_tracefork_flag == -1)
 159 -    linux_test_for_tracefork ();
 160 +    linux_test_for_tracefork (pid);
 161    return linux_supports_tracefork_flag;
 162  }
 163
 164  static int
 165 -linux_supports_tracevforkdone (void)
 166 +linux_supports_tracevforkdone (int pid)
 167  {
 168    if (linux_supports_tracefork_flag == -1)
 169 -    linux_test_for_tracefork ();
 170 +    linux_test_for_tracefork (pid);
 171    return linux_supports_tracevforkdone_flag;
 172  }
 173
 174 @@ -242,12 +289,12 @@ linux_enable_event_reporting (ptid_t pti
 175    int pid = ptid_get_pid (ptid);
 176    int options;
 177
 178 -  if (! linux_supports_tracefork ())
 179 +  if (! linux_supports_tracefork (pid))
 180      return;
 181
 182    options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACEEXEC
 183      | PTRACE_O_TRACECLONE;
 184 -  if (linux_supports_tracevforkdone ())
 185 +  if (linux_supports_tracevforkdone (pid))
 186      options |= PTRACE_O_TRACEVFORKDONE;
 187
 188    /* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support
 189 @@ -308,7 +355,8 @@ child_follow_fork (int follow_child)
 190
 191        if (has_vforked)
 192         {
 193 -         if (linux_supports_tracevforkdone ())
 194 +         gdb_assert (linux_supports_tracefork_flag >= 0);
 195 +         if (linux_supports_tracevforkdone (0))
 196             {
 197               int status;
 198
 199 @@ -476,7 +524,7 @@ linux_handle_extended_wait (int pid, int
 200  int
 201  child_insert_fork_catchpoint (int pid)
 202  {
 203 -  if (! linux_supports_tracefork ())
 204 +  if (! linux_supports_tracefork (pid))
 205      error ("Your system does not support fork catchpoints.");
 206
 207    return 0;
 208 @@ -485,7 +533,7 @@ child_insert_fork_catchpoint (int pid)
 209  int
 210  child_insert_vfork_catchpoint (int pid)
 211  {
 212 -  if (!linux_supports_tracefork ())
 213 +  if (!linux_supports_tracefork (pid))
 214      error ("Your system does not support vfork catchpoints.");
 215
 216    return 0;
 217 @@ -494,7 +542,7 @@ child_insert_vfork_catchpoint (int pid)
 218  int
 219  child_insert_exec_catchpoint (int pid)
 220  {
 221 -  if (!linux_supports_tracefork ())
 222 +  if (!linux_supports_tracefork (pid))
 223      error ("Your system does not support exec catchpoints.");
 224
 225    return 0;