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/* Copyright (C) 1992, 1993, 1994, 1997, 1998, 1999, 2000, 2003, 2004, 2005,

   2007, 2008, 2009, 2010 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "observer.h"

#include "gdbcmd.h"

#include "target.h"

#include "ada-lang.h"

#include "gdbcore.h"

#include "inferior.h"

#include "gdbthread.h"

/* The name of the array in the GNAT runtime where the Ada Task Control

   Block of each task is stored.  */

#define KNOWN_TASKS_NAME "system__tasking__debug__known_tasks"

/* The maximum number of tasks known to the Ada runtime */

static const int MAX_NUMBER_OF_KNOWN_TASKS = 1000;

enum task_states

{

  Unactivated,

  Runnable,

  Terminated,

  Activator_Sleep,

  Acceptor_Sleep,

  Entry_Caller_Sleep,

  Async_Select_Sleep,

  Delay_Sleep,

  Master_Completion_Sleep,

  Master_Phase_2_Sleep,

  Interrupt_Server_Idle_Sleep,

  Interrupt_Server_Blocked_Interrupt_Sleep,

  Timer_Server_Sleep,

  AST_Server_Sleep,

  Asynchronous_Hold,

  Interrupt_Server_Blocked_On_Event_Flag,

  Activating,

  Acceptor_Delay_Sleep

};

/* A short description corresponding to each possible task state.  */

static const char *task_states[] = {

  N_("Unactivated"),

  N_("Runnable"),

  N_("Terminated"),

  N_("Child Activation Wait"),

  N_("Accept or Select Term"),

  N_("Waiting on entry call"),

  N_("Async Select Wait"),

  N_("Delay Sleep"),

  N_("Child Termination Wait"),

  N_("Wait Child in Term Alt"),

  "",

  "",

  "",

  "",

  N_("Asynchronous Hold"),

  "",

  N_("Activating"),

  N_("Selective Wait")

};

/* A longer description corresponding to each possible task state.  */

static const char *long_task_states[] = {

  N_("Unactivated"),

  N_("Runnable"),

  N_("Terminated"),

  N_("Waiting for child activation"),

  N_("Blocked in accept or select with terminate"),

  N_("Waiting on entry call"),

  N_("Asynchronous Selective Wait"),

  N_("Delay Sleep"),

  N_("Waiting for children termination"),

  N_("Waiting for children in terminate alternative"),

  "",

  "",

  "",

  "",

  N_("Asynchronous Hold"),

  "",

  N_("Activating"),

  N_("Blocked in selective wait statement")

};

/* The index of certain important fields in the Ada Task Control Block

   record and sub-records.  */

struct tcb_fieldnos

{

  /* Fields in record Ada_Task_Control_Block.  */

  int common;

  int entry_calls;

  int atc_nesting_level;

  /* Fields in record Common_ATCB.  */

  int state;

  int parent;

  int priority;

  int image;

  int image_len;     /* This field may be missing.  */

  int call;

  int ll;

  /* Fields in Task_Primitives.Private_Data.  */

  int ll_thread;

  int ll_lwp;        /* This field may be missing.  */

  /* Fields in Common_ATCB.Call.all.  */

  int call_self;

};

/* The type description for the ATCB record and subrecords, and

   the associated tcb_fieldnos. For efficiency reasons, these are made

   static globals so that we can compute them only once the first time

   and reuse them later.  Set to NULL if the types haven't been computed

   yet, or if they may be obsolete (for instance after having loaded

   a new binary).  */

static struct type *atcb_type = NULL;

static struct type *atcb_common_type = NULL;

static struct type *atcb_ll_type = NULL;

static struct type *atcb_call_type = NULL;

static struct tcb_fieldnos fieldno;

/* Set to 1 when the cached address of System.Tasking.Debug.Known_Tasks

   might be stale and so needs to be recomputed.  */

static int ada_tasks_check_symbol_table = 1;

/* The list of Ada tasks.

   Note: To each task we associate a number that the user can use to

   reference it - this number is printed beside each task in the tasks

   info listing displayed by "info tasks".  This number is equal to

   its index in the vector + 1.  Reciprocally, to compute the index

   of a task in the vector, we need to substract 1 from its number.  */

typedef struct ada_task_info ada_task_info_s;

DEF_VEC_O(ada_task_info_s);

static VEC(ada_task_info_s) *task_list = NULL;

/* When non-zero, this flag indicates that the current task_list

   is obsolete, and should be recomputed before it is accessed.  */

static int stale_task_list_p = 1;

/* Return the task number of the task whose ptid is PTID, or zero

   if the task could not be found.  */

int

ada_get_task_number (ptid_t ptid)

{

  int i;

  for (i=0; i < VEC_length (ada_task_info_s, task_list); i++)

    if (ptid_equal (VEC_index (ada_task_info_s, task_list, i)->ptid, ptid))

      return i + 1;

  return 0;  /* No matching task found.  */

}

/* Return the task number of the task that matches TASK_ID, or zero

   if the task could not be found.  */

static int

get_task_number_from_id (CORE_ADDR task_id)

{

  int i;

  for (i = 0; i < VEC_length (ada_task_info_s, task_list); i++)

    {

      struct ada_task_info *task_info =

        VEC_index (ada_task_info_s, task_list, i);

      if (task_info->task_id == task_id)

        return i + 1;

    }

  /* Task not found.  Return 0.  */

  return 0;

}

/* Return non-zero if TASK_NUM is a valid task number.  */

int

valid_task_id (int task_num)

{

  ada_build_task_list (0);

  return (task_num > 0

          && task_num <= VEC_length (ada_task_info_s, task_list));

}

/* Return non-zero iff the task STATE corresponds to a non-terminated

   task state.  */

static int

ada_task_is_alive (struct ada_task_info *task_info)

{

  return (task_info->state != Terminated);

}

/* Extract the contents of the value as a string whose length is LENGTH,

   and store the result in DEST.  */

static void

value_as_string (char *dest, struct value *val, int length)

{

  memcpy (dest, value_contents (val), length);

  dest[length] = '\0';

}

/* Extract the string image from the fat string corresponding to VAL,

   and store it in DEST.  If the string length is greater than MAX_LEN,

   then truncate the result to the first MAX_LEN characters of the fat

   string.  */

static void

read_fat_string_value (char *dest, struct value *val, int max_len)

{

  struct value *array_val;

  struct value *bounds_val;

  int len;

  /* The following variables are made static to avoid recomputing them

     each time this function is called.  */

  static int initialize_fieldnos = 1;

  static int array_fieldno;

  static int bounds_fieldno;

  static int upper_bound_fieldno;

  /* Get the index of the fields that we will need to read in order

     to extract the string from the fat string.  */

  if (initialize_fieldnos)

    {

      struct type *type = value_type (val);

      struct type *bounds_type;

      array_fieldno = ada_get_field_index (type, "P_ARRAY", 0);

      bounds_fieldno = ada_get_field_index (type, "P_BOUNDS", 0);

      bounds_type = TYPE_FIELD_TYPE (type, bounds_fieldno);

      if (TYPE_CODE (bounds_type) == TYPE_CODE_PTR)

        bounds_type = TYPE_TARGET_TYPE (bounds_type);

      if (TYPE_CODE (bounds_type) != TYPE_CODE_STRUCT)

        error (_("Unknown task name format. Aborting"));

      upper_bound_fieldno = ada_get_field_index (bounds_type, "UB0", 0);

      initialize_fieldnos = 0;

    }

  /* Get the size of the task image by checking the value of the bounds.

     The lower bound is always 1, so we only need to read the upper bound.  */

  bounds_val = value_ind (value_field (val, bounds_fieldno));

  len = value_as_long (value_field (bounds_val, upper_bound_fieldno));

  /* Make sure that we do not read more than max_len characters...  */

  if (len > max_len)

    len = max_len;

  /* Extract LEN characters from the fat string.  */

  array_val = value_ind (value_field (val, array_fieldno));

  read_memory (value_address (array_val), dest, len);

  /* Add the NUL character to close the string.  */

  dest[len] = '\0';

}

/* Return the address of the Known_Tasks array maintained in

   the Ada Runtime.  Return NULL if the array could not be found,

   meaning that the inferior program probably does not use tasking.

   In order to provide a fast response time, this function caches

   the Known_Tasks array address after the lookup during the first

   call. Subsequent calls will simply return this cached address.  */

static CORE_ADDR

get_known_tasks_addr (void)

{

  static CORE_ADDR known_tasks_addr = 0;

  if (ada_tasks_check_symbol_table)

    {

      struct minimal_symbol *msym;

      msym = lookup_minimal_symbol (KNOWN_TASKS_NAME, NULL, NULL);

      if (msym != NULL)

        known_tasks_addr = SYMBOL_VALUE_ADDRESS (msym);

      else

        {

          if (target_lookup_symbol (KNOWN_TASKS_NAME, &known_tasks_addr) != 0)

            return 0;

        }

      /* FIXME: brobecker 2003-03-05: Here would be a much better place

         to attach the ada-tasks observers, instead of doing this

         unconditionaly in _initialize_tasks. This would avoid an

         unecessary notification when the inferior does not use tasking

         or as long as the user does not use the ada-tasks commands.

         Unfortunately, this is not possible for the moment: the current

         code resets ada__tasks_check_symbol_table back to 1 whenever

         symbols for a new program are being loaded. If we place the

         observers intialization here, we will end up adding new observers

         everytime we do the check for Ada tasking-related symbols

         above. This would currently have benign effects, but is still

         undesirable. The cleanest approach is probably to create a new

         observer to notify us when the user is debugging a new program.

         We would then reset ada__tasks_check_symbol_table back to 1

         during the notification, but also detach all observers.

         BTW: observers are probably not reentrant, so detaching during

         a notification may not be the safest thing to do... Sigh...

         But creating the new observer would be a good idea in any case,

         since this allow us to make ada__tasks_check_symbol_table

         static, which is a good bonus.  */

      ada_tasks_check_symbol_table = 0;

    }

  return known_tasks_addr;

}

/* Get from the debugging information the type description of all types

   related to the Ada Task Control Block that will be needed in order to

   read the list of known tasks in the Ada runtime.  Also return the

   associated ATCB_FIELDNOS.

   Error handling:  Any data missing from the debugging info will cause

   an error to be raised, and none of the return values to be set.

   Users of this function can depend on the fact that all or none of the

   return values will be set.  */

static void

get_tcb_types_info (struct type **atcb_type,

                    struct type **atcb_common_type,

                    struct type **atcb_ll_type,

                    struct type **atcb_call_type,

                    struct tcb_fieldnos *atcb_fieldnos)

{

  struct type *type;

  struct type *common_type;

  struct type *ll_type;

  struct type *call_type;

  struct tcb_fieldnos fieldnos;

  const char *atcb_name = "system__tasking__ada_task_control_block___XVE";

  const char *atcb_name_fixed = "system__tasking__ada_task_control_block";

  const char *common_atcb_name = "system__tasking__common_atcb";

  const char *private_data_name = "system__task_primitives__private_data";

  const char *entry_call_record_name = "system__tasking__entry_call_record";

  struct symbol *atcb_sym =

    lookup_symbol (atcb_name, NULL, VAR_DOMAIN, NULL);

  const struct symbol *common_atcb_sym =

    lookup_symbol (common_atcb_name, NULL, VAR_DOMAIN, NULL);

  const struct symbol *private_data_sym =

    lookup_symbol (private_data_name, NULL, VAR_DOMAIN, NULL);

  const struct symbol *entry_call_record_sym =

    lookup_symbol (entry_call_record_name, NULL, VAR_DOMAIN, NULL);

  if (atcb_sym == NULL || atcb_sym->type == NULL)

    {

      /* In Ravenscar run-time libs, the  ATCB does not have a dynamic

         size, so the symbol name differs.  */

      atcb_sym = lookup_symbol (atcb_name_fixed, NULL, VAR_DOMAIN, NULL);

      if (atcb_sym == NULL || atcb_sym->type == NULL)

        error (_("Cannot find Ada_Task_Control_Block type. Aborting"));

      type = atcb_sym->type;

    }

  else

    {

      /* Get a static representation of the type record

         Ada_Task_Control_Block.  */

      type = atcb_sym->type;

      type = ada_template_to_fixed_record_type_1 (type, NULL, 0, NULL, 0);

    }

  if (common_atcb_sym == NULL || common_atcb_sym->type == NULL)

    error (_("Cannot find Common_ATCB type. Aborting"));

  if (private_data_sym == NULL || private_data_sym->type == NULL)

    error (_("Cannot find Private_Data type. Aborting"));

  if (entry_call_record_sym == NULL || entry_call_record_sym->type == NULL)

    error (_("Cannot find Entry_Call_Record type. Aborting"));

  /* Get the type for Ada_Task_Control_Block.Common.  */

  common_type = common_atcb_sym->type;

  /* Get the type for Ada_Task_Control_Bloc.Common.Call.LL.  */

  ll_type = private_data_sym->type;

  /* Get the type for Common_ATCB.Call.all.  */

  call_type = entry_call_record_sym->type;

  /* Get the field indices.  */

  fieldnos.common = ada_get_field_index (type, "common", 0);

  fieldnos.entry_calls = ada_get_field_index (type, "entry_calls", 1);

  fieldnos.atc_nesting_level =

    ada_get_field_index (type, "atc_nesting_level", 1);

  fieldnos.state = ada_get_field_index (common_type, "state", 0);

  fieldnos.parent = ada_get_field_index (common_type, "parent", 1);

  fieldnos.priority = ada_get_field_index (common_type, "base_priority", 0);

  fieldnos.image = ada_get_field_index (common_type, "task_image", 1);

  fieldnos.image_len = ada_get_field_index (common_type, "task_image_len", 1);

  fieldnos.call = ada_get_field_index (common_type, "call", 1);

  fieldnos.ll = ada_get_field_index (common_type, "ll", 0);

  fieldnos.ll_thread = ada_get_field_index (ll_type, "thread", 0);

  fieldnos.ll_lwp = ada_get_field_index (ll_type, "lwp", 1);

  fieldnos.call_self = ada_get_field_index (call_type, "self", 0);

  /* On certain platforms such as x86-windows, the "lwp" field has been

     named "thread_id".  This field will likely be renamed in the future,

     but we need to support both possibilities to avoid an unnecessary

     dependency on a recent compiler.  We therefore try locating the

     "thread_id" field in place of the "lwp" field if we did not find

     the latter.  */

  if (fieldnos.ll_lwp < 0)

    fieldnos.ll_lwp = ada_get_field_index (ll_type, "thread_id", 1);

  /* Set all the out parameters all at once, now that we are certain

     that there are no potential error() anymore.  */

  *atcb_type = type;

  *atcb_common_type = common_type;

  *atcb_ll_type = ll_type;

  *atcb_call_type = call_type;

  *atcb_fieldnos = fieldnos;

}

/* Build the PTID of the task from its COMMON_VALUE, which is the "Common"

   component of its ATCB record.  This PTID needs to match the PTID used

   by the thread layer.  */

static ptid_t

ptid_from_atcb_common (struct value *common_value)

{

  long thread = 0;

  CORE_ADDR lwp = 0;

  struct value *ll_value;

  ptid_t ptid;

  ll_value = value_field (common_value, fieldno.ll);

  if (fieldno.ll_lwp >= 0)

    lwp = value_as_address (value_field (ll_value, fieldno.ll_lwp));

  thread = value_as_long (value_field (ll_value, fieldno.ll_thread));

  ptid = target_get_ada_task_ptid (lwp, thread);

  return ptid;

}

/* Read the ATCB data of a given task given its TASK_ID (which is in practice

   the address of its assocated ATCB record), and store the result inside

   TASK_INFO.  */

static void

read_atcb (CORE_ADDR task_id, struct ada_task_info *task_info)

{

  struct value *tcb_value;

  struct value *common_value;

  struct value *atc_nesting_level_value;

  struct value *entry_calls_value;

  struct value *entry_calls_value_element;

  int called_task_fieldno = -1;

  const char ravenscar_task_name[] = "Ravenscar task";

  if (atcb_type == NULL)

    get_tcb_types_info (&atcb_type, &atcb_common_type, &atcb_ll_type,

                        &atcb_call_type, &fieldno);

  tcb_value = value_from_contents_and_address (atcb_type, NULL, task_id);

  common_value = value_field (tcb_value, fieldno.common);

  /* Fill in the task_id.  */

  task_info->task_id = task_id;

  /* Compute the name of the task.

     Depending on the GNAT version used, the task image is either a fat

     string, or a thin array of characters.  Older versions of GNAT used

     to use fat strings, and therefore did not need an extra field in

     the ATCB to store the string length. For efficiency reasons, newer

     versions of GNAT replaced the fat string by a static buffer, but this

     also required the addition of a new field named "Image_Len" containing

     the length of the task name. The method used to extract the task name

     is selected depending on the existence of this field.

     In some run-time libs (e.g. Ravenscar), the name is not in the ATCB;

     we may want to get it from the first user frame of the stack. For now,

     we just give a dummy name.  */

  if (fieldno.image_len == -1)

    {

      if (fieldno.image >= 0)

        read_fat_string_value (task_info->name,

                               value_field (common_value, fieldno.image),

                               sizeof (task_info->name) - 1);

      else

        strcpy (task_info->name, ravenscar_task_name);

    }

  else

    {

      int len = value_as_long (value_field (common_value, fieldno.image_len));

      value_as_string (task_info->name,

                       value_field (common_value, fieldno.image), len);

    }

  /* Compute the task state and priority.  */

  task_info->state = value_as_long (value_field (common_value, fieldno.state));

  task_info->priority =

    value_as_long (value_field (common_value, fieldno.priority));

  /* If the ATCB contains some information about the parent task,

     then compute it as well.  Otherwise, zero.  */

  if (fieldno.parent >= 0)

    task_info->parent =

      value_as_address (value_field (common_value, fieldno.parent));

  else

    task_info->parent = 0;

  /* If the ATCB contains some information about entry calls, then

     compute the "called_task" as well.  Otherwise, zero.  */

  if (fieldno.atc_nesting_level > 0 && fieldno.entry_calls > 0)

    {

      /* Let My_ATCB be the Ada task control block of a task calling the

         entry of another task; then the Task_Id of the called task is

         in My_ATCB.Entry_Calls (My_ATCB.ATC_Nesting_Level).Called_Task.  */

      atc_nesting_level_value = value_field (tcb_value,

                                             fieldno.atc_nesting_level);

      entry_calls_value =

        ada_coerce_to_simple_array_ptr (value_field (tcb_value,

                                                     fieldno.entry_calls));

      entry_calls_value_element =

        value_subscript (entry_calls_value,

                         value_as_long (atc_nesting_level_value));

      called_task_fieldno =

        ada_get_field_index (value_type (entry_calls_value_element),

                             "called_task", 0);

      task_info->called_task =

        value_as_address (value_field (entry_calls_value_element,

                                       called_task_fieldno));

    }

  else

    {

      task_info->called_task = 0;

    }

  /* If the ATCB cotnains some information about RV callers,

     then compute the "caller_task".  Otherwise, zero.  */

  task_info->caller_task = 0;

  if (fieldno.call >= 0)

    {

      /* Get the ID of the caller task from Common_ATCB.Call.all.Self.

         If Common_ATCB.Call is null, then there is no caller.  */

      const CORE_ADDR call =

        value_as_address (value_field (common_value, fieldno.call));

      struct value *call_val;

      if (call != 0)

        {

          call_val =

            value_from_contents_and_address (atcb_call_type, NULL, call);

          task_info->caller_task =

            value_as_address (value_field (call_val, fieldno.call_self));

        }

    }

  /* And finally, compute the task ptid.  */

  if (ada_task_is_alive (task_info))

    task_info->ptid = ptid_from_atcb_common (common_value);

  else

    task_info->ptid = null_ptid;

}

/* Read the ATCB info of the given task (identified by TASK_ID), and

   add the result to the TASK_LIST.  */

static void

add_ada_task (CORE_ADDR task_id)

{

  struct ada_task_info task_info;

  read_atcb (task_id, &task_info);

  VEC_safe_push (ada_task_info_s, task_list, &task_info);

}

/* Read the Known_Tasks array from the inferior memory, and store

   it in TASK_LIST.  Return non-zero upon success.  */

static int

read_known_tasks_array (void)

{

  const int target_ptr_byte =

    gdbarch_ptr_bit (target_gdbarch) / TARGET_CHAR_BIT;

  const CORE_ADDR known_tasks_addr = get_known_tasks_addr ();

  const int known_tasks_size = target_ptr_byte * MAX_NUMBER_OF_KNOWN_TASKS;

  gdb_byte *known_tasks = alloca (known_tasks_size);

  int i;

  /* Step 1: Clear the current list, if necessary.  */

  VEC_truncate (ada_task_info_s, task_list, 0);

  /* If the application does not use task, then no more needs to be done.

     It is important to have the task list cleared (see above) before we

     return, as we don't want a stale task list to be used...  This can

     happen for instance when debugging a non-multitasking program after

     having debugged a multitasking one.  */

  if (known_tasks_addr == 0)

    return 0;

  /* Step 2: Build a new list by reading the ATCBs from the Known_Tasks

     array in the Ada runtime.  */

  read_memory (known_tasks_addr, known_tasks, known_tasks_size);

  for (i = 0; i < MAX_NUMBER_OF_KNOWN_TASKS; i++)

    {

      struct type *data_ptr_type =

        builtin_type (target_gdbarch)->builtin_data_ptr;

      CORE_ADDR task_id =

        extract_typed_address (known_tasks + i * target_ptr_byte,

                               data_ptr_type);

      if (task_id != 0)

        add_ada_task (task_id);

    }

  /* Step 3: Unset stale_task_list_p, to avoid re-reading the Known_Tasks

     array unless needed.  Then report a success.  */

  stale_task_list_p = 0;

  return 1;

}

/* Builds the task_list by reading the Known_Tasks array from

   the inferior.  Prints an appropriate message and returns non-zero

   if it failed to build this list.  */

int

ada_build_task_list (int warn_if_null)

{

  if (!target_has_stack)

    error (_("Cannot inspect Ada tasks when program is not running"));

  if (stale_task_list_p)

    read_known_tasks_array ();

  if (task_list == NULL)

    {

      if (warn_if_null)

        printf_filtered (_("Your application does not use any Ada tasks.\n"));

      return 0;

    }

  return 1;

}

/* Print a one-line description of the task whose number is TASKNO.

   The formatting should fit the "info tasks" array.  */

static void

short_task_info (int taskno)

{

  const struct ada_task_info *const task_info =

    VEC_index (ada_task_info_s, task_list, taskno - 1);

  int active_task_p;

  gdb_assert (task_info != NULL);

  /* Print a star if this task is the current task (or the task currently

     selected).  */

  active_task_p = ptid_equal (task_info->ptid, inferior_ptid);

  if (active_task_p)

    printf_filtered ("*");

  else

    printf_filtered (" ");

  /* Print the task number.  */

  printf_filtered ("%3d", taskno);

  /* Print the Task ID.  */

  printf_filtered (" %9lx", (long) task_info->task_id);

  /* Print the Task ID of the task parent.  */

  printf_filtered (" %4d", get_task_number_from_id (task_info->parent));

  /* Print the base priority of the task.  */

  printf_filtered (" %3d", task_info->priority);

  /* Print the task current state.  */

  if (task_info->caller_task)

    printf_filtered (_(" Accepting RV with %-4d"),

                     get_task_number_from_id (task_info->caller_task));