rom/exec/findtask.c

   1 /*
   2     Copyright © 1995-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Search a task by name.
   6     Lang: english
   7 */
   8 #include <exec/execbase.h>
   9 #include <aros/libcall.h>
  10 #include <proto/exec.h>
  11
  12 #include "exec_intern.h"
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17
  18         AROS_LH1(struct Task *, FindTask,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(CONST_STRPTR, name, A1),
  22
  23 /*  LOCATION */
  24         struct ExecBase *, SysBase, 49, Exec)
  25
  26 /*  FUNCTION
  27         Find a task with a given name or get the address of the current task.
  28         Finding the address of the current task is a very quick function
  29         call, but finding a special task is a very CPU intensive instruction.
  30         Note that generally a task may already be gone when this function
  31         returns.
  32
  33     INPUTS
  34         name - Pointer to name or NULL for current task.
  35
  36     RESULT
  37         Address of task structure found.
  38
  39     NOTES
  40
  41     EXAMPLE
  42
  43     BUGS
  44
  45     SEE ALSO
  46
  47     INTERNALS
  48
  49 ******************************************************************************/
  50 {
  51     AROS_LIBFUNC_INIT
  52
  53 #if defined(__AROSEXEC_SMP__)
  54     spinlock_t *listLock;
  55 #endif
  56     struct Task *ret;
  57
  58     /* Quick return for a quick argument */
  59     if (name == NULL)
  60         return GET_THIS_TASK;
  61
  62     /* Always protect task lists */
  63 #if defined(__AROSEXEC_SMP__)
  64     listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskRunningSpinLock, SPINLOCK_MODE_READ);
  65     Forbid();
  66         /* Then into the waiting list. */
  67     ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskRunning, name);
  68     if (ret == NULL)
  69     {
  70         EXEC_SPINLOCK_UNLOCK(listLock);
  71         Permit();
  72         listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskReadySpinLock, SPINLOCK_MODE_READ);
  73         Forbid();
  74 #else
  75     Disable();
  76 #endif
  77
  78     /* First look into the ready list. */
  79     ret = (struct Task *)FindName(&SysBase->TaskReady, name);
  80     if (ret == NULL)
  81     {
  82 #if defined(__AROSEXEC_SMP__)
  83         EXEC_SPINLOCK_UNLOCK(listLock);
  84         Permit();
  85         listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskWaitSpinLock, SPINLOCK_MODE_READ);
  86         Forbid();
  87 #endif
  88         /* Then into the waiting list. */
  89         ret = (struct Task *)FindName(&SysBase->TaskWait, name);
  90         if (ret == NULL)
  91         {
  92             /*
  93                 Finally test the running task(s). Note that generally
  94                 you know the name of your own task - so it is close
  95                 to nonsense to look for it this way.
  96             */
  97             char *s1;
  98             const char *s2 = name;
  99
 100 #if defined(__AROSEXEC_SMP__)
 101             EXEC_SPINLOCK_UNLOCK(listLock);
 102             Permit();
 103             listLock = EXEC_SPINLOCK_LOCK(&PrivExecBase(SysBase)->TaskRunningSpinLock, SPINLOCK_MODE_READ);
 104             Forbid();
 105             ForeachNode(&PrivExecBase(SysBase)->TaskRunning, ret)
 106             {
 107                 s1 = ret->tc_Node.ln_Name;
 108 #else
 109             s1 = GET_THIS_TASK->tc_Node.ln_Name;
 110 #endif
 111             /* Check as long as the names are identical. */
 112             while (*s1++ == *s2)
 113                 /* Terminator found? */
 114                 if (!*s2++)
 115                 {
 116                     /* Got it. */
 117 #if defined(__AROSEXEC_SMP__)
 118 #else
 119                     ret = GET_THIS_TASK;
 120 #endif
 121                     break;
 122                 }
 123 #if defined(__AROSEXEC_SMP__)
 124             }
 125 #endif
 126         }
 127     }
 128
 129 #if defined(__AROSEXEC_SMP__)
 130     }
 131     EXEC_SPINLOCK_UNLOCK(listLock);
 132     Permit();
 133 #else
 134     Enable();
 135 #endif
 136
 137     /* Return whatever was found. */
 138     return ret;
 139
 140     AROS_LIBFUNC_EXIT
 141 } /* FindTask */
 142