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glibc  2.9
Functions
pthread_getattr_np.c File Reference
#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include "pthreadP.h"
#include <lowlevellock.h>
#include <ldsodefs.h>

Go to the source code of this file.

Functions

int pthread_getattr_np (pthread_t thread_id, pthread_attr_t *attr)

Function Documentation

int pthread_getattr_np ( pthread_t  thread_id,
pthread_attr_t attr 
)

Definition at line 34 of file pthread_getattr_np.c.

{
  struct pthread *thread = (struct pthread *) thread_id;
  struct pthread_attr *iattr = (struct pthread_attr *) attr;
  int ret = 0;

  lll_lock (thread->lock, LLL_PRIVATE);

  /* The thread library is responsible for keeping the values in the
     thread desriptor up-to-date in case the user changes them.  */
  memcpy (&iattr->schedparam, &thread->schedparam,
         sizeof (struct sched_param));
  iattr->schedpolicy = thread->schedpolicy;

  /* Clear the flags work.  */
  iattr->flags = thread->flags;

  /* The thread might be detached by now.  */
  if (IS_DETACHED (thread))
    iattr->flags |= ATTR_FLAG_DETACHSTATE;

  /* This is the guardsize after adjusting it.  */
  iattr->guardsize = thread->reported_guardsize;

  /* The sizes are subject to alignment.  */
  if (__builtin_expect (thread->stackblock != NULL, 1))
    {
      iattr->stacksize = thread->stackblock_size;
      iattr->stackaddr = (char *) thread->stackblock + iattr->stacksize;
    }
  else
    {
      /* No stack information available.  This must be for the initial
        thread.  Get the info in some magical way.  */
      assert (abs (thread->pid) == thread->tid);

      /* Stack size limit.  */
      struct rlimit rl;

      /* The safest way to get the top of the stack is to read
        /proc/self/maps and locate the line into which
        __libc_stack_end falls.  */
      FILE *fp = fopen ("/proc/self/maps", "rc");
      if (fp == NULL)
       ret = errno;
      /* We need the limit of the stack in any case.  */
      else
       {
         if (getrlimit (RLIMIT_STACK, &rl) != 0)
           ret = errno;
         else
           {
             /* We need no locking.  */
             __fsetlocking (fp, FSETLOCKING_BYCALLER);

             /* Until we found an entry (which should always be the case)
               mark the result as a failure.  */
             ret = ENOENT;

             char *line = NULL;
             size_t linelen = 0;
             uintptr_t last_to = 0;

             while (! feof_unlocked (fp))
              {
                if (__getdelim (&line, &linelen, '\n', fp) <= 0)
                  break;

                uintptr_t from;
                uintptr_t to;
                if (sscanf (line, "%" SCNxPTR "-%" SCNxPTR, &from, &to) != 2)
                  continue;
                if (from <= (uintptr_t) __libc_stack_end
                    && (uintptr_t) __libc_stack_end < to)
                  {
                    /* Found the entry.  Now we have the info we need.  */
                    iattr->stacksize = rl.rlim_cur;
                    iattr->stackaddr = (void *) to;

                    /* The limit might be too high.  */
                    if ((size_t) iattr->stacksize
                       > (size_t) iattr->stackaddr - last_to)
                     iattr->stacksize = (size_t) iattr->stackaddr - last_to;

                    /* We succeed and no need to look further.  */
                    ret = 0;
                    break;
                  }
                last_to = to;
              }

             free (line);
           }

         fclose (fp);
       }
    }

  iattr->flags |= ATTR_FLAG_STACKADDR;

  if (ret == 0)
    {
      size_t size = 16;
      cpu_set_t *cpuset = NULL;

      do
       {
         size <<= 1;

         void *newp = realloc (cpuset, size);
         if (newp == NULL)
           {
             ret = ENOMEM;
             break;
           }
         cpuset = (cpu_set_t *) newp;

         ret = __pthread_getaffinity_np (thread_id, size, cpuset);
       }
      /* Pick some ridiculous upper limit.  Is 8 million CPUs enough?  */
      while (ret == EINVAL && size < 1024 * 1024);

      if (ret == 0)
       {
         iattr->cpuset = cpuset;
         iattr->cpusetsize = size;
       }
      else
       {
         free (cpuset);
         if (ret == ENOSYS)
           {    
             /* There is no such functionality.  */
             ret = 0;
             iattr->cpuset = NULL;
             iattr->cpusetsize = 0;
           }
       }
    }

  lll_unlock (thread->lock, LLL_PRIVATE);

  return ret;
}

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