OSUtil.c

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// -*-Mode: C++;-*- // technically C99

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//***************************************************************************
//
// File: 
//   $HeadURL$
//
// Purpose:
//   OS Utilities
//
// Description:
//   [The set of functions, macros, etc. defined in the file]
//
// Author:
//   Nathan Tallent, John Mellor-Crummey, Rice University.
//
//***************************************************************************

//************************* System Include Files ****************************

#include <sys/types.h> // getpid()
#include <setjmp.h>
#include <signal.h>

#include <stdio.h> // snprintf
#include <stdlib.h>
#include <string.h>

#define __USE_XOPEN_EXTENDED // for gethostid()
#include <unistd.h>

//*************************** User Include Files ****************************

#include "OSUtil.h"
#include <include/linux_info.h>

//*************************** macros **************************

#define KERNEL_NAME_FORMAT    "%s." HOSTID_FORMAT

//*************************** Forward Declarations **************************

//***************************************************************************
// 
//***************************************************************************

uint
OSUtil_pid()
{
  pid_t pid = getpid();
  return (uint)pid;
}


const char*
OSUtil_jobid()
{
  char* jid = NULL;
 
  // LSF
  jid = getenv("LSB_JOBID");
  if (jid) {
    return jid;
  }


  // Cobalt
  jid = getenv("COBALT_JOBID");
  if (jid) {
    return jid;
  }

  // PBS
  jid = getenv("PBS_JOBID");
  if (jid) {
    return jid;
  }

  // SLURM
  jid = getenv("SLURM_JOB_ID");
  if (jid) {
    return jid;
  }

  // Sun Grid Engine
  jid = getenv("JOB_ID");
  if (jid) {
    return jid;
  }

  return jid;
}


// On early RH/CentOS 6.x systems, the statically linked gethostid()
// throws an FPE (floating point exception) and does not return.  So,
// wrap the function with sigsetjmp().  We cache the value, so the
// performance hit is negligible.

#define OSUtil_hostid_NULL (-1)
#define OSUtil_hostid_fail (0x0bad1d);

static sigjmp_buf hostid_jbuf;
static int hostid_jbuf_active;

static void
hostid_fpe_handler(int sig)
{
  if (hostid_jbuf_active) {
    siglongjmp(hostid_jbuf, 1);
  }

  // can't get here
  abort();
}

long
OSUtil_hostid()
{
  static long hostid = OSUtil_hostid_NULL;
  struct sigaction act, old_act;

  if (hostid == OSUtil_hostid_NULL) {
    memset(&act, 0, sizeof(act));
    memset(&old_act, 0, sizeof(old_act));
    act.sa_handler = hostid_fpe_handler;
    act.sa_flags = 0;
    sigemptyset(&act.sa_mask);

    hostid_jbuf_active = 0;
    sigaction(SIGFPE, &act, &old_act);

    if (sigsetjmp(hostid_jbuf, 1) == 0) {
      // normal return
      hostid_jbuf_active = 1;

      // gethostid returns long, but only 32 bits
      hostid = (uint32_t) gethostid();
    }
    else {
      // error return from signal handler
      hostid = OSUtil_hostid_fail;
    }
    hostid_jbuf_active = 0;

    // reset the handler so we don't get called again
    sigaction(SIGFPE, &old_act, NULL);
  }

  return hostid;
}

int
OSUtil_setCustomKernelName(char *buffer, size_t max_chars)
{
  int n = snprintf(buffer, max_chars, KERNEL_NAME_FORMAT,
           LINUX_KERNEL_NAME_REAL, OSUtil_hostid());

  return n;
}


int
OSUtil_setCustomKernelNameWrap(char *buffer, size_t max_chars)
{
  int n = snprintf(buffer, max_chars, "<" KERNEL_NAME_FORMAT ">",
           LINUX_KERNEL_NAME_REAL, OSUtil_hostid());

  return n;
}