/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Copyright (c) University of Cambridge 1996 */
/* See the file NOTICE for conditions of use and distribution. */

#ifdef STAND_ALONE
#include <signal.h>
#include <stdio.h>
#include <time.h>
#endif

/* This source file contains "default" system-dependent functions which
provide functionality (or lack of it) in cases where the OS-specific os.c
file has not. Some of them are tailored by macros defined in os.h files. */


#ifndef OS_RESTARTING_SIGNAL
/*************************************************
*          Set up restarting signal              *
*************************************************/

/* This function has the same functionality as the ANSI C signal() function,
except that it arranges that, if the signal happens during a system call, the
system call gets restarted. Different versions of Unix have different defaults,
and different ways of achieving this. If the functionality is not available,
the signal should be set to be ignored. */

void
os_restarting_signal(int sig, void (*handler)(int))
{
/* Many systems have the SA_RESTART sigaction for specifying that a signal
should restart system calls. These include SunOS5, AIX, BSDI, IRIX, FreeBSD,
OSF1, Linux and HP-UX 10 (but *not* HP-UX 9). */

#ifdef SA_RESTART
struct sigaction act;
act.sa_handler = handler;
sigemptyset(&(act.sa_mask));
act.sa_flags = SA_RESTART;
sigaction(sig, &act, NULL);

#ifdef STAND_ALONE
printf("Used SA_RESTART\n");
#endif

/* SunOS4 and Ultrix default to non-interruptable signals, with SV_INTERRUPT
for making them interruptable. This seems to be a dying fashion. */

#elif defined SV_INTERRUPT
signal(sig, handler);

#ifdef STAND_ALONE
printf("Used default signal()\n");
#endif


/* If neither SA_RESTART nor SV_INTERRUPT is available we don't know how to
set up a restarting signal, so simply suppress the facility. */

#else
signal(sig, SIG_IGN);

#ifdef STAND_ALONE
printf("Used SIG_IGN\n");
#endif

#endif
}

#endif	/* OS_RESTARTING_SIGNAL */


#ifndef OS_NON_RESTARTING_SIGNAL
/*************************************************
*          Set up non-restarting signal          *
*************************************************/

/* This function has the same functionality as the ANSI C signal() function,
except that it arranges that, if the signal happens during a system call, the
system call gets interrupted. Different versions of Unix have different
defaults, and different ways of achieving this. For systems for which we
don't know what to do, just use the normal signal() function. */

void
os_non_restarting_signal(int sig, void (*handler)(int))
{
/* Many systems have the SA_RESTART sigaction for specifying that a signal
should restart system calls. These include SunOS5, AIX, BSDI, IRIX, FreeBSD,
OSF1, Linux and HP-UX 10 (but *not* HP-UX 9). */

#ifdef SA_RESTART
struct sigaction act;
act.sa_handler = handler;
sigemptyset(&(act.sa_mask));
act.sa_flags = 0;
sigaction(sig, &act, NULL);

#ifdef STAND_ALONE
printf("Used sigaction() with flags = 0\n");
#endif

/* SunOS4 and Ultrix default to non-interruptable signals, with SV_INTERRUPT
for making them interruptable. This seems to be a dying fashion. */

#elif defined SV_INTERRUPT
struct sigvec sv;
sv.sv_handler = handler;
sv.sv_flags = SV_INTERRUPT;
sv.sv_mask = -1;
sigvec(sig, &sv, NULL);

#ifdef STAND_ALONE
printf("Used sigvec() with flags = SV_INTERRUPT\n");
#endif

/* If neither SA_RESTART nor SV_INTERRUPT is available we don't know how to
set up a restarting signal, so just use the standard signal() function. */

#else
signal(sig, handler);

#ifdef STAND_ALONE
printf("Used default signal()\n");
#endif

#endif
}

#endif	/* OS_NON_RESTARTING_SIGNAL */



#ifdef STRERROR_FROM_ERRLIST
/*************************************************
*     Provide strerror() for non-ANSI libraries  *
*************************************************/

/* Some old-fashioned systems still around (e.g. SunOS4) don't have strerror()
in their libraries, but can provide the same facility by this simple
alternative function. */

char *
strerror(int n)
{
if (n < 0 || n >= sys_nerr) return "unknown error number";
return sys_errlist[n];
}
#endif /* STRERROR_FROM_ERRLIST */



#ifndef OS_STRSIGNAL
/*************************************************
*      Provide strsignal() for systems without   *
*************************************************/

/* Some systems have strsignal() to turn signal numbers into names; others
may have other means of doing this. This function is used for those systems
that have nothing. It provides a basic translation for the common standard
signal numbers. I've been extra cautious with the ifdef's here. Probably more
than is necessary... */

char *
os_strsignal(int n)
{
switch (n)
  {
  #ifdef SIGHUP
  case SIGHUP:  return "hangup";
  #endif

  #ifdef SIGINT
  case SIGINT:  return "interrupt";
  #endif

  #ifdef SIGQUIT
  case SIGQUIT: return "quit";
  #endif

  #ifdef SIGILL
  case SIGILL:  return "illegal instruction";
  #endif

  #ifdef SIGTRAP
  case SIGTRAP: return "trace trap";
  #endif

  #ifdef SIGABRT
  case SIGABRT: return "abort";
  #endif

  #ifdef SIGEMT
  case SIGEMT:  return "EMT instruction";
  #endif

  #ifdef SIGFPE
  case SIGFPE:  return "arithmetic exception";
  #endif

  #ifdef SIGKILL
  case SIGKILL: return "killed";
  #endif

  #ifdef SIGBUS
  case SIGBUS:  return "bus error";
  #endif

  #ifdef SIGSEGV
  case SIGSEGV: return "segmentation fault";
  #endif

  #ifdef SIGSYS
  case SIGSYS:  return "bad system call";
  #endif

  #ifdef SIGPIPE
  case SIGPIPE: return "broken pipe";
  #endif

  #ifdef SIGALRM
  case SIGALRM: return "alarm";
  #endif

  #ifdef SIGTERM
  case SIGTERM: return "terminated";
  #endif

  #ifdef SIGUSR1
  case SIGUSR1: return "user signal 1";
  #endif

  #ifdef SIGUSR2
  case SIGUSR2: return "user signal 2";
  #endif

  #ifdef SIGCHLD
  case SIGCHLD: return "child stop or exit";
  #endif

  #ifdef SIGPWR
  case SIGPWR:  return "power fail/restart";
  #endif

  #ifdef SIGURG
  case SIGURG:  return "urgent condition on I/O channel";
  #endif

  #ifdef SIGSTOP
  case SIGSTOP: return "stop";
  #endif

  #ifdef SIGTSTP
  case SIGTSTP: return "stop from tty";
  #endif

  #ifdef SIGXCPU
  case SIGXCPU: return "exceeded CPU limit";
  #endif

  #ifdef SIGXFSZ
  case SIGXFSZ: return "exceeded file size limit";
  #endif

  default:      return "unrecognized signal number";
  }
}
#endif /* OS_STRSIGNAL */



#ifndef OS_STREXIT
/*************************************************
*      Provide strexit() for systems without   *
*************************************************/

/* Actually, I don't know of any system that has a strexit() function to turn
exit codes into text, but this function is implemented this way so that if any
OS does have such a thing, it could be used instead of this build-in one. */

char *
os_strexit(int n)
{
switch (n)
  {
  /* On systems without sysexits.h we can assume only those exit codes
  that are given a default value in exim.h. */

  #ifndef NO_SYSEXITS
  case EX_USAGE:       return "(could mean usage or syntax error)";
  case EX_DATAERR:     return "(could mean error in input data)";
  case EX_NOINPUT:     return "(could mean input data missing)";
  case EX_NOUSER:      return "(could mean user nonexistent)";
  case EX_NOHOST:      return "(could mean host nonexistent)";
  case EX_SOFTWARE:    return "(could mean internal software error)";
  case EX_OSERR:       return "(could mean internal operating system error)";
  case EX_OSFILE:      return "(could mean system file missing)";
  case EX_IOERR:       return "(could mean input/output error)";
  case EX_PROTOCOL:    return "(could mean protocol error)";
  case EX_NOPERM:      return "(could mean permission denied)";
  #endif

  case EX_UNAVAILABLE: return "(could mean service or program unavailable)";
  case EX_CANTCREAT:   return "(could mean can't create output file)";
  case EX_TEMPFAIL:    return "(could mean temporary error)";
  case EX_CONFIG:      return "(could mean configuration error)";
  default:             return "";
  }
}
#endif /* OS_STREXIT */




/***********************************************************
*                   Load average function                  *
***********************************************************/

/* Although every Unix seems to have a different way of getting the load
average, a number of them have things in common. Some common variants are
provided below, but if an OS has unique requirements it can be handled in
a specific os.c file. What is required is a function called os_getloadavg
which takes no arguments and passes back the load average * 1000 as an int,
or -1 if no data is available. */


/* ----------------------------------------------------------------------- */
/* If the OS has got a BSD getloadavg() function, life is very easy. */

#if !defined(OS_LOAD_AVERAGE) && defined(HAVE_BSD_GETLOADAVG)
#define OS_LOAD_AVERAGE

int
os_getloadavg(void)
{
double avg;
int loads = getloadavg (&avg, 1);
if (loads != 1) return -1;
return (int)(avg * 1000.0);
}
#endif
/* ----------------------------------------------------------------------- */



/* ----------------------------------------------------------------------- */
/* Only SunOS5 has the kstat functions as far as I know, but put the code
here as there is the -hal variant, and other systems might follow this road one
day. */

#if !defined(OS_LOAD_AVERAGE) && defined(HAVE_KSTAT)
#define OS_LOAD_AVERAGE

#include <kstat.h>

int
os_getloadavg(void)
{
int avg;
kstat_ctl_t *kc;
kstat_t *ksp;
kstat_named_t *kn;

if ((kc = kstat_open()) == NULL ||
    (ksp = kstat_lookup(kc, LOAD_AVG_KSTAT_MODULE, 0, LOAD_AVG_KSTAT))
        == NULL ||
     kstat_read(kc, ksp, NULL) < 0 ||
    (kn = kstat_data_lookup(ksp, LOAD_AVG_SYMBOL)) == NULL)
  return -1;

avg = (int)(((double)(kn->LOAD_AVG_FIELD)/FSCALE) * 1000.0);

kstat_close(kc);
return avg;
}

#endif
/* ----------------------------------------------------------------------- */



/* ----------------------------------------------------------------------- */
/* Handle OS where a kernel symbol has to be read from /dev/kmem */

#if !defined(OS_LOAD_AVERAGE) && defined(HAVE_DEV_KMEM)
#define OS_LOAD_AVERAGE

#include <nlist.h>

static int  avg_kd = -1;
static long avg_offset;

int
os_getloadavg(void)
{
LOAD_AVG_TYPE avg;

if (avg_kd < 0)
  {
  struct nlist nl[2];
  nl[0].n_name = LOAD_AVG_SYMBOL;
  nl[1].n_name = "";
  nlist (KERNEL_PATH, nl);
  avg_offset = (long)nl[0].n_value;
  avg_kd = open ("/dev/kmem", 0);
  if (avg_kd < 0) return -1;
  (void) fcntl(avg_kd, F_SETFD, FD_CLOEXEC);
  }

if (lseek (avg_kd, avg_offset, 0) == -1L
    || read (avg_kd, (char *)(&avg), sizeof (avg)) != sizeof(avg))
  return -1;

return (int)(((double)avg/FSCALE)*1000.0);
}

#endif
/* ----------------------------------------------------------------------- */



/* ----------------------------------------------------------------------- */
/* If nothing is known about this OS, then the load average facility is
not available. */

#ifndef OS_LOAD_AVERAGE

int
os_getloadavg(void)
{
return -1;
}

#endif

/* ----------------------------------------------------------------------- */



/*************************************************
**************************************************
*             Stand-alone test program           *
**************************************************
*************************************************/

/* This is for testing os_getloadavg(). */

#ifdef STAND_ALONE

#ifdef CLOCKS_PER_SEC
#define REAL_CLOCK_TICK CLOCKS_PER_SEC
#else
  #ifdef CLK_TCK
  #define REAL_CLOCK_TICK CLK_TCK
  #else
  #define REAL_CLOCK_TICK 1000000   /* SunOS4 */
  #endif
#endif

void
sigalrm_handler(int sig)
{
printf("SIGALRM handler run\n");
}


int main(int argc, char **argv)
{
char buffer[128];
int fd = fileno(stdin);
int rc;

printf("Testing restarting signal; wait for handler message, then type a line\n");
strcpy(buffer, "*** default ***\n");
os_restarting_signal(SIGALRM, sigalrm_handler);
alarm(2);
if ((rc = read(fd, buffer, sizeof(buffer))) < 0)
  printf("No data read\n");
else
  {
  buffer[rc] = 0;
  printf("Read: %s", buffer);
  }
alarm(0);

printf("Testing non-restarting signal; should read no data after handler message\n");
strcpy(buffer, "*** default ***\n");
os_non_restarting_signal(SIGALRM, sigalrm_handler);
alarm(2);
if ((rc = read(fd, buffer, sizeof(buffer))) < 0)
  printf("No data read\n");
else
  {
  buffer[rc] = 0;
  printf("Read: %s", buffer);
  }
alarm(0);
printf("Testing load averages\n");

for (;;)
  {
  int avg;
  clock_t used;
  clock_t before = clock();
  avg = os_getloadavg();
  used = clock() - before;
  printf("cpu time = %.2f ", (double)used/REAL_CLOCK_TICK);
  if (avg < 0)
    {
    printf("load average not available\n");
    break;
    }
  printf("load average = %.2f\n", (double)avg/1000.0);
  sleep(2);
  }
return 0;
}

#endif

/* End of os.c */