source: trunk/third/top/machine/m_sunos4.c @ 16185

/*
 * top - a top users display for Unix
 *
 * SYNOPSIS:  any Sun running SunOS version 4.x
 *
 * DESCRIPTION:
 * This is the machine-dependent module for SunOS 4.x.
 * This makes top work on the following systems:
 *      SunOS 4.0
 *      SunOS 4.0.1
 *      SunOS 4.0.2 (including 386i architecture)
 *      SunOS 4.0.3
 *      SunOS 4.1
 *      SunOS 4.1.1
 *      SunOS 4.1.2 (including MP architectures)
 *      SunOS 4.1.3 (including MP architectures)
 *      SunOS 4.1.3_U1 (including MP architectures)
 *      SunOS 4.1.4 (including MP architectures)
 *      Solbourne OS/MP PRIOR to 4.1A
 *
 * LIBS:  -lkvm
 *
 * CFLAGS: -DHAVE_GETOPT -DORDER
 *
 * AUTHOR:  William LeFebvre <wnl@groupsys.com>
 * Solbourne support by David MacKenzie <djm@eng.umd.edu>
 */

/*
 * #ifdef MULTIPROCESSOR means Sun MP.
 * #ifdef solbourne is for Solbourne.
 */

#include <sys/types.h>
#include <sys/signal.h>

/* make sure param.h gets loaded with KERNEL defined to get PZERO & NZERO */
#define KERNEL
#include <sys/param.h>
#undef KERNEL

#include <stdio.h>
#include <kvm.h>
#include <nlist.h>
#include <math.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <sys/proc.h>
#include <sys/dk.h>
#include <sys/vm.h>
#include <sys/file.h>
#include <sys/time.h>
#include <vm/page.h>

#ifdef solbourne
#include <sys/syscall.h>
#endif

/* Older versions of SunOS don't have a typedef for pid_t.
   Hopefully this will catch all those cases without causing other problems.
 */
#ifndef __sys_stdtypes_h
typedef int pid_t;
#endif

#include "top.h"
#include "machine.h"
#include "utils.h"

/* declarations for load_avg */
#include "loadavg.h"

/* get_process_info passes back a handle.  This is what it looks like: */

struct handle
{
    struct proc **next_proc;    /* points to next valid proc pointer */
    int remaining;              /* number of pointers remaining */
};

/* define what weighted cpu is.  */
#define weighted_cpu(pct, pp) ((pp)->p_time == 0 ? 0.0 : \
                         ((pct) / (1.0 - exp((pp)->p_time * logcpu))))

/* what we consider to be process size: */
#define PROCSIZE(pp) ((pp)->p_tsize + (pp)->p_dsize + (pp)->p_ssize)

/* definitions for indices in the nlist array */
#define X_AVENRUN       0
#define X_CCPU          1
#define X_MPID          2
#define X_NPROC         3
#define X_PROC          4
#define X_TOTAL         5
#define X_CP_TIME       6
#define X_PAGES         7
#define X_EPAGES        8

static struct nlist nlst[] = {
#ifdef i386
    { "avenrun" },              /* 0 */
    { "ccpu" },                 /* 1 */
    { "mpid" },                 /* 2 */
    { "nproc" },                /* 3 */
    { "proc" },                 /* 4 */
    { "total" },                /* 5 */
    { "cp_time" },              /* 6 */
    { "pages" },                /* 7 */
    { "epages" },               /* 8 */
#else
    { "_avenrun" },             /* 0 */
    { "_ccpu" },                /* 1 */
    { "_mpid" },                /* 2 */
    { "_nproc" },               /* 3 */
    { "_proc" },                /* 4 */
    { "_total" },               /* 5 */
    { "_cp_time" },             /* 6 */
    { "_pages" },               /* 7 */
    { "_epages" },              /* 8 */
#ifdef MULTIPROCESSOR
    { "_ncpu" },
#define X_NCPU          9
    { "_xp_time" },
#define X_XP_TIME       10
#endif
#endif
    { 0 }
};

/*
 *  These definitions control the format of the per-process area
 */

static char header[] =
  "  PID X        PRI NICE  SIZE   RES STATE   TIME   WCPU    CPU COMMAND";
/* 0123456   -- field to fill in starts at header+6 */
#define UNAME_START 6

#define Proc_format \
        "%5d %-8.8s %3d %4d %5s %5s %-5s %-6s %5.2f%% %5.2f%% %s"


/* process state names for the "STATE" column of the display */
/* the extra nulls in the string "run" are for adding a slash and
   the processor number when needed */

char *state_abbrev[] =
{
    "", "sleep", "WAIT", "run\0\0\0", "start", "zomb", "stop"
};

/* values that we stash away in _init and use in later routines */

static double logcpu;
kvm_t *kd;

/* these are retrieved from the kernel in _init */

static unsigned long proc;
static          int  nproc;
static load_avg ccpu;
static unsigned long pages;
static unsigned long epages;
static          int  ncpu = 0;

/* these are offsets obtained via nlist and used in the get_ functions */

static unsigned long mpid_offset;
static unsigned long avenrun_offset;
static unsigned long total_offset;
static unsigned long cp_time_offset;
#ifdef MULTIPROCESSOR
static unsigned long xp_time_offset;
#endif

/* these are for calculating cpu state percentages */

static long cp_time[CPUSTATES];
static long cp_old[CPUSTATES];
static long cp_diff[CPUSTATES];
#ifdef MULTIPROCESSOR
static long xp_time[NCPU][XPSTATES];
/* for now we only accumulate spin time, but extending this to pick up
   other stuff in xp_time is trivial.  */
static long xp_old[NCPU];
#endif

/* these are for detailing the process states */

int process_states[7];
char *procstatenames[] = {
    "", " sleeping, ", " ABANDONED, ", " running, ", " starting, ",
    " zombie, ", " stopped, ",
    NULL
};

/* these are for detailing the cpu states */

int cpu_states[5];
char *cpustatenames[] = {
    "user", "nice", "system", "idle",
#ifdef MULTIPROCESSOR
    "spin",
#define XCP_SPIN 4
#endif
    NULL
};

/* these are for detailing the memory statistics */

int memory_stats[4];
char *memorynames[] = {
    "K available, ", "K in use, ", "K free, ", "K locked", NULL
};

/* these are names given to allowed sorting orders -- first is default */
char *ordernames[] = 
{"cpu", "size", "res", NULL};

/* forward definitions for comparison functions */
int compare_cpu();
int compare_size();
int compare_res();

int (*proc_compares[])() = {
    compare_cpu,
    compare_size,
    compare_res,
    NULL };


/* these are for keeping track of the proc array */

static int bytes;
static int pref_len;
static struct proc *pbase;
static struct proc **pref;

/* these are for getting the memory statistics */

static struct page *physpage;
static int bytesize;
static int count;
static int pageshift;           /* log base 2 of the pagesize */

/* define pagetok in terms of pageshift */

#define pagetok(size) ((size) << pageshift)

/* useful externals */
extern int errno;
extern char *sys_errlist[];

long lseek();
long time();

machine_init(statics)

struct statics *statics;

{
    register int i;
    register int pagesize;

    /* initialize the kernel interface */
    if ((kd = kvm_open(NULL, NULL, NULL, O_RDONLY, "top")) == NULL)
    {
        perror("kvm_open");
        return(-1);
    }

    /* get the list of symbols we want to access in the kernel */
    if ((i = kvm_nlist(kd, nlst)) < 0)
    {
        fprintf(stderr, "top: nlist failed\n");
        return(-1);
    }

#ifdef MULTIPROCESSOR
    /* were ncpu and xp_time not found in the nlist? */
    if (i > 0 && nlst[X_NCPU].n_type == 0 && nlst[X_XP_TIME].n_type == 0)
    {
        /* we were compiled on an MP system but we are not running on one */
        /* so we will pretend this didn't happen and set ncpu = 1 */
        i -= 2;
        ncpu = 1;
    }
#endif

#ifdef solbourne
    {
        unsigned int status, type;

        /* Get the number of CPUs on this system.  */
        syscall(SYS_getcpustatus, &status, &ncpu, &type);
    }
#endif

    /* make sure they were all found */
    if (i > 0 && check_nlist(nlst) > 0)
    {
        return(-1);
    }

    /* get the symbol values out of kmem */
    (void) getkval(nlst[X_PROC].n_value,   (int *)(&proc),      sizeof(proc),
            nlst[X_PROC].n_name);
    (void) getkval(nlst[X_NPROC].n_value,  &nproc,              sizeof(nproc),
            nlst[X_NPROC].n_name);
    (void) getkval(nlst[X_CCPU].n_value,   (int *)(&ccpu),      sizeof(ccpu),
            nlst[X_CCPU].n_name);
    (void) getkval(nlst[X_PAGES].n_value,  (int *)(&pages),     sizeof(pages),
            nlst[X_PAGES].n_name);
    (void) getkval(nlst[X_EPAGES].n_value, (int *)(&epages),    sizeof(epages),
            nlst[X_EPAGES].n_name);
#ifdef MULTIPROCESSOR
    if (ncpu == 0)
    {
        /* if ncpu > 0 then we are not really on an MP system */
        (void) getkval(nlst[X_NCPU].n_value,   (int *)(&ncpu),  sizeof(ncpu),
                       nlst[X_NCPU].n_name);
    }
#endif

    /* stash away certain offsets for later use */
    mpid_offset = nlst[X_MPID].n_value;
    avenrun_offset = nlst[X_AVENRUN].n_value;
    total_offset = nlst[X_TOTAL].n_value;
    cp_time_offset = nlst[X_CP_TIME].n_value;
#ifdef MULTIPROCESSOR
    xp_time_offset = nlst[X_XP_TIME].n_value;
#endif

    /* this is used in calculating WCPU -- calculate it ahead of time */
    logcpu = log(loaddouble(ccpu));

    /* allocate space for proc structure array and array of pointers */
    bytes = nproc * sizeof(struct proc);
    pbase = (struct proc *)malloc(bytes);
    pref  = (struct proc **)malloc(nproc * sizeof(struct proc *));

    /* Just in case ... */
    if (pbase == (struct proc *)NULL || pref == (struct proc **)NULL)
    {
        fprintf(stderr, "top: can't allocate sufficient memory\n");
        return(-1);
    }

    /* allocate a table to hold all the page structs */
    bytesize = epages - pages;
    count = bytesize / sizeof(struct page);
    physpage = (struct page *)malloc(epages - pages);
    if (physpage == NULL)
    {
        fprintf(stderr, "top: can't allocate sufficient memory\n");
        return(-1);
    }
   
    /* get the page size with "getpagesize" and calculate pageshift from it */
    pagesize = getpagesize();
    pageshift = 0;
    while (pagesize > 1)
    {
        pageshift++;
        pagesize >>= 1;
    }

    /* we only need the amount of log(2)1024 for our conversion */
    pageshift -= LOG1024;

#if defined(MULTIPROCESSOR) || defined(solbourne)
    /* add a slash to the "run" state abbreviation */
    if (ncpu > 1)
    {
        state_abbrev[SRUN][3] = '/';
    }
#endif

    /* fill in the statics information */
    statics->procstate_names = procstatenames;
    statics->cpustate_names = cpustatenames;
    statics->memory_names = memorynames;
#ifdef ORDER
    statics->order_names = ordernames;
#endif

    /* all done! */
    return(0);
}

char *format_header(uname_field)

register char *uname_field;

{
    register char *ptr;

    ptr = header + UNAME_START;
    while (*uname_field != '\0')
    {
        *ptr++ = *uname_field++;
    }

    return(header);
}

get_system_info(si)

struct system_info *si;

{
    load_avg avenrun[3];
    long total;
#ifdef MULTIPROCESSOR
    long half_total;
#endif

    /* get the cp_time array */
    (void) getkval(cp_time_offset, (int *)cp_time, sizeof(cp_time),
                   "_cp_time");

#ifdef MULTIPROCESSOR
    /* get the xp_time array as well */
    if (ncpu > 1)
    {
        (void) getkval(xp_time_offset, (int *)xp_time, sizeof(xp_time),
                       "_xp_time");
    }
#endif

    /* get load average array */
    (void) getkval(avenrun_offset, (int *)avenrun, sizeof(avenrun),
                   "_avenrun");

    /* get mpid -- process id of last process */
    (void) getkval(mpid_offset, &(si->last_pid), sizeof(si->last_pid),
                   "_mpid");

    /* get the array of physpage descriptors */
    (void) getkval(pages, (int *)physpage, bytesize, "array _page");

    /* convert load averages to doubles */
    {
        register int i;
        register double *infoloadp;
        register load_avg *sysloadp;

        infoloadp = si->load_avg;
        sysloadp = avenrun;
        for (i = 0; i < 3; i++)
        {
            *infoloadp++ = loaddouble(*sysloadp++);
        }
    }

    /* convert cp_time counts to percentages */
    total = percentages(CPUSTATES, cpu_states, cp_time, cp_old, cp_diff);

#ifdef MULTIPROCESSOR
    /* calculate spin time from all processors */
    if (ncpu > 1)
    {
        register int c;
        register int i;
        register long sum;
        register long change;

        /* collect differences for each processor and add them */
        sum = 0;
        for (i = 0; i < ncpu; i++)
        {
            c = xp_time[i][XP_SPIN];
            change = c - xp_old[i];
            if (change < 0)
            {
                /* counter wrapped */
                change = (long)((unsigned long)c -
                                (unsigned long)xp_old[i]);
            }
            sum += change;
            xp_old[i] = c;
        }

        /*
         *  NOTE:  I am assuming that the ticks found in xp_time are
         *  already included in the ticks accumulated in cp_time.  To
         *  get an accurate reflection, therefore, we have to subtract
         *  the spin time from the system time and recompute those two
         *  percentages.
         */
        half_total = total / 2l;
        cp_diff[CP_SYS] -= sum;
        cpu_states[CP_SYS] = (int)((cp_diff[CP_SYS] * 1000 + half_total) /
                                   total);
        cpu_states[XCP_SPIN] = (int)((sum * 1000 + half_total) / total);
    }
#endif

    /* sum memory statistics */
    {
        register struct page *pp;
        register int cnt;
        register int inuse;
        register int free;
        register int locked;

        /* bop thru the array counting page types */
        pp = physpage;
        inuse = free = locked = 0;
        for (cnt = count; --cnt >= 0; pp++)
        {
            if (pp->p_free)
                free++;
            else if (pp->p_lock || pp->p_keepcnt > 0)
                locked++;
            else
                inuse++;
        }

        /* convert memory stats to Kbytes */
        memory_stats[0] = pagetok(inuse + free);
        memory_stats[1] = pagetok(inuse);
        memory_stats[2] = pagetok(free);
        memory_stats[3] = pagetok(locked);
    }

    /* set arrays and strings */
    si->cpustates = cpu_states;
    si->memory = memory_stats;
}

static struct handle handle;

caddr_t get_process_info(si, sel, compare)

struct system_info *si;
struct process_select *sel;
int (*compare)();

{
    register int i;
    register int total_procs;
    register int active_procs;
    register struct proc **prefp;
    register struct proc *pp;

    /* these are copied out of sel for speed */
    int show_idle;
    int show_system;
    int show_uid;
    int show_command;

    /* read all the proc structures in one fell swoop */
    (void) getkval(proc, (int *)pbase, bytes, "proc array");

    /* get a pointer to the states summary array */
    si->procstates = process_states;

    /* set up flags which define what we are going to select */
    show_idle = sel->idle;
    show_system = sel->system;
    show_uid = sel->uid != -1;
    show_command = sel->command != NULL;

    /* count up process states and get pointers to interesting procs */
    total_procs = 0;
    active_procs = 0;
    bzero((char *)process_states, sizeof(process_states));
    prefp = pref;
    for (pp = pbase, i = 0; i < nproc; pp++, i++)
    {
        /*
         *  Place pointers to each valid proc structure in pref[].
         *  Process slots that are actually in use have a non-zero
         *  status field.  Processes with SSYS set are system
         *  processes---these get ignored unless show_sysprocs is set.
         */
        if (pp->p_stat != 0 &&
            (show_system || ((pp->p_flag & SSYS) == 0)))
        {
            total_procs++;
            process_states[pp->p_stat]++;
            if ((pp->p_stat != SZOMB) &&
                (show_idle || (pp->p_pctcpu != 0) || (pp->p_stat == SRUN)) &&
                (!show_uid || pp->p_uid == (uid_t)sel->uid))
            {
                *prefp++ = pp;
                active_procs++;
            }
        }
    }

    /* if requested, sort the "interesting" processes */
    if (compare != NULL)
    {
        qsort((char *)pref, active_procs, sizeof(struct proc *), compare);
    }

    /* remember active and total counts */
    si->p_total = total_procs;
    si->p_active = pref_len = active_procs;

    /* pass back a handle */
    handle.next_proc = pref;
    handle.remaining = active_procs;
    return((caddr_t)&handle);
}

char fmt[MAX_COLS];             /* static area where result is built */

char *format_next_process(handle, get_userid)

caddr_t handle;
char *(*get_userid)();

{
    register struct proc *pp;
    register long cputime;
    register double pct;
    struct user u;
    struct handle *hp;

    /* find and remember the next proc structure */
    hp = (struct handle *)handle;
    pp = *(hp->next_proc++);
    hp->remaining--;
    
    /* get the process's user struct and set cputime */
    if (getu(pp, &u) == -1)
    {
        (void) strcpy(u.u_comm, "<swapped>");
        cputime = 0;
    }
    else
    {
        /* set u_comm for system processes */
        if (u.u_comm[0] == '\0')
        {
            if (pp->p_pid == 0)
            {
                (void) strcpy(u.u_comm, "Swapper");
            }
            else if (pp->p_pid == 2)
            {
                (void) strcpy(u.u_comm, "Pager");
            }
        }

        cputime = u.u_ru.ru_utime.tv_sec + u.u_ru.ru_stime.tv_sec;
    }

    /* calculate the base for cpu percentages */
    pct = pctdouble(pp->p_pctcpu);

#ifdef MULTIPROCESSOR
    /*
     *  If there is more than one cpu then add the processor number to
     *  the "run/" string.  Note that this will only show up if the
     *  process is in the run state.  Also note:  when they
     *  start making Suns with more than 9 processors this will break
     *  since the string will then be more than 5 characters.
     */
    if (ncpu > 1)
    {
        state_abbrev[SRUN][4] = (pp->p_cpuid & 0xf) + '0';
    }
#endif
#ifdef solbourne
    if (ncpu > 1)
      {
        state_abbrev[SRUN][4] = (pp->p_lastcpu) + '0';
      }
#endif

    /* format this entry */
    sprintf(fmt,
            Proc_format,
            pp->p_pid,
            (*get_userid)(pp->p_uid),
            pp->p_pri - PZERO,
            pp->p_nice - NZERO,
            format_k(pagetok(PROCSIZE(pp))),
            format_k(pagetok(pp->p_rssize)),
            state_abbrev[pp->p_stat],
            format_time(cputime),
            100.0 * weighted_cpu(pct, pp),
            100.0 * pct,
            printable(u.u_comm));

    /* return the result */
    return(fmt);
}

/*
 *  getu(p, u) - get the user structure for the process whose proc structure
 *      is pointed to by p.  The user structure is put in the buffer pointed
 *      to by u.  Return 0 if successful, -1 on failure (such as the process
 *      being swapped out).
 */

getu(p, u)

register struct proc *p;
struct user *u;

{
    register struct user *lu;

    lu = kvm_getu(kd, p);
    if (lu == NULL)
    {
        return(-1);
    }
    else
    {
        *u = *lu;
        return(0);
    }
}

/*
 * check_nlist(nlst) - checks the nlist to see if any symbols were not
 *              found.  For every symbol that was not found, a one-line
 *              message is printed to stderr.  The routine returns the
 *              number of symbols NOT found.
 */

int check_nlist(nlst)

register struct nlist *nlst;

{
    register int i;

    /* check to see if we got ALL the symbols we requested */
    /* this will write one line to stderr for every symbol not found */

    i = 0;
    while (nlst->n_name != NULL)
    {
#ifdef i386
        if (nlst->n_value == 0)
#else
        if (nlst->n_type == 0)
#endif
        {
            /* this one wasn't found */
            fprintf(stderr, "kernel: no symbol named `%s'\n", nlst->n_name);
            i = 1;
        }
        nlst++;
    }

    return(i);
}


/*
 *  getkval(offset, ptr, size, refstr) - get a value out of the kernel.
 *      "offset" is the byte offset into the kernel for the desired value,
 *      "ptr" points to a buffer into which the value is retrieved,
 *      "size" is the size of the buffer (and the object to retrieve),
 *      "refstr" is a reference string used when printing error meessages,
 *          if "refstr" starts with a '!', then a failure on read will not
 *          be fatal (this may seem like a silly way to do things, but I
 *          really didn't want the overhead of another argument).
 *      
 */

getkval(offset, ptr, size, refstr)

unsigned long offset;
int *ptr;
int size;
char *refstr;

{
    if (kvm_read(kd, offset, ptr, size) != size)
    {
        if (*refstr == '!')
        {
            return(0);
        }
        else
        {
            fprintf(stderr, "top: kvm_read for %s: %s\n",
                refstr, sys_errlist[errno]);
            quit(23);
            /*NOTREACHED*/
        }
    }
    return(1);
}
    
/* comparison routines for qsort */

/*
 * There are currently four possible comparison routines.  main selects
 * one of these by indexing in to the array proc_compares.
 *
 * Possible keys are defined as macros below.  Currently these keys are
 * defined:  percent cpu, cpu ticks, process state, resident set size,
 * total virtual memory usage.  The process states are ordered as follows
 * (from least to most important):  WAIT, zombie, sleep, stop, start, run.
 * The array declaration below maps a process state index into a number
 * that reflects this ordering.
 */

/* First, the possible comparison keys.  These are defined in such a way
   that they can be merely listed in the source code to define the actual
   desired ordering.
 */

#define ORDERKEY_PCTCPU  if (lresult = p2->p_pctcpu - p1->p_pctcpu,\
                             (result = lresult > 0 ? 1 : lresult < 0 ? -1 : 0) == 0)
#define ORDERKEY_CPTICKS if ((result = p2->p_cpticks - p1->p_cpticks) == 0)
#define ORDERKEY_STATE   if ((result = sorted_state[p2->p_stat] - \
                              sorted_state[p1->p_stat])  == 0)
#define ORDERKEY_PRIO    if ((result = p2->p_pri - p1->p_pri) == 0)
#define ORDERKEY_RSSIZE  if ((result = p2->p_rssize - p1->p_rssize) == 0)
#define ORDERKEY_MEM     if ((result = PROCSIZE(p2) - PROCSIZE(p1)) == 0)

/* Now the array that maps process state to a weight */

static unsigned char sorted_state[] =
{
    0,  /* not used             */
    3,  /* sleep                */
    1,  /* ABANDONED (WAIT)     */
    6,  /* run                  */
    5,  /* start                */
    2,  /* zombie               */
    4   /* stop                 */
};
 
/* compare_cpu - the comparison function for sorting by cpu percentage */

compare_cpu(pp1, pp2)

struct proc **pp1;
struct proc **pp2;

{
    register struct proc *p1;
    register struct proc *p2;
    register int result;
    register pctcpu lresult;

    /* remove one level of indirection */
    p1 = *pp1;
    p2 = *pp2;

    ORDERKEY_PCTCPU
    ORDERKEY_CPTICKS
    ORDERKEY_STATE
    ORDERKEY_PRIO
    ORDERKEY_RSSIZE
    ORDERKEY_MEM
    ;

    return(result);
}

/* compare_size - the comparison function for sorting by total memory usage */

compare_size(pp1, pp2)

struct proc **pp1;
struct proc **pp2;

{
    register struct proc *p1;
    register struct proc *p2;
    register int result;
    register pctcpu lresult;

    /* remove one level of indirection */
    p1 = *pp1;
    p2 = *pp2;

    ORDERKEY_MEM
    ORDERKEY_RSSIZE
    ORDERKEY_PCTCPU
    ORDERKEY_CPTICKS
    ORDERKEY_STATE
    ORDERKEY_PRIO
    ;

    return(result);
}

/* compare_res - the comparison function for sorting by resident set size */

compare_res(pp1, pp2)

struct proc **pp1;
struct proc **pp2;

{
    register struct proc *p1;
    register struct proc *p2;
    register int result;
    register pctcpu lresult;

    /* remove one level of indirection */
    p1 = *pp1;
    p2 = *pp2;

    ORDERKEY_RSSIZE
    ORDERKEY_MEM
    ORDERKEY_PCTCPU
    ORDERKEY_CPTICKS
    ORDERKEY_STATE
    ORDERKEY_PRIO
    ;

    return(result);
}

/*
 * proc_owner(pid) - returns the uid that owns process "pid", or -1 if
 *              the process does not exist.
 *              It is EXTREMLY IMPORTANT that this function work correctly.
 *              If top runs setuid root (as in SVR4), then this function
 *              is the only thing that stands in the way of a serious
 *              security problem.  It validates requests for the "kill"
 *              and "renice" commands.
 */

int proc_owner(pid)

int pid;

{
    register int cnt;
    register struct proc **prefp;
    register struct proc *pp;

    prefp = pref;
    cnt = pref_len;
    while (--cnt >= 0)
    {
        if ((pp = *prefp++)->p_pid == (pid_t)pid)
        {
            return((int)pp->p_uid);
        }
    }
    return(-1);
}