/* $OpenBSD: procname.c,v 1.20 2022/02/22 17:35:01 deraadt Exp $ */

/*
 * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/signal.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/stat.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifndef nitems
#define nitems(_a) (sizeof((_a)) / sizeof((_a)[0]))
#endif

#define is_runnable(p) \
        ((p)->p_stat == SRUN || (p)->p_stat == SIDL || (p)->p_stat == SONPROC)
#define is_stopped(p) \
        ((p)->p_stat == SSTOP || (p)->p_stat == SDEAD)

static struct kinfo_proc *cmp_procs(struct kinfo_proc *, struct kinfo_proc *);
char    *get_proc_name(int, char *);
char    *get_proc_cwd(int);

static struct kinfo_proc *
cmp_procs(struct kinfo_proc *p1, struct kinfo_proc *p2)
{
        if (is_runnable(p1) && !is_runnable(p2))
                return (p1);
        if (!is_runnable(p1) && is_runnable(p2))
                return (p2);

        if (is_stopped(p1) && !is_stopped(p2))
                return (p1);
        if (!is_stopped(p1) && is_stopped(p2))
                return (p2);

        if (p1->p_estcpu > p2->p_estcpu)
                return (p1);
        if (p1->p_estcpu < p2->p_estcpu)
                return (p2);

        if (p1->p_slptime < p2->p_slptime)
                return (p1);
        if (p1->p_slptime > p2->p_slptime)
                return (p2);

        if ((p1->p_flag & P_SINTR) && !(p2->p_flag & P_SINTR))
                return (p1);
        if (!(p1->p_flag & P_SINTR) && (p2->p_flag & P_SINTR))
                return (p2);

        if (strcmp(p1->p_comm, p2->p_comm) < 0)
                return (p1);
        if (strcmp(p1->p_comm, p2->p_comm) > 0)
                return (p2);

        if (p1->p_pid > p2->p_pid)
                return (p1);
        return (p2);
}

char *
get_proc_name(int fd, char *tty)
{
        int              mib[6] = { CTL_KERN, KERN_PROC, KERN_PROC_PGRP, 0,
                                    sizeof(struct kinfo_proc), 0 };
        struct stat      sb;
        size_t           len;
        struct kinfo_proc *buf, *newbuf, *bestp;
        u_int            i;
        char            *name;

        buf = NULL;

        if (stat(tty, &sb) == -1)
                return (NULL);
        if ((mib[3] = tcgetpgrp(fd)) == -1)
                return (NULL);

retry:
        if (sysctl(mib, nitems(mib), NULL, &len, NULL, 0) == -1)
                goto error;
        len = (len * 5) / 4;

        if ((newbuf = realloc(buf, len)) == NULL)
                goto error;
        buf = newbuf;

        mib[5] = (int)(len / sizeof(struct kinfo_proc));
        if (sysctl(mib, nitems(mib), buf, &len, NULL, 0) == -1) {
                if (errno == ENOMEM)
                        goto retry;
                goto error;
        }

        bestp = NULL;
        for (i = 0; i < len / sizeof (struct kinfo_proc); i++) {
                if ((dev_t)buf[i].p_tdev != sb.st_rdev)
                        continue;
                if (bestp == NULL)
                        bestp = &buf[i];
                else
                        bestp = cmp_procs(&buf[i], bestp);
        }

        name = NULL;
        if (bestp != NULL)
                name = strdup(bestp->p_comm);

        free(buf);
        return (name);

error:
        free(buf);
        return (NULL);
}

char *
get_proc_cwd(int fd)
{
        int             name[] = { CTL_KERN, KERN_PROC_CWD, 0 };
        static char     path[PATH_MAX];
        size_t          pathlen = sizeof path;

        if ((name[2] = tcgetpgrp(fd)) == -1)
                return (NULL);
        if (sysctl(name, 3, path, &pathlen, NULL, 0) != 0)
                return (NULL);
        return (path);
}