/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Originally written by Eric Cooper in Fall 1981.
 * Inspired by a version 6 program by Len Levin, 1978.
 * Several pieces of code lifted from Bill Joy's 4BSD ps.
 * Most recently, hacked beyond recognition for 4.4BSD by Steven McCanne,
 * Lawrence Berkeley Laboratory.
 *
 * Portions of this software were developed by the Computer Systems
 * Engineering group at Lawrence Berkeley Laboratory under DARPA
 * contract BG 91-66 and contributed to Berkeley.
 */

#include <sys/param.h>
#include <sys/ptrace.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/linker_set.h>
#include <sys/sysctl.h>
#include <sys/wait.h>

#include <err.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "extern.h"
int pflags;

static void     killed(int);
static void     usage(void) __dead2;

static pid_t pid;
static bool kflag = false;

SET_DECLARE(dumpset, struct dumpers);

static int
open_corefile(char *corefile)
{
        char fname[MAXPATHLEN];
        int fd;

        if (corefile == NULL) {
                (void)snprintf(fname, sizeof(fname), "core.%d", pid);
                corefile = fname;
        }
        fd = open(corefile, O_RDWR | O_CREAT | O_TRUNC, DEFFILEMODE);
        if (fd < 0)
                err(1, "%s", corefile);
        return (fd);
}

static void
kcoredump(int fd, pid_t pid)
{
        struct ptrace_coredump pc;
        int error, res, ret, waited;

        error = ptrace(PT_ATTACH, pid, NULL, 0);
        if (error != 0)
                err(1, "attach");

        waited = waitpid(pid, &res, 0);
        if (waited == -1)
                err(1, "wait for STOP");

        ret = 0;
        memset(&pc, 0, sizeof(pc));
        pc.pc_fd = fd;
        pc.pc_flags = (pflags & PFLAGS_FULL) != 0 ? PC_ALL : 0;
        error = ptrace(PT_COREDUMP, pid, (void *)&pc, sizeof(pc));
        if (error == -1) {
                warn("coredump");
                ret = 1;
        }

        waited = waitpid(pid, &res, WNOHANG);
        if (waited == -1) {
                warn("wait after coredump");
                ret = 1;
        }

        error = ptrace(PT_DETACH, pid, NULL, 0);
        if (error == -1) {
                warn("detach failed, check process status");
                ret = 1;
        }

        exit(ret);
}

int
main(int argc, char *argv[])
{
        int ch, efd, fd, name[4];
        char *binfile, *corefile;
        char passpath[MAXPATHLEN];
        struct dumpers **d, *dumper;
        size_t len;

        pflags = 0;
        corefile = NULL;
        while ((ch = getopt(argc, argv, "c:fk")) != -1) {
                switch (ch) {
                case 'c':
                        corefile = optarg;
                        break;
                case 'f':
                        pflags |= PFLAGS_FULL;
                        break;
                case 'k':
                        kflag = true;
                        break;
                default:
                        usage();
                        break;
                }
        }
        argv += optind;
        argc -= optind;

        /* XXX we should check that the pid argument is really a number */
        switch (argc) {
        case 1:
                pid = atoi(argv[0]);
                break;
        case 2:
                binfile = argv[0];
                pid = atoi(argv[1]);
                break;
        default:
                usage();
        }

        if (kflag) {
                fd = open_corefile(corefile);
                kcoredump(fd, pid);
        }

        if (argc == 1) {
                name[0] = CTL_KERN;
                name[1] = KERN_PROC;
                name[2] = KERN_PROC_PATHNAME;
                name[3] = pid;
                len = sizeof(passpath);
                if (sysctl(name, 4, passpath, &len, NULL, 0) == -1)
                        errx(1, "kern.proc.pathname failure");
                binfile = passpath;
        }
        efd = open(binfile, O_RDONLY, 0);
        if (efd < 0)
                err(1, "%s", binfile);
        dumper = NULL;
        SET_FOREACH(d, dumpset) {
                lseek(efd, 0, SEEK_SET);
                if (((*d)->ident)(efd, pid, binfile)) {
                        dumper = (*d);
                        lseek(efd, 0, SEEK_SET);
                        break;
                }
        }
        if (dumper == NULL)
                errx(1, "Invalid executable file");
        fd = open_corefile(corefile);

        dumper->dump(efd, fd, pid);
        (void)close(fd);
        (void)close(efd);
        exit(0);
}

void
usage(void)
{

        (void)fprintf(stderr,
            "usage: gcore [-kf] [-c core] [executable] pid\n");
        exit(1);
}