/*-
 * Copyright (c) 1992, 1993, 2019
 *      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.
 *
 * @(#) Copyright (c) 1992, 1993 The Regents of the University of California.  All rights reserved.
 * @(#)gcore.c  8.2 (Berkeley) 9/23/93
 * $FreeBSD: src/usr.bin/gcore/gcore.c,v 1.15.2.2 2001/08/17 20:56:22 mikeh Exp $
 */

/*
 * 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/time.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <machine/elf.h>

#include <machine/vmparam.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "extern.h"

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

kvm_t *kd;

static pid_t pid;
ssize_t gcore_seg_limit = -1;
int gcore_verbose;

int
main(int argc, char **argv)
{
        void *exec;
        int ch, cnt, efd, fd, sflag;
        char *binfile, *corefile;
        char *eptr;
        char fname[MAXPATHLEN + 1];

        sflag = 0;
        corefile = NULL;
        while ((ch = getopt(argc, argv, "c:l:sv")) != -1) {
                switch (ch) {
                case 'c':
                        corefile = optarg;
                        break;
                case 'l':
                        gcore_seg_limit = strtol(optarg, &eptr, 0);
                        switch(*eptr) {
                        case 0:
                                break;
                        case 't':
                        case 'T':
                                gcore_seg_limit *= 1024;
                                /* fall through */
                        case 'g':
                        case 'G':
                                gcore_seg_limit *= 1024;
                                /* fall through */
                        case 'm':
                        case 'M':
                                gcore_seg_limit *= 1024;
                                /* fall through */
                        case 'k':
                        case 'K':
                                gcore_seg_limit *= 1024;
                                break;
                        default:
                                usage();
                                break;
                        }
                        break;
                case 's':
                        sflag = 1;
                        break;
                case 'v':
                        gcore_verbose = 1;
                        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]);
                asprintf(&binfile, "/proc/%d/file", pid);
                if (binfile == NULL)
                        errx(1, "allocation failure");
                break;
        case 2:
                pid = atoi(argv[1]);
                binfile = argv[0];
                break;
        default:
                usage();
        }

        efd = open(binfile, O_RDONLY, 0);
        if (efd < 0)
                err(1, "%s", binfile);

        cnt = read(efd, &exec, sizeof(Elf_Ehdr));
        if (cnt != sizeof(Elf_Ehdr))
                errx(1, "%s exec header: %s",
                    binfile, cnt > 0 ? strerror(EIO) : strerror(errno));
        if (IS_ELF(*(Elf_Ehdr *)&exec)) {
                close(efd);
        } else
                errx(1, "Invalid executable file");

        if (corefile == NULL) {
                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);

        if (sflag) {
                signal(SIGHUP, killed);
                signal(SIGINT, killed);
                signal(SIGTERM, killed);
                if (kill(pid, SIGSTOP) == -1)
                        err(1, "%d: stop signal", pid);
                atexit(restart_target);
        }

        elf_coredump(fd, pid);

        close(fd);
        exit(0);
}

static void
killed(int sig)
{
        restart_target();
        signal(sig, SIG_DFL);
        kill(getpid(), sig);
}

static void
restart_target(void)
{
        kill(pid, SIGCONT);
}

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