/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008 Robert N. M. Watson
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

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

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

#include "ddb.h"

/*
 * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
 * for a crash dump using libkvm.
 */
#define SYSCTL_DDB_CAPTURE_BUFOFF       "debug.ddb.capture.bufoff"
#define SYSCTL_DDB_CAPTURE_BUFSIZE      "debug.ddb.capture.bufsize"
#define SYSCTL_DDB_CAPTURE_MAXBUFSIZE   "debug.ddb.capture.maxbufsize"
#define SYSCTL_DDB_CAPTURE_DATA         "debug.ddb.capture.data"
#define SYSCTL_DDB_CAPTURE_INPROGRESS   "debug.ddb.capture.inprogress"

static struct nlist namelist[] = {
#define X_DB_CAPTURE_BUF        0
        { .n_name = "_db_capture_buf" },
#define X_DB_CAPTURE_BUFSIZE    1
        { .n_name = "_db_capture_bufsize" },
#define X_DB_CAPTURE_MAXBUFSIZE 2
        { .n_name = "_db_capture_maxbufsize" },
#define X_DB_CAPTURE_BUFOFF     3
        { .n_name = "_db_capture_bufoff" },
#define X_DB_CAPTURE_INPROGRESS 4
        { .n_name = "_db_capture_inprogress" },
        { .n_name = "" },
};

static int
kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
    size_t offset)
{
        ssize_t ret;

        ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
            size);
        if (ret < 0 || (size_t)ret != size)
                return (-1);
        return (0);
}

static int
kread_symbol(kvm_t *kvm, int read_index, void *address, size_t size,
    size_t offset)
{
        ssize_t ret;

        ret = kvm_read(kvm, namelist[read_index].n_value + offset, address, size);
        if (ret < 0 || (size_t)ret != size)
                return (-1);
        return (0);
}

static void
ddb_capture_print_kvm(kvm_t *kvm)
{
        u_int db_capture_bufoff;
        char *buffer, *db_capture_buf;

        if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
            sizeof(db_capture_buf), 0) < 0)
                errx(-1, "kvm: unable to read db_capture_buf");

        if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
            sizeof(db_capture_bufoff), 0) < 0)
                errx(-1, "kvm: unable to read db_capture_bufoff");

        buffer = malloc(db_capture_bufoff + 1);
        if (buffer == NULL)
                err(-1, "malloc: db_capture_bufoff (%u)",
                    db_capture_bufoff);
        bzero(buffer, db_capture_bufoff + 1);

        if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
                errx(-1, "kvm: unable to read buffer");

        printf("%s\n", buffer);
        free(buffer);
}

static void
ddb_capture_print_sysctl(void)
{
        size_t buflen, len;
        char *buffer;
        int ret;

repeat:
        if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
                err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
        if (buflen == 0)
                return;
        buffer = malloc(buflen);
        if (buffer == NULL)
                err(EX_OSERR, "malloc");
        bzero(buffer, buflen);
        len = buflen;
        ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
        if (ret < 0 && errno != ENOMEM)
                err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
        if (ret < 0) {
                free(buffer);
                goto repeat;
        }

        printf("%s\n", buffer);
        free(buffer);
}

static void
ddb_capture_status_kvm(kvm_t *kvm)
{
        u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;

        if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
            sizeof(db_capture_bufoff), 0) < 0)
                errx(-1, "kvm: unable to read db_capture_bufoff");
        if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
            sizeof(db_capture_bufsize), 0) < 0)
                errx(-1, "kvm: unable to read db_capture_bufsize");
        if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
            &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
                err(-1, "kvm: unable to read db_capture_inprogress");
        printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
        if (db_capture_inprogress)
                printf("capture is on\n");
        else
                printf("capture is off\n");

}

static void
ddb_capture_status_sysctl(void)
{
        u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
        size_t len;

        len = sizeof(db_capture_bufoff);
        if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
            NULL, 0) < 0)
                err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
        len = sizeof(db_capture_bufoff);
        if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
            &len, NULL, 0) < 0)
                err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
        len = sizeof(db_capture_inprogress);
        if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
            &db_capture_inprogress, &len, NULL, 0) < 0)
                err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
        printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
        if (db_capture_inprogress)
                printf("capture is on\n");
        else
                printf("capture is off\n");
}

void
ddb_capture(int argc, char *argv[])
{
        char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
        kvm_t *kvm;
        int ch;

        mflag = NULL;
        nflag = NULL;
        kvm = NULL;
        while ((ch = getopt(argc, argv, "M:N:")) != -1) {
                switch (ch) {
                case 'M':
                        mflag = optarg;
                        break;

                case 'N':
                        nflag = optarg;
                        break;

                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (argc != 1)
                usage();

        if (mflag != NULL) {
                kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
                if (kvm == NULL)
                        errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
                if (kvm_nlist(kvm, namelist) != 0)
                        errx(-1, "ddb_capture: kvm_nlist");
        } else if (nflag != NULL)
                usage();
        if (strcmp(argv[0], "print") == 0) {
                if (kvm != NULL)
                        ddb_capture_print_kvm(kvm);
                else
                        ddb_capture_print_sysctl();
        } else if (strcmp(argv[0], "status") == 0) {
                if (kvm != NULL)
                        ddb_capture_status_kvm(kvm);
                else
                        ddb_capture_status_sysctl();
        } else
                usage();
}