/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 2018 The FreeBSD Foundation.
 *
 * 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 <err.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static const size_t bufsize = 65536;

/* SDM vol 3 9.11.1 Intel microcode header. */
struct microcode_update_header {
        uint32_t header_version;
        uint32_t update_revision;
        uint32_t date;                  /* BCD mmddyyyy */
        uint32_t processor_signature;
        uint32_t checksum;              /* Over update data and header */
        uint32_t loader_revision;
        uint32_t processor_flags;
        uint32_t data_size;
        uint32_t total_size;
        uint32_t reserved[3];
};

/*
 * SDM vol 2A CPUID EAX = 01h Returns Model, Family, Stepping Information.
 * Caller must free the returned string.
 */

static char *
format_signature(uint32_t signature)
{
        char *buf;
        unsigned family, model, stepping;

        family = (signature & 0xf00) >> 8;
        model = (signature & 0xf0) >> 4;
        stepping = signature & 0xf;
        if (family == 0x06 || family == 0x0f)
                model += (signature & 0xf0000) >> 12;
        if (family == 0x0f)
                family += (signature & 0xff00000) >> 20;
        asprintf(&buf, "%02x-%02x-%02x", family, model, stepping);
        if (buf == NULL)
                err(1, "asprintf");
        return (buf);
}

static void
dump_header(const struct microcode_update_header *hdr)
{
        char *sig_str;
        int i;
        bool platformid_printed;

        sig_str = format_signature(hdr->processor_signature);
        printf("header version\t0x%x\n", hdr->header_version);
        printf("revision\t0x%x\n", hdr->update_revision);
        printf("date\t\t0x%x\t%04x-%02x-%02x\n", hdr->date,
            hdr->date & 0xffff, (hdr->date & 0xff000000) >> 24,
            (hdr->date & 0xff0000) >> 16);
        printf("signature\t0x%x\t\t%s\n", hdr->processor_signature, sig_str);
        printf("checksum\t0x%x\n", hdr->checksum);
        printf("loader revision\t0x%x\n", hdr->loader_revision);
        printf("processor flags\t0x%x", hdr->processor_flags);
        platformid_printed = false;
        for (i = 0; i < 8; i++) {
                if (hdr->processor_flags & 1 << i) {
                        printf("%s%d", platformid_printed ? ", " : "\t\t", i);
                        platformid_printed = true;
                }
        }
        printf("\n");
        printf("datasize\t0x%x\t\t0x%x\n", hdr->data_size,
            hdr->data_size != 0 ? hdr->data_size : 2000);
        printf("size\t\t0x%x\t\t0x%x\n", hdr->total_size,
            hdr->total_size != 0 ? hdr->total_size : 2048);
        free(sig_str);
}

static void
usage(void)
{

        printf("ucode-split [-nv] microcode_file\n");
        exit(1);
}

int
main(int argc, char *argv[])
{
        struct microcode_update_header hdr;
        char *buf, *output_file, *sig_str;
        size_t len, resid;
        ssize_t rv;
        int c, ifd, ofd;
        bool nflag, vflag;

        nflag = vflag = false;
        while ((c = getopt(argc, argv, "nv")) != -1) {
                switch (c) {
                case 'n':
                        nflag = true;
                        break;
                case 'v':
                        vflag = true;
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (argc != 1)
                usage();

        ifd = open(argv[0], O_RDONLY);
        if (ifd < 0)
                err(1, "open");

        buf = malloc(bufsize);
        if (buf == NULL)
                err(1, "malloc");

        for (;;) {
                /* Read header. */
                rv = read(ifd, &hdr, sizeof(hdr));
                if (rv < 0) {
                        err(1, "read");
                } else if (rv == 0) {
                        break;
                } else if (rv < (ssize_t)sizeof(hdr)) {
                        errx(1, "invalid microcode header");
                }
                if (hdr.header_version != 1)
                        errx(1, "invalid header version");

                if (vflag)
                        dump_header(&hdr);

                resid = (hdr.total_size != 0 ? hdr.total_size : 2048) -
                    sizeof(hdr);
                if (resid > 1 << 24) /* Arbitrary chosen maximum size. */
                        errx(1, "header total_size too large");

                if (nflag) {
                        if (lseek(ifd, resid, SEEK_CUR) == -1)
                                err(1, "lseek");
                        printf("\n");
                } else {
                        sig_str = format_signature(hdr.processor_signature);
                        asprintf(&output_file, "%s.%02x", sig_str,
                            hdr.processor_flags & 0xff);
                        free(sig_str);
                        if (output_file == NULL)
                                err(1, "asprintf");
                        ofd = open(output_file, O_WRONLY | O_CREAT | O_TRUNC,
                            0600);
                        if (ofd < 0)
                                err(1, "open");
        
                        /* Write header. */
                        rv = write(ofd, &hdr, sizeof(hdr));
                        if (rv < (ssize_t)sizeof(hdr))
                                err(1, "write");
        
                        /* Copy data. */
                        while (resid > 0) {
                                len = resid < bufsize ? resid : bufsize;
                                rv = read(ifd, buf, len);
                                if (rv < 0)
                                        err(1, "read");
                                else if (rv < (ssize_t)len)
                                        errx(1, "truncated microcode data");
                                if (write(ofd, buf, len) < (ssize_t)len)
                                        err(1, "write");
                                resid -= len;
                        }
                        if (vflag)
                                printf("written to %s\n\n", output_file);
                        close(ofd);
                        free(output_file);
                }
        }
}