/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1998 Robert Nordier
 * 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/param.h>
#include <sys/endian.h>
#include <sys/stat.h>
#include <sys/mman.h>

/* XXX make this work as an i386/amd64 cross-tool */
#include <machine/exec.h>
#undef __LDPGSZ
#define __LDPGSZ        4096

#include <netinet/in.h>

#include <a.out.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "btx.h"
#include "elfh.h"

#define BTX_PATH                "/sys/boot/i386/btx"

#define I_LDR   0               /* BTX loader */
#define I_BTX   1               /* BTX kernel */
#define I_CLNT  2               /* Client program */

#define F_BIN   0               /* Binary */
#define F_AOUT  1               /* ZMAGIC a.out */
#define F_ELF   2               /* 32-bit ELF */
#define F_CNT   3               /* Number of formats */

#define IMPURE  1               /* Writable text */
#define MAXU32  0xffffffff      /* Maximum unsigned 32-bit quantity */

struct hdr {
    uint32_t fmt;               /* Format */
    uint32_t flags;             /* Bit flags */
    uint32_t size;              /* Size of file */
    uint32_t text;              /* Size of text segment */
    uint32_t data;              /* Size of data segment */
    uint32_t bss;               /* Size of bss segment */
    uint32_t org;               /* Program origin */
    uint32_t entry;             /* Program entry point */
};

static const char *const fmtlist[] = {"bin", "aout", "elf"};

static const char binfo[] =
    "kernel: ver=%u.%02u size=%x load=%x entry=%x map=%uM "
    "pgctl=%x:%x\n";
static const char cinfo[] =
    "client: fmt=%s size=%x text=%x data=%x bss=%x entry=%x\n";
static const char oinfo[] =
    "output: fmt=%s size=%x text=%x data=%x org=%x entry=%x\n";

static const char *lname =
    BTX_PATH "/btxldr/btxldr";  /* BTX loader */
static const char *bname =
    BTX_PATH "/btx/btx";        /* BTX kernel */
static const char *oname =
    "a.out";                    /* Output filename */

static int ppage = -1;          /* First page present */
static int wpage = -1;          /* First page writable */

static unsigned int format;     /* Output format */

static uint32_t centry;         /* Client entry address */
static uint32_t lentry;         /* Loader entry address */

static int Eflag;               /* Client entry option */

static int quiet;               /* Inhibit warnings */
static int verbose;             /* Display information */

static const char *tname;       /* Temporary output file */
static const char *fname;       /* Current input file */

static void cleanup(void);
static void btxld(const char *);
static void getbtx(int, struct btx_hdr *);
static void gethdr(int, struct hdr *);
static void puthdr(int, struct hdr *);
static void copy(int, int, size_t, off_t);
static size_t readx(int, void *, size_t, off_t);
static void writex(int, const void *, size_t);
static void seekx(int, off_t);
static unsigned int optfmt(const char *);
static uint32_t optaddr(const char *);
static int optpage(const char *, int);
static void Warn(const char *, const char *, ...);
static void usage(void) __dead2;

/*
 * A link editor for BTX clients.
 */
int
main(int argc, char *argv[])
{
    int c;

    while ((c = getopt(argc, argv, "qvb:E:e:f:l:o:P:W:")) != -1)
        switch (c) {
        case 'q':
            quiet = 1;
            break;
        case 'v':
            verbose = 1;
            break;
        case 'b':
            bname = optarg;
            break;
        case 'E':
            centry = optaddr(optarg);
            Eflag = 1;
            break;
        case 'e':
            lentry = optaddr(optarg);
            break;
        case 'f':
            format = optfmt(optarg);
            break;
        case 'l':
            lname = optarg;
            break;
        case 'o':
            oname = optarg;
            break;
        case 'P':
            ppage = optpage(optarg, 1);
            break;
        case 'W':
            wpage = optpage(optarg, BTX_MAXCWR);
            break;
        default:
            usage();
        }
    argc -= optind;
    argv += optind;
    if (argc != 1)
        usage();
    atexit(cleanup);
    btxld(*argv);
    return 0;
}

/*
 * Clean up after errors.
 */
static void
cleanup(void)
{
    if (tname)
        (void)remove(tname);
}

/*
 * Read the input files; write the output file; display information.
 */
static void
btxld(const char *iname)
{
    char name[FILENAME_MAX];
    struct btx_hdr btx, btxle;
    struct hdr ihdr, ohdr;
    unsigned int ldr_size, cwr;
    int fdi[3], fdo, i;

    ldr_size = 0;

    for (i = I_LDR; i <= I_CLNT; i++) {
        fname = i == I_LDR ? lname : i == I_BTX ? bname : iname;
        if ((fdi[i] = open(fname, O_RDONLY)) == -1)
            err(2, "%s", fname);
        switch (i) {
        case I_LDR:
            gethdr(fdi[i], &ihdr);
            if (ihdr.fmt != F_BIN)
                Warn(fname, "Loader format is %s; processing as %s",
                     fmtlist[ihdr.fmt], fmtlist[F_BIN]);
            ldr_size = ihdr.size;
            break;
        case I_BTX:
            getbtx(fdi[i], &btx);
            break;
        case I_CLNT:
            gethdr(fdi[i], &ihdr);
            if (ihdr.org && ihdr.org != BTX_PGSIZE)
                Warn(fname,
                     "Client origin is 0x%x; expecting 0 or 0x%x",
                     ihdr.org, BTX_PGSIZE);
        }
    }
    memset(&ohdr, 0, sizeof(ohdr));
    ohdr.fmt = format;
    ohdr.text = ldr_size;
    ohdr.data = btx.btx_textsz + ihdr.size;
    ohdr.org = lentry;
    ohdr.entry = lentry;
    cwr = 0;
    if (wpage > 0 || (wpage == -1 && !(ihdr.flags & IMPURE))) {
        if (wpage > 0)
            cwr = wpage;
        else {
            cwr = howmany(ihdr.text, BTX_PGSIZE);
            if (cwr > BTX_MAXCWR)
                cwr = BTX_MAXCWR;
        }
    }
    if (ppage > 0 || (ppage && wpage && ihdr.org >= BTX_PGSIZE)) {
        btx.btx_flags |= BTX_MAPONE;
        if (!cwr)
            cwr++;
    }
    btx.btx_pgctl -= cwr;
    btx.btx_entry = Eflag ? centry : ihdr.entry;
    if ((size_t)snprintf(name, sizeof(name), "%s.tmp", oname) >= sizeof(name))
        errx(2, "%s: Filename too long", oname);
    if ((fdo = open(name, O_CREAT | O_TRUNC | O_WRONLY, 0666)) == -1)
        err(2, "%s", name);
    if (!(tname = strdup(name)))
        err(2, NULL);
    puthdr(fdo, &ohdr);
    for (i = I_LDR; i <= I_CLNT; i++) {
        fname = i == I_LDR ? lname : i == I_BTX ? bname : iname;
        switch (i) {
        case I_LDR:
            copy(fdi[i], fdo, ldr_size, 0);
            seekx(fdo, ohdr.size += ohdr.text);
            break;
        case I_BTX:
            btxle = btx;
            btxle.btx_pgctl = htole16(btxle.btx_pgctl);
            btxle.btx_textsz = htole16(btxle.btx_textsz);
            btxle.btx_entry = htole32(btxle.btx_entry);
            writex(fdo, &btxle, sizeof(btxle));
            copy(fdi[i], fdo, btx.btx_textsz - sizeof(btx),
                 sizeof(btx));
            break;
        case I_CLNT:
            copy(fdi[i], fdo, ihdr.size, 0);
            if (ftruncate(fdo, ohdr.size += ohdr.data))
                err(2, "%s", tname);
        }
        if (close(fdi[i]))
            err(2, "%s", fname);
    }
    if (close(fdo))
        err(2, "%s", tname);
    if (rename(tname, oname))
        err(2, "%s: Can't rename to %s", tname, oname);
    free((void*)(intptr_t)tname);
    tname = NULL;
    if (verbose) {
        printf(binfo, btx.btx_majver, btx.btx_minver, btx.btx_textsz,
               BTX_ORIGIN(btx), BTX_ENTRY(btx), BTX_MAPPED(btx) *
               BTX_PGSIZE / 0x100000, !!(btx.btx_flags & BTX_MAPONE),
               BTX_MAPPED(btx) - btx.btx_pgctl - BTX_PGBASE /
               BTX_PGSIZE - BTX_MAPPED(btx) * 4 / BTX_PGSIZE);
        printf(cinfo, fmtlist[ihdr.fmt], ihdr.size, ihdr.text,
               ihdr.data, ihdr.bss, ihdr.entry);
        printf(oinfo, fmtlist[ohdr.fmt], ohdr.size, ohdr.text,
               ohdr.data, ohdr.org, ohdr.entry);
    }
}

/*
 * Read BTX file header.
 */
static void
getbtx(int fd, struct btx_hdr * btx)
{
    if (readx(fd, btx, sizeof(*btx), 0) != sizeof(*btx) ||
        btx->btx_magic[0] != BTX_MAG0 ||
        btx->btx_magic[1] != BTX_MAG1 ||
        btx->btx_magic[2] != BTX_MAG2)
        errx(1, "%s: Not a BTX kernel", fname);
    btx->btx_pgctl = le16toh(btx->btx_pgctl);
    btx->btx_textsz = le16toh(btx->btx_textsz);
    btx->btx_entry = le32toh(btx->btx_entry);
}

/*
 * Get file size and read a.out or ELF header.
 */
static void
gethdr(int fd, struct hdr *hdr)
{
    struct stat sb;
    const struct exec *ex;
    const Elf32_Ehdr *ee;
    const Elf32_Phdr *ep;
    void *p;
    unsigned int fmt, x, n, i;

    memset(hdr, 0, sizeof(*hdr));
    if (fstat(fd, &sb))
        err(2, "%s", fname);
    if (sb.st_size > MAXU32)
        errx(1, "%s: Too big", fname);
    hdr->size = sb.st_size;
    if (!hdr->size)
        return;
    if ((p = mmap(NULL, hdr->size, PROT_READ, MAP_SHARED, fd,
                  0)) == MAP_FAILED)
        err(2, "%s", fname);
    for (fmt = F_CNT - 1; !hdr->fmt && fmt; fmt--)
        switch (fmt) {
        case F_AOUT:
            ex = p;
            if (hdr->size >= sizeof(struct exec) && !N_BADMAG(*ex)) {
                hdr->fmt = fmt;
                x = N_GETMAGIC(*ex);
                if (x == OMAGIC || x == NMAGIC) {
                    if (x == NMAGIC)
                        Warn(fname, "Treating %s NMAGIC as OMAGIC",
                             fmtlist[fmt]);
                    hdr->flags |= IMPURE;
                }
                hdr->text = le32toh(ex->a_text);
                hdr->data = le32toh(ex->a_data);
                hdr->bss = le32toh(ex->a_bss);
                hdr->entry = le32toh(ex->a_entry);
                if (le32toh(ex->a_entry) >= BTX_PGSIZE)
                    hdr->org = BTX_PGSIZE;
            }
            break;
        case F_ELF:
            ee = p;
            if (hdr->size >= sizeof(Elf32_Ehdr) && IS_ELF(*ee)) {
                hdr->fmt = fmt;
                for (n = i = 0; i < le16toh(ee->e_phnum); i++) {
                    ep = (void *)((uint8_t *)p + le32toh(ee->e_phoff) +
                                  le16toh(ee->e_phentsize) * i);
                    if (le32toh(ep->p_type) == PT_LOAD)
                        switch (n++) {
                        case 0:
                            hdr->text = le32toh(ep->p_filesz);
                            hdr->org = le32toh(ep->p_paddr);
                            if (le32toh(ep->p_flags) & PF_W)
                                hdr->flags |= IMPURE;
                            break;
                        case 1:
                            hdr->data = le32toh(ep->p_filesz);
                            hdr->bss = le32toh(ep->p_memsz) -
                                le32toh(ep->p_filesz);
                            break;
                        case 2:
                            Warn(fname,
                                 "Ignoring extra %s PT_LOAD segments",
                                 fmtlist[fmt]);
                        }
                }
                hdr->entry = le32toh(ee->e_entry);
            }
        }
    if (munmap(p, hdr->size))
        err(2, "%s", fname);
}

/*
 * Write a.out or ELF header.
 */
static void
puthdr(int fd, struct hdr *hdr)
{
    struct exec ex;
    struct elfh eh;

    switch (hdr->fmt) {
    case F_AOUT:
        memset(&ex, 0, sizeof(ex));
        N_SETMAGIC(ex, ZMAGIC, MID_I386, 0);
        hdr->text = N_ALIGN(ex, hdr->text);
        ex.a_text = htole32(hdr->text);
        hdr->data = N_ALIGN(ex, hdr->data);
        ex.a_data = htole32(hdr->data);
        ex.a_entry = htole32(hdr->entry);
        writex(fd, &ex, sizeof(ex));
        hdr->size = N_ALIGN(ex, sizeof(ex));
        seekx(fd, hdr->size);
        break;
    case F_ELF:
        eh = elfhdr;
        eh.e.e_entry = htole32(hdr->entry);
        eh.p[0].p_vaddr = eh.p[0].p_paddr = htole32(hdr->org);
        eh.p[0].p_filesz = eh.p[0].p_memsz = htole32(hdr->text);
        eh.p[1].p_offset = htole32(le32toh(eh.p[0].p_offset) +
            le32toh(eh.p[0].p_filesz));
        eh.p[1].p_vaddr = eh.p[1].p_paddr =
            htole32(roundup2(le32toh(eh.p[0].p_paddr) + le32toh(eh.p[0].p_memsz),
            4096));
        eh.p[1].p_filesz = eh.p[1].p_memsz = htole32(hdr->data);
        eh.sh[2].sh_addr = eh.p[0].p_vaddr;
        eh.sh[2].sh_offset = eh.p[0].p_offset;
        eh.sh[2].sh_size = eh.p[0].p_filesz;
        eh.sh[3].sh_addr = eh.p[1].p_vaddr;
        eh.sh[3].sh_offset = eh.p[1].p_offset;
        eh.sh[3].sh_size = eh.p[1].p_filesz;
        writex(fd, &eh, sizeof(eh));
        hdr->size = sizeof(eh);
    }
}

/*
 * Safe copy from input file to output file.
 */
static void
copy(int fdi, int fdo, size_t nbyte, off_t offset)
{
    char buf[8192];
    size_t n;

    while (nbyte) {
        if ((n = sizeof(buf)) > nbyte)
            n = nbyte;
        if (readx(fdi, buf, n, offset) != n)
            errx(2, "%s: Short read", fname);
        writex(fdo, buf, n);
        nbyte -= n;
        offset = -1;
    }
}

/*
 * Safe read from input file.
 */
static size_t
readx(int fd, void *buf, size_t nbyte, off_t offset)
{
    ssize_t n;

    if (offset != -1 && lseek(fd, offset, SEEK_SET) != offset)
        err(2, "%s", fname);
    if ((n = read(fd, buf, nbyte)) == -1)
        err(2, "%s", fname);
    return n;
}

/*
 * Safe write to output file.
 */
static void
writex(int fd, const void *buf, size_t nbyte)
{
    ssize_t n;

    if ((n = write(fd, buf, nbyte)) == -1)
        err(2, "%s", tname);
    if ((size_t)n != nbyte)
        errx(2, "%s: Short write", tname);
}

/*
 * Safe seek in output file.
 */
static void
seekx(int fd, off_t offset)
{
    if (lseek(fd, offset, SEEK_SET) != offset)
        err(2, "%s", tname);
}

/*
 * Convert an option argument to a format code.
 */
static unsigned int
optfmt(const char *arg)
{
    unsigned int i;

    for (i = 0; i < F_CNT && strcmp(arg, fmtlist[i]); i++);
    if (i == F_CNT)
        errx(1, "%s: Unknown format", arg);
    return i;
}

/*
 * Convert an option argument to an address.
 */
static uint32_t
optaddr(const char *arg)
{
    char *s;
    unsigned long x;

    errno = 0;
    x = strtoul(arg, &s, 0);
    if (errno || !*arg || *s || x > MAXU32)
        errx(1, "%s: Illegal address", arg);
    return x;
}

/*
 * Convert an option argument to a page number.
 */
static int
optpage(const char *arg, int hi)
{
    char *s;
    long x;

    errno = 0;
    x = strtol(arg, &s, 0);
    if (errno || !*arg || *s || x < 0 || x > hi)
        errx(1, "%s: Illegal page number", arg);
    return x;
}

/*
 * Display a warning.
 */
static void
Warn(const char *locus, const char *fmt, ...)
{
    va_list ap;
    char *s;

    if (!quiet) {
        asprintf(&s, "%s: Warning: %s", locus, fmt);
        va_start(ap, fmt);
        vwarnx(s, ap);
        va_end(ap);
        free(s);
    }
}

/*
 * Display usage information.
 */
static void
usage(void)
{
    fprintf(stderr, "%s\n%s\n",
    "usage: btxld [-qv] [-b file] [-E address] [-e address] [-f format]",
    "             [-l file] [-o filename] [-P page] [-W page] file");
    exit(1);
}