ndisasm.c

/* ndisasm.c   the Netwide Disassembler main module
 *
 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <inttypes.h>

#include "insns.h"
#include "nasm.h"
#include "nasmlib.h"
#include "sync.h"
#include "disasm.h"

#define BPL 8                   /* bytes per line of hex dump */

static const char *help =
    "usage: ndisasm [-a] [-i] [-h] [-r] [-u] [-b bits] [-o origin] [-s sync...]\n"
    "               [-e bytes] [-k start,bytes] [-p vendor] file\n"
    "   -a or -i activates auto (intelligent) sync\n"
    "   -u sets USE32 (32-bit mode)\n"
    "   -b 16 or -b 32 sets number of bits too\n"
    "   -h displays this text\n"
    "   -r or -v displays the version number\n"
    "   -e skips <bytes> bytes of header\n"
    "   -k avoids disassembling <bytes> bytes from position <start>\n"
    "   -p selects the preferred vendor instruction set (intel, amd, cyrix, idt)\n";

static void output_ins(uint32_t, uint8_t *, int, char *);
static void skip(uint32_t dist, FILE * fp);

int main(int argc, char **argv)
{
    uint8_t buffer[INSN_MAX * 2], *p, *q;
    char outbuf[256];
    char *pname = *argv;
    char *filename = NULL;
    uint32_t nextsync, synclen, initskip = 0L;
    int lenread;
    int32_t lendis;
    int autosync = FALSE;
    int bits = 16;
    int eof = FALSE;
    uint32_t prefer = 0;
    int rn_error;
    int32_t offset;
    FILE *fp;

    offset = 0;
    init_sync();

    while (--argc) {
        char *v, *vv, *p = *++argv;
        if (*p == '-' && p[1]) {
            p++;
            while (*p)
                switch (tolower(*p)) {
                case 'a':      /* auto or intelligent sync */
                case 'i':
                    autosync = TRUE;
                    p++;
                    break;
                case 'h':
                    fprintf(stderr, help);
                    return 0;
                case 'r':
                case 'v':
                    fprintf(stderr,
                            "NDISASM version %s compiled " __DATE__ "\n",
                            NASM_VER);
                    return 0;
                case 'u':      /* USE32 */
                    bits = 32;
                    p++;
                    break;
                case 'b':      /* bits */
                    v = p[1] ? p + 1 : --argc ? *++argv : NULL;
                    if (!v) {
                        fprintf(stderr, "%s: `-b' requires an argument\n",
                                pname);
                        return 1;
                    }
                    if (!strcmp(v, "16"))
                        bits = 16;
                    else if (!strcmp(v, "32"))
                        bits = 32;
                    else {
                        fprintf(stderr, "%s: argument to `-b' should"
                                " be `16' or `32'\n", pname);
                    }
                    p = "";     /* force to next argument */
                    break;
                case 'o':      /* origin */
                    v = p[1] ? p + 1 : --argc ? *++argv : NULL;
                    if (!v) {
                        fprintf(stderr, "%s: `-o' requires an argument\n",
                                pname);
                        return 1;
                    }
                    offset = readnum(v, &rn_error);
                    if (rn_error) {
                        fprintf(stderr,
                                "%s: `-o' requires a numeric argument\n",
                                pname);
                        return 1;
                    }
                    p = "";     /* force to next argument */
                    break;
                case 's':      /* sync point */
                    v = p[1] ? p + 1 : --argc ? *++argv : NULL;
                    if (!v) {
                        fprintf(stderr, "%s: `-s' requires an argument\n",
                                pname);
                        return 1;
                    }
                    add_sync(readnum(v, &rn_error), 0L);
                    if (rn_error) {
                        fprintf(stderr,
                                "%s: `-s' requires a numeric argument\n",
                                pname);
                        return 1;
                    }
                    p = "";     /* force to next argument */
                    break;
                case 'e':      /* skip a header */
                    v = p[1] ? p + 1 : --argc ? *++argv : NULL;
                    if (!v) {
                        fprintf(stderr, "%s: `-e' requires an argument\n",
                                pname);
                        return 1;
                    }
                    initskip = readnum(v, &rn_error);
                    if (rn_error) {
                        fprintf(stderr,
                                "%s: `-e' requires a numeric argument\n",
                                pname);
                        return 1;
                    }
                    p = "";     /* force to next argument */
                    break;
                case 'k':      /* skip a region */
                    v = p[1] ? p + 1 : --argc ? *++argv : NULL;
                    if (!v) {
                        fprintf(stderr, "%s: `-k' requires an argument\n",
                                pname);
                        return 1;
                    }
                    vv = strchr(v, ',');
                    if (!vv) {
                        fprintf(stderr,
                                "%s: `-k' requires two numbers separated"
                                " by a comma\n", pname);
                        return 1;
                    }
                    *vv++ = '\0';
                    nextsync = readnum(v, &rn_error);
                    if (rn_error) {
                        fprintf(stderr,
                                "%s: `-k' requires numeric arguments\n",
                                pname);
                        return 1;
                    }
                    synclen = readnum(vv, &rn_error);
                    if (rn_error) {
                        fprintf(stderr,
                                "%s: `-k' requires numeric arguments\n",
                                pname);
                        return 1;
                    }
                    add_sync(nextsync, synclen);
                    p = "";     /* force to next argument */
                    break;
                case 'p':      /* preferred vendor */
                    v = p[1] ? p + 1 : --argc ? *++argv : NULL;
                    if (!v) {
                        fprintf(stderr, "%s: `-p' requires an argument\n",
                                pname);
                        return 1;
                    }
                    if (!strcmp(v, "intel")) {
                        prefer = 0;     /* Default */
                    } else if (!strcmp(v, "amd")) {
                        prefer = IF_AMD | IF_3DNOW;
                    } else if (!strcmp(v, "cyrix")) {
                        prefer = IF_CYRIX | IF_3DNOW;
                    } else if (!strcmp(v, "idt") || !strcmp(v, "centaur")
                               || !strcmp(v, "winchip")) {
                        prefer = IF_3DNOW;
                    } else {
                        fprintf(stderr,
                                "%s: unknown vendor `%s' specified with `-p'\n",
                                pname, v);
                        return 1;
                    }
                    p = "";     /* force to next argument */
                    break;
                default:       /*bf */
                    fprintf(stderr, "%s: unrecognised option `-%c'\n",
                            pname, *p);
                    return 1;
                }
        } else if (!filename) {
            filename = p;
        } else {
            fprintf(stderr, "%s: more than one filename specified\n",
                    pname);
            return 1;
        }
    }

    if (!filename) {
        fprintf(stderr, help, pname);
        return 0;
    }

    if (strcmp(filename, "-")) {
        fp = fopen(filename, "rb");
        if (!fp) {
            fprintf(stderr, "%s: unable to open `%s': %s\n",
                    pname, filename, strerror(errno));
            return 1;
        }
    } else
        fp = stdin;

    if (initskip > 0)
        skip(initskip, fp);

    /*
     * This main loop is really horrible, and wants rewriting with
     * an axe. It'll stay the way it is for a while though, until I
     * find the energy...
     */

    p = q = buffer;
    nextsync = next_sync(offset, &synclen);
    do {
        uint32_t to_read = buffer + sizeof(buffer) - p;
        if (to_read > nextsync - offset - (p - q))
            to_read = nextsync - offset - (p - q);
        if (to_read) {
            lenread = fread(p, 1, to_read, fp);
            if (lenread == 0)
                eof = TRUE;     /* help along systems with bad feof */
        } else
            lenread = 0;
        p += lenread;
        if ((uint32_t)offset == nextsync) {
            if (synclen) {
                fprintf(stdout, "%08lX  skipping 0x%lX bytes\n", offset,
                        synclen);
                offset += synclen;
                skip(synclen, fp);
            }
            p = q = buffer;
            nextsync = next_sync(offset, &synclen);
        }
        while (p > q && (p - q >= INSN_MAX || lenread == 0)) {
            lendis =
                disasm(q, outbuf, sizeof(outbuf), bits, offset, autosync,
                       prefer);
            if (!lendis || lendis > (p - q)
                || (uint32_t)lendis > nextsync - offset)
                lendis = eatbyte(q, outbuf, sizeof(outbuf));
            output_ins(offset, q, lendis, outbuf);
            q += lendis;
            offset += lendis;
        }
        if (q >= buffer + INSN_MAX) {
            uint8_t *r = buffer, *s = q;
            int count = p - q;
            while (count--)
                *r++ = *s++;
            p -= (q - buffer);
            q = buffer;
        }
    } while (lenread > 0 || !(eof || feof(fp)));

    if (fp != stdin)
        fclose(fp);

    return 0;
}

static void output_ins(uint32_t offset, uint8_t *data,
                       int datalen, char *insn)
{
    int bytes;
    fprintf(stdout, "%08lX  ", offset);

    bytes = 0;
    while (datalen > 0 && bytes < BPL) {
        fprintf(stdout, "%02X", *data++);
        bytes++;
        datalen--;
    }

    fprintf(stdout, "%*s%s\n", (BPL + 1 - bytes) * 2, "", insn);

    while (datalen > 0) {
        fprintf(stdout, "         -");
        bytes = 0;
        while (datalen > 0 && bytes < BPL) {
            fprintf(stdout, "%02X", *data++);
            bytes++;
            datalen--;
        }
        fprintf(stdout, "\n");
    }
}

/*
 * Skip a certain amount of data in a file, either by seeking if
 * possible, or if that fails then by reading and discarding.
 */
static void skip(uint32_t dist, FILE * fp)
{
    char buffer[256];           /* should fit on most stacks :-) */

    /*
     * Got to be careful with fseek: at least one fseek I've tried
     * doesn't approve of SEEK_CUR. So I'll use SEEK_SET and
     * ftell... horrible but apparently necessary.
     */
    if (fseek(fp, dist + ftell(fp), SEEK_SET)) {
        while (dist > 0) {
            uint32_t len = (dist < sizeof(buffer) ?
                                 dist : sizeof(buffer));
            if (fread(buffer, 1, len, fp) < len) {
                perror("fread");
                exit(1);
            }
            dist -= len;
        }
    }
}