boot.c

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/*      boot.c - Load and start Minix.                  Author: Kees J. Bot
 *                                                              27 Dec 1991
 */

char version[]=         "2.20";

#define BIOS    (!UNIX)         /* Either uses BIOS or UNIX syscalls. */

#define nil 0
#define _POSIX_SOURCE   1
#define _MINIX          1
#include <stddef.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include <string.h>
#include <errno.h>
#include <ibm/partition.h>
#include <minix/config.h>
#include <minix/type.h>
#include <minix/com.h>
#include <minix/dmap.h>
#include <minix/const.h>
#include <minix/minlib.h>
#include <minix/syslib.h>
#if BIOS
#include <kernel/const.h>
#include <kernel/type.h>
#endif
#if UNIX
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#endif
#include "rawfs.h"
#undef EXTERN
#define EXTERN  /* Empty */
#include "boot.h"

#define arraysize(a)            (sizeof(a) / sizeof((a)[0]))
#define arraylimit(a)           ((a) + arraysize(a))
#define between(a, c, z)        ((unsigned) ((c) - (a)) <= ((z) - (a)))

int fsok= -1;           /* File system state.  Initially unknown. */

static int block_size;

#if BIOS

/* this data is reserved for BIOS int 0x13 to put the 'specification packet'
 * in. It has a structure of course, but we don't define a struct because
 * of compiler padding. We fiddle out the bytes ourselves later.
 */
unsigned char boot_spec[24];

char *bios_err(int err)
/* Translate BIOS error code to a readable string.  (This is a rare trait
 * known as error checking and reporting.  Take a good look at it, you won't
 * see it often.)
 */
{
        static struct errlist {
                int     err;
                char    *what;
        } errlist[] = {
#if !DOS
                { 0x00, "No error" },
                { 0x01, "Invalid command" },
                { 0x02, "Address mark not found" },
                { 0x03, "Disk write-protected" },
                { 0x04, "Sector not found" },
                { 0x05, "Reset failed" },
                { 0x06, "Floppy disk removed" },
                { 0x07, "Bad parameter table" },
                { 0x08, "DMA overrun" },
                { 0x09, "DMA crossed 64 KB boundary" },
                { 0x0A, "Bad sector flag" },
                { 0x0B, "Bad track flag" },
                { 0x0C, "Media type not found" },
                { 0x0D, "Invalid number of sectors on format" },
                { 0x0E, "Control data address mark detected" },
                { 0x0F, "DMA arbitration level out of range" },
                { 0x10, "Uncorrectable CRC or ECC data error" },
                { 0x11, "ECC corrected data error" },
                { 0x20, "Controller failed" },
                { 0x40, "Seek failed" },
                { 0x80, "Disk timed-out" },
                { 0xAA, "Drive not ready" },
                { 0xBB, "Undefined error" },
                { 0xCC, "Write fault" },
                { 0xE0, "Status register error" },
                { 0xFF, "Sense operation failed" }
#else /* DOS */
                { 0x00, "No error" },
                { 0x01, "Function number invalid" },
                { 0x02, "File not found" },
                { 0x03, "Path not found" },
                { 0x04, "Too many open files" },
                { 0x05, "Access denied" },
                { 0x06, "Invalid handle" },
                { 0x0C, "Access code invalid" },
#endif /* DOS */
        };
        struct errlist *errp;

        for (errp= errlist; errp < arraylimit(errlist); errp++) {
                if (errp->err == err) return errp->what;
        }
        return "Unknown error";
}

char *unix_err(int err)
/* Translate the few errors rawfs can give. */
{
        switch (err) {
        case ENOENT:    return "No such file or directory";
        case ENOTDIR:   return "Not a directory";
        default:        return "Unknown error";
        }
}

void rwerr(char *rw, off_t sec, int err)
{
        printf("\n%s error 0x%02x (%s) at sector %ld absolute\n",
                rw, err, bios_err(err), sec);
}

void readerr(off_t sec, int err)        { rwerr("Read", sec, err); }
void writerr(off_t sec, int err)        { rwerr("Write", sec, err); }

void readblock(off_t blk, char *buf, int block_size)
/* Read blocks for the rawfs package. */
{
        int r;
        u32_t sec= lowsec + blk * RATIO(block_size);

        if(!block_size) {
                printf("block_size 0\n");
                exit(1);
        }

        if ((r= readsectors(mon2abs(buf), sec, 1 * RATIO(block_size))) != 0) {
                readerr(sec, r); exit(1);
        }
}

#define istty           (1)
#define alarm(n)        (0)

#endif /* BIOS */

#if UNIX

/* The Minix boot block must start with these bytes: */
char boot_magic[] = { 0x31, 0xC0, 0x8E, 0xD8, 0xFA, 0x8E, 0xD0, 0xBC };

struct biosdev {
        char *name;             /* Name of device. */
        int device;             /* Device to edit parameters. */
} bootdev;

struct termios termbuf;
int istty;

void quit(int status)
{
        if (istty) (void) tcsetattr(0, TCSANOW, &termbuf);
        exit(status);
}

#define exit(s) quit(s)

void report(char *label)
/* edparams: label: No such file or directory */
{
        fprintf(stderr, "edparams: %s: %s\n", label, strerror(errno));
}

void fatal(char *label)
{
        report(label);
        exit(1);
}

void *alloc(void *m, size_t n)
{
        m= m == nil ? malloc(n) : realloc(m, n);
        if (m == nil) fatal("");
        return m;
}

#define malloc(n)       alloc(nil, n)
#define realloc(m, n)   alloc(m, n)

#define mon2abs(addr)   ((void *) (addr))

int rwsectors(int rw, void *addr, u32_t sec, int nsec)
{
        ssize_t r;
        size_t len= nsec * SECTOR_SIZE;

        if (lseek(bootdev.device, sec * SECTOR_SIZE, SEEK_SET) == -1)
                return errno;

        if (rw == 0) {
                r= read(bootdev.device, (char *) addr, len);
        } else {
                r= write(bootdev.device, (char *) addr, len);
        }
        if (r == -1) return errno;
        if (r != len) return EIO;
        return 0;
}

#define readsectors(a, s, n)     rwsectors(0, (a), (s), (n))
#define writesectors(a, s, n)    rwsectors(1, (a), (s), (n))
#define readerr(sec, err)       (errno= (err), report(bootdev.name))
#define writerr(sec, err)       (errno= (err), report(bootdev.name))
#define putch(c)                putchar(c)
#define unix_err(err)           strerror(err)

void readblock(off_t blk, char *buf, int block_size)
/* Read blocks for the rawfs package. */
{
        if(!block_size) fatal("block_size 0");
        errno= EIO;
        if (lseek(bootdev.device, blk * block_size, SEEK_SET) == -1
                || read(bootdev.device, buf, block_size) != block_size)
        {
                fatal(bootdev.name);
        }
}

sig_atomic_t trapsig;

void trap(int sig)
{
        trapsig= sig;
        signal(sig, trap);
}

int escape(void)
{
        if (trapsig == SIGINT) {
                trapsig= 0;
                return 1;
        }
        return 0;
}

static unsigned char unchar;

int getch(void)
{
        unsigned char c;

        fflush(stdout);

        if (unchar != 0) {
                c= unchar;
                unchar= 0;
                return c;
        }

        switch (read(0, &c, 1)) {
        case -1:
                if (errno != EINTR) fatal("");
                return(ESC);
        case 0:
                if (istty) putch('\n');
                exit(0);
        default:
                if (istty && c == termbuf.c_cc[VEOF]) {
                        putch('\n');
                        exit(0);
                }
                return c;
        }
}

#define ungetch(c)      ((void) (unchar = (c)))

#define get_tick()              ((u32_t) time(nil))
#define clear_screen()          printf("[clear]")
#define boot_device(device)     printf("[boot %s]\n", device)
#define ctty(line)              printf("[ctty %s]\n", line)
#define bootminix()             (run_trailer() && printf("[boot]\n"))
#define off()                   printf("[off]")

#endif /* UNIX */

char *readline(void)
/* Read a line including a newline with echoing. */
{
        char *line;
        size_t i, z;
        int c;

        i= 0;
        z= 20;
        line= malloc(z * sizeof(char));

        do {
                c= getch();

                if (strchr("\b\177\25\30", c) != nil) {
                        /* Backspace, DEL, ctrl-U, or ctrl-X. */
                        do {
                                if (i == 0) break;
                                printf("\b \b");
                                i--;
                        } while (c == '\25' || c == '\30');
                } else
                if (c < ' ' && c != '\n') {
                        putch('\7');
                } else {
                        putch(c);
                        line[i++]= c;
                        if (i == z) {
                                z*= 2;
                                line= realloc(line, z * sizeof(char));
                        }
                }
        } while (c != '\n');
        line[i]= 0;
        return line;
}

int sugar(char *tok)
/* Recognize special tokens. */
{
        return strchr("=(){};\n", tok[0]) != nil;
}

char *onetoken(char **aline)
/* Returns a string with one token for tokenize. */
{
        char *line= *aline;
        size_t n;
        char *tok;

        /* Skip spaces and runs of newlines. */
        while (*line == ' ' || (*line == '\n' && line[1] == '\n')) line++;

        *aline= line;

        /* Don't do odd junk (nor the terminating 0!). */
        if ((unsigned) *line < ' ' && *line != '\n') return nil;

        if (*line == '(') {
                /* Function argument, anything goes but () must match. */
                int depth= 0;

                while ((unsigned) *line >= ' ') {
                        if (*line == '(') depth++;
                        if (*line++ == ')' && --depth == 0) break;
                }
        } else
        if (sugar(line)) {
                /* Single character token. */
                line++;
        } else {
                /* Multicharacter token. */
                do line++; while ((unsigned) *line > ' ' && !sugar(line));
        }
        n= line - *aline;
        tok= malloc((n + 1) * sizeof(char));
        memcpy(tok, *aline, n);
        tok[n]= 0;
        if (tok[0] == '\n') tok[0]= ';';        /* ';' same as '\n' */

        *aline= line;
        return tok;
}

/* Typed commands form strings of tokens. */

typedef struct token {
        struct token    *next;  /* Next in a command chain. */
        char            *token;
} token;

token **tokenize(token **acmds, char *line)
/* Takes a line apart to form tokens.  The tokens are inserted into a command
 * chain at *acmds.  Tokenize returns a reference to where another line could
 * be added.  Tokenize looks at spaces as token separators, and recognizes only
 * ';', '=', '{', '}', and '\n' as single character tokens.  One token is
 * formed from '(' and ')' with anything in between as long as more () match.
 */
{
        char *tok;
        token *newcmd;

        while ((tok= onetoken(&line)) != nil) {
                newcmd= malloc(sizeof(*newcmd));
                newcmd->token= tok;
                newcmd->next= *acmds;
                *acmds= newcmd;
                acmds= &newcmd->next;
        }
        return acmds;
}

token *cmds;            /* String of commands to execute. */
int err;                /* Set on an error. */

char *poptoken(void)
/* Pop one token off the command chain. */
{
        token *cmd= cmds;
        char *tok= cmd->token;

        cmds= cmd->next;
        free(cmd);

        return tok;
}

void voidtoken(void)
/* Remove one token from the command chain. */
{
        free(poptoken());
}

void parse_code(char *code)
/* Tokenize a string of monitor code, making sure there is a delimiter.  It is
 * to be executed next.  (Prepended to the current input.)
 */
{
        if (cmds != nil && cmds->token[0] != ';') (void) tokenize(&cmds, ";");
        (void) tokenize(&cmds, code);
}

int interrupt(void)
/* Clean up after an ESC has been typed. */
{
        if (escape()) {
                printf("[ESC]\n");
                err= 1;
                return 1;
        }
        return 0;
}

#if BIOS

int activate;

struct biosdev {
        char name[8];
        int device, primary, secondary;
} bootdev, tmpdev;

int get_master(char *master, struct part_entry **table, u32_t pos)
/* Read a master boot sector and its partition table. */
{
        int r, n;
        struct part_entry *pe, **pt;

        if ((r= readsectors(mon2abs(master), pos, 1)) != 0) return r;

        pe= (struct part_entry *) (master + PART_TABLE_OFF);
        for (pt= table; pt < table + NR_PARTITIONS; pt++) *pt= pe++;

        /* DOS has the misguided idea that partition tables must be sorted. */
        if (pos != 0) return 0;         /* But only the primary. */

        n= NR_PARTITIONS;
        do {
                for (pt= table; pt < table + NR_PARTITIONS-1; pt++) {
                        if (pt[0]->sysind == NO_PART
                                        || pt[0]->lowsec > pt[1]->lowsec) {
                                pe= pt[0]; pt[0]= pt[1]; pt[1]= pe;
                        }
                }
        } while (--n > 0);
        return 0;
}

void initialize(void)
{
        char master[SECTOR_SIZE];
        struct part_entry *table[NR_PARTITIONS];
        int r, p;
        u32_t masterpos;
        char *argp;

        /* Copy the boot program to the far end of low memory, this must be
         * done to get out of the way of Minix, and to put the data area
         * cleanly inside a 64K chunk if using BIOS I/O (no DMA problems).
         */
        u32_t oldaddr= caddr;
        u32_t memend= mem[0].base + mem[0].size;
        u32_t newaddr= (memend - runsize) & ~0x0000FL;
#if !DOS
        u32_t dma64k= (memend - 1) & ~0x0FFFFL;


        /* Check if data segment crosses a 64K boundary. */
        if (newaddr + (daddr - caddr) < dma64k)  {
                newaddr= (dma64k - runsize) & ~0x0000FL;
        }
#endif

        /* Set the new caddr for relocate. */
        caddr= newaddr;

        /* Copy code and data. */
        raw_copy(newaddr, oldaddr, runsize);

        /* Make the copy running. */
        relocate();

#if !DOS

        /* Take the monitor out of the memory map if we have memory to spare,
         * and also keep the BIOS data area safe (1.5K), plus a bit extra for
         * where we may have to put a.out headers for older kernels.
         */
        if (mon_return = (mem[1].size > 512*1024L)) mem[0].size = newaddr;
        mem[0].base += 2048;
        mem[0].size -= 2048;

        /* Find out what the boot device and partition was. */
        bootdev.name[0]= 0;
        bootdev.device= device;
        bootdev.primary= -1;
        bootdev.secondary= -1;

        if (device < 0x80) {
                /* Floppy. */
                strcpy(bootdev.name, "fd0");
                bootdev.name[2] += bootdev.device;
                return;
        }

        /* Disk: Get the partition table from the very first sector, and
         * determine the partition we booted from using the information from
         * the booted partition entry as passed on by the bootstrap (rem_part).
         * All we need from it is the partition offset.
         */
        raw_copy(mon2abs(&lowsec),
                vec2abs(&rem_part) + offsetof(struct part_entry, lowsec),
                sizeof(lowsec));

        masterpos= 0;   /* Master bootsector position. */

        for (;;) {
                /* Extract the partition table from the master boot sector. */
                if ((r= get_master(master, table, masterpos)) != 0) {
                        readerr(masterpos, r); exit(1);
                }

                /* See if you can find "lowsec" back. */
                for (p= 0; p < NR_PARTITIONS; p++) {
                        if (lowsec - table[p]->lowsec < table[p]->size) break;
                }

                if (lowsec == table[p]->lowsec) {       /* Found! */
                        if (bootdev.primary < 0)
                                bootdev.primary= p;
                        else
                                bootdev.secondary= p;
                        break;
                }

                if (p == NR_PARTITIONS || bootdev.primary >= 0
                                        || table[p]->sysind != MINIX_PART) {
                        /* The boot partition cannot be named, this only means
                         * that "bootdev" doesn't work.
                         */
                        bootdev.device= -1;
                        return;
                }

                /* See if the primary partition is subpartitioned. */
                bootdev.primary= p;
                masterpos= table[p]->lowsec;
        }
        strcpy(bootdev.name, "d0p0");
        bootdev.name[1] += (device - 0x80);
        bootdev.name[3] += bootdev.primary;
        if (bootdev.secondary >= 0) {
                strcat(bootdev.name, "s0");
                bootdev.name[5] += bootdev.secondary;
        }

#else /* DOS */
        /* Take the monitor out of the memory map if we have memory to spare,
         * note that only half our PSP is needed at the new place, the first
         * half is to be kept in its place.
         */
        if (mem[1].size > 0) mem[0].size = newaddr + 0x80 - mem[0].base;

        /* Parse the command line. */
        argp= PSP + 0x81;
        argp[PSP[0x80]]= 0;
        while (between('\1', *argp, ' ')) argp++;
        vdisk= argp;
        while (!between('\0', *argp, ' ')) argp++;
        while (between('\1', *argp, ' ')) *argp++= 0;
        if (*vdisk == 0) {
                printf("\nUsage: boot <vdisk> [commands ...]\n");
                exit(1);
        }
        drun= *argp == 0 ? "main" : argp;

        if ((r= dev_open()) != 0) {
                printf("\n%s: Error %02x (%s)\n", vdisk, r, bios_err(r));
                exit(1);
        }

        /* Find the active partition on the virtual disk. */
        if ((r= get_master(master, table, 0)) != 0) {
                readerr(0, r); exit(1);
        }

        strcpy(bootdev.name, "d0");
        bootdev.primary= -1;
        for (p= 0; p < NR_PARTITIONS; p++) {
                if (table[p]->bootind != 0 && table[p]->sysind == MINIX_PART) {
                        bootdev.primary= p;
                        strcat(bootdev.name, "p0");
                        bootdev.name[3] += p;
                        lowsec= table[p]->lowsec;
                        break;
                }
        }
#endif /* DOS */
}

#endif /* BIOS */

/* Reserved names: */
enum resnames {
        R_NULL, R_BOOT, R_CTTY, R_DELAY, R_ECHO, R_EXIT, R_HELP,
        R_LS, R_MENU, R_OFF, R_SAVE, R_SET, R_TRAP, R_UNSET
};

char resnames[][6] = {
        "", "boot", "ctty", "delay", "echo", "exit", "help",
        "ls", "menu", "off", "save", "set", "trap", "unset",
};

/* Using this for all null strings saves a lot of memory. */
#define null (resnames[0])

int reserved(char *s)
/* Recognize reserved strings. */
{
        int r;

        for (r= R_BOOT; r <= R_UNSET; r++) {
                if (strcmp(s, resnames[r]) == 0) return r;
        }
        return R_NULL;
}

void sfree(char *s)
/* Free a non-null string. */
{
        if (s != nil && s != null) free(s);
}

char *copystr(char *s)
/* Copy a non-null string using malloc. */
{
        char *c;

        if (*s == 0) return null;
        c= malloc((strlen(s) + 1) * sizeof(char));
        strcpy(c, s);
        return c;
}

int is_default(environment *e)
{
        return (e->flags & E_SPECIAL) && e->defval == nil;
}

environment **searchenv(char *name)
{
        environment **aenv= &env;

        while (*aenv != nil && strcmp((*aenv)->name, name) != 0) {
                aenv= &(*aenv)->next;
        }

        return aenv;
}

#define b_getenv(name)  (*searchenv(name))
/* Return the environment *structure* belonging to name, or nil if not found. */

char *b_value(char *name)
/* The value of a variable. */
{
        environment *e= b_getenv(name);

        return e == nil || !(e->flags & E_VAR) ? nil : e->value;
}

char *b_body(char *name)
/* The value of a function. */
{
        environment *e= b_getenv(name);

        return e == nil || !(e->flags & E_FUNCTION) ? nil : e->value;
}

int b_setenv(int flags, char *name, char *arg, char *value)
/* Change the value of an environment variable.  Returns the flags of the
 * variable if you are not allowed to change it, 0 otherwise.
 */
{
        environment **aenv, *e;

        if (*(aenv= searchenv(name)) == nil) {
                if (reserved(name)) return E_RESERVED;
                e= malloc(sizeof(*e));
                e->name= copystr(name);
                e->flags= flags;
                e->defval= nil;
                e->next= nil;
                *aenv= e;
        } else {
                e= *aenv;

                /* Don't change special variables to functions or vv. */
                if (e->flags & E_SPECIAL
                        && (e->flags & E_FUNCTION) != (flags & E_FUNCTION)
                ) return e->flags;

                e->flags= (e->flags & E_STICKY) | flags;
                if (is_default(e)) {
                        e->defval= e->value;
                } else {
                        sfree(e->value);
                }
                sfree(e->arg);
        }
        e->arg= copystr(arg);
        e->value= copystr(value);

        return 0;
}

int b_setvar(int flags, char *name, char *value)
/* Set variable or simple function. */
{
        int r;

        if((r=b_setenv(flags, name, null, value))) {
                return r;
        }

        return r;
}

void b_unset(char *name)
/* Remove a variable from the environment.  A special variable is reset to
 * its default value.
 */
{
        environment **aenv, *e;

        if ((e= *(aenv= searchenv(name))) == nil) return;

        if (e->flags & E_SPECIAL) {
                if (e->defval != nil) {
                        sfree(e->arg);
                        e->arg= null;
                        sfree(e->value);
                        e->value= e->defval;
                        e->defval= nil;
                }
        } else {
                sfree(e->name);
                sfree(e->arg);
                sfree(e->value);
                *aenv= e->next;
                free(e);
        }
}

long a2l(char *a)
/* Cheap atol(). */
{
        int sign= 1;
        long n= 0;

        if (*a == '-') { sign= -1; a++; }

        while (between('0', *a, '9')) n= n * 10 + (*a++ - '0');

        return sign * n;
}

char *ul2a(u32_t n, unsigned b)
/* Transform a long number to ascii at base b, (b >= 8). */
{
        static char num[(CHAR_BIT * sizeof(n) + 2) / 3 + 1];
        char *a= arraylimit(num) - 1;
        static char hex[16] = "0123456789ABCDEF";

        do *--a = hex[(int) (n % b)]; while ((n/= b) > 0);
        return a;
}

char *ul2a10(u32_t n)
/* Transform a long number to ascii at base 10. */
{
        return ul2a(n, 10);
}

unsigned a2x(char *a)
/* Ascii to hex. */
{
        unsigned n= 0;
        int c;

        for (;;) {
                c= *a;
                if (between('0', c, '9')) c= c - '0' + 0x0;
                else
                if (between('A', c, 'F')) c= c - 'A' + 0xA;
                else
                if (between('a', c, 'f')) c= c - 'a' + 0xa;
                else
                        break;
                n= (n<<4) | c;
                a++;
        }
        return n;
}

void get_parameters(void)
{
        char params[SECTOR_SIZE + 1];
        token **acmds;
        int r, bus, processor;
        memory *mp;
        static char bus_type[][4] = {
                "xt", "at", "mca"
        };
        static char vid_type[][4] = {
                "mda", "cga", "ega", "ega", "vga", "vga"
        };
        static char vid_chrome[][6] = {
                "mono", "color"
        };

        /* Variables that Minix needs: */
        b_setvar(E_SPECIAL|E_VAR|E_DEV, "rootdev", "ram");
        b_setvar(E_SPECIAL|E_VAR|E_DEV, "ramimagedev", "bootdev");
        b_setvar(E_SPECIAL|E_VAR, "ramsize", "0");
#if BIOS
        processor = getprocessor();
        if(processor == 1586) processor = 686;
        b_setvar(E_SPECIAL|E_VAR, "processor", ul2a10(processor));
        b_setvar(E_SPECIAL|E_VAR, "bus", bus_type[get_bus()]);
        b_setvar(E_SPECIAL|E_VAR, "video", vid_type[get_video()]);
        b_setvar(E_SPECIAL|E_VAR, "chrome", vid_chrome[get_video() & 1]);
        params[0]= 0;
        for (mp= mem; mp < arraylimit(mem); mp++) {
                if (mp->size == 0) continue;
                if (params[0] != 0) strcat(params, ",");
                strcat(params, ul2a(mp->base, 0x10));
                strcat(params, ":");
                strcat(params, ul2a(mp->size, 0x10));
        }
        b_setvar(E_SPECIAL|E_VAR, "memory", params);

#if DOS
        b_setvar(E_SPECIAL|E_VAR, "dosfile-d0", vdisk);
#endif

#endif
#if UNIX
        b_setvar(E_SPECIAL|E_VAR, "processor", "?");
        b_setvar(E_SPECIAL|E_VAR, "bus", "?");
        b_setvar(E_SPECIAL|E_VAR, "video", "?");
        b_setvar(E_SPECIAL|E_VAR, "chrome", "?");
        b_setvar(E_SPECIAL|E_VAR, "memory", "?");
        b_setvar(E_SPECIAL|E_VAR, "c0", "?");
#endif

        /* Variables boot needs: */
        b_setvar(E_SPECIAL|E_VAR, "image", "boot/image");
        b_setvar(E_SPECIAL|E_FUNCTION, "leader", 
                "echo --- Welcome to MINIX 3. This is the boot monitor. ---\\n");
        b_setvar(E_SPECIAL|E_FUNCTION, "main", "menu");
        b_setvar(E_SPECIAL|E_FUNCTION, "trailer", "");

        /* Default hidden menu function: */
        b_setenv(E_RESERVED|E_FUNCTION, null, "=,Start MINIX", "boot");

        /* Tokenize bootparams sector. */
        if ((r= readsectors(mon2abs(params), lowsec+PARAMSEC, 1)) != 0) {
                readerr(lowsec+PARAMSEC, r);
                exit(1);
        }
        params[SECTOR_SIZE]= 0;
        acmds= tokenize(&cmds, params);

        /* Stuff the default action into the command chain. */
#if UNIX
        (void) tokenize(acmds, ":;");
#elif DOS
        (void) tokenize(tokenize(acmds, ":;leader;"), drun);
#else /* BIOS */
        (void) tokenize(acmds, ":;leader;main");
#endif
}

char *addptr;

void addparm(char *n)
{
        while (*n != 0 && *addptr != 0) *addptr++ = *n++;
}

void save_parameters(void)
/* Save nondefault environment variables to the bootparams sector. */
{
        environment *e;
        char params[SECTOR_SIZE + 1];
        int r;

        /* Default filling: */
        memset(params, '\n', SECTOR_SIZE);

        /* Don't touch the 0! */
        params[SECTOR_SIZE]= 0;
        addptr= params;

        for (e= env; e != nil; e= e->next) {
                if (e->flags & E_RESERVED || is_default(e)) continue;

                addparm(e->name);
                if (e->flags & E_FUNCTION) {
                        addparm("(");
                        addparm(e->arg);
                        addparm(")");
                } else {
                        addparm((e->flags & (E_DEV|E_SPECIAL)) != E_DEV
                                                        ? "=" : "=d ");
                }
                addparm(e->value);
                if (*addptr == 0) {
                        printf("The environment is too big\n");
                        return;
                }
                *addptr++= '\n';
        }

        /* Save the parameters on disk. */
        if ((r= writesectors(mon2abs(params), lowsec+PARAMSEC, 1)) != 0) {
                writerr(lowsec+PARAMSEC, r);
                printf("Can't save environment\n");
        }
}

void show_env(void)
/* Show the environment settings. */
{
        environment *e;
        unsigned more= 0;
        int c;

        for (e= env; e != nil; e= e->next) {
                if (e->flags & E_RESERVED) continue;
                if (!istty && is_default(e)) continue;

                if (e->flags & E_FUNCTION) {
                        printf("%s(%s) %s\n", e->name, e->arg, e->value);
                } else {
                        printf(is_default(e) ? "%s = (%s)\n" : "%s = %s\n",
                                e->name, e->value);
                }

                if (e->next != nil && istty && ++more % 20 == 0) {
                        printf("More? ");
                        c= getch();
                        if (c == ESC || c > ' ') {
                                putch('\n');
                                if (c > ' ') ungetch(c);
                                break;
                        }
                        printf("\b\b\b\b\b\b");
                }
        }
}

int numprefix(char *s, char **ps)
/* True iff s is a string of digits.  *ps will be set to the first nondigit
 * if non-nil, otherwise the string should end.
 */
{
        char *n= s;

        while (between('0', *n, '9')) n++;

        if (n == s) return 0;

        if (ps == nil) return *n == 0;

        *ps= n;
        return 1;
}

int numeric(char *s)
{
        return numprefix(s, (char **) nil);
}

#if BIOS

/* Device numbers of standard MINIX devices. */
#define DEV_FD0         0x0200
static dev_t dev_cNd0[] = { 0x0300, 0x0800, 0x0A00, 0x0C00, 0x1000 };
#define minor_p0s0         128

static int block_size;

dev_t name2dev(char *name)
/* Translate, say, /dev/c0d0p2 to a device number.  If the name can't be
 * found on the boot device, then do some guesswork.  The global structure
 * "tmpdev" will be filled in based on the name, so that "boot d1p0" knows
 * what device to boot without interpreting device numbers.
 */
{
        dev_t dev;
        ino_t ino;
        int drive;
        struct stat st;
        char *n, *s;

        /* "boot *d0p2" means: make partition 2 active before you boot it. */
        if ((activate= (name[0] == '*'))) name++;

        /* The special name "bootdev" must be translated to the boot device. */
        if (strcmp(name, "bootdev") == 0) {
                if (bootdev.device == -1) {
                        printf("The boot device could not be named\n");
                        errno= 0;
                        return -1;
                }
                name= bootdev.name;
        }

        /* If our boot device doesn't have a file system, or we want to know
         * what a name means for the BIOS, then we need to interpret the
         * device name ourselves: "fd" = floppy, "c0d0" = hard disk, etc.
         */
        tmpdev.device= tmpdev.primary= tmpdev.secondary= -1;
        dev= -1;
        n= name;
        if (strncmp(n, "/dev/", 5) == 0) n+= 5;

        if (strcmp(n, "ram") == 0) {
                dev= DEV_RAM;
        } else
        if (strcmp(n, "boot") == 0) {
                dev= DEV_BOOT;
        } else
        if (n[0] == 'f' && n[1] == 'd' && numeric(n+2)) {
                /* Floppy. */
                tmpdev.device= a2l(n+2);
                dev= DEV_FD0 + tmpdev.device;
        } else
        if ((n[0] == 'h' || n[0] == 's') && n[1] == 'd' && numprefix(n+2, &s)
                && (*s == 0 || (between('a', *s, 'd') && s[1] == 0))
        ) {
                /* Old style hard disk (backwards compatibility.) */
                dev= a2l(n+2);
                tmpdev.device= dev / (1 + NR_PARTITIONS);
                tmpdev.primary= (dev % (1 + NR_PARTITIONS)) - 1;
                if (*s != 0) {
                        /* Subpartition. */
                        tmpdev.secondary= *s - 'a';
                        dev= minor_p0s0
                                + (tmpdev.device * NR_PARTITIONS
                                        + tmpdev.primary) * NR_PARTITIONS
                                + tmpdev.secondary;
                }
                tmpdev.device+= 0x80;
                dev+= n[0] == 'h' ? dev_cNd0[0] : dev_cNd0[2];
        } else {
                /* Hard disk. */
                int ctrlr= 0;

                if (n[0] == 'c' && between('0', n[1], '4')) {
                        ctrlr= (n[1] - '0');
                        tmpdev.device= 0;
                        n+= 2;
                }
                if (n[0] == 'd' && between('0', n[1], '7')) {
                        tmpdev.device= (n[1] - '0');
                        n+= 2;
                        if (n[0] == 'p' && between('0', n[1], '3')) {
                                tmpdev.primary= (n[1] - '0');
                                n+= 2;
                                if (n[0] == 's' && between('0', n[1], '3')) {
                                        tmpdev.secondary= (n[1] - '0');
                                        n+= 2;
                                }
                        }
                }
                if (*n == 0) {
                        dev= dev_cNd0[ctrlr];
                        if (tmpdev.secondary < 0) {
                                dev += tmpdev.device * (NR_PARTITIONS+1)
                                        + (tmpdev.primary + 1);
                        } else {
                                dev += minor_p0s0
                                        + (tmpdev.device * NR_PARTITIONS
                                            + tmpdev.primary) * NR_PARTITIONS
                                        + tmpdev.secondary;
                        }
                        tmpdev.device+= 0x80;
                }
        }

        /* Look the name up on the boot device for the UNIX device number. */
        if (fsok == -1) fsok= r_super(&block_size) != 0;
        if (fsok) {
                /* The current working directory is "/dev". */
                ino= r_lookup(r_lookup(ROOT_INO, "dev"), name);

                if (ino != 0) {
                        /* Name has been found, extract the device number. */
                        r_stat(ino, &st);
                        if (!S_ISBLK(st.st_mode)) {
                                printf("%s is not a block device\n", name);
                                errno= 0;
                                return (dev_t) -1;
                        }
                        dev= st.st_rdev;
                }
        }

        if (tmpdev.primary < 0) activate= 0;    /* Careful now! */

        if (dev == -1) {
                printf("Can't recognize '%s' as a device\n", name);
                errno= 0;
        }
        return dev;
}

#if DEBUG
static void apm_perror(char *label, u16_t ax)
{
        unsigned ah;
        char *str;

        ah= (ax >> 8);
        switch(ah)
        {
        case 0x01: str= "APM functionality disabled"; break;
        case 0x03: str= "interface not connected"; break;
        case 0x09: str= "unrecognized device ID"; break;
        case 0x0A: str= "parameter value out of range"; break;
        case 0x0B: str= "interface not engaged"; break;
        case 0x60: str= "unable to enter requested state"; break;
        case 0x86: str= "APM not present"; break;
        default: printf("%s: error 0x%02x\n", label, ah); return;
        }
        printf("%s: %s\n", label, str);
}

#define apm_printf printf
#else
#define apm_perror(label, ax) ((void)0)
#define apm_printf
#endif

static void off(void)
{
        bios_env_t be;
        unsigned al, ah;

        /* Try to switch off the system. Print diagnostic information
         * that can be useful if the operation fails.
         */

        be.ax= 0x5300;  /* APM, Installation check */
        be.bx= 0;       /* Device, APM BIOS */
        int15(&be);
        if (be.flags & FL_CARRY)
        {
                apm_perror("APM installation check failed", be.ax);
                return;
        }
        if (be.bx != (('P' << 8) | 'M'))
        {
                apm_printf("APM signature not found (got 0x%04x)\n", be.bx);
                return;
        }

        ah= be.ax >> 8;
        if (ah > 9)
                ah= (ah >> 4)*10 + (ah & 0xf);
        al= be.ax & 0xff;
        if (al > 9)
                al= (al >> 4)*10 + (al & 0xf);
        apm_printf("APM version %u.%u%s%s%s%s%s\n",
                ah, al,
                (be.cx & 0x1) ? ", 16-bit PM" : "",
                (be.cx & 0x2) ? ", 32-bit PM" : "",
                (be.cx & 0x4) ? ", CPU-Idle" : "",
                (be.cx & 0x8) ? ", APM-disabled" : "",
                (be.cx & 0x10) ? ", APM-disengaged" : "");

        /* Connect */
        be.ax= 0x5301;  /* APM, Real mode interface connect */
        be.bx= 0x0000;  /* APM BIOS */
        int15(&be);
        if (be.flags & FL_CARRY)
        {
                apm_perror("APM real mode connect failed", be.ax);
                return;
        }

        /* Ask for a seat upgrade */
        be.ax= 0x530e;  /* APM, Driver Version */
        be.bx= 0x0000;  /* BIOS */
        be.cx= 0x0102;  /* version 1.2 */
        int15(&be);
        if (be.flags & FL_CARRY)
        {
                apm_perror("Set driver version failed", be.ax);
                goto disco;
        }

        /* Is this version really worth reporting. Well, if the system
         * does switch off, you won't see it anyway.
         */
        ah= be.ax >> 8;
        if (ah > 9)
                ah= (ah >> 4)*10 + (ah & 0xf);
        al= be.ax & 0xff;
        if (al > 9)
                al= (al >> 4)*10 + (al & 0xf);
        apm_printf("Got APM connection version %u.%u\n", ah, al);

        /* Enable */
        be.ax= 0x5308;  /* APM, Enable/disable power management */
        be.bx= 0x0001;  /* All device managed by APM BIOS */
#if 0
        /* For old APM 1.0 systems, we need 0xffff. Assume that those
         * systems do not exist.
         */
        be.bx= 0xffff;  /* All device managed by APM BIOS (compat) */
#endif
        be.cx= 0x0001;  /* Enable power management */
        int15(&be);
        if (be.flags & FL_CARRY)
        {
                apm_perror("Enable power management failed", be.ax);
                goto disco;
        }

        /* Off */
        be.ax= 0x5307;  /* APM, Set Power State */
        be.bx= 0x0001;  /* All devices managed by APM */
        be.cx= 0x0003;  /* Off */
        int15(&be);
        if (be.flags & FL_CARRY)
        {
                apm_perror("Set power state failed", be.ax);
                goto disco;
        }

        apm_printf("Power off sequence successfully completed.\n\n");
        apm_printf("Ha, ha, just kidding!\n");

disco:
        /* Disconnect */
        be.ax= 0x5304;  /* APM, interface disconnect */
        be.bx= 0x0000;  /* APM BIOS */
        int15(&be);
        if (be.flags & FL_CARRY)
        {
                apm_perror("APM interface disconnect failed", be.ax);
                return;
        }
}

#if !DOS
#define B_NOSIG         -1      /* "No signature" error code. */

int exec_bootstrap(void)
/* Load boot sector from the disk or floppy described by tmpdev and execute it.
 */
{
        int r, n, dirty= 0;
        char master[SECTOR_SIZE];
        struct part_entry *table[NR_PARTITIONS], dummy, *active= &dummy;
        u32_t masterpos;

        active->lowsec= 0;

        /* Select a partition table entry. */
        while (tmpdev.primary >= 0) {
                masterpos= active->lowsec;

                if ((r= get_master(master, table, masterpos)) != 0) return r;

                active= table[tmpdev.primary];

                /* How does one check a partition table entry? */
                if (active->sysind == NO_PART) return B_NOSIG;

                tmpdev.primary= tmpdev.secondary;
                tmpdev.secondary= -1;
        }

        if (activate && !active->bootind) {
                for (n= 0; n < NR_PARTITIONS; n++) table[n]->bootind= 0;
                active->bootind= ACTIVE_FLAG;
                dirty= 1;
        }

        /* Read the boot sector. */
        if ((r= readsectors(BOOTPOS, active->lowsec, 1)) != 0) return r;

        /* Check signature word. */
        if (get_word(BOOTPOS+SIGNATOFF) != SIGNATURE) return B_NOSIG;

        /* Write the partition table if a member must be made active. */
        if (dirty && (r= writesectors(mon2abs(master), masterpos, 1)) != 0)
                return r;

        bootstrap(device, active);
}

void boot_device(char *devname)
/* Boot the device named by devname. */
{
        dev_t dev= name2dev(devname);
        int save_dev= device;
        int r;
        char *err;

        if (tmpdev.device < 0) {
                if (dev != -1) printf("Can't boot from %s\n", devname);
                return;
        }

        /* Change current device and try to load and execute its bootstrap. */
        device= tmpdev.device;

        if ((r= dev_open()) == 0) r= exec_bootstrap();

        err= r == B_NOSIG ? "Not bootable" : bios_err(r);
        printf("Can't boot %s: %s\n", devname, err);

        /* Restore boot device setting. */
        device= save_dev;
        (void) dev_open();
}

void ctty(char *line)
{
        if (between('0', line[0], '3') && line[1] == 0) {
                serial_init(line[0] - '0');
        } else {
                printf("Bad serial line number: %s\n", line);
        }
}

#else /* DOS */

void boot_device(char *devname)
/* No booting of other devices under DOS. */
{
        printf("Can't boot devices under DOS\n");
}

void ctty(char *line)
/* Don't know how to handle serial lines under DOS. */
{
        printf("No serial line support under DOS\n");
}

#endif /* DOS */
#endif /* BIOS */

void ls(char *dir)
/* List the contents of a directory. */
{
        ino_t ino;
        struct stat st;
        char name[NAME_MAX+1];

        if (fsok == -1) fsok= r_super(&block_size) != 0;
        if (!fsok) return;

        /* (,) construct because r_stat returns void */
        if ((ino= r_lookup(ROOT_INO, dir)) == 0 ||
                (r_stat(ino, &st), r_readdir(name)) == -1)
        {
                printf("ls: %s: %s\n", dir, unix_err(errno));
                return;
        }
        (void) r_readdir(name); /* Skip ".." too. */

        while ((ino= r_readdir(name)) != 0) printf("%s/%s\n", dir, name);
}

u32_t milli_time(void)
{
        return get_tick() * MSEC_PER_TICK;
}

u32_t milli_since(u32_t base)
{
        return (milli_time() + (TICKS_PER_DAY*MSEC_PER_TICK) - base)
                        % (TICKS_PER_DAY*MSEC_PER_TICK);
}

char *Thandler;
u32_t Tbase, Tcount;

void unschedule(void)
/* Invalidate a waiting command. */
{
        alarm(0);

        if (Thandler != nil) {
                free(Thandler);
                Thandler= nil;
        }
}

void schedule(long msec, char *cmd)
/* Schedule command at a certain time from now. */
{
        unschedule();
        Thandler= cmd;
        Tbase= milli_time();
        Tcount= msec;
        alarm(1);
}

int expired(void)
/* Check if the timer expired for getch(). */
{
        return (Thandler != nil && milli_since(Tbase) >= Tcount);
}

void delay(char *msec)
/* Delay for a given time. */
{
        u32_t base, count;

        if ((count= a2l(msec)) == 0) return;
        base= milli_time();

        alarm(1);

        do {
                pause();
        } while (!interrupt() && !expired() && milli_since(base) < count);
}

enum whatfun { NOFUN, SELECT, DEFFUN, USERFUN } menufun(environment *e)
{
        if (!(e->flags & E_FUNCTION) || e->arg[0] == 0) return NOFUN;
        if (e->arg[1] != ',') return SELECT;
        return e->flags & E_RESERVED ? DEFFUN : USERFUN;
}

void menu(void)
/* By default:  Show a simple menu.
 * Multiple kernels/images:  Show extra selection options.
 * User defined function:  Kill the defaults and show these.
 * Wait for a keypress and execute the given function.
 */
{
        int c, def= 1;
        char *choice= nil;
        environment *e;

        /* Just a default menu? */
        for (e= env; e != nil; e= e->next) if (menufun(e) == USERFUN) def= 0;

        printf("\nHit a key as follows:\n\n");

        /* Show the choices. */
        for (e= env; e != nil; e= e->next) {
                switch (menufun(e)) {
                case DEFFUN:
                        if (!def) break;
                        /*FALL THROUGH*/
                case USERFUN:
                        printf("    %c  %s\n", e->arg[0], e->arg+2);
                        break;
                case SELECT:
                        printf("    %c  Select %s kernel\n", e->arg[0],e->name);
                        break;
                default:;
                }
        }

        /* Wait for a keypress. */
        do {
                c= getch();
                if (interrupt() || expired()) return;

                unschedule();

                for (e= env; e != nil; e= e->next) {
                        switch (menufun(e)) {
                        case DEFFUN:
                                if (!def) break;
                        case USERFUN:
                        case SELECT:
                                if (c == e->arg[0]) choice= e->value;
                        }
                }
        } while (choice == nil);

        /* Execute the chosen function. */
        printf("%c\n", c);
        (void) tokenize(&cmds, choice);
}

void help(void)
/* Not everyone is a rocket scientist. */
{
        struct help {
                char    *thing;
                char    *help;
        } *pi;
        static struct help info[] = {
                { nil,  "Names:" },
                { "rootdev",            "Root device" },
                { "ramimagedev",        "Device to use as RAM disk image " },
                { "ramsize",            "RAM disk size (if no image device) " },
                { "bootdev",            "Special name for the boot device" },
                { "fd0, d0p2, c0d0p1s0",        "Devices (as in /dev)" },
                { "image",              "Name of the boot image to use" },
                { "main",               "Startup function" },
                { "bootdelay",          "Delay in msec after loading image" },
                { nil,  "Commands:" },
                { "name = [device] value",  "Set environment variable" },
                { "name() { ... }",         "Define function" },
                { "name(key,text) { ... }",
                        "A menu option like: minix(=,Start MINIX) {boot}" },
                { "name",               "Call function" },
                { "boot [device]",      "Boot Minix or another O.S." },
                { "ctty [line]",        "Duplicate to serial line" },
                { "delay [msec]",       "Delay (500 msec default)" },
                { "echo word ...",      "Display the words" },
                { "ls [directory]",     "List contents of directory" },
                { "menu",               "Show menu and choose menu option" },
                { "save / set",         "Save or show environment" },
                { "trap msec command",  "Schedule command " },
                { "unset name ...",     "Unset variable or set to default" },
                { "exit / off",         "Exit the Monitor / Power off" },
        };

        for (pi= info; pi < arraylimit(info); pi++) {
                if (pi->thing != nil) printf("    %-24s- ", pi->thing);
                printf("%s\n", pi->help);
        }
}

void execute(void)
/* Get one command from the command chain and execute it. */
{
        token *second, *third, *fourth, *sep;
        char *name;
        int res;
        size_t n= 0;

        if (err) {
                /* An error occured, stop interpreting. */
                while (cmds != nil) voidtoken();
                return;
        }

        if (expired()) {        /* Timer expired? */
                parse_code(Thandler);
                unschedule();
        }

        /* There must be a separator lurking somewhere. */
        for (sep= cmds; sep != nil && sep->token[0] != ';'; sep= sep->next) n++;

        name= cmds->token;
        res= reserved(name);
        if ((second= cmds->next) != nil
                && (third= second->next) != nil)
                        fourth= third->next;

                /* Null command? */
        if (n == 0) {
                voidtoken();
                return;
        } else
                /* name = [device] value? */
        if ((n == 3 || n == 4)
                && !sugar(name)
                && second->token[0] == '='
                && !sugar(third->token)
                && (n == 3 || (n == 4 && third->token[0] == 'd'
                                        && !sugar(fourth->token)
        ))) {
                char *value= third->token;
                int flags= E_VAR;

                if (n == 4) { value= fourth->token; flags|= E_DEV; }

                if ((flags= b_setvar(flags, name, value)) != 0) {
                        printf("%s is a %s\n", name,
                                flags & E_RESERVED ? "reserved word" :
                                                "special function");
                        err= 1;
                }
                while (cmds != sep) voidtoken();
                return;
        } else
                /* name '(arg)' ... ? */
        if (n >= 3
                && !sugar(name)
                && second->token[0] == '('
        ) {
                token *fun;
                int c, flags, depth;
                char *body;
                size_t len;

                sep= fun= third;
                depth= 0;
                len= 1;
                while (sep != nil) {
                        if ((c= sep->token[0]) == ';' && depth == 0) break;
                        len+= strlen(sep->token) + 1;
                        sep= sep->next;
                        if (c == '{') depth++;
                        if (c == '}' && --depth == 0) break;
                }

                body= malloc(len * sizeof(char));
                *body= 0;

                while (fun != sep) {
                        strcat(body, fun->token);
                        if (!sugar(fun->token)
                                && !sugar(fun->next->token)
                        ) strcat(body, " ");
                        fun= fun->next;
                }
                second->token[strlen(second->token)-1]= 0;

                if (depth != 0) {
                        printf("Missing '}'\n");
                        err= 1;
                } else
                if ((flags= b_setenv(E_FUNCTION, name,
                                        second->token+1, body)) != 0) {
                        printf("%s is a %s\n", name,
                                flags & E_RESERVED ? "reserved word" :
                                                "special variable");
                        err= 1;
                }
                while (cmds != sep) voidtoken();
                free(body);
                return;
        } else
                /* Grouping? */
        if (name[0] == '{') {
                token **acmds= &cmds->next;
                char *t;
                int depth= 1;

                /* Find and remove matching '}' */
                depth= 1;
                while (*acmds != nil) {
                        t= (*acmds)->token;
                        if (t[0] == '{') depth++;
                        if (t[0] == '}' && --depth == 0) { t[0]= ';'; break; }
                        acmds= &(*acmds)->next;
                }
                voidtoken();
                return;
        } else
                /* Command coming up, check if ESC typed. */
        if (interrupt()) {
                return;
        } else
                /* unset name ..., echo word ...? */
        if (n >= 1 && (res == R_UNSET || res == R_ECHO)) {
                char *arg= poptoken(), *p;

                for (;;) {
                        free(arg);
                        if (cmds == sep) break;
                        arg= poptoken();
                        if (res == R_UNSET) {   /* unset arg */
                                b_unset(arg);
                        } else {                /* echo arg */
                                p= arg;
                                while (*p != 0) {
                                        if (*p != '\\') {
                                                putch(*p);
                                        } else
                                        switch (*++p) {
                                        case 0:
                                                if (cmds == sep) return;
                                                continue;
                                        case 'n':
                                                putch('\n');
                                                break;
                                        case 'v':
                                                printf(version);
                                                break;
                                        case 'c':
                                                clear_screen();
                                                break;
                                        case 'w':
                                                for (;;) {
                                                        if (interrupt())
                                                                return;
                                                        if (getch() == '\n')
                                                                break;
                                                }
                                                break;
                                        default:
                                                putch(*p);
                                        }
                                        p++;
                                }
                                putch(cmds != sep ? ' ' : '\n');
                        }
                }
                return;
        } else
                /* boot -opts? */
        if (n == 2 && res == R_BOOT && second->token[0] == '-') {
                static char optsvar[]= "bootopts";
                (void) b_setvar(E_VAR, optsvar, second->token);
                voidtoken();
                voidtoken();
                bootminix();
                b_unset(optsvar);
                return;
        } else
                /* boot device, ls dir, delay msec? */
        if (n == 2 && (res == R_BOOT || res == R_CTTY
                        || res == R_DELAY || res == R_LS)
        ) {
                if (res == R_BOOT) boot_device(second->token);
                if (res == R_CTTY) ctty(second->token);
                if (res == R_DELAY) delay(second->token);
                if (res == R_LS) ls(second->token);
                voidtoken();
                voidtoken();
                return;
        } else
                /* trap msec command? */
        if (n == 3 && res == R_TRAP && numeric(second->token)) {
                long msec= a2l(second->token);

                voidtoken();
                voidtoken();
                schedule(msec, poptoken());
                return;
        } else
                /* Simple command. */
        if (n == 1) {
                char *body;
                int ok= 0;

                name= poptoken();

                switch (res) {
                case R_BOOT:    bootminix();    ok= 1;  break;
                case R_DELAY:   delay("500");   ok= 1;  break;
                case R_LS:      ls(null);       ok= 1;  break;
                case R_MENU:    menu();         ok= 1;  break;
                case R_SAVE:    save_parameters(); ok= 1;break;
                case R_SET:     show_env();     ok= 1;  break;
                case R_HELP:    help();         ok= 1;  break;
                case R_EXIT:    exit(0);
                case R_OFF:     off();          ok= 1;  break;
                }

                /* Command to check bootparams: */
                if (strcmp(name, ":") == 0) ok= 1;

                /* User defined function. */
                if (!ok && (body= b_body(name)) != nil) {
                        (void) tokenize(&cmds, body);
                        ok= 1;
                }
                if (!ok) printf("%s: unknown function", name);
                free(name);
                if (ok) return;
        } else {
                /* Syntax error. */
                printf("Can't parse:");
                while (cmds != sep) {
                        printf(" %s", cmds->token); voidtoken();
                }
        }

        /* Getting here means that the command is not understood. */
        printf("\nTry 'help'\n");
        err= 1;
}

int run_trailer(void)
/* Run the trailer function between loading Minix and handing control to it.
 * Return true iff there was no error.
 */
{
        token *save_cmds= cmds;

        cmds= nil;
        (void) tokenize(&cmds, "trailer");
        while (cmds != nil) execute();
        cmds= save_cmds;
        return !err;
}

void monitor(void)
/* Read a line and tokenize it. */
{
        char *line;

        unschedule();           /* Kill a trap. */
        err= 0;                 /* Clear error state. */

        if (istty) printf("%s>", bootdev.name);
        line= readline();
        (void) tokenize(&cmds, line);
        free(line);
        (void) escape();        /* Forget if ESC typed. */
}

#if BIOS

unsigned char cdspec[25];
void bootcdinfo(u32_t, int *, int drive);

void boot(void)
/* Load Minix and start it, among other things. */
{

        /* Initialize tables. */
        initialize();

        /* Get environment variables from the parameter sector. */
        get_parameters();

        while (1) {
                /* While there are commands, execute them! */

                while (cmds != nil) execute();

                /* The "monitor" is just a "read one command" thing. */
                monitor();
        }
}
#endif /* BIOS */

#if UNIX

void main(int argc, char **argv)
/* Do not load or start anything, just edit parameters. */
{
        int i;
        char bootcode[SECTOR_SIZE];
        struct termios rawterm;

        istty= (argc <= 2 && tcgetattr(0, &termbuf) == 0);

        if (argc < 2) {
                fprintf(stderr, "Usage: edparams device [command ...]\n");
                exit(1);
        }

        /* Go over the arguments, changing control characters to spaces. */
        for (i= 2; i < argc; i++) {
                char *p;

                for (p= argv[i]; *p != 0; p++) {
                        if ((unsigned) *p < ' ' && *p != '\n') *p= ' ';
                }
        }

        bootdev.name= argv[1];
        if (strncmp(bootdev.name, "/dev/", 5) == 0) bootdev.name+= 5;
        if ((bootdev.device= open(argv[1], O_RDWR, 0666)) < 0)
                fatal(bootdev.name);

        /* Check if it is a bootable Minix device. */
        if (readsectors(mon2abs(bootcode), lowsec, 1) != 0
                || memcmp(bootcode, boot_magic, sizeof(boot_magic)) != 0) {
                fprintf(stderr, "edparams: %s: not a bootable Minix device\n",
                        bootdev.name);
                exit(1);
        }

        /* Print greeting message.  */
        if (istty) printf("Boot parameters editor.\n");

        signal(SIGINT, trap);
        signal(SIGALRM, trap);

        if (istty) {
                rawterm= termbuf;
                rawterm.c_lflag&= ~(ICANON|ECHO|IEXTEN);
                rawterm.c_cc[VINTR]= ESC;
                if (tcsetattr(0, TCSANOW, &rawterm) < 0) fatal("");
        }

        /* Get environment variables from the parameter sector. */
        get_parameters();

        i= 2;
        for (;;) {
                /* While there are commands, execute them! */
                while (cmds != nil || i < argc) {
                        if (cmds == nil) {
                                /* A command line command. */
                                parse_code(argv[i++]);
                        }
                        execute();

                        /* Bail out on errors if not interactive. */
                        if (err && !istty) exit(1);
                }

                /* Commands on the command line? */
                if (argc > 2) break;

                /* The "monitor" is just a "read one command" thing. */
                monitor();
        }
        exit(0);
}
#endif /* UNIX */

/*
 * $PchId: boot.c,v 1.14 2002/02/27 19:46:14 philip Exp $
 */

---