/*
 * login() is a stupid little login process that loads a prototype
 * environment before forking off processes.
 */
#include <stdio.h>
#include <malloc.h>
#include <process.h>
#include <string.h>

char *format();
char *basename();

/*
 * login, itself
 */
main(argc,argv)
char **argv;
{
    char homedir[200];
    char logname[200];
    char *tenv;
    char *ptr;
    char *site;
    extern char *getenv();
#define Skip(x,c)	if (ptr=strchr(x,c)) *ptr++ = 0; else continue

    FILE *fp;
    char line[200];
    char login[100];
    char *who, *home, *cmd, *args;
    int drv;

    if (fp=fopen("/etc/login.env", "r")) {
	while (fgets(line, 200, fp)) {
	    strtok(line, "\n");
	    if (line[0] != '#')
		putenv(format(strdup(line)));
	}
	fclose(fp);
    }
    if ((site = getenv("SITE")) == (char*)0)
	site = "ms-dos";

    fp = fopen("/etc/passwd", "r");
    printf("%s login: ", site);
    fflush(stdout);
    while (gets(login)) {
	if (strlen(login) == 0)
	    goto next2;
	while (fgets(line, 200, fp)) {
	    strtok(line, "\n");
	    Skip(who=line, ';');		/* username */
	    Skip(ptr, ';');			/* password */
	    Skip(ptr, ';');			/* uid */
	    Skip(ptr, ';');			/* gid */
	    Skip(ptr, ';');			/* gcos */
	    Skip(home=ptr, ';');		/* home directory */
	    if (ptr = strchr(cmd=ptr, ' ')) {
		*ptr++ = 0;
		args = ptr;
	    }
	    else
		args = (char*)0;

	    format(args);

	    if (strcmp(login, who) == 0) {
		if (home[1] == ':') {
		    /* stupid kludge */
		    drv = home[0] & ~0x20;
		    drv -= ('A' - 1);
		    _chdrive(drv);
		}
		chdir(home);
		sprintf(homedir, "HOME=%s", home);
		putenv(homedir);
		sprintf(logname, "LOGNAME=%s", who);
		putenv(logname);
		spawnl(P_OVERLAY, cmd, basename(cmd), args, (char*)0);
		printf("cannot load %s\n", cmd);
		goto next;
	    }
	}
	puts("Fat chance, buddo!\n");
next:   rewind(fp);
next2:	fputs("login: ", stdout);
	fflush(stdout);
    }
    exit(0);
} /* main */

/*
 * format() takes a string and processes appropriate escapes. Because ms-dos
 * likes backslashes, they are not the best way of escaping things, so...
 * We use % to introduce escape seqences:
 * %s - a space
 * %b - a backspace
 * %n - a newline
 * %f - a formfeed
 * %r - a return
 * %E - an escape char
 * %% - a %
 * %<digits> - is the ascii character specified by those digits
 */
char *
format(s)
register char *s;
{
    register char *p;
    register c;
    char *base = s;

    if (base == (char*)0)
	return (char*)0;
    for (p=s; *s; s++, p++) {
	if (*s == '%') {
	    switch (*++s) {
	    case 's':   *p = ' ';   break;
	    case 'b':	*p = '\b';  break;
	    case 'n':	*p = '\n';  break;
	    case 'r':	*p = '\r';  break;
	    case 'f':	*p = '\f';  break;
	    case 'E':	*p = '\033';break;
	    case '%':	*p = '%';   break;
	    case '0': case '1': case '2': case '3': case '4':
	    case '5': case '6': case '7': case '8': case '9':
			for (c=0, --s; isalpha(s[1]);++s)
			    c = (c*10) + (*s  - '0');
			*p = c;
			break;
	    default:	*p = '?';   break;
	    }
	}
	else if (p < s)
	    *p = *s;
    }
    *p = 0;
    return base;
} /* format */

/*
 * basename() returns the base part of a filename, with extension intact
 */
char *
basename(s)
register char *s;
{
    register char *t;

    for (t=s+strlen(s)-1; t >= s; --t)
	if (*t == '\\' || *t == '/' || *t == ':')
	    return 1+t;
    return s;
} /* basename */