#include <u.h>#include <libc.h>#include <auth.h> static int	debug;static char	cwd[8192];static char	*parts[256];static int	mflags[nelem(parts)];static int	nparts; static voidbinderr(char *new, char *old, int flag){	char dash[4] = { '-' }; 	if(debug){		if(flag & MCREATE)			dash[2] = 'c'; 		switch(flag){		case MCREATE|MREPL:		case MREPL:			dash[0] = ' ';			if(dash[2] == 'c')				dash[1] = '-';			else				dash[1] = ' ';			break;		case MBEFORE:			dash[1] = 'b';			break;		case MAFTER:			dash[1] = 'a';			break;		}		fprint(2, "bind %s %s %s\n", dash, new, old);	}	if(bind(new, old, flag) < 0)		sysfatal("bind %s: %r", new);} static voidresolvenames(char **names, int nname){	int i; 	for(i = 0; i < nname; i++){		if(names[i] == nil)			continue;		cleanname(names[i]);		switch(names[i][0]){		case '#':		case '/':			break;		default:			names[i] = cleanname(smprint("%s/%s", cwd, names[i]));		}	}} static voidsandbox(char **names, int *flags, int nname){	char *parts[32];	char rootskel[128];	char src[8192], targ[8192], dir[8192], skel[8192];	char name[8192];	char *newroot;	Dir *d;	int i, j, n; 	snprint(rootskel, sizeof rootskel, "/mnt/d/newroot.%d", getpid());	binderr(rootskel, "/", MBEFORE); 	newroot = rootskel + strlen("/mnt/d"); 	for(j = 0; j < nname; j++){		if(names[j] == nil)			continue;		utfecpy(name, &name[sizeof name-1], names[j]);		n = gettokens(name, parts, nelem(parts), "/");		utfecpy(targ, &targ[sizeof targ-1], newroot);		memset(src, 0, sizeof src);		for(i = 0; i < n; i++){			utfecpy(dir, &dir[sizeof dir-1], targ);			snprint(targ, sizeof targ, "%s/%s", targ, parts[i]);			snprint(src, sizeof src, "%s/%s", src, parts[i]);			d = dirstat(targ);			if(d != nil){				free(d);				continue;			}			d = dirstat(src);			if(d == nil)				continue;			if(d->mode & DMDIR)				snprint(skel, sizeof skel, "/mnt/d/%s", parts[i]);			else				snprint(skel, sizeof skel, "/mnt/f/%s", parts[i]);			free(d);			binderr(skel, dir, MBEFORE);		}		if(flags[j] != -1)			binderr(names[j], targ, flags[j]);	}	binderr(newroot, "/", MREPL);} voidskelfs(void){	int p[2];	int dfd; 	pipe(p);	switch(rfork(RFFDG|RFREND|RFPROC|RFNAMEG)){	case -1:		sysfatal("fork");	case 0:		close(p[1]);		dup(p[0], 0);		dup(p[0], 1);		execl("/bin/skelfs", "skelfs", debug > 1 ? "-Di" : "-i", nil);		sysfatal("exec /bin/skelfs: %r");	}	close(p[0]);	dfd = dup(p[1], -1);	if(mount(p[1], -1, "/mnt/f", MREPL, "file") < 0)		sysfatal("/mnt/f mount setup: %r");	if(mount(dfd, -1, "/mnt/d", MREPL, "dir") < 0)		sysfatal("/mnt/d mount setup: %r");} static voidpush(char *path, int flag){	if(nparts == nelem(parts))		sysfatal("too many bound paths");	parts[nparts] = path;	mflags[nparts++] = flag;} voidusage(void){	fprint(2, "usage %s: [ -s ] [ -rc file ] [ -e devs ] command arg ...\n", argv0);	exits("usage");} voidmain(int argc, char **argv){	char **argp, devs[128];	int i, narg, dfd;	char *a;	int sflag; 	nparts = 0;	narg = 0;	memset(devs, 0, sizeof devs);	sflag = 0;	argp = argv;	ARGBEGIN{	case 'D':		debug++;	case 'd':		debug++;		break;	case 'r':		a = EARGF(usage());		push(a, MREPL);		break;	case 'c':		a = EARGF(usage());		push(a, MREPL|MCREATE);		break;	case 'e':		snprint(devs, sizeof devs, "%s%s", devs, EARGF(usage()));		break;	case 's':		sflag = 1;		break;	default:		usage();		break;	}ARGEND 	if(argc == 0 && !sflag)		usage(); 	if(getwd(cwd, sizeof(cwd)) == nil)		sysfatal("getwd: %r");	push(cwd, -1);	if(sflag){		snprint(devs, sizeof devs, "%s%s", devs, "|d");		push("/srv", MREPL|MCREATE);		push("/env", MREPL|MCREATE);		push("/rc", MREPL);		push("/bin", MREPL);		argp[narg++] = "/bin/rc";	} else {		if(access(argv[0], AEXIST) == -1){			if((argv[0] = smprint("/bin/%s", argv[0])) == nil)				sysfatal("smprint: %r");			if(access(argv[0], AEXIST) == -1)				sysfatal("could not stat %s %r", argv[0]);		}		push(argv[0], MREPL);	}	for(i = 0; i < argc; i++)		argp[narg++] = argv[i];	argp[narg] = nil; 	rfork(RFNAMEG|RFFDG);	skelfs();	dfd = open("/dev/drivers", OWRITE|OCEXEC);	if(dfd < 0)		sysfatal("could not /dev/drivers: %r"); 	resolvenames(parts, nparts);	sandbox(parts, mflags, nparts); 	if(debug)		fprint(2, "chdev %s\n", devs); 	if(devs[0] != '\0'){		if(fprint(dfd, "chdev & %s", devs) <= 0)			sysfatal("could not write chdev: %r");	} else {		if(fprint(dfd, "chdev ~") <= 0)			sysfatal("could not write chdev: %r");	}	close(dfd); 	if(chdir(cwd) < 0)		sysfatal("chdir %s: %r", cwd);	exec(argp[0], argp);	sysfatal("exec: %r");}