#include <u.h>#include <libc.h>#include <auth.h>#include <fcall.h> /* * Rather than reading /adm/users, which is a lot of work for * a toy program, we assume all groups have the form *	NNN:user:user: * meaning that each user is the leader of his own group. */ enum{	OPERM	= 0x3,		/* mask of all permission types in open mode */	Nram	= 512,}; typedef struct Fid Fid;typedef struct Ram Ram; struct Fid{	short	busy;	short	open;	short	rclose;	int	fid;	Fid	*next;	char	*user;	Ram	*ram;}; struct Ram{	short	busy;	short	open;	long	parent;		/* index in Ram array */	Qid	qid;	long	perm;	char	name[NAMELEN];	ulong	atime;	ulong	mtime;	char	*user;	char	*group;	char	*data;	long	ndata;}; enum{	Pexec =		1,	Pwrite = 	2,	Pread = 	4,	Pother = 	1,	Pgroup = 	8,	Powner =	64,}; ulong	path;		/* incremented for each new file */Fid	*fids;Ram	ram[Nram];int	nram;int	mfd[2];char	user[NAMELEN];char	mdata[MAXMSG+MAXFDATA];Fcall	rhdr;Fcall	thdr; Fid *	newfid(int);void	ramstat(Ram*, char*);void	error(char*);void	io(void);void	*erealloc(void*, ulong);void	*emalloc(ulong);void	usage(void);int	perm(Fid*, Ram*, int); char	*rflush(Fid*), *rnop(Fid*), *rsession(Fid*),	*rattach(Fid*), *rclone(Fid*), *rwalk(Fid*),	*rclwalk(Fid*), *ropen(Fid*), *rcreate(Fid*),	*rread(Fid*), *rwrite(Fid*), *rclunk(Fid*),	*rremove(Fid*), *rstat(Fid*), *rwstat(Fid*); char 	*(*fcalls[])(Fid*) = {	[Tflush]	rflush,	[Tsession]	rsession,	[Tnop]		rnop,	[Tattach]	rattach,	[Tclone]	rclone,	[Twalk]		rwalk,	[Tclwalk]	rclwalk,	[Topen]		ropen,	[Tcreate]	rcreate,	[Tread]		rread,	[Twrite]	rwrite,	[Tclunk]	rclunk,	[Tremove]	rremove,	[Tstat]		rstat,	[Twstat]	rwstat,}; char	Eperm[] =	"permission denied";char	Enotdir[] =	"not a directory";char	Enoauth[] =	"no authentication in ramfs";char	Enotexist[] =	"file does not exist";char	Einuse[] =	"file in use";char	Eexist[] =	"file exists";char	Enotowner[] =	"not owner";char	Eisopen[] = 	"file already open for I/O";char	Excl[] = 	"exclusive use file already open";char	Ename[] = 	"illegal name"; int debug; voidnotifyf(void *a, char *s){	USED(a);	if(strncmp(s, "interrupt", 9) == 0)		noted(NCONT);	noted(NDFLT);} voidmain(int argc, char *argv[]){	Ram *r;	char *defmnt;	int p[2];	char buf[12];	int fd;	int stdio = 0; 	defmnt = "/tmp";	ARGBEGIN{	case 'd':		debug = 1;		break;	case 'i':		defmnt = 0;		stdio = 1;		mfd[0] = 0;		mfd[1] = 1;		break;	case 's':		defmnt = 0;		break;	case 'm':		defmnt = ARGF();		break;	default:		usage();	}ARGEND 	if(pipe(p) < 0)		error("pipe failed");	if(!stdio){		mfd[0] = p[0];		mfd[1] = p[0];		if(defmnt == 0){			fd = create("#s/ramfs", OWRITE, 0666);			if(fd < 0)				error("create of /srv/ramfs failed");			sprint(buf, "%d", p[1]);			if(write(fd, buf, strlen(buf)) < 0)				error("writing /srv/ramfs");		}	} 	notify(notifyf);	nram = 1;	r = &ram[0];	r->busy = 1;	r->data = 0;	r->ndata = 0;	r->perm = CHDIR | 0775;	r->qid.path = CHDIR;	r->qid.vers = 0;	r->parent = 0;	r->user = user;	r->group = user;	r->atime = time(0);	r->mtime = r->atime;	strcpy(r->name, ".");	strcpy(user, getuser()); 	if(debug)		fmtinstall('F', fcallconv);	switch(rfork(RFFDG|RFPROC|RFNAMEG|RFNOTEG)){	case -1:		error("fork");	case 0:		close(p[1]);		io();		break;	default:		close(p[0]);	/* don't deadlock if child fails */		if(defmnt && mount(p[1], defmnt, MREPL|MCREATE, "") < 0)			error("mount failed");	}	exits(0);} char*rnop(Fid *f){	USED(f);	return 0;} char*rsession(Fid *unused){	Fid *f; 	USED(unused); 	for(f = fids; f; f = f->next)		if(f->busy)			rclunk(f);	memset(thdr.authid, 0, sizeof(thdr.authid));	memset(thdr.authdom, 0, sizeof(thdr.authdom));	memset(thdr.chal, 0, sizeof(thdr.chal));	return 0;} char*rflush(Fid *f){	USED(f);	return 0;} char*rattach(Fid *f){	/* no authentication! */	f->busy = 1;	f->rclose = 0;	f->ram = &ram[0];	thdr.qid = f->ram->qid;	if(rhdr.uname[0])		f->user = strdup(rhdr.uname);	else		f->user = "none";	return 0;} char*rclone(Fid *f){	Fid *nf; 	if(f->open)		return Eisopen;	if(f->ram->busy == 0)		return Enotexist;	nf = newfid(rhdr.newfid);	nf->busy = 1;	nf->open = 0;	nf->rclose = 0;	nf->ram = f->ram;	nf->user = f->user;	/* no ref count; the leakage is minor */	return 0;} char*rwalk(Fid *f){	Ram *r;	char *name;	Ram *parent; 	if((f->ram->qid.path & CHDIR) == 0)		return Enotdir;	if(f->ram->busy == 0)		return Enotexist;	f->ram->atime = time(0);	name = rhdr.name;	if(strcmp(name, ".") == 0){		thdr.qid = f->ram->qid;		return 0;	}	parent = &ram[f->ram->parent];	if(!perm(f, parent, Pexec))		return Eperm;	if(strcmp(name, "..") == 0){		f->ram = parent;		thdr.qid = f->ram->qid;		return 0;	}	for(r=ram; r < &ram[nram]; r++)		if(r->busy && r->parent==f->ram-ram && strcmp(name, r->name)==0){			thdr.qid = r->qid;			f->ram = r;			return 0;		}	return Enotexist;} char *rclwalk(Fid *f){	Fid *nf;	char *err; 	nf = newfid(rhdr.newfid);	nf->busy = 1;	nf->rclose = 0;	nf->ram = f->ram;	nf->user = f->user;	if(err = rwalk(nf))		rclunk(nf);	return err;} char *ropen(Fid *f){	Ram *r;	int mode, trunc; 	if(f->open)		return Eisopen;	r = f->ram;	if(r->busy == 0)		return Enotexist;	if(r->perm & CHEXCL)		if(r->open)			return Excl;	mode = rhdr.mode;	if(r->qid.path & CHDIR){		if(mode != OREAD)			return Eperm;		thdr.qid = r->qid;		return 0;	}	if(mode & ORCLOSE){		/* must be able to write parent */		if(!perm(f, &ram[r->parent], Pwrite))			return Eperm;		f->rclose = 1;	}	trunc = mode & OTRUNC;	mode &= OPERM;	if(mode==OWRITE || mode==ORDWR || trunc)		if(!perm(f, r, Pwrite))			return Eperm;	if(mode==OREAD || mode==ORDWR)		if(!perm(f, r, Pread))			return Eperm;	if(mode==OEXEC)		if(!perm(f, r, Pexec))			return Eperm;	if(trunc && (r->perm&CHAPPEND)==0){		r->ndata = 0;		if(r->data)			free(r->data);		r->data = 0;		r->qid.vers++;	}	thdr.qid = r->qid;	f->open = 1;	r->open++;	return 0;} char *rcreate(Fid *f){	Ram *r;	char *name;	long parent, prm; 	if(f->open)		return Eisopen;	if(f->ram->busy == 0)		return Enotexist;	parent = f->ram - ram;	if((f->ram->qid.path&CHDIR) == 0)		return Enotdir;	/* must be able to write parent */	if(!perm(f, f->ram, Pwrite))		return Eperm;	prm = rhdr.perm;	name = rhdr.name;	if(strcmp(name, ".")==0 || strcmp(name, "..")==0)		return Ename;	for(r=ram; r<&ram[nram]; r++)		if(r->busy && parent==r->parent)		if(strcmp((char*)name, r->name)==0)			return Einuse;	for(r=ram; r->busy; r++)		if(r == &ram[Nram-1])			return "no free ram resources";	r->busy = 1;	r->qid.path = ++path;	r->qid.vers = 0;	if(prm & CHDIR)		r->qid.path |= CHDIR;	r->parent = parent;	strcpy(r->name, (char*)name);	r->user = f->user;	r->group = f->ram->group;	if(prm & CHDIR)		prm = (prm&~0777) | (f->ram->perm&prm&0777);	else		prm = (prm&(~0777|0111)) | (f->ram->perm&prm&0666);	r->perm = prm;	r->ndata = 0;	if(r-ram >= nram)		nram = r - ram + 1;	r->atime = time(0);	r->mtime = r->atime;	f->ram->mtime = r->atime;	f->ram = r;	thdr.qid = r->qid;	f->open = 1;	r->open++;	return 0;} char*rread(Fid *f){	Ram *r;	char *buf;	long off;	int n, cnt; 	if(f->ram->busy == 0)		return Enotexist;	n = 0;	thdr.count = 0;	off = rhdr.offset;	buf = thdr.data;	cnt = rhdr.count;	if(f->ram->qid.path & CHDIR){		cnt = (rhdr.count/DIRLEN)*DIRLEN;		if(off%DIRLEN)			return "i/o error";		for(r=ram+1; off; r++){			if(r->busy && r->parent==f->ram-ram)				off -= DIRLEN;			if(r == &ram[nram-1])				return 0;		}		for(; r<&ram[nram] && n < cnt; r++){			if(!r->busy || r->parent!=f->ram-ram)				continue;			ramstat(r, buf+n);			n += DIRLEN;		}		thdr.count = n;		return 0;	}	r = f->ram;	if(off >= r->ndata)		return 0;	r->atime = time(0);	n = cnt;	if(off+n > r->ndata)		n = r->ndata - off;	thdr.data = r->data+off;	thdr.count = n;	return 0;} char*rwrite(Fid *f){	Ram *r;	ulong off;	int cnt; 	r = f->ram;	if(r->busy == 0)		return Enotexist;	off = rhdr.offset;	if(r->perm & CHAPPEND)		off = r->ndata;	cnt = rhdr.count;	if(r->qid.path & CHDIR)		return "file is a directory";	if(off > 100*1024*1024)		/* sanity check */		return "write too big";	if(off+cnt > r->ndata)		r->data = erealloc(r->data, off+cnt);	if(off > r->ndata)		memset(r->data+r->ndata, 0, off-r->ndata);	if(off+cnt > r->ndata)		r->ndata = off+cnt;	memmove(r->data+off, rhdr.data, cnt);	r->qid.vers++;	r->mtime = time(0);	thdr.count = cnt;	return 0;} void

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