nfs.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

			return 0;
		}
		if(readplus == 0){
			rerrstr(e, sizeof e);
			if(strstr(e, "procedure unavailable") || strstr(e, "not supported"))
				readplus = -1;
		}
		if(readplus == 0)
			fprint(2, "readdirplus: %r\n");
	}
	if(readplus == 1)
		return -1;

	memset(&tx, 0, sizeof tx);
	nfs3Call(a, &tx.call, Nfs3CallTReadDir);
	tx.handle = *h;
	tx.count = count;
	tx.cookie = cookie;

	memset(&rx, 0, sizeof rx);
	nfs3Call(a, &rx.call, Nfs3CallRReadDir);

	if(sunClientRpc(nfscli, tag, &tx.call, &rx.call, pfreeme) < 0)
		return -1;
	if(rx.status != Nfs3Ok){
		free(*pfreeme);
		*pfreeme = 0;
		nfs3Errstr(rx.status);
		return -1;
	}

	/* readplus failed but read succeeded */
	readplus = -1;

	*unpack = nfs3EntryUnpack;
	*pcount = rx.count;
	*pp = rx.data;
	return 0;
}

/*
 * name <-> int translation
 */
typedef struct Map Map;
typedef struct User User;
typedef struct Group Group;

Map *map;
Map emptymap;

struct User
{
	char *name;
	uint uid;
	uint gid;
	uint g[16];
	uint ng;
	uchar *auth;
	int nauth;
};

struct Group
{
	char *name;	/* same pos as in User struct */
	uint gid;	/* same pos as in User struct */
};

struct Map
{
	int nuser;
	int ngroup;
	User *user;
	User **ubyname;
	User **ubyid;
	Group *group;
	Group **gbyname;
	Group **gbyid;
};

User*
finduser(User **u, int nu, char *s)
{
	int lo, hi, mid, n;

	hi = nu;
	lo = 0;
	while(hi > lo){
		mid = (lo+hi)/2;
		n = strcmp(u[mid]->name, s);
		if(n == 0)
			return u[mid];
		if(n < 0)
			lo = mid+1;
		else
			hi = mid;
	}
	return nil;
}

int
strtoid(User **u, int nu, char *s, u32int *id)
{
	u32int x;
	char *p;
	User *uu;

	x = strtoul(s, &p, 10);
	if(*s != 0 && *p == 0){
		*id = x;
		return 0;
	}

	uu = finduser(u, nu, s);
	if(uu == nil)
		return -1;
	*id = uu->uid;
	return 0;
}

char*
idtostr(User **u, int nu, u32int id)
{
	char buf[32];
	int lo, hi, mid;

	hi = nu;
	lo = 0;
	while(hi > lo){
		mid = (lo+hi)/2;
		if(u[mid]->uid == id)
			return estrdup9p(u[mid]->name);
		if(u[mid]->uid < id)
			lo = mid+1;
		else
			hi = mid;
	}
	snprint(buf, sizeof buf, "%ud", id);	
	return estrdup9p(buf);
}		
char*
uidtostr(u32int uid)
{
	return idtostr(map->ubyid, map->nuser, uid);
}

char*
gidtostr(u32int gid)
{
	return idtostr((User**)map->gbyid, map->ngroup, gid);
}

int
strtouid(char *s, u32int *id)
{
	return strtoid(map->ubyname, map->nuser, s, id);
}

int
strtogid(char *s, u32int *id)
{
	return strtoid((User**)map->gbyid, map->ngroup, s, id);
}


int
idcmp(const void *va, const void *vb)
{
	User **a, **b;

	a = (User**)va;
	b = (User**)vb;
	return (*a)->uid - (*b)->uid;
}

int
namecmp(const void *va, const void *vb)
{
	User **a, **b;

	a = (User**)va;
	b = (User**)vb;
	return strcmp((*a)->name, (*b)->name);
}

void
closemap(Map *m)
{
	int i;

	for(i=0; i<m->nuser; i++){
		free(m->user[i].name);
		free(m->user[i].auth);
	}
	for(i=0; i<m->ngroup; i++)
		free(m->group[i].name);
	free(m->user);
	free(m->group);
	free(m->ubyid);
	free(m->ubyname);
	free(m->gbyid);
	free(m->gbyname);
	free(m);
}

Map*
readmap(char *passwd, char *group)
{
	char *s, *f[10], *p, *nextp, *name;
	uchar *q, *eq;
	int i, n, nf, line, uid, gid;
	Biobuf *b;
	Map *m;
	User *u;
	Group *g;
	SunAuthUnix au;

	m = emalloc(sizeof(Map));

	if((b = Bopen(passwd, OREAD)) == nil){
		free(m);
		return nil;
	}
	line = 0;
	for(; (s = Brdstr(b, '\n', 1)) != nil; free(s)){
		line++;
		if(s[0] == '#')
			continue;
		nf = getfields(s, f, nelem(f), 0, ":");
		if(nf < 4)
			continue;
		name = f[0];
		uid = strtol(f[2], &p, 10);
		if(f[2][0] == 0 || *p != 0){
			fprint(2, "%s:%d: non-numeric id in third field\n", passwd, line);
			continue;
		}
		gid = strtol(f[3], &p, 10);
		if(f[3][0] == 0 || *p != 0){
			fprint(2, "%s:%d: non-numeric id in fourth field\n", passwd, line);
			continue;
		}
		if(m->nuser%32 == 0)
			m->user = erealloc(m->user, (m->nuser+32)*sizeof(m->user[0]));
		u = &m->user[m->nuser++];
		u->name = estrdup9p(name);
		u->uid = uid;
		u->gid = gid;
		u->ng = 0;
		u->auth = 0;
		u->nauth = 0;
	}
	Bterm(b);
	m->ubyname = emalloc(m->nuser*sizeof(User*));
	m->ubyid = emalloc(m->nuser*sizeof(User*));
	for(i=0; i<m->nuser; i++){
		m->ubyname[i] = &m->user[i];
		m->ubyid[i] = &m->user[i];
	}
	qsort(m->ubyname, m->nuser, sizeof(m->ubyname[0]), namecmp);
	qsort(m->ubyid, m->nuser, sizeof(m->ubyid[0]), idcmp);

	if((b = Bopen(group, OREAD)) == nil){
		closemap(m);
		return nil;
	}
	line = 0;
	for(; (s = Brdstr(b, '\n', 1)) != nil; free(s)){
		line++;
		if(s[0] == '#')
			continue;
		nf = getfields(s, f, nelem(f), 0, ":");
		if(nf < 4)
			continue;
		name = f[0];
		gid = strtol(f[2], &p, 10);
		if(f[2][0] == 0 || *p != 0){
			fprint(2, "%s:%d: non-numeric id in third field\n", group, line);
			continue;
		}
		if(m->ngroup%32 == 0)
			m->group = erealloc(m->group, (m->ngroup+32)*sizeof(m->group[0]));
		g = &m->group[m->ngroup++];
		g->name = estrdup9p(name);
		g->gid = gid;

		for(p=f[3]; *p; p=nextp){
			if((nextp = strchr(p, ',')) != nil)
				*nextp++ = 0;
			else
				nextp = p+strlen(p);
			u = finduser(m->ubyname, m->nuser, p);
			if(u == nil){
				if(verbose)
					fprint(2, "%s:%d: unknown user %s\n", group, line, p);
				continue;
			}
			if(u->ng >= nelem(u->g)){
				fprint(2, "%s:%d: user %s is in too many groups; ignoring %s\n", group, line, p, name);
				continue;
			}
			u->g[u->ng++] = gid;
		}
	}
	Bterm(b);
	m->gbyname = emalloc(m->ngroup*sizeof(Group*));
	m->gbyid = emalloc(m->ngroup*sizeof(Group*));
	for(i=0; i<m->ngroup; i++){
		m->gbyname[i] = &m->group[i];
		m->gbyid[i] = &m->group[i];
	}
	qsort(m->gbyname, m->ngroup, sizeof(m->gbyname[0]), namecmp);
	qsort(m->gbyid, m->ngroup, sizeof(m->gbyid[0]), idcmp);

	for(i=0; i<m->nuser; i++){
		au.stamp = 0;
		au.sysname = sys;
		au.uid = m->user[i].uid;
		au.gid = m->user[i].gid;
		memmove(au.g, m->user[i].g, sizeof au.g);
		au.ng = m->user[i].ng;
		n = sunAuthUnixSize(&au);
		q = emalloc(n);
		eq = q+n;
		m->user[i].auth = q;
		m->user[i].nauth = n;
		if(sunAuthUnixPack(q, eq, &q, &au) < 0 || q != eq){
			fprint(2, "sunAuthUnixPack failed for %s\n", m->user[i].name);
			free(m->user[i].auth);
			m->user[i].auth = 0;
			m->user[i].nauth = 0;
		}
	}

	return m;
}

Auth*
mkauth(char *user)
{
	Auth *a;
	uchar *p;
	int n;
	SunAuthUnix au;
	User *u;

	u = finduser(map->ubyname, map->nuser, user);
	if(u == nil || u->nauth == 0){
		/* nobody */
		au.stamp = 0;
		au.uid = -1;
		au.gid = -1;
		au.ng = 0;
		au.sysname = sys;
		n = sunAuthUnixSize(&au);
		a = emalloc(sizeof(Auth)+n);
		a->data = (uchar*)&a[1];
		a->ndata = n;
		if(sunAuthUnixPack(a->data, a->data+a->ndata, &p, &au) < 0
		|| p != a->data+a->ndata){
			free(a);
			return nil;
		}
		a->ref = 1;
if(verbose)print("creds for %s: %.*H\n", user, a->ndata, a->data);
		return a;
	}

	a = emalloc(sizeof(Auth)+u->nauth);
	a->data = (uchar*)&a[1];
	a->ndata = u->nauth;
	memmove(a->data, u->auth, a->ndata);
	a->ref = 1;
if(verbose)print("creds for %s: %.*H\n", user, a->ndata, a->data);
	return a;
}

void
freeauth(Auth *a)
{
	if(--a->ref > 0)
		return;
	free(a);
}

/*
 * 9P server
 */
void
responderrstr(Req *r)
{
	char e[ERRMAX];

	rerrstr(e, sizeof e);
	respond(r, e);
}

void
fsdestroyfid(Fid *fid)
{
	FidAux *aux;

	aux = fid->aux;
	if(aux == nil)
		return;
	freeauth(aux->auth);
	free(aux->name);
	free(aux);
}

void
attrToQid(Nfs3Attr *attr, Qid *qid)
{
	qid->path = attr->fileid;
	qid->vers = attr->mtime.sec;
	qid->type = 0;
	if(attr->type == Nfs3FileDir)
		qid->type |= QTDIR;
}

void
attrToDir(Nfs3Attr *attr, Dir *d)
{
	d->mode = attr->mode & 0777;
	if(attr->type == Nfs3FileDir)
		d->mode |= DMDIR;
	d->uid = uidtostr(attr->uid);
	d->gid = gidtostr(attr->gid);
	d->length = attr->size;
	attrToQid(attr, &d->qid);
	d->mtime = attr->mtime.sec;
	d->atime = attr->atime.sec;
	d->muid = nil;
}

void
fsattach(Req *r)
{
	char *path;
	Auth *auth;
	FidAux *aux;
	Nfs3Attr attr;
	Nfs3Handle h;

	path = r->ifcall.aname;
	if(path==nil || path[0]==0)
		path = defaultpath;

	auth = mkauth(r->ifcall.uname);

	if(mountMnt(auth, r->tag, path, &h) < 0
	|| nfsGetattr(auth, r->tag, &h, &attr) < 0){
		freeauth(auth);
		responderrstr(r);
		return;
	}

	aux = emalloc(sizeof(FidAux));
	aux->auth = auth;
	aux->handle = h;
	aux->cookie = 0;
	aux->name = nil;
	memset(&aux->parent, 0, sizeof aux->parent);
	r->fid->aux = aux;
	attrToQid(&attr, &r->fid->qid);
	r->ofcall.qid = r->fid->qid;
	respond(r, nil);
}

void
fsopen(Req *r)
{
	FidAux *aux;
	Nfs3Attr attr;
	Nfs3SetAttr sa;
	u1int have;
	ulong a, b;

	aux = r->fid->aux;
	a = 0;
	switch(r->ifcall.mode&OMASK){
	case OREAD:
		a = 0x0001;
		break;
	case OWRITE:
		a = 0x0004;
		break;
	case ORDWR:
		a = 0x0001|0x0004;
		break;
	case OEXEC:
		a = 0x20;
		break;
	}
	if(r->ifcall.mode&OTRUNC)
		a |= 0x0004;

	if(nfsAccess(aux->auth, r->tag, &aux->handle, a, &b, &have, &attr) < 0
	|| (!have && nfsGetattr(aux->auth, r->tag, &aux->handle, &attr) < 0)){
    Error:
		responderrstr(r);
		return;
	}
	if(a != b){
		respond(r, "permission denied");
		return;
	}
	if(r->ifcall.mode&OTRUNC){
		memset(&sa, 0, sizeof sa);
		sa.setSize = 1;
		if(nfsSetattr(aux->auth, r->tag, &aux->handle, &sa) < 0)
			goto Error;
	}
	attrToQid(&attr, &r->fid->qid);
	r->ofcall.qid = r->fid->qid;
	respond(r, nil);
}

void
fscreate(Req *r)
{
	FidAux *aux;
	u1int have;
	Nfs3Attr attr;
	Nfs3Handle h;
	ulong mode;
	uint gid;
	int (*mk)(Auth*, ulong, Nfs3Handle*, char*, Nfs3Handle*, ulong, uint, u1int*, Nfs3Attr*);

	aux = r->fid->aux;

	/*
	 * Plan 9 has no umask, so let's use the
	 * parent directory bits like Plan 9 does.
	 * What the heck, let's inherit the group too.
	 * (Unix will let us set the group to anything
	 * since we're the owner!)
	 */
	if(nfsGetattr(aux->auth, r->tag, &aux->handle, &attr) < 0){
		responderrstr(r);
		return;
	}
	mode = r->ifcall.perm&0777;
	if(r->ifcall.perm&DMDIR)
		mode &= (attr.mode&0666) | ~0666;
	else