nfsserver.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

#include "all.h"

/*
 *	Cf. /lib/rfc/rfc1094
 */

static int	nfsnull(int, Rpccall*, Rpccall*);
static int	nfsgetattr(int, Rpccall*, Rpccall*);
static int	nfssetattr(int, Rpccall*, Rpccall*);
static int	nfsroot(int, Rpccall*, Rpccall*);
static int	nfslookup(int, Rpccall*, Rpccall*);
static int	nfsreadlink(int, Rpccall*, Rpccall*);
static int	nfsread(int, Rpccall*, Rpccall*);
static int	nfswritecache(int, Rpccall*, Rpccall*);
static int	nfswrite(int, Rpccall*, Rpccall*);
static int	nfscreate(int, Rpccall*, Rpccall*);
static int	nfsremove(int, Rpccall*, Rpccall*);
static int	nfsrename(int, Rpccall*, Rpccall*);
static int	nfslink(int, Rpccall*, Rpccall*);
static int	nfssymlink(int, Rpccall*, Rpccall*);
static int	nfsmkdir(int, Rpccall*, Rpccall*);
static int	nfsrmdir(int, Rpccall*, Rpccall*);
static int	nfsreaddir(int, Rpccall*, Rpccall*);
static int	nfsstatfs(int, Rpccall*, Rpccall*);

Procmap nfsproc[] = {
	0, nfsnull,	/* void */
	1, nfsgetattr,	/* Fhandle */
	2, nfssetattr,	/* Fhandle, Sattr */
	3, nfsroot,	/* void */
	4, nfslookup,	/* Fhandle, String */
	5, nfsreadlink,	/* Fhandle */
	6, nfsread,	/* Fhandle, long, long, long */
	7, nfswritecache,/* void */
	8, nfswrite,	/* Fhandle, long, long, long, String */
	9, nfscreate,	/* Fhandle, String, Sattr */
	10, nfsremove,	/* Fhandle, String */
	11, nfsrename,	/* Fhandle, String, Fhandle, String */
	12, nfslink,	/* Fhandle, Fhandle, String */
	13, nfssymlink,	/* Fhandle, String, String, Sattr */
	14, nfsmkdir,	/* Fhandle, String, Sattr */
	15, nfsrmdir,	/* Fhandle, String */
	16, nfsreaddir,	/* Fhandle, long, long */
	17, nfsstatfs,	/* Fhandle */
	0, 0
};

void	nfsinit(int, char**);
extern void	mntinit(int, char**);
extern Procmap	mntproc[];

Progmap progmap[] = {
	100005, 1, mntinit, mntproc,
	100003, 2, nfsinit, nfsproc,
	0, 0, 0,
};

int	myport = 2049;
long	nfstime;
int	conftime;

void
main(int argc, char *argv[])
{
	server(argc, argv, myport, progmap);
}

static void
doalarm(void)
{
	nfstime = time(0);
	mnttimer(nfstime);
	if(conftime+5*60 < nfstime){
		conftime = nfstime;
		readunixidmaps(config);
	}
}

void
nfsinit(int argc, char **argv)
{
	/*
	 * mntinit will have already parsed our options.
	 */
	USED(argc, argv);
	clog("nfs file server init\n");
	rpcalarm = doalarm;
	nfstime = time(0);
}

static int
nfsnull(int n, Rpccall *cmd, Rpccall *reply)
{
	USED(n, reply);
	chat("nfsnull...");
	showauth(&cmd->cred);
	chat("OK\n");
	return 0;
}

static int
nfsgetattr(int n, Rpccall *cmd, Rpccall *reply)
{
	Xfid *xf;
	Dir dir;
	uchar *dataptr = reply->results;

	chat("getattr...");
	if(n != FHSIZE)
		return garbage(reply, "bad count");
	xf = rpc2xfid(cmd, &dir);
	if(xf == 0)
		return error(reply, NFSERR_STALE);
	chat("%s...", xf->xp->name);
	PLONG(NFS_OK);
	dataptr += dir2fattr(cmd->up, &dir, dataptr);
	chat("OK\n");
	return dataptr - (uchar *)reply->results;
}

static int
nfssetattr(int n, Rpccall *cmd, Rpccall *reply)
{
	Xfid *xf;
	Dir dir, nd;
	Sattr sattr;
	int r;
	uchar *argptr = cmd->args;
	uchar *dataptr = reply->results;

	chat("setattr...");
	if(n <= FHSIZE)
		return garbage(reply, "count too small");
	xf = rpc2xfid(cmd, &dir);
	argptr += FHSIZE;
	argptr += convM2sattr(argptr, &sattr);
	if(argptr != &((uchar *)cmd->args)[n])
		return garbage(reply, "bad count");
	chat("mode=0%lo,u=%ld,g=%ld,size=%ld,atime=%ld,mtime=%ld...",
		sattr.mode, sattr.uid, sattr.gid, sattr.size,
		sattr.atime, sattr.mtime);
	if(xf == 0)
		return error(reply, NFSERR_STALE);
	if(sattr.uid != NOATTR || sattr.gid != NOATTR)
		return error(reply, NFSERR_PERM);
	if(sattr.size == 0){
		if(xf->xp->s != xf->xp->parent->s){
			if(xfauthremove(xf, cmd->user) < 0)
				return error(reply, NFSERR_PERM);
		}else if(dir.length && xfopen(xf, Trunc|Oread|Owrite) < 0)
			return error(reply, NFSERR_PERM);
	}else if(sattr.size != NOATTR)
		return error(reply, NFSERR_PERM);
	r = 0;
	nulldir(&nd);
	if(sattr.mode != NOATTR)
		++r, nd.mode = (dir.mode & ~0777) | (sattr.mode & 0777);
	if(sattr.atime != NOATTR)
		++r, nd.atime = sattr.atime;
	if(sattr.mtime != NOATTR)
		++r, nd.mtime = sattr.mtime;
	chat("sattr.mode=%luo dir.mode=%luo nd.mode=%luo...", sattr.mode, dir.mode, nd.mode);
	if(r){
		r = xfwstat(xf, &nd);
		if(r < 0)
			return error(reply, NFSERR_PERM);
	}
	if(xfstat(xf, &dir) < 0)
		return error(reply, NFSERR_STALE);
	PLONG(NFS_OK);
	dataptr += dir2fattr(cmd->up, &dir, dataptr);
	chat("OK\n");
	return dataptr - (uchar *)reply->results;
}

static int
nfsroot(int n, Rpccall *cmd, Rpccall *reply)
{
	USED(n, reply);
	chat("nfsroot...");
	showauth(&cmd->cred);
	chat("OK\n");
	return 0;
}

static int
nfslookup(int n, Rpccall *cmd, Rpccall *reply)
{
	Xfile *xp;
	Xfid *xf, *newxf;
	String elem;
	Dir dir;
	uchar *argptr = cmd->args;
	uchar *dataptr = reply->results;

	chat("lookup...");
	if(n <= FHSIZE)
		return garbage(reply, "count too small");
	xf = rpc2xfid(cmd, 0);
	argptr += FHSIZE;
	argptr += string2S(argptr, &elem);
	if(argptr != &((uchar *)cmd->args)[n])
		return garbage(reply, "bad count");
	if(xf == 0)
		return error(reply, NFSERR_STALE);
	xp = xf->xp;
	if(!(xp->qid.type & QTDIR))
		return error(reply, NFSERR_NOTDIR);
	chat("%s -> \"%.*s\"...", xp->name, utfnlen(elem.s, elem.n), elem.s);
	if(xp->s->noauth == 0 && xp->parent == xp && elem.s[0] == '#')
		newxf = xfauth(xp, &elem);
	else
		newxf = xfwalkcr(Twalk, xf, &elem, 0);
	if(newxf == 0)
		return error(reply, NFSERR_NOENT);
	if(xfstat(newxf, &dir) < 0)
		return error(reply, NFSERR_IO);
	PLONG(NFS_OK);
	dataptr += xp2fhandle(newxf->xp, dataptr);
	dataptr += dir2fattr(cmd->up, &dir, dataptr);
	chat("OK\n");
	return dataptr - (uchar *)reply->results;
}

static int
nfsreadlink(int n, Rpccall *cmd, Rpccall *reply)
{
	USED(n, reply);
	chat("readlink...");
	showauth(&cmd->cred);
	return error(reply, NFSERR_NOENT);
}

static int
nfsread(int n, Rpccall *cmd, Rpccall *reply)
{
	Session *s;
	Xfid *xf;
	Dir dir;
	int offset, count;
	uchar *argptr = cmd->args;
	uchar *dataptr = reply->results;
	uchar *readptr = dataptr + 4 + 17*4 + 4;

	chat("read...");
	if(n != FHSIZE+12)
		return garbage(reply, "bad count");
	xf = rpc2xfid(cmd, 0);
	argptr += FHSIZE;
	offset = GLONG();
	count = GLONG();
	if(xf == 0)
		return error(reply, NFSERR_STALE);
	chat("%s %d %d...", xf->xp->name, offset, count);
	if(xf->xp->s != xf->xp->parent->s){
		count = xfauthread(xf, offset, readptr, count);
	}else{
		if(xfopen(xf, Oread) < 0)
			return error(reply, NFSERR_PERM);
		if(count > 8192)
			count = 8192;
		s = xf->xp->s;
		setfid(s, xf->opfid);
		xf->opfid->tstale = nfstime + 60;
		s->f.offset = offset;
		s->f.count = count;
		if(xmesg(s, Tread) < 0)
			return error(reply, NFSERR_IO);
		count = s->f.count;
		memmove(readptr, s->f.data, count);
	}
	if(xfstat(xf, &dir) < 0)
		return error(reply, NFSERR_IO);
	PLONG(NFS_OK);
	dataptr += dir2fattr(cmd->up, &dir, dataptr);
	PLONG(count);
	dataptr += ROUNDUP(count);
	chat("%d OK\n", count);
	return dataptr - (uchar *)reply->results;
}

static int
nfswritecache(int n, Rpccall *cmd, Rpccall *reply)
{
	USED(n, reply);
	chat("writecache...");
	showauth(&cmd->cred);
	chat("OK\n");
	return 0;
}

static int
nfswrite(int n, Rpccall *cmd, Rpccall *reply)
{
	Session *s;
	Xfid *xf;
	Dir dir;
	int offset, count;
	uchar *argptr = cmd->args;
	uchar *dataptr = reply->results;

	chat("write...");
	if(n < FHSIZE+16)
		return garbage(reply, "count too small");
	xf = rpc2xfid(cmd, 0);
	argptr += FHSIZE + 4;
	offset = GLONG();
	argptr += 4;
	count = GLONG();
	if(xf == 0)
		return error(reply, NFSERR_STALE);
	chat("%s %d %d...", xf->xp->name, offset, count);
	if(xf->xp->s != xf->xp->parent->s){
		if(xfauthwrite(xf, offset, argptr, count) < 0)
			return error(reply, NFSERR_IO);
	}else{
		if(xfopen(xf, Owrite) < 0)
			return error(reply, NFSERR_PERM);
		s = xf->xp->s;
		setfid(s, xf->opfid);
		xf->opfid->tstale = nfstime + 60;
		s->f.offset = offset;
		s->f.count = count;
		s->f.data = (char *)argptr;
		if(xmesg(s, Twrite) < 0)
			return error(reply, NFSERR_IO);
	}
	if(xfstat(xf, &dir) < 0)