proc.c

讲述linux的初始化过程

	smb_close_socket(server);

	if (pid == 0) {
		printk(KERN_ERR "smb_retry: no connection process\n");
		server->state = CONN_RETRIED;
		goto out;
	}

	/*
	 * Clear the pid to enable the ioctl.
	 */
	server->conn_pid = 0;

	/*
	 * Note: use the "priv" flag, as a user process may need to reconnect.
	 */
	error = kill_proc(pid, SIGUSR1, 1);
	if (error) {
		printk(KERN_ERR "smb_retry: signal failed, error=%d\n", error);
		goto out_restore;
	}
	VERBOSE("signalled pid %d, waiting for new connection\n", pid);

	/*
	 * Wait for the new connection.
	 */
#ifdef SMB_RETRY_INTR
	interruptible_sleep_on_timeout(&server->wait,  5*HZ);
	if (signal_pending(current))
		printk(KERN_INFO "smb_retry: caught signal\n");
#else
	/*
	 * We don't want to be interrupted. For example, what if 'current'
	 * already has recieved a signal? sleep_on would terminate immediately
	 * and smbmount would not be able to re-establish connection.
	 *
	 * smbmount should be able to reconnect later, but it can't because
	 * it will get an -EIO on attempts to open the mountpoint!
	 */
	sleep_on_timeout(&server->wait, 5*HZ);
#endif

	/*
	 * Check for a valid connection.
	 */
	if (server->state == CONN_VALID) {
		/* This should be changed to VERBOSE, except many smbfs
		   problems is with the userspace daemon not reconnecting. */
		PARANOIA("sucessful, new pid=%d, generation=%d\n",
			 server->conn_pid, server->generation);
		result = 1;
	}

	/*
	 * Restore the original pid if we didn't get a new one.
	 */
out_restore:
	if (!server->conn_pid)
		server->conn_pid = pid;

out:
	return result;
}

/* smb_request_ok: We expect the server to be locked. Then we do the
   request and check the answer completely. When smb_request_ok
   returns 0, you can be quite sure that everything went well. When
   the answer is <=0, the returned number is a valid unix errno. */

static int
smb_request_ok(struct smb_sb_info *s, int command, int wct, int bcc)
{
	int result = -EIO;

	s->rcls = 0;
	s->err = 0;

	/* Make sure we have a connection */
	if (s->state != CONN_VALID)
	{
		if (!smb_retry(s))
			goto out;
	}

	if (smb_request(s) < 0)
	{
		DEBUG1("smb_request failed\n");
		goto out;
	}
	if (smb_valid_packet(s->packet) != 0)
	{
		PARANOIA("invalid packet!\n");
		goto out;
	}

	/*
	 * Check for server errors.  The current smb_errno() routine
	 * is squashing some error codes, but I don't think this is
	 * correct: after a server error the packet won't be valid.
	 */
	if (s->rcls != 0)
	{
		result = -smb_errno(s);
		if (!result)
			printk(KERN_DEBUG "smb_request_ok: rcls=%d, err=%d mapped to 0\n",
				s->rcls, s->err);
		/*
		 * Exit now even if the error was squashed ...
		 * packet verify will fail anyway.
		 */
		goto out;
	}
	result = smb_verify(s->packet, command, wct, bcc);

out:
	return result;
}

/*
 * This implements the NEWCONN ioctl. It installs the server pid,
 * sets server->state to CONN_VALID, and wakes up the waiting process.
 *
 * Note that this must be called with the server locked, except for
 * the first call made after mounting the volume. The server pid
 * will be set to zero to indicate that smbfs is awaiting a connection.
 */
int
smb_newconn(struct smb_sb_info *server, struct smb_conn_opt *opt)
{
	struct file *filp;
	int error;

	VERBOSE("fd=%d, pid=%d\n", opt->fd, current->pid);

	/*
	 * Make sure we don't already have a pid ...
	 */
	error = -EINVAL;
	if (server->conn_pid)
		goto out;

	error = -EACCES;
	if (current->uid != server->mnt->mounted_uid && 
	    !capable(CAP_SYS_ADMIN))
		goto out;

	error = -EBADF;
	filp = fget(opt->fd);
	if (!filp)
		goto out;
	if (!smb_valid_socket(filp->f_dentry->d_inode))
		goto out_putf;

	server->sock_file = filp;
	server->conn_pid = current->pid;
	smb_catch_keepalive(server);
	server->opt = *opt;
	server->generation += 1;
	server->state = CONN_VALID;
	error = 0;

	/* check if we have an old smbmount that uses seconds for the 
	   serverzone */
	if (server->opt.serverzone > 12*60 || server->opt.serverzone < -12*60)
		server->opt.serverzone /= 60;

	/* now that we have an established connection we can detect the server
	   type and enable bug workarounds */
	if (server->opt.protocol == SMB_PROTOCOL_NT1 &&
	    (server->opt.max_xmit < 0x1000) &&
	    !(server->opt.capabilities & SMB_CAP_NT_SMBS)) {
		server->mnt->flags |= SMB_MOUNT_WIN95;
#ifdef SMBFS_DEBUG_VERBOSE
		printk(KERN_NOTICE "smb_newconn: detected WIN95 server\n");
#endif
	}

	VERBOSE("protocol=%d, max_xmit=%d, pid=%d capabilities=0x%x\n",
		server->opt.protocol, server->opt.max_xmit, server->conn_pid,
		server->opt.capabilities);

out:
#ifdef SMB_RETRY_INTR
	wake_up_interruptible(&server->wait);
#else
	wake_up(&server->wait);
#endif
	return error;

out_putf:
	fput(filp);
	goto out;
}

/* smb_setup_header: We completely set up the packet. You only have to
   insert the command-specific fields */

__u8 *
smb_setup_header(struct smb_sb_info * server, __u8 command, __u16 wct, __u16 bcc)
{
	__u32 xmit_len = SMB_HEADER_LEN + wct * sizeof(__u16) + bcc + 2;
	__u8 *p = server->packet;
	__u8 *buf = server->packet;

	if (xmit_len > server->packet_size)
		printk(KERN_DEBUG "smb_setup_header: "
		       "Aieee, xmit len > packet! len=%d, size=%d\n",
		       xmit_len, server->packet_size);

	p = smb_encode_smb_length(p, xmit_len - 4);

	*p++ = 0xff;
	*p++ = 'S';
	*p++ = 'M';
	*p++ = 'B';
	*p++ = command;

	memset(p, '\0', 19);
	p += 19;
	p += 8;

	WSET(buf, smb_tid, server->opt.tid);
	WSET(buf, smb_pid, 1);
	WSET(buf, smb_uid, server->opt.server_uid);
	WSET(buf, smb_mid, 1);

	if (server->opt.protocol > SMB_PROTOCOL_CORE)
	{
		*(buf+smb_flg) = 0x8;
		WSET(buf, smb_flg2, 0x3);
	}
	*p++ = wct;		/* wct */
	p += 2 * wct;
	WSET(p, 0, bcc);
	return p + 2;
}

static void
smb_setup_bcc(struct smb_sb_info *server, __u8 * p)
{
	__u8 *packet = server->packet;
	__u8 *pbcc = packet + SMB_HEADER_LEN + 2 * SMB_WCT(packet);
	__u16 bcc = p - (pbcc + 2);

	WSET(pbcc, 0, bcc);
	smb_encode_smb_length(packet,
			      SMB_HEADER_LEN + 2 * SMB_WCT(packet) - 2 + bcc);
}

/*
 * We're called with the server locked, and we leave it that way.
 */
static int
smb_proc_open(struct smb_sb_info *server, struct dentry *dentry, int wish)
{
	struct inode *ino = dentry->d_inode;
	int mode, read_write = 0x42, read_only = 0x40;
	int res;
	char *p;

	/*
	 * Attempt to open r/w, unless there are no write privileges.
	 */
	mode = read_write;
	if (!(ino->i_mode & (S_IWUSR | S_IWGRP | S_IWOTH)))
		mode = read_only;
#if 0
	/* FIXME: why is this code not in? below we fix it so that a caller
	   wanting RO doesn't get RW. smb_revalidate_inode does some 
	   optimization based on access mode. tail -f needs it to be correct. */
	if (!(wish & (O_WRONLY | O_RDWR)))
		mode = read_only;
#endif

      retry:
	p = smb_setup_header(server, SMBopen, 2, 0);
	WSET(server->packet, smb_vwv0, mode);
	WSET(server->packet, smb_vwv1, aSYSTEM | aHIDDEN | aDIR);
	*p++ = 4;
	res = smb_encode_path(server, p, dentry, NULL);
	if (res < 0)
		goto out;
	p += res;

	smb_setup_bcc(server, p);

	res = smb_request_ok(server, SMBopen, 7, 0);
	if (res != 0) {
		if (smb_retry(server))
			goto retry;

		if (mode == read_write &&
		    (res == -EACCES || res == -ETXTBSY || res == -EROFS))
		{
			VERBOSE("%s/%s R/W failed, error=%d, retrying R/O\n",
				DENTRY_PATH(dentry), res);
			mode = read_only;
			goto retry;
		}
		goto out;
	}
	/* We should now have data in vwv[0..6]. */

	ino->u.smbfs_i.fileid = WVAL(server->packet, smb_vwv0);
	ino->u.smbfs_i.attr   = WVAL(server->packet, smb_vwv1);
	/* smb_vwv2 has mtime */
	/* smb_vwv4 has size  */
	ino->u.smbfs_i.access = (WVAL(server->packet, smb_vwv6) & SMB_ACCMASK);
	if (!(wish & (O_WRONLY | O_RDWR)))
		ino->u.smbfs_i.access = SMB_O_RDONLY;
	ino->u.smbfs_i.open = server->generation;

out:
	return res;
}

/*
 * Make sure the file is open, and check that the access
 * is compatible with the desired access.
 */
int
smb_open(struct dentry *dentry, int wish)
{
	struct inode *inode = dentry->d_inode;
	int result;

	result = -ENOENT;
	if (!inode)
	{
		printk(KERN_ERR "smb_open: no inode for dentry %s/%s\n",
		       DENTRY_PATH(dentry));
		goto out;
	}

	if (!smb_is_open(inode))
	{
		struct smb_sb_info *server = SMB_SERVER(inode);
		smb_lock_server(server);
		result = 0;
		if (!smb_is_open(inode))
			result = smb_proc_open(server, dentry, wish);
		smb_unlock_server(server);
		if (result)
		{
			PARANOIA("%s/%s open failed, result=%d\n",
				 DENTRY_PATH(dentry), result);
			goto out;
		}
		/*
		 * A successful open means the path is still valid ...
		 */
		smb_renew_times(dentry);
	}

	/*
	 * Check whether the access is compatible with the desired mode.
	 */
	result = 0;
	if (inode->u.smbfs_i.access != wish && 
	    inode->u.smbfs_i.access != SMB_O_RDWR)
	{
		PARANOIA("%s/%s access denied, access=%x, wish=%x\n",
			 DENTRY_PATH(dentry), inode->u.smbfs_i.access, wish);
		result = -EACCES;
	}
out:
	return result;
}

/* We're called with the server locked */

static int 
smb_proc_close(struct smb_sb_info *server, __u16 fileid, __u32 mtime)
{
	smb_setup_header(server, SMBclose, 3, 0);
	WSET(server->packet, smb_vwv0, fileid);
	DSET(server->packet, smb_vwv1, utc2local(server, mtime));
	return smb_request_ok(server, SMBclose, 0, 0);
}

/*
 * Called with the server locked.
 *
 * Win NT 4.0 has an apparent bug in that it fails to update the
 * modify time when writing to a file. As a workaround, we update
 * both modify and access time locally, and post the times to the
 * server when closing the file.
 */
static int 
smb_proc_close_inode(struct smb_sb_info *server, struct inode * ino)
{
	int result = 0;
	if (smb_is_open(ino))
	{
		/*
		 * We clear the open flag in advance, in case another
 		 * process observes the value while we block below.
		 */
		ino->u.smbfs_i.open = 0;

		/*
		 * Kludge alert: SMB timestamps are accurate only to
		 * two seconds ... round the times to avoid needless
		 * cache invalidations!
		 */
		if (ino->i_mtime & 1)
			ino->i_mtime--;
		if (ino->i_atime & 1)
			ino->i_atime--;
		/*
		 * If the file is open with write permissions,
		 * update the time stamps to sync mtime and atime.
		 */
		if ((server->opt.protocol >= SMB_PROTOCOL_LANMAN2) &&
		    !(ino->u.smbfs_i.access == SMB_O_RDONLY))
		{
			struct smb_fattr fattr;
			smb_get_inode_attr(ino, &fattr);
			smb_proc_setattr_ext(server, ino, &fattr);
		}

		result = smb_proc_close(server, ino->u.smbfs_i.fileid,
						ino->i_mtime);
		ino->u.smbfs_i.cache_valid &= ~SMB_F_LOCALWRITE;
		/*
		 * Force a revalidation after closing ... some servers
		 * don't post the size until the file has been closed.
		 */
		if (server->opt.protocol < SMB_PROTOCOL_NT1)
			ino->u.smbfs_i.oldmtime = 0;
		ino->u.smbfs_i.closed = jiffies;
	}
	return result;
}

int
smb_close(struct inode *ino)
{
	int result = 0;

	if (smb_is_open(ino))
	{
		struct smb_sb_info *server = SMB_SERVER(ino);
		smb_lock_server(server);
		result = smb_proc_close_inode(server, ino);
		smb_unlock_server(server);
	}
	return result;
}

/*
 * This is used to close a file following a failed instantiate.
 * Since we don't have an inode, we can't use any of the above.
 */
int
smb_close_fileid(struct dentry *dentry, __u16 fileid)
{
	struct smb_sb_info *server = server_from_dentry(dentry);
	int result;

	smb_lock_server(server);
	result = smb_proc_close(server, fileid, CURRENT_TIME);
	smb_unlock_server(server);
	return result;
}

/* In smb_proc_read and smb_proc_write we do not retry, because the
   file-id would not be valid after a reconnection. */

int
smb_proc_read(struct inode *inode, off_t offset, int count, char *data)
{
	struct smb_sb_info *server = server_from_inode(inode);
	__u16 returned_count, data_len;
	unsigned char *buf;
	int result;

	smb_lock_server(server);
	smb_setup_header(server, SMBread, 5, 0);
	buf = server->packet;
	WSET(buf, smb_vwv0, inode->u.smbfs_i.fileid);
	WSET(buf, smb_vwv1, count);
	DSET(buf, smb_vwv2, offset);
	WSET(buf, smb_vwv4, 0);

	result = smb_request_ok(server, SMBread, 5, -1);
	if (result < 0)
		goto out;
	returned_count = WVAL(server->packet, smb_vwv0);

	buf = SMB_BUF(server->packet);
	data_len = WVAL(buf, 1);

	/* we can NOT simply trust the data_len given by the server ... */
	if (data_len > server->packet_size - (buf+3 - server->packet)) {
		printk(KERN_ERR "smb_proc_read: invalid data length!! "
		       "%d > %d - (%p - %p)\n",
		       data_len, server->packet_size, buf+3, server->packet);
		result = -EIO;
		goto out;
	}

	memcpy(data, buf+3, data_len);

	if (returned_count != data_len) {
		printk(KERN_NOTICE "smb_proc_read: returned != data_len\n");
		printk(KERN_NOTICE "smb_proc_read: ret_c=%d, data_len=%d\n",
		       returned_count, data_len);
	}
	result = data_len;

out:
	VERBOSE("ino=%ld, fileid=%d, count=%d, result=%d\n",
		inode->ino, inode->u.smbfs_i.fileid, count, result);
	smb_unlock_server(server);
	return result;
}

int
smb_proc_write(struct inode *inode, off_t offset, int count, const char *data)
{
	struct smb_sb_info *server = server_from_inode(inode);
	int result;
	__u8 *p;
	
	VERBOSE("ino=%ld, fileid=%d, count=%d@%ld, packet_size=%d\n",
		inode->ino, inode->u.smbfs_i.fileid, count, offset,
		server->packet_size);

	smb_lock_server(server);
	p = smb_setup_header(server, SMBwrite, 5, count + 3);
	WSET(server->packet, smb_vwv0, inode->u.smbfs_i.fileid);
	WSET(server->packet, smb_vwv1, count);
	DSET(server->packet, smb_vwv2, offset);
	WSET(server->packet, smb_vwv4, 0);

	*p++ = 1;
	WSET(p, 0, count);
	memcpy(p+2, data, count);

	result = smb_request_ok(server, SMBwrite, 1, 0);
	if (result >= 0)
		result = WVAL(server->packet, smb_vwv0);

	smb_unlock_server(server);
	return result;
}

int
smb_proc_create(struct dentry *dentry, __u16 attr, time_t ctime, __u16 *fileid)
{
	struct smb_sb_info *server = server_from_dentry(dentry);
	char *p;
	int result;

	smb_lock_server(server);

      retry:
	p = smb_setup_header(server, SMBcreate, 3, 0);
	WSET(server->packet, smb_vwv0, attr);
	DSET(server->packet, smb_vwv1, utc2local(server, ctime));
	*p++ = 4;
	result = smb_encode_path(server, p, dentry, NULL);
	if (result < 0)
		goto out;
	p += result;
	smb_setup_bcc(server, p);

	result = smb_request_ok(server, SMBcreate, 1, 0);
	if (result < 0) {
		if (smb_retry(server))
			goto retry;
		goto out;
	}
	*fileid = WVAL(server->packet, smb_vwv0);
	result = 0;

out:
	smb_unlock_server(server);
	return result;
}

int
smb_proc_mv(struct dentry *old_dentry, struct dentry *new_dentry)
{
	struct smb_sb_info *server = server_from_dentry(old_dentry);
	char *p;
	int result;

	smb_lock_server(server);

      retry:
	p = smb_setup_header(server, SMBmv, 1, 0);
	WSET(server->packet, smb_vwv0, aSYSTEM | aHIDDEN | aDIR);

	*p++ = 4;
	result = smb_encode_path(server, p, old_dentry, NULL);
	if (result < 0)
		goto out;
	p += result;

	*p++ = 4;
	result = smb_encode_path(server, p, new_dentry, NULL);
	if (result < 0)