minix/servers/vfs/request.c

/* This file deals with protection in the file system.  It contains the code
 * for four system calls that relate to protection.
 *
 * The entry points into this file are
 *   do_chmod:	perform the CHMOD and FCHMOD system calls
 *   do_chown:	perform the CHOWN and FCHOWN system calls
 *   do_umask:	perform the UMASK system call
 *   do_access:	perform the ACCESS system call
 *
 * Changes for VFS:
 *   Jul 2006 (Balazs Gerofi)
 */

#include "fs.h"
#include <unistd.h>
#include <minix/callnr.h>
#include "file.h"
#include "fproc.h"
#include "param.h"

#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"



/*===========================================================================*
 *				do_chmod				     *
 *===========================================================================*/
PUBLIC int do_chmod()
{
  struct filp *flp;
  struct vnode *vp;
  int r;
  uid_t uid;
  gid_t gid;
  mode_t new_mode;
    
  if (call_nr == CHMOD) {
      /* Perform the chmod(name, mode) system call. */
      if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);

      /* Request lookup */
      r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &vp);
      if (r != OK) return r;
  } 
  else if (call_nr == FCHMOD) {
      if (!(flp = get_filp(m_in.m3_i1))) return err_code;
      vp= flp->filp_vno;
      dup_vnode(vp);
  }
  else panic(__FILE__, "do_chmod called with strange call_nr", call_nr);

  uid= fp->fp_effuid;
  gid= fp->fp_effgid;

  /* Only the owner or the super_user may change the mode of a file.
   * No one may change the mode of a file on a read-only file system.
   */
  if (vp->v_uid != uid && uid != SU_UID)
	r = EPERM;
  else
	r = read_only(vp);

  /* If error, return inode. */
  if (r != OK)	{
	put_vnode(vp);
	return(r);
  }

  /* Now make the change. Clear setgid bit if file is not in caller's grp */
  if (uid != SU_UID && vp->v_gid != gid) 
	  m_in.mode &= ~I_SET_GID_BIT;

  /* Issue request */
  r = req_chmod(vp->v_fs_e, vp->v_inode_nr, m_in.mode, &new_mode);

  if (r == OK)
  	vp->v_mode = new_mode;
  put_vnode(vp);

  return OK;
}

/*===========================================================================*
 *				do_chown				     *
 *===========================================================================*/
PUBLIC int do_chown()
{
  int inode_nr;
  int fs_e;
  struct filp *flp;
  struct vnode *vp;
  int r;
  uid_t uid;
  gid_t gid;
  mode_t new_mode;
  
  if (call_nr == CHOWN) {
      /* Perform the chmod(name, mode) system call. */
      if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
      
      /* Request lookup */
      r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &vp);
      if (r != OK) return r;
  } 
  else if (call_nr == FCHOWN) {
      if (!(flp = get_filp(m_in.m1_i1))) return err_code;
      vp= flp->filp_vno;
      dup_vnode(vp);
  }
  else panic(__FILE__, "do_chmod called with strange call_nr", call_nr);

  uid= fp->fp_effuid;
  gid= fp->fp_effgid;

  r= OK;
  if (uid == SU_UID) {
	/* The super user can do anything. */
  } else {
	/* Regular users can only change groups of their own files. */
	if (vp->v_uid != uid)
		r = EPERM;	/* File does not belong to the caller */
	if (vp->v_uid != m_in.owner) 
		r = EPERM;	/* no giving away */
	if (gid != m_in.group)
		r = EPERM;	/* only change to the current gid */
  }
  if (r != OK) {
	put_vnode(vp);
	return r;
  }

  /* Issue request */
  r = req_chown(vp->v_fs_e, vp->v_inode_nr, m_in.owner, m_in.group, &new_mode);

  if(r == OK) {
  	vp->v_uid = m_in.owner;
  	vp->v_gid = m_in.group;
  	vp->v_mode = new_mode;
  }

  put_vnode(vp);

  return r;
}


/*===========================================================================*
 *				do_umask				     *
 *===========================================================================*/
PUBLIC int do_umask()
{
/* Perform the umask(co_mode) system call. */
  register mode_t r;

  r = ~fp->fp_umask;		/* set 'r' to complement of old mask */
  fp->fp_umask = ~(m_in.co_mode & RWX_MODES);
  return(r);			/* return complement of old mask */
}


/*===========================================================================*
 *				do_access				     *
 *===========================================================================*/
PUBLIC int do_access()
{
/* Perform the access(name, mode) system call. */
  int r;
  struct vnode *vp;
    
  /* First check to see if the mode is correct. */
  if ( (m_in.mode & ~(R_OK | W_OK | X_OK)) != 0 && m_in.mode != F_OK)
	return(EINVAL);

  if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);

  /* Request lookup */
  r = lookup_vp(0 /*flags*/, TRUE /*use_realuid*/, &vp);
  if (r != OK) return r;

  r= forbidden(vp, m_in.mode, 1 /*use_realuid*/);
  put_vnode(vp);
  return r;
}


/*===========================================================================*
 *				forbidden				     *
 *===========================================================================*/
PUBLIC int forbidden(struct vnode *vp, mode_t access_desired, int use_realuid)
{
/* Given a pointer to an inode, 'rip', and the access desired, determine
 * if the access is allowed, and if not why not.  The routine looks up the
 * caller's uid in the 'fproc' table.  If access is allowed, OK is returned
 * if it is forbidden, EACCES is returned.
 */

  register struct super_block *sp;
  register mode_t bits, perm_bits;
  uid_t uid;
  gid_t gid;
  int r, shift, type;

  if (vp->v_uid == (uid_t)-1 || vp->v_gid == (gid_t)-1)
  {
	printf("forbidden: bad uid/gid in vnode: inode %d on dev 0x%x\n",
		vp->v_inode_nr, vp->v_dev);
	printf("forbidden: last allocated at %s, %d\n", vp->v_file, vp->v_line);
	return EACCES;
  }

  /* Isolate the relevant rwx bits from the mode. */
  bits = vp->v_mode;
  if (use_realuid)
  {
	uid= fp->fp_realuid;
	gid= fp->fp_realgid;
  }
  else
  {
	uid= fp->fp_effuid;
	gid= fp->fp_effgid;
  }
  if (uid == SU_UID) {
	/* Grant read and write permission.  Grant search permission for
	 * directories.  Grant execute permission (for non-directories) if
	 * and only if one of the 'X' bits is set.
	 */
	if ( (bits & I_TYPE) == I_DIRECTORY ||
	     bits & ((X_BIT << 6) | (X_BIT << 3) | X_BIT))
		perm_bits = R_BIT | W_BIT | X_BIT;
	else
		perm_bits = R_BIT | W_BIT;
  } else {
	if (uid == vp->v_uid) shift = 6;	/* owner */
	else if (gid == vp->v_gid ) shift = 3;	/* group */
	else shift = 0;					/* other */
	perm_bits = (bits >> shift) & (R_BIT | W_BIT | X_BIT);
  }

  /* If access desired is not a subset of what is allowed, it is refused. */
  r = OK;
  if ((perm_bits | access_desired) != perm_bits) {
  	r = EACCES;
  	}

  /* Check to see if someone is trying to write on a file system that is
   * mounted read-only.
   */
  if (r == OK)
	if (access_desired & W_BIT)
	 	r = read_only(vp);

  return(r);
}


/*===========================================================================*
 *				read_only				     *
 *===========================================================================*/
PUBLIC int read_only(vp)
struct vnode *vp;		/* ptr to inode whose file sys is to be cked */
{
/* Check to see if the file system on which the inode 'ip' resides is mounted
 * read only.  If so, return EROFS, else return OK.
 */
  register struct vmnt *mp;

  mp = vp->v_vmnt;
  return(mp->m_flags ? EROFS : OK);
}


/* This file contains the wrapper functions for issueing a request
 * and receiving response from FS processes.
 * Each function builds a request message according to the request
 * parameter, calls the most low-level fs_sendrec and copies
 * back the response.
 * The low-level fs_sendrec handles the recovery mechanism from
 * a dead driver and reissues the request.
 *
 *  Sep 2006 (Balazs Gerofi)
 */

#include "fs.h"
#include <string.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/keymap.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <minix/u64.h>
#include <unistd.h>

#include <minix/vfsif.h>
#include "fproc.h"
#include "vmnt.h"
#include "vnode.h"
#include "param.h"

FORWARD _PROTOTYPE(int fs_sendrec_f, (char *file, int line, endpoint_t fs_e, message *reqm));

#define fs_sendrec(e, m) fs_sendrec_f(__FILE__, __LINE__, (e), (m))


/*===========================================================================*
 *			req_breadwrite					     *
 *===========================================================================*/
PUBLIC int req_breadwrite(fs_e, user_e, dev, pos, num_of_bytes, user_addr,
	rw_flag, new_posp, cum_iop)
endpoint_t fs_e;
endpoint_t user_e;
dev_t dev;
u64_t pos;
unsigned int num_of_bytes;
char *user_addr;
int rw_flag;
u64_t *new_posp;
unsigned int *cum_iop;
{
    int r;
    cp_grant_id_t gid;
    message m;

    gid= cpf_grant_magic(fs_e, user_e, (vir_bytes)user_addr,
	num_of_bytes, (rw_flag == READING ? CPF_WRITE : CPF_READ));
    if (gid == -1)
	panic(__FILE__, "req_breadwrite: cpf_grant_magic failed", NO_NUM);

    /* Fill in request message */
    m.m_type = rw_flag == READING ? REQ_BREAD_S : REQ_BWRITE_S;
    m.REQ_XFD_BDEV = dev;
    m.REQ_XFD_GID = gid;
    m.REQ_XFD_POS_LO = ex64lo(pos);
    m.REQ_XFD_POS_HI = ex64hi(pos);
    m.REQ_XFD_NBYTES = num_of_bytes;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid);

    if (r != OK) return r;

    /* Fill in response structure */
    *new_posp = make64(m.RES_XFD_POS_LO, m.RES_XFD_POS_HI);
    *cum_iop = m.RES_XFD_CUM_IO;

    return OK;
}


/*===========================================================================*
 *				req_chmod	      			     *
 *===========================================================================*/
PUBLIC int req_chmod(fs_e, inode_nr, rmode, new_modep)
int fs_e;
ino_t inode_nr;
mode_t rmode;
mode_t *new_modep;
{
    message m;
    int r;

    /* Fill in request message */
    m.m_type = REQ_CHMOD;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_MODE = rmode;
    m.REQ_UID = fp->fp_effuid;
    m.REQ_GID = fp->fp_effgid;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    /* Copy back actual mode. */
    if (r == OK)
	*new_modep = m.RES_MODE;

    return r;
}


/* Structure for REQ_CHOWN request */
typedef struct chown_req {
        int fs_e;
        ino_t inode_nr;
        uid_t uid;
        gid_t gid;
        uid_t newuid;
        gid_t newgid;
} chown_req_t;


/*===========================================================================*
 *				req_chown          			     *
 *===========================================================================*/
PUBLIC int req_chown(fs_e, inode_nr, newuid, newgid, new_modep)
endpoint_t fs_e;
ino_t inode_nr;
uid_t newuid;
gid_t newgid;
mode_t *new_modep;
{
    message m;
    int r;

    /* Fill in request message */
    m.m_type = REQ_CHOWN;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_UID = fp->fp_effuid;
    m.REQ_GID = fp->fp_effgid;
    m.REQ_NEW_UID = newuid;
    m.REQ_NEW_GID = newgid;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    /* Return new mode to caller. */
    *new_modep = m.RES_MODE;

    return r;
}


/*===========================================================================*
 *				req_create				     *
 *===========================================================================*/
int req_create(fs_e, inode_nr, omode, uid, gid, path, res)
int fs_e;
ino_t inode_nr;
int omode;
uid_t uid;
gid_t gid;
char *path;
node_details_t *res; 
{
    int r;
    cp_grant_id_t grant_id;
    size_t len;
    message m;

    len= strlen(path) + 1;
    grant_id= cpf_grant_direct(fs_e, (vir_bytes)path, len, CPF_READ);
    if (grant_id == -1)
	panic(__FILE__, "req_create: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_CREATE_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_MODE = omode;
    m.REQ_UID = uid;
    m.REQ_GID = gid;
    m.REQ_GRANT = grant_id;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(grant_id);

    if (r != OK) return r;

    /* Fill in response structure */
    res->fs_e = m.m_source;
    res->inode_nr = m.RES_INODE_NR;
    res->fmode = m.RES_MODE;
    res->fsize = m.RES_FILE_SIZE;
    res->uid = m.RES_UID;
    res->gid = m.RES_GID;
    res->dev = m.RES_DEV;
    res->inode_index = m.RES_INODE_INDEX;

    return OK;
}


/*===========================================================================*
 *				req_flush	      			     *
 *===========================================================================*/
PUBLIC int req_flush(fs_e, dev)
endpoint_t fs_e; 
dev_t dev;
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_FLUSH;
    m.REQ_DEV = dev;
    
    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_fstatfs	    			     *
 *===========================================================================*/
PUBLIC int req_fstatfs(fs_e, inode_nr, who_e, buf)
int fs_e;
ino_t inode_nr;
int who_e;
char *buf;
{
  int r;
  cp_grant_id_t gid;
  message m;

  gid= cpf_grant_magic(fs_e, who_e, (vir_bytes)buf, sizeof(struct statfs),
		CPF_WRITE);
  if (gid < 0)
	return gid;

  /* Fill in request message */
  m.m_type = REQ_FSTATFS;
  m.REQ_INODE_NR = inode_nr;
  m.REQ_GRANT = gid;

  /* Send/rec request */
  r= fs_sendrec(fs_e, &m);

  cpf_revoke(gid);

  return r;
}


/*===========================================================================*
 *				req_ftrunc	     			     *
 *===========================================================================*/
PUBLIC int req_ftrunc(fs_e, inode_nr, start, end)
endpoint_t fs_e;
ino_t inode_nr;
off_t start;
off_t end;
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_FTRUNC;
    m.REQ_FD_INODE_NR = inode_nr;
    m.REQ_FD_START = start;
    m.REQ_FD_END = end;

    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_getdents	     			     *
 *===========================================================================*/
PUBLIC int req_getdents(fs_e, inode_nr, pos, gid, size, pos_change)
endpoint_t fs_e;
ino_t inode_nr;
off_t pos;
cp_grant_id_t gid;
size_t size;
off_t *pos_change;
{
	int r;
	message m;

	m.m_type= REQ_GETDENTS;
	m.REQ_GDE_INODE= inode_nr;
	m.REQ_GDE_GRANT= gid;
	m.REQ_GDE_SIZE= size;
	m.REQ_GDE_POS= pos;

	r = fs_sendrec(fs_e, &m);
	*pos_change= m.RES_GDE_POS_CHANGE;
	return r;
}


/*===========================================================================*
 *				req_inhibread	  			     *
 *===========================================================================*/
PUBLIC int req_inhibread(fs_e, inode_nr)
endpoint_t fs_e;
ino_t inode_nr;
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_INHIBREAD;
    m.REQ_INODE_NR = inode_nr;

    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_link	       			     *
 *===========================================================================*/
PUBLIC int req_link(fs_e, link_parent, lastc, linked_file)
endpoint_t fs_e;
ino_t link_parent;
char *lastc;
ino_t linked_file;
{
    int r;
    cp_grant_id_t gid;
    size_t len;
    message m;

    len= strlen(lastc) + 1;
    gid= cpf_grant_direct(fs_e, (vir_bytes)lastc, len, CPF_READ);
    if (gid == -1)
	panic(__FILE__, "req_link: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_LINK_S;
    m.REQ_LINKED_FILE = linked_file;
    m.REQ_LINK_PARENT = link_parent;
    m.REQ_GRANT = gid;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid);

    return r;
}
    

/*===========================================================================*
 *				req_lookup	                   	     *
 *===========================================================================*/
PUBLIC int req_lookup(fs_e, path_off, dir_ino, root_ino, uid, gid, flags, res)
endpoint_t fs_e;
size_t path_off;
ino_t dir_ino;
ino_t root_ino;
uid_t uid;
gid_t gid;
int flags;
lookup_res_t *res;
{
    int r;
    size_t len;
    cp_grant_id_t grant_id;
    message m;

#if 0
    printf("req_lookup_s: fs %d, ino %d, root %d, string (off %d) '%s'\n",
	fs_e, dir_ino, root_ino, path_off, user_fullpath+path_off);
#endif

    grant_id= cpf_grant_direct(fs_e, (vir_bytes)user_fullpath,
	sizeof(user_fullpath), CPF_READ|CPF_WRITE);
    if (grant_id == -1)
	panic(__FILE__, "req_lookup_s: cpf_grant_direct failed", NO_NUM);
    len= strlen(user_fullpath+path_off) + 1;

    /* Fill in request message */
    m.m_type = REQ_LOOKUP_S;
    m.REQ_L_GRANT = grant_id;
    m.REQ_L_PATH_LEN = len;
    m.REQ_L_PATH_SIZE = sizeof(user_fullpath);
    m.REQ_L_PATH_OFF = path_off;
    m.REQ_L_DIR_INO = dir_ino;
    m.REQ_L_ROOT_INO = root_ino;
    m.REQ_L_FLAGS = flags;
    m.REQ_L_UID = uid;
    m.REQ_L_GID = gid;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(grant_id);

    /* Fill in response according to the return value */
    res->fs_e = m.m_source;
    switch (r) {
        case OK:
            res->inode_nr = m.RES_INODE_NR;
            res->fmode = m.RES_MODE;
            res->fsize = m.RES_FILE_SIZE;
            res->dev = m.RES_DEV;
	    res->uid= m.RES_UID;
	    res->gid= m.RES_GID;
            break;
        case EENTERMOUNT:
            res->inode_nr = m.RES_INODE_NR;
            res->char_processed = m.RES_OFFSET;
	    res->symloop = m.RES_SYMLOOP2;
	    break;
        case ELEAVEMOUNT:
            res->char_processed = m.RES_OFFSET;
	    res->symloop = m.RES_SYMLOOP2;
	    break;
        case ESYMLINK:
            res->char_processed = m.RES_OFFSET;
            res->symloop = m.RES_SYMLOOP2;
            break;
	default:
	    break;
    }

    return r;
}


/*===========================================================================*
 *				req_mkdir	      			     *
 *===========================================================================*/
PUBLIC int req_mkdir(fs_e, inode_nr, lastc, uid, gid, dmode)
endpoint_t fs_e;
ino_t inode_nr;
char *lastc;
uid_t uid;
gid_t gid;
mode_t dmode;
{
    int r;
    cp_grant_id_t grant_id;
    size_t len;
    message m;

    len= strlen(lastc) + 1;
    grant_id= cpf_grant_direct(fs_e, (vir_bytes)lastc, len, CPF_READ);
    if (gid == -1)
	panic(__FILE__, "req_mkdir: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_MKDIR_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_MODE = dmode;
    m.REQ_UID = uid;
    m.REQ_GID = gid;
    m.REQ_GRANT = grant_id;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(grant_id);

    return r;
}


/* Structure for REQ_MKNOD request */
typedef struct mknod_req {
        int fs_e;
        ino_t inode_nr;
        uid_t uid;
        gid_t gid;
        mode_t rmode;
        dev_t dev;
        char *lastc;
} mknod_req_t;



/*===========================================================================*
 *				req_newnode	      			     *
 *===========================================================================*/
PUBLIC int req_newnode(fs_e, uid, gid, dmode, dev, res)
endpoint_t fs_e;
uid_t uid;
gid_t gid;
mode_t dmode;
dev_t dev;
struct node_details *res;
{
    int r;
    message m;

    /* Fill in request message */
    m.m_type = REQ_NEWNODE;
    m.REQ_MODE = dmode;
    m.REQ_DEVx = dev;
    m.REQ_UID = uid;
    m.REQ_GID = gid;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    res->fs_e = m.m_source;
    res->inode_nr = m.RES_INODE_NR;
    res->fmode = m.RES_MODE;
    res->fsize = m.RES_FILE_SIZE;
    res->dev = m.RES_DEV;
    res->uid= m.RES_UID;
    res->gid= m.RES_GID;

    return r;
}


/*===========================================================================*
 *				req_mountpoint	                 	     *
 *===========================================================================*/
PUBLIC int req_mountpoint(fs_e, inode_nr)
endpoint_t fs_e;
ino_t inode_nr;
{
    int r;
    message m;

    /* Fill in request message */
    m.m_type = REQ_MOUNTPOINT_S;
    m.REQ_INODE_NR = inode_nr;

    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_mknod	      			     *
 *===========================================================================*/
PUBLIC int req_mknod(fs_e, inode_nr, lastc, uid, gid, dmode, dev)
endpoint_t fs_e;
ino_t inode_nr;
char *lastc;
uid_t uid;
gid_t gid;
mode_t dmode;
dev_t dev;
{
    int r;
    size_t len;
    cp_grant_id_t grant_id;
    message m;

    len= strlen(lastc) + 1;
    grant_id= cpf_grant_direct(fs_e, (vir_bytes)lastc, len, CPF_READ);
    if (gid == -1)
	panic(__FILE__, "req_mknod: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_MKNOD_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_MODE = dmode;
    m.REQ_DEVx = dev;
    m.REQ_UID = uid;
    m.REQ_GID = gid;
    m.REQ_GRANT = grant_id;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(grant_id);

    return r;
}


/*===========================================================================*
 *				req_putnode				     *
 *===========================================================================*/
PUBLIC int req_putnode(fs_e, inode_nr, count)
int fs_e;
ino_t inode_nr;
int count;
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_PUTNODE;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_COUNT = count;

    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_rdlink	     			     *
 *===========================================================================*/
PUBLIC int req_rdlink(fs_e, inode_nr, who_e, buf, len)
endpoint_t fs_e;
ino_t inode_nr;
endpoint_t who_e;
vir_bytes buf;
size_t len;
{
    message m;
    int r;
    cp_grant_id_t gid;

    gid= cpf_grant_magic(fs_e, who_e, buf, len, CPF_WRITE);
    if (gid == -1)
	panic(__FILE__, "req_rdlink: cpf_grant_magic failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_RDLINK_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_GRANT = gid;
    m.REQ_SLENGTH = len;

    /* Send/rec request */
    r= fs_sendrec(fs_e, &m);

    cpf_revoke(gid);

    return r;
}


/*===========================================================================*
 *				req_readsuper	                  	     *
 *===========================================================================*/
PUBLIC int req_readsuper(fs_e, label, dev, readonly, isroot, res_nodep)
endpoint_t fs_e;
char *label;
dev_t dev;
int readonly;
int isroot;
struct node_details *res_nodep;
{
    int r;
    cp_grant_id_t gid;
    size_t len;
    message m;

    len= strlen(label)+1;
    gid= cpf_grant_direct(fs_e, (vir_bytes)label, len, CPF_READ);
    if (gid == -1)
	panic(__FILE__, "req_req_readsuper: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_READSUPER_S;
    m.REQ_READONLY = readonly;
    m.REQ_GRANT2 = gid;
    m.REQ_DEV = dev;
    m.REQ_ISROOT = isroot;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    if ((r = fs_sendrec(fs_e, &m)) != OK) return r;

    /* Fill in response structure */
    res_nodep->fs_e = m.m_source;
    res_nodep->inode_nr = m.RES_INODE_NR;
    res_nodep->fmode = m.RES_MODE;
    res_nodep->fsize = m.RES_FILE_SIZE;
    res_nodep->uid = m.RES_UID;
    res_nodep->gid = m.RES_GID;

    return OK;
}

/* Structure for REQ_READ and REQ_WRITE request */
typedef struct readwrite_req {
	int rw_flag;
	endpoint_t fs_e;
        endpoint_t user_e;
	ino_t inode_nr;
	unsigned short inode_index;
	int seg;
	u64_t pos;
	unsigned int num_of_bytes;
	char *user_addr;
} readwrite_req_t;


/*===========================================================================*
 *				req_readwrite				     *
 *===========================================================================*/
PUBLIC int req_readwrite(fs_e, inode_nr, inode_index, pos, rw_flag, user_e,
	user_addr, num_of_bytes, new_posp, cum_iop)
endpoint_t fs_e;
ino_t inode_nr;
unsigned short inode_index;
u64_t pos;
int rw_flag;
endpoint_t user_e;
char *user_addr;
unsigned int num_of_bytes;
u64_t *new_posp;
unsigned int *cum_iop;
{
    int r;
    cp_grant_id_t gid;
    message m;

    if (ex64hi(pos) != 0)
	panic(__FILE__, "req_readwrite: pos too large", NO_NUM);

    gid= cpf_grant_magic(fs_e, user_e, (vir_bytes)user_addr,
	num_of_bytes, (rw_flag == READING ? CPF_WRITE : CPF_READ));
    if (gid == -1)
	panic(__FILE__, "req_readwrite: cpf_grant_magic failed", NO_NUM);

    /* Fill in request message */
    m.m_type = rw_flag == READING ? REQ_READ_S : REQ_WRITE_S;
    m.REQ_FD_INODE_NR = inode_nr;
    m.REQ_FD_GID = gid;
    m.REQ_FD_POS = ex64lo(pos);
    m.REQ_FD_NBYTES = num_of_bytes;
    m.REQ_FD_INODE_INDEX = inode_index;
    
    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid);

    if (r != OK) return r;

    /* Fill in response structure */
    *new_posp = cvul64(m.RES_FD_POS);
    *cum_iop = m.RES_FD_CUM_IO;

    return OK;
}


/*===========================================================================*
 *				req_rename	     			     *
 *===========================================================================*/
PUBLIC int req_rename(fs_e, old_dir, old_name, new_dir, new_name)
endpoint_t fs_e;
ino_t old_dir;
char *old_name;
ino_t new_dir;
char *new_name;
{
    int r;
    cp_grant_id_t gid_old, gid_new;
    size_t len_old, len_new;
    message m;

    len_old= strlen(old_name) + 1;
    gid_old= cpf_grant_direct(fs_e, (vir_bytes)old_name, len_old,
	CPF_READ);
    if (gid_old == -1)
	panic(__FILE__, "req_rename: cpf_grant_direct failed", NO_NUM);
    len_new= strlen(new_name) + 1;
    gid_new= cpf_grant_direct(fs_e, (vir_bytes)new_name, len_new,
	CPF_READ);
    if (gid_new == -1)
	panic(__FILE__, "req_rename: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_RENAME_S;
    m.REQ_REN_OLD_DIR = old_dir;
    m.REQ_REN_NEW_DIR = new_dir;
    m.REQ_REN_GRANT_OLD = gid_old;
    m.REQ_REN_LEN_OLD = len_old;
    m.REQ_REN_GRANT_NEW = gid_new;
    m.REQ_REN_LEN_NEW = len_new;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid_old);
    cpf_revoke(gid_new);

    return r;
}


/*===========================================================================*
 *				req_rmdir	      			     *
 *===========================================================================*/
PUBLIC int req_rmdir(fs_e, inode_nr, lastc)
endpoint_t fs_e;
ino_t inode_nr;
char *lastc;
{
    int r;
    cp_grant_id_t gid;
    size_t len;
    message m;

    len= strlen(lastc) + 1;
    gid= cpf_grant_direct(fs_e, (vir_bytes)lastc, len, CPF_READ);
    if (gid == -1)
	panic(__FILE__, "req_rmdir: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_RMDIR_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_GRANT = gid;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid);

    return r;
}


/*===========================================================================*
 *				req_slink	      			     *
 *===========================================================================*/
PUBLIC int req_slink(fs_e, inode_nr, lastc, who_e, path_addr, path_length,
	uid, gid)
endpoint_t fs_e;
ino_t inode_nr;
char *lastc;
endpoint_t who_e;
char *path_addr;
unsigned short path_length;
uid_t uid;
gid_t gid;
{
    int r;
    size_t len;
    cp_grant_id_t gid_name, gid_buf;
    message m;

    len= strlen(lastc) + 1;
    gid_name= cpf_grant_direct(fs_e, (vir_bytes)lastc, len,
	CPF_READ);
    if (gid_name == -1)
	panic(__FILE__, "req_slink: cpf_grant_direct failed", NO_NUM);

    gid_buf= cpf_grant_magic(fs_e, who_e, (vir_bytes)path_addr,
	path_length, CPF_READ);
    if (gid_buf == -1)
    {
	cpf_revoke(gid_buf);
	panic(__FILE__, "req_slink: cpf_grant_magic failed", NO_NUM);
    }

    /* Fill in request message */
    m.m_type = REQ_SLINK_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_UID = uid;
    m.REQ_GID = gid;
    m.REQ_GRANT = gid_name;
    m.REQ_PATH_LEN = len;
    m.REQ_GRANT2 = gid_buf;
    m.REQ_SLENGTH = path_length;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid_name);
    cpf_revoke(gid_buf);

    return r;
}


/*===========================================================================*
 *				req_stat	       			     *
 *===========================================================================*/
PUBLIC int req_stat(fs_e, inode_nr, who_e, buf, pos)
int fs_e;
ino_t inode_nr;
int who_e;
char *buf;
int pos;
{
  cp_grant_id_t gid;
  int r;
  message m;
  struct stat sb;

  if (pos != 0)
  {
	gid= cpf_grant_direct(fs_e, (vir_bytes)&sb, sizeof(struct stat),
		CPF_WRITE);
  }
  else
  {
	gid= cpf_grant_magic(fs_e, who_e, (vir_bytes)buf, sizeof(struct stat),
		CPF_WRITE);
  }
  if (gid < 0)
	return gid;

  /* Fill in request message */
  m.m_type = REQ_STAT;
  m.REQ_INODE_NR = inode_nr;
  m.REQ_GRANT = gid;

  /* Send/rec request */
  r= fs_sendrec(fs_e, &m);

  cpf_revoke(gid);

  if (r == OK && pos != 0)
  {
	sb.st_size -= pos;
	r= sys_vircopy(SELF, D, (vir_bytes)&sb, who_e, D, (vir_bytes)buf, 
		sizeof(struct stat));
  }

  return r;
}


/*===========================================================================*
 *				req_sync	       			     *
 *===========================================================================*/
PUBLIC int req_sync(fs_e)
endpoint_t fs_e; 
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_SYNC;
    
    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}

/* Structure for REQ_UNLINK request */
typedef struct unlink_req {
        int fs_e;
        ino_t d_inode_nr;
        uid_t uid;
        gid_t gid;
        char *lastc;
} unlink_req_t;



/*===========================================================================*
 *				req_unlink	     			     *
 *===========================================================================*/
PUBLIC int req_unlink(fs_e, inode_nr, lastc)
endpoint_t fs_e;
ino_t inode_nr;
char *lastc;
{
    cp_grant_id_t gid;
    size_t len;
    int r;
    message m;

    len= strlen(lastc) + 1;
    gid= cpf_grant_direct(fs_e, (vir_bytes)lastc, len, CPF_READ);
    if (gid == -1)
	panic(__FILE__, "req_unlink: cpf_grant_direct failed", NO_NUM);

    /* Fill in request message */
    m.m_type = REQ_UNLINK_S;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_GRANT = gid;
    m.REQ_PATH_LEN = len;

    /* Send/rec request */
    r = fs_sendrec(fs_e, &m);

    cpf_revoke(gid);

    return r;
}


/*===========================================================================*
 *				req_unmount	    			     *
 *===========================================================================*/
PUBLIC int req_unmount(fs_e)
endpoint_t fs_e; 
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_UNMOUNT;
    
    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_utime	      			     *
 *===========================================================================*/
PUBLIC int req_utime(fs_e, inode_nr, actime, modtime)
endpoint_t fs_e;
ino_t inode_nr;
time_t actime;
time_t modtime;
{
    message m;

    /* Fill in request message */
    m.m_type = REQ_UTIME;
    m.REQ_INODE_NR = inode_nr;
    m.REQ_ACTIME = actime;
    m.REQ_MODTIME = modtime;

    /* Send/rec request */
    return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_newdriver          			     *
 *===========================================================================*/
PUBLIC int req_newdriver(fs_e, dev, driver_e)
endpoint_t fs_e;
Dev_t dev;
endpoint_t driver_e;
{
/* Note: this is the only request function that doesn't use the 
 * fs_sendrec internal routine, since we want to avoid the dead
 * driver recovery mechanism here. This function is actually called 
 * during the recovery.
 */
    message m;
    int r;

    /* Fill in request message */
    m.m_type = REQ_NEW_DRIVER;
    m.REQ_DEV = dev;
    m.REQ_DRIVER_E = driver_e;

    /* Issue request */
    if ((r = sendrec(fs_e, &m)) != OK) {
        printf("VFSreq_newdriver: error sending message to %d: %d\n", fs_e, r);
        return r;
    }

    return OK;
}





/*===========================================================================*
 *				fs_sendrec				     *
 *===========================================================================*/
PRIVATE int fs_sendrec_f(char *file, int line, endpoint_t fs_e, message *reqm)
{
/* This is the low level function that sends requests to FS processes.
 * It also handles driver recovery mechanism and reissuing the
 * request which failed due to a dead driver.
 */
  int r, old_driver_e, new_driver_e;
  message origm, m;
  struct vmnt *vmp;

  if (fs_e == PM_PROC_NR)
  {
	printf("from %s, %d\n", file, line);
	panic(__FILE__, "talking to PM", NO_NUM);
  }

  /* Make a copy of the request so that we can load it back in
   * case of a dead driver */
  origm = *reqm;
  
  for (;;) {
      /* Do the actual send, receive */
      if (OK != (r=sendrec(fs_e, reqm))) {
          printf("VFS:fs_sendrec:%s:%d: error sending message. FS_e: %d req_nr: %d err: %d\n", 
                  file, line, fs_e, reqm->m_type, r);
      }

      if(r == OK) {
      	/* Sendrec was okay */
      	break;
      }

      /* Dead driver */
      if (r == EDEADSRCDST || r == EDSTDIED || r == ESRCDIED) {
          old_driver_e = NONE;
          /* Find old driver by endpoint */
          for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
              if (vmp->m_fs_e == fs_e) {   /* found FS */
                  old_driver_e = vmp->m_driver_e;
                  dmap_unmap_by_endpt(old_driver_e); /* unmap driver */
                  break;
              }
          }
         
          /* No FS ?? */
          if (old_driver_e == NONE)
              panic(__FILE__, "VFSdead_driver: couldn't find FS\n", fs_e);

          /* Wait for a new driver. */
          for (;;) {
              new_driver_e = 0;
              printf("VFSdead_driver: waiting for new driver\n");
              r = receive(RS_PROC_NR, &m);
              if (r != OK) {
                  panic(__FILE__, "VFSdead_driver: unable to receive from RS", 
				  r);
              }
              if (m.m_type == DEVCTL) {
                  /* Map new driver */
                  r = fs_devctl(m.ctl_req, m.dev_nr, m.driver_nr,
                          m.dev_style, m.m_force);
                  if (m.ctl_req == DEV_MAP && r == OK) {
                      new_driver_e = m.driver_nr;
                      printf("VFSdead_driver: new driver endpoint: %d\n",
                              new_driver_e);
                  }
              }
              else {
                  panic(__FILE__, "VFSdead_driver: got message from RS, type", 
                          m.m_type);
              }
              m.m_type = r;
              if ((r = send(RS_PROC_NR, &m)) != OK) {
                  panic(__FILE__, "VFSdead_driver: unable to send to RS",
                          r);
              }
              /* New driver is ready */
              if (new_driver_e) break;
          }
          
          /* Copy back original request */
          *reqm = origm;  
          continue;
      }

       printf("fs_sendrec: unhandled error %d sending to %d\n", r, fs_e);
       panic(__FILE__, "fs_sendrec: unhandled error", NO_NUM);
  }

  /* Return message type */
  return reqm->m_type;
}