minix/servers/vfs/request.c

/* 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.
 */

#include "fs.h"
#include <string.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/statvfs.h>
#include <minix/vfsif.h>
#include <minix/com.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(
  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 grant_id;
  message m;

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

  /* Fill in request message */
  m.m_type = rw_flag == READING ? REQ_BREAD : REQ_BWRITE;
  m.REQ_DEV2 = dev;
  m.REQ_GRANT = grant_id;
  m.REQ_SEEK_POS_LO = ex64lo(pos);
  m.REQ_SEEK_POS_HI = ex64hi(pos);
  m.REQ_NBYTES = num_of_bytes;

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

  /* Fill in response structure */
  *new_posp = make64(m.RES_SEEK_POS_LO, m.RES_SEEK_POS_HI);
  *cum_iop = m.RES_NBYTES;

  return(OK);
}


/*===========================================================================*
 *				req_chmod	      			     *
 *===========================================================================*/
PUBLIC int req_chmod(
  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;

  /* Send/rec request */
  r = fs_sendrec(fs_e, &m);
  
  /* Copy back actual mode. */
  *new_modep = m.RES_MODE;

  return(r);
}


/*===========================================================================*
 *				req_chown          			     *
 *===========================================================================*/
PUBLIC int req_chown(
  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 = newuid;
  m.REQ_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				     *
 *===========================================================================*/
PUBLIC int req_create(
  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;

  if (path[0] == '/')
  	panic("req_create: filename starts with '/'");

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

  /* Fill in request message */
  m.m_type	= REQ_CREATE;
  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_LO;
  res->uid	= m.RES_UID;
  res->gid	= m.RES_GID;
  res->dev	= m.RES_DEV;
  
  return(OK);
}


/*===========================================================================*
 *				req_flush	      			     *
 *===========================================================================*/
PUBLIC int req_flush(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(int fs_e, int who_e, char *buf)
{
  int r;
  cp_grant_id_t grant_id;
  message m;

  grant_id = cpf_grant_magic(fs_e, who_e, (vir_bytes) buf, sizeof(struct statfs),
			CPF_WRITE);
  if(grant_id == -1) 
	  panic("req_fstatfs: cpf_grant_magic failed");

  /* Fill in request message */
  m.m_type = REQ_FSTATFS;
  m.REQ_GRANT = grant_id;

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

  return(r);
}


/*===========================================================================*
 *				req_statvfs	    			     *
 *===========================================================================*/
PUBLIC int req_statvfs(int fs_e, int who_e, char *buf)
{
  int r;
  cp_grant_id_t grant_id;
  message m;

  grant_id = cpf_grant_magic(fs_e, who_e, (vir_bytes) buf, sizeof(struct statvfs),
			CPF_WRITE);
  if(grant_id == -1) 
	  panic("req_statvfs: cpf_grant_magic failed");

  /* Fill in request message */
  m.m_type = REQ_STATVFS;
  m.REQ_GRANT = grant_id;

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

  return(r);
}


/*===========================================================================*
 *				req_ftrunc	     			     *
 *===========================================================================*/
PUBLIC int req_ftrunc(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_INODE_NR = inode_nr;
  m.REQ_TRC_START_LO = start;
  m.REQ_TRC_START_HI = 0;	/* Not used for now, so clear it. */
  m.REQ_TRC_END_LO = end;
  m.REQ_TRC_END_HI = 0;		/* Not used for now, so clear it. */
  
  /* Send/rec request */
  return fs_sendrec(fs_e, &m);
}


/*===========================================================================*
 *				req_getdents	     			     *
 *===========================================================================*/
PUBLIC int req_getdents(
  endpoint_t fs_e,
  ino_t inode_nr,
  u64_t pos,
  char *buf,
  size_t size,
  u64_t *new_pos
)
{
  int r;
  message m;
  cp_grant_id_t grant_id;
  
  grant_id = cpf_grant_magic(fs_e, who_e, (vir_bytes) buf, size, CPF_WRITE);
  if (grant_id < 0)
  	panic("req_getdents: cpf_grant_magic failed: %d", grant_id);

  m.m_type = REQ_GETDENTS;
  m.REQ_INODE_NR = inode_nr;
  m.REQ_GRANT = grant_id;
  m.REQ_MEM_SIZE = size;
  m.REQ_SEEK_POS_LO = ex64lo(pos);
  m.REQ_SEEK_POS_HI = 0;	/* Not used for now, so clear it. */
  
  r = fs_sendrec(fs_e, &m);
  cpf_revoke(grant_id);
  
  if (r == OK) {
	  *new_pos = cvul64(m.RES_SEEK_POS_LO);
	  r = m.RES_NBYTES;
  }

  return(r);
}


/*===========================================================================*
 *				req_inhibread	  			     *
 *===========================================================================*/
PUBLIC int req_inhibread(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(
  endpoint_t fs_e,
  ino_t link_parent,
  char *lastc,
  ino_t linked_file
)
{
  int r;
  cp_grant_id_t grant_id;
  const size_t len = strlen(lastc) + 1;
  message m;

  grant_id = cpf_grant_direct(fs_e, (vir_bytes)lastc, len, CPF_READ);
  if(grant_id == -1)
	  panic("req_link: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_LINK;
  m.REQ_INODE_NR = linked_file;
  m.REQ_DIR_INO = link_parent;
  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_lookup	                   	     *
 *===========================================================================*/
PUBLIC int req_lookup(
  endpoint_t fs_e,
  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, grant_id2;
  message m;
  vfs_ucred_t credentials;

  grant_id = cpf_grant_direct(fs_e, (vir_bytes) user_fullpath,
			      sizeof(user_fullpath), CPF_READ | CPF_WRITE);
  if(grant_id == -1)
	  panic("req_lookup: cpf_grant_direct failed");

  len = strlen(user_fullpath) + 1;

  m.m_type		= REQ_LOOKUP;
  m.REQ_GRANT		= grant_id;
  m.REQ_PATH_LEN 	= len;
  m.REQ_PATH_SIZE 	= sizeof(user_fullpath);
  m.REQ_DIR_INO 	= dir_ino;
  m.REQ_ROOT_INO 	= root_ino;

  if(fp->fp_ngroups > 0) { /* Is the process member of multiple groups? */
  	/* In that case the FS has to copy the uid/gid credentials */
  	int i;

  	/* Set credentials */
  	credentials.vu_uid = fp->fp_effuid;
  	credentials.vu_gid = fp->fp_effgid;
  	credentials.vu_ngroups = fp->fp_ngroups;
  	for (i = 0; i < fp->fp_ngroups; i++) 
  		credentials.vu_sgroups[i] = fp->fp_sgroups[i];

	grant_id2 = cpf_grant_direct(fs_e, (vir_bytes) &credentials,
				     sizeof(credentials), CPF_READ);
	if(grant_id2 == -1)
		panic("req_lookup: cpf_grant_direct failed");

	m.REQ_GRANT2	= grant_id2;
	m.REQ_UCRED_SIZE= sizeof(credentials);
  	flags		|= PATH_GET_UCRED;
  } else {
  	/* When there's only one gid, we can send it directly */
	m.REQ_UID	= uid;
	m.REQ_GID	= gid;
	flags		&= ~PATH_GET_UCRED;
  }

  m.REQ_FLAGS		= flags;

  /* Send/rec request */
  r = fs_sendrec(fs_e, &m);
  cpf_revoke(grant_id);
  if(fp->fp_ngroups > 0) cpf_revoke(grant_id2); 

  /* 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_LO;
	  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_SYMLOOP;
	  break;
  case ELEAVEMOUNT:
	  res->char_processed = m.RES_OFFSET;
	  res->symloop = m.RES_SYMLOOP;
	  break;
  case ESYMLINK:
	  res->char_processed = m.RES_OFFSET;
	  res->symloop = m.RES_SYMLOOP;
	  break;
  default:
	  break;
  }
  
  return(r);
}


/*===========================================================================*
 *				req_mkdir	      			     *
 *===========================================================================*/
PUBLIC int req_mkdir(
  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(grant_id == -1)
	  panic("req_mkdir: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_MKDIR;
  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);
}


/*===========================================================================*
 *				req_mknod	      			     *
 *===========================================================================*/
PUBLIC int req_mknod(
  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(grant_id == -1)
	  panic("req_mknod: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_MKNOD;
  m.REQ_INODE_NR = inode_nr;
  m.REQ_MODE = dmode;
  m.REQ_DEV = 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_mountpoint	                 	     *
 *===========================================================================*/
PUBLIC int req_mountpoint(endpoint_t fs_e, ino_t inode_nr)
{
  message m;

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

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


/*===========================================================================*
 *				req_newnode	      			     *
 *===========================================================================*/
PUBLIC int req_newnode(
  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_DEV = 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_LO;
  res->dev	= m.RES_DEV;
  res->uid	= m.RES_UID;
  res->gid	= m.RES_GID;

  return(r);
}


/*===========================================================================*
 *				req_newdriver          			     *
 *===========================================================================*/
PUBLIC int req_newdriver(
  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("%s:%d VFS req_newdriver: error sending message %d to %d\n",
		 __FILE__, __LINE__, r, fs_e);
	  util_stacktrace();
	  return(r);
  }

  return(OK);
}



/*===========================================================================*
 *				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;
char *buf;
size_t len;
{
  message m;
  int r;
  cp_grant_id_t grant_id;

  grant_id = cpf_grant_magic(fs_e, who_e, (vir_bytes) buf, len, CPF_WRITE);
  if(grant_id == -1)
	  panic("req_rdlink: cpf_grant_magic failed");

  /* Fill in request message */
  m.m_type = REQ_RDLINK;
  m.REQ_INODE_NR = inode_nr;
  m.REQ_GRANT = grant_id;
  m.REQ_MEM_SIZE = len;
  
  /* Send/rec request */
  r = fs_sendrec(fs_e, &m);
  cpf_revoke(grant_id);

  if(r == OK) r = m.RES_NBYTES;

  return(r);
}


/*===========================================================================*
 *				req_readsuper	                  	     *
 *===========================================================================*/
PUBLIC int req_readsuper(
  endpoint_t fs_e,
  char *label,
  dev_t dev,
  int readonly,
  int isroot,
  struct node_details *res_nodep
)
{
  int r;
  cp_grant_id_t grant_id;
  size_t len;
  message m;
  
  len = strlen(label)+1;
  grant_id = cpf_grant_direct(fs_e, (vir_bytes) label, len, CPF_READ);
  if (grant_id == -1)
	  panic("req_readsuper: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_READSUPER;
  m.REQ_FLAGS = 0;
  if(readonly) m.REQ_FLAGS |= REQ_RDONLY;
  if(isroot)   m.REQ_FLAGS |= REQ_ISROOT;   
  m.REQ_GRANT = grant_id;
  m.REQ_DEV = dev;
  m.REQ_PATH_LEN = len;
  
  /* Send/rec request */
  r = fs_sendrec(fs_e, &m);
  cpf_revoke(grant_id);

  if(r == OK) {
	/* 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_LO;
	res_nodep->uid = m.RES_UID;
	res_nodep->gid = m.RES_GID;
  }

  return(r);
}


/*===========================================================================*
 *				req_readwrite				     *
 *===========================================================================*/
PUBLIC int req_readwrite(fs_e, inode_nr, pos, rw_flag, user_e,
	user_addr, num_of_bytes, new_posp, cum_iop)
endpoint_t fs_e;
ino_t inode_nr;
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 grant_id;
  message m;

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

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

  /* Fill in request message */
  m.m_type = rw_flag == READING ? REQ_READ : REQ_WRITE;
  m.REQ_INODE_NR = inode_nr;
  m.REQ_GRANT = grant_id;
  m.REQ_SEEK_POS_LO = ex64lo(pos);
  m.REQ_SEEK_POS_HI = 0;	/* Not used for now, so clear it. */
  m.REQ_NBYTES = num_of_bytes;
  
  /* Send/rec request */
  r = fs_sendrec(fs_e, &m);
  cpf_revoke(grant_id);

  if (r == OK) {
	/* Fill in response structure */
	*new_posp = cvul64(m.RES_SEEK_POS_LO);
	*cum_iop = m.RES_NBYTES;
  }
  
  return(r);
}


/*===========================================================================*
 *				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("req_rename: cpf_grant_direct failed");

  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("req_rename: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_RENAME;
  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 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(grant_id == -1)
	  panic("req_rmdir: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_RMDIR;
  m.REQ_INODE_NR = inode_nr;
  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_slink	      			     *
 *===========================================================================*/
PUBLIC int req_slink(
  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("req_slink: cpf_grant_direct failed");

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

  /* Fill in request message */
  m.m_type = REQ_SLINK;
  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_GRANT3 = gid_buf;
  m.REQ_MEM_SIZE = 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 grant_id;
  int r;
  message m;
  struct stat sb;

  if (pos != 0)
	  grant_id = cpf_grant_direct(fs_e, (vir_bytes) &sb,
	  			      sizeof(struct stat), CPF_WRITE);
  else
	  grant_id = cpf_grant_magic(fs_e, who_e, (vir_bytes) buf,
				sizeof(struct stat), CPF_WRITE);

  if (grant_id < 0)
	panic("req_stat: cpf_grant_* failed");

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

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

  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);
}


/*===========================================================================*
 *				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 grant_id;
  size_t len;
  int r;
  message m;
  
  len = strlen(lastc) + 1;
  grant_id = cpf_grant_direct(fs_e, (vir_bytes) lastc, len, CPF_READ);
  if(grant_id == -1)
	  panic("req_unlink: cpf_grant_direct failed");

  /* Fill in request message */
  m.m_type = REQ_UNLINK;
  m.REQ_INODE_NR = inode_nr;
  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_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);
}


/*===========================================================================*
 *				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;
  message origm, m;

  if(fs_e <= 0 || fs_e == NONE)
	panic("talking to bogus endpoint: %d", fs_e);

  /* Make a copy of the request so that we can load it back in
   * case of a dead driver */
  origm = *reqm;

  /* In response to the request we sent, some file systems may send back their
   * own VFS request, instead of a reply. VFS currently offers limited support
   * for this. As long as the FS keeps sending requests, we process them and
   * send back a reply. We break out of the loop as soon as the FS sends a
   * reply to the original request.
   *
   * There is no form of locking or whatever on global data structures, so it
   * is quite easy to mess things up; hence, 'limited' support. A future async
   * VFS will solve this problem for good.
   */
  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);
		util_stacktrace();
		return(r);
	}

	/* If the type field is 0 (OK) or negative (E*), this is a reply. If it
	 * contains a positive nonzero value, this is a request.
	 */
	if (reqm->m_type <= 0)
		break; /* Reply */

	if (reqm->m_type == -EENTERMOUNT || reqm->m_type == -ELEAVEMOUNT ||
	    reqm->m_type == -ESYMLINK) {

		reqm->m_type = -reqm->m_type;
		break; /* Reply */
	}

	/* Request */
	nested_fs_call(reqm);
  }

#if 0
      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 */
#if 0
                  old_driver_e = vmp->m_driver_e;
#endif
                  dmap_unmap_by_endpt(old_driver_e); /* unmap driver */
                  break;
              }
          }
         
          /* No FS ?? */
          if (old_driver_e == NONE)
              panic("VFSdead_driver: couldn't find FS: %d", fs_e);

          /* Wait for a new driver. */
          for (;;) {
              new_driver_e = 0;
              printf("VFSdead_driver: waiting for new driver\n");
              r = sef_receive(RS_PROC_NR, &m);
              if (r != OK) {
			panic("VFSdead_driver: unable to receive from RS: %d",  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("VFSdead_driver: got message from RS type: %d", m.m_type);
              }
              m.m_type = r;
              if ((r = send(RS_PROC_NR, &m)) != OK) {
			panic("VFSdead_driver: unable to send to RS: %d", 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("fs_sendrec: unhandled error");
  }
#endif

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