minix/servers/mfs/open.c

#include "fs.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include "buf.h"
#include "inode.h"
#include "super.h"

#include <minix/vfsif.h>

PRIVATE char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
FORWARD _PROTOTYPE( struct inode *new_node, (struct inode *ldirp, 
	char *string, mode_t bits, zone_t z0));


/*===========================================================================*
 *				fs_open 				     *
 *===========================================================================*/
PUBLIC int fs_open()
{
  int r, b, exist = TRUE;
  struct inode *ldirp;
  struct inode *rip;
  int oflags;
  mode_t omode;
  mode_t bits;
  char lastc[NAME_MAX];
  
  /* Read request message */
  oflags = fs_m_in.REQ_FLAGS;
  omode = fs_m_in.REQ_MODE;
  
  
  caller_uid = fs_m_in.REQ_UID;
  caller_gid = fs_m_in.REQ_GID;
  
  /* Device number only for device special files */
  fs_m_out.RES_DEV = NO_DEV;
  
  /* Remap the bottom two bits of oflags. */
  bits = (mode_t) mode_map[oflags & O_ACCMODE];
  

  /* If O_CREATE is set, try to make the file. */ 
  if (oflags & O_CREAT) {
	  phys_bytes len;
	  /* Copy the last component */
	  len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
	  err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH, 
		  SELF, (vir_bytes) lastc, (phys_bytes) len);
	  if (err_code != OK) return err_code;
 	  MFS_NUL(lastc, len, sizeof(lastc));

	  /* Get last directory inode */
	  if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by creat() failed\n", SELF_E);
		  return ENOENT;
	  }

	  /* Create a new inode by calling new_node(). */
	  rip = new_node(ldirp, lastc, omode, NO_ZONE);
	  r = err_code;
	  if (r == OK) exist = FALSE;      /* we just created the file */
	  else if (r != EEXIST) {
		  put_inode(ldirp);
		  return(r); /* other error */
	  }
	  else exist = !(oflags & O_EXCL); /* file exists, if the O_EXCL 
					      flag is set this is an error */
  } 
  else {
	  /* Get file inode. */
	  if ( (rip = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode by open() failed\n", SELF_E);
		  return ENOENT;
	  }
	  ldirp = NIL_INODE;
  }

  /* Only do the normal open code if we didn't just create the file. */
  if (exist) {
  	/* Check protections. */
  	if ((r = forbidden(rip, bits)) == OK) {
  		/* Opening reg. files directories and special files differ. */
	  	switch (rip->i_mode & I_TYPE) {
    		   case I_REGULAR: 
			/* Truncate regular file if O_TRUNC. */
			if (oflags & O_TRUNC) {
				panic(__FILE__, "O_TRUNC in mfs.", oflags);
#if 0
				if ((r = forbidden(rip, W_BIT)) !=OK) break;
				truncate_inode(rip, 0);
				wipe_inode(rip);
				/* Send the inode from the inode cache to the
				 * block cache, so it gets written on the next
				 * cache flush.
				 */
				rw_inode(rip, WRITING);
#endif
			}
			break;
 
	    	   case I_DIRECTORY: 
			/* Directories may be read but not written. */
			r = (bits & W_BIT ? EISDIR : OK);
			break;

	     	   case I_CHAR_SPECIAL:
     		   case I_BLOCK_SPECIAL:
                        /* Send back the device number */
			fs_m_out.RES_DEV = (Dev_t) rip->i_zone[0];
			break;
                        
                   case I_NAMED_PIPE:
			rip->i_pipe = I_PIPE;
                        break;
 		}
  	}
  }

  /* If error, release inode. */
  if (r != OK) {
        put_inode(ldirp);
	put_inode(rip);
	return(r);
  }

  /* Reply message */
  fs_m_out.m_source = rip->i_dev;  /* filled with FS endpoint by the system */
  fs_m_out.RES_INODE_NR = rip->i_num;
  fs_m_out.RES_MODE = rip->i_mode;
  fs_m_out.RES_FILE_SIZE = rip->i_size;
  fs_m_out.RES_INODE_INDEX = (rip - &inode[0]) / sizeof(struct inode);

  /* This values are needed for the execution */
  fs_m_out.RES_UID = rip->i_uid;
  fs_m_out.RES_GID = rip->i_gid;
  if ((rip->i_mode & I_TYPE) == I_REGULAR) fs_m_out.RES_CTIME = rip->i_ctime;

  /* Drop parent dir */
  put_inode(ldirp);
  
  return OK;
}

/*===========================================================================*
 *				fs_create 				     *
 *===========================================================================*/
PUBLIC int fs_create()
{
  phys_bytes len;
  int r, b;
  struct inode *ldirp;
  struct inode *rip;
  mode_t omode;
  char lastc[NAME_MAX];
  
  /* Read request message */
  omode = fs_m_in.REQ_MODE;
  
  caller_uid = fs_m_in.REQ_UID;
  caller_gid = fs_m_in.REQ_GID;
  
  /* Try to make the file. */ 

  /* Copy the last component */
  len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
  err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH, 
	SELF, (vir_bytes) lastc, (phys_bytes) len);
  if (err_code != OK) return err_code;
  MFS_NUL(lastc, len, sizeof(lastc));

  /* Get last directory inode */
  if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by creat() failed\n", SELF_E);
	  return ENOENT;
  }

  /* Create a new inode by calling new_node(). */
  rip = new_node(ldirp, lastc, omode, NO_ZONE);
  r = err_code;

  /* If error, release inode. */
  if (r != OK) {
        put_inode(ldirp);
	put_inode(rip);
	return(r);
  }

  /* Reply message */
  fs_m_out.m_source = rip->i_dev;  /* filled with FS endpoint by the system */
  fs_m_out.RES_INODE_NR = rip->i_num;
  fs_m_out.RES_MODE = rip->i_mode;
  fs_m_out.RES_FILE_SIZE = rip->i_size;
  fs_m_out.RES_INODE_INDEX = (rip - &inode[0]) / sizeof(struct inode);

  /* This values are needed for the execution */
  fs_m_out.RES_UID = rip->i_uid;
  fs_m_out.RES_GID = rip->i_gid;
  if ((rip->i_mode & I_TYPE) == I_REGULAR) fs_m_out.RES_CTIME = rip->i_ctime;

  /* Drop parent dir */
  put_inode(ldirp);
  
  return OK;
}

/*===========================================================================*
 *				fs_mknod				     *
 *===========================================================================*/
PUBLIC int fs_mknod()
{
  struct inode *ip, *ldirp;
  char lastc[NAME_MAX];
  phys_bytes len;

  /* Copy the last component and set up caller's user and group id */
  len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
  err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH, SELF, 
            (vir_bytes) lastc, (phys_bytes) len);
  if (err_code != OK) return err_code;
  MFS_NUL(lastc, len, sizeof(lastc));
  
  caller_uid = fs_m_in.REQ_UID;
  caller_gid = fs_m_in.REQ_GID;
  
  /* Get last directory inode */
  if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by mknod() failed\n", SELF_E);
      return ENOENT;
  }
  
  /* Try to create the new node */
  ip = new_node(ldirp, lastc, fs_m_in.REQ_MODE, (zone_t) fs_m_in.REQ_DEV);

  put_inode(ip);
  put_inode(ldirp);
  return(err_code);
}


/*===========================================================================*
 *				fs_mkdir				     *
 *===========================================================================*/
PUBLIC int fs_mkdir()
{
  int r1, r2;			/* status codes */
  ino_t dot, dotdot;		/* inode numbers for . and .. */
  struct inode *rip, *ldirp;
  char lastc[NAME_MAX];         /* last component */
  phys_bytes len;

  /* Copy the last component and set up caller's user and group id */
  len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(lastc));
  err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH, SELF, 
            (vir_bytes) lastc, (phys_bytes) len);
  if (err_code != OK) return err_code;
  MFS_NUL(lastc, len, sizeof(lastc));
  
  caller_uid = fs_m_in.REQ_UID;
  caller_gid = fs_m_in.REQ_GID;
  
  /* Get last directory inode */
  if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by mkdir() failed\n", SELF_E);
      return ENOENT;
  }
  
  /* Next make the inode. If that fails, return error code. */
  rip = new_node(ldirp, lastc, fs_m_in.REQ_MODE, (zone_t) 0);

  if (rip == NIL_INODE || err_code == EEXIST) {
	put_inode(rip);		/* can't make dir: it already exists */
	put_inode(ldirp);
	return(err_code);
  }

  /* Get the inode numbers for . and .. to enter in the directory. */
  dotdot = ldirp->i_num;	/* parent's inode number */
  dot = rip->i_num;		/* inode number of the new dir itself */

  /* Now make dir entries for . and .. unless the disk is completely full. */
  /* Use dot1 and dot2, so the mode of the directory isn't important. */
  rip->i_mode = fs_m_in.REQ_MODE;	/* set mode */
  r1 = search_dir(rip, dot1, &dot, ENTER);	/* enter . in the new dir */
  r2 = search_dir(rip, dot2, &dotdot, ENTER);	/* enter .. in the new dir */

  /* If both . and .. were successfully entered, increment the link counts. */
  if (r1 == OK && r2 == OK) {
	/* Normal case.  It was possible to enter . and .. in the new dir. */
	rip->i_nlinks++;	/* this accounts for . */
	ldirp->i_nlinks++;	/* this accounts for .. */
	ldirp->i_dirt = DIRTY;	/* mark parent's inode as dirty */
  } else {
	/* It was not possible to enter . or .. probably disk was full -
	 * links counts haven't been touched.
	 */
	if(search_dir(ldirp, lastc, (ino_t *) 0, DELETE) != OK)
		panic(__FILE__, "Dir disappeared ", rip->i_num);
	rip->i_nlinks--;	/* undo the increment done in new_node() */
  }
  rip->i_dirt = DIRTY;		/* either way, i_nlinks has changed */

  put_inode(ldirp);		/* return the inode of the parent dir */
  put_inode(rip);		/* return the inode of the newly made dir */
  return(err_code);		/* new_node() always sets 'err_code' */
}

/*===========================================================================*
 *                             fs_slink					     *
 *===========================================================================*/
PUBLIC int fs_slink()
{
  phys_bytes len;
  struct inode *sip;           /* inode containing symbolic link */
  struct inode *ldirp;         /* directory containing link */
  register int r;              /* error code */
  char string[NAME_MAX];       /* last component of the new dir's path name */
  struct buf *bp;              /* disk buffer for link */
    
  caller_uid = fs_m_in.REQ_UID;
  caller_gid = fs_m_in.REQ_GID;
  
  /* Temporarily open the dir. */
  if ( (ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
        return(EINVAL);
  }
  
  /* Copy the link name's last component */
  len = MFS_MIN(fs_m_in.REQ_PATH_LEN, sizeof(string));
  r = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH,
          SELF, (vir_bytes) string, (phys_bytes) len);
  if (r != OK) return r;
  MFS_NUL(string, len, sizeof(string));
  
  /* Create the inode for the symlink. */
  sip = new_node(ldirp, string, (mode_t) (I_SYMBOLIC_LINK | RWX_MODES),
                 (zone_t) 0);

  /* Allocate a disk block for the contents of the symlink.
   * Copy contents of symlink (the name pointed to) into first disk block.
   */
  if ((r = err_code) == OK) {
       r = (bp = new_block(sip, (off_t) 0)) == NIL_BUF ? err_code : 
           sys_vircopy(fs_m_in.REQ_WHO_E, D, (vir_bytes) fs_m_in.REQ_USER_ADDR,
                   SELF, D, (vir_bytes) bp->b_data, 
                   (vir_bytes) fs_m_in.REQ_SLENGTH);

	if(r == OK) {
		bp->b_data[_MIN_BLOCK_SIZE-1] = '\0';
		sip->i_size = strlen(bp->b_data);
		/*if(sip->i_size != m_in.name1_length-1) {*/
		if(sip->i_size != fs_m_in.REQ_SLENGTH) {
			/* This can happen if the user provides a buffer
			 * with a \0 in it. This can cause a lot of trouble
			 * when the symlink is used later. We could just use
			 * the strlen() value, but we want to let the user
			 * know he did something wrong. ENAMETOOLONG doesn't
			 * exactly describe the error, but there is no
			 * ENAMETOOWRONG.
			 */
			r = ENAMETOOLONG;
		}
	}
  
       put_block(bp, DIRECTORY_BLOCK); 	/* put_block() accepts NIL_BUF. */
  
       if (r != OK) {
               sip->i_nlinks = 0;
               if (search_dir(ldirp, string, (ino_t *) 0, DELETE) != OK)
                       panic(__FILE__, "Symbolic link vanished", NO_NUM);
       } 
  }

  /* put_inode() accepts NIL_INODE as a noop, so the below are safe. */
  put_inode(sip);
  put_inode(ldirp);

  return(r);
}



/*===========================================================================*
 *				new_node				     *
 *===========================================================================*/
PRIVATE struct inode *new_node(struct inode *ldirp,
	char *string, mode_t bits, zone_t z0)
{
/* New_node() is called by fs_open(), fs_mknod(), and fs_mkdir().  
 * In all cases it allocates a new inode, makes a directory entry for it in
 * the ldirp directory with string name, and initializes it.  
 * It returns a pointer to the inode if it can do this; 
 * otherwise it returns NIL_INODE.  It always sets 'err_code'
 * to an appropriate value (OK or an error code).
 * 
 * The parsed path rest is returned in 'parsed' if parsed is nonzero. It
 * has to hold at least NAME_MAX bytes.
 */

  register struct inode *rip;
  register int r;

  /* Get final component of the path. */
  rip = advance(&ldirp, string);

  if (S_ISDIR(bits) && 
      (ldirp)->i_nlinks >= ((ldirp)->i_sp->s_version == V1 ?
      CHAR_MAX : SHRT_MAX)) {
        /* New entry is a directory, alas we can't give it a ".." */
        put_inode(rip);
        err_code = EMLINK;
        return(NIL_INODE);
  }

  if ( rip == NIL_INODE && err_code == ENOENT) {
	/* Last path component does not exist.  Make new directory entry. */
	if ( (rip = alloc_inode((ldirp)->i_dev, bits)) == NIL_INODE) {
		/* Can't creat new inode: out of inodes. */
		return(NIL_INODE);
	}

	/* Force inode to the disk before making directory entry to make
	 * the system more robust in the face of a crash: an inode with
	 * no directory entry is much better than the opposite.
	 */
	rip->i_nlinks++;
	rip->i_zone[0] = z0;		/* major/minor device numbers */
	rw_inode(rip, WRITING);		/* force inode to disk now */

	/* New inode acquired.  Try to make directory entry. */
	if ((r = search_dir(ldirp, string, &rip->i_num, ENTER)) != OK) {
		rip->i_nlinks--;	/* pity, have to free disk inode */
		rip->i_dirt = DIRTY;	/* dirty inodes are written out */
		put_inode(rip);	/* this call frees the inode */
		err_code = r;
		return(NIL_INODE);
	}

  } else {
	/* Either last component exists, or there is some problem. */
	if (rip != NIL_INODE || err_code == EENTERMOUNT || 
			err_code == ELEAVEMOUNT)
		r = EEXIST;
	else
		r = err_code;
  }

  /* The caller has to return the directory inode (*ldirp).  */
  err_code = r;
  return(rip);
}






/*===========================================================================*
 *				fs_inhibread				     *
 *===========================================================================*/
PUBLIC int fs_inhibread()
{
  struct inode *rip;
  
  if ((rip = find_inode(fs_dev, fs_m_in.REQ_INODE_NR))== NIL_INODE){
      printf("FSinhibread: couldn't find inode %d\n", fs_m_in.REQ_INODE_NR);
      return EINVAL;
  }

  /* inhibit read ahead */
  rip->i_seek = ISEEK;	
  
  return OK;
}