minix/fs/pfs/link.c

   1 #include "fs.h"
   2 #include "buf.h"
   3 #include "inode.h"
   4 #include <minix/vfsif.h>
   5
   6 /*===========================================================================*
   7  *                              fs_ftrunc                                    *
   8  *===========================================================================*/
   9 int fs_ftrunc(message *fs_m_in, message *fs_m_out)
  10 {
  11   struct inode *rip;
  12   off_t start;
  13   ino_t inumb;
  14
  15   inumb = fs_m_in->m_vfs_fs_ftrunc.inode;
  16
  17   if( (rip = find_inode(inumb)) == NULL) return(EINVAL);
  18
  19   start = fs_m_in->m_vfs_fs_ftrunc.trc_start;
  20
  21   return truncate_inode(rip, start);
  22 }
  23
  24
  25 /*===========================================================================*
  26  *                              truncate_inode                               *
  27  *===========================================================================*/
  28 int truncate_inode(rip, newsize)
  29 register struct inode *rip;     /* pointer to inode to be truncated */
  30 off_t newsize;                  /* inode must become this size */
  31 {
  32 /* Set inode to a certain size, freeing any zones no longer referenced
  33  * and updating the size in the inode. If the inode is extended, the
  34  * extra space is a hole that reads as zeroes.
  35  *
  36  * Nothing special has to happen to file pointers if inode is opened in
  37  * O_APPEND mode, as this is different per fd and is checked when
  38  * writing is done.
  39  */
  40
  41   /* Pipes can shrink, so adjust size to make sure all zones are removed. */
  42   if(newsize != 0) return(EINVAL);      /* Only truncate pipes to 0. */
  43   rip->i_size = newsize;
  44
  45   /* Next correct the inode size. */
  46   wipe_inode(rip);      /* Pipes can only be truncated to 0. */
  47
  48   return(OK);
  49 }