servers/pfs/link.c

   1 #include "fs.h"
   2 #include <sys/stat.h>
   3 #include <string.h>
   4 #include <minix/com.h>
   5 #include <minix/callnr.h>
   6 #include "buf.h"
   7 #include "inode.h"
   8 #include <minix/vfsif.h>
   9
  10 /*===========================================================================*
  11  *                              fs_ftrunc                                    *
  12  *===========================================================================*/
  13 PUBLIC int fs_ftrunc(void)
  14 {
  15   struct inode *rip;
  16   off_t start, end;
  17   int r;
  18   ino_t inumb;
  19
  20   inumb = fs_m_in.REQ_INODE_NR;
  21
  22   if( (rip = find_inode(inumb)) == NIL_INODE) return(EINVAL);
  23
  24   start = fs_m_in.REQ_TRC_START_LO;
  25   end = fs_m_in.REQ_TRC_END_LO;
  26
  27   return truncate_inode(rip, start);
  28 }
  29
  30
  31 /*===========================================================================*
  32  *                              truncate_inode                               *
  33  *===========================================================================*/
  34 PUBLIC int truncate_inode(rip, newsize)
  35 register struct inode *rip;     /* pointer to inode to be truncated */
  36 off_t newsize;                  /* inode must become this size */
  37 {
  38 /* Set inode to a certain size, freeing any zones no longer referenced
  39  * and updating the size in the inode. If the inode is extended, the
  40  * extra space is a hole that reads as zeroes.
  41  *
  42  * Nothing special has to happen to file pointers if inode is opened in
  43  * O_APPEND mode, as this is different per fd and is checked when
  44  * writing is done.
  45  */
  46   int scale;
  47
  48   /* Pipes can shrink, so adjust size to make sure all zones are removed. */
  49   if(newsize != 0) return(EINVAL);      /* Only truncate pipes to 0. */
  50   rip->i_size = newsize;
  51
  52   /* Next correct the inode size. */
  53   wipe_inode(rip);      /* Pipes can only be truncated to 0. */
  54
  55   return(OK);
  56 }
  57