copyfs.fist

来自「Solaris操作系统下的过滤驱动程序, C源码程序.」· FIST 代码 · 共 72 行

%{
#include "fist.h"
%}
debug off;
filter sca;
filter data;
add_mk copyfs.mk;
%%

%%

int
copyfs_encode_buffers(char *hidden_pages_data, /* A PAGE_SIZE buffer
						  (already allocated)
						  passed to us to fill in
					       */
		      char *page_data, /* The data we are to encode */
		      int *need_to_call,
		      unsigned to, /* how much to encode in page_data */
		      inode_t *inode, /* The inode in question */
		      vfs_t *vfs, /* vfs_t ??? unused */
		      void **opaque)	/* Opaque data */
     /* encodes the data in page_data into hidden_pages_data. Returns
	-errno for error, and the size of hidden_pages_data for success */
{
  print_entry_location();
  memcpy(hidden_pages_data, page_data, to);
  *need_to_call = 0;
  print_exit_status(to);
  return(to);
}


int
copyfs_decode_buffers(int num_hidden_pages, /* The number of pages in
					       hidden_pages_data */
		      char **hidden_pages_data, /* An array of pages
						   containing encoded
						   data */
		      char *page_data, /* A pre-allocated PAGE_SIZE
					  buffer to write the decoded
					  data to */
		      inode_t *inode,  /* The inode of the file in
					  question */
		      vfs_t *vfs,      /* vfs_t, unused */
		      void *opaque)	   /* opaque data filled in by
					      wrapfs_Sca_count_pages,
					      containing an int, the
					      starting offset within the
					      first page of hidden_pages_data
					      of the encoded page we want
					   */
     /* Returns -errno for error, or the number of bytes decoded on success
	(Should usually return PAGE_SIZE bytes) */
{
  int err = 0, tmp = 0;

  if (num_hidden_pages != 1) {
    printk("copyfs: Too many pages! (%d)\n",num_hidden_pages);
    err = -EIO;
    goto out;
  }

  tmp = (int) opaque;
  err = PAGE_CACHE_SIZE - tmp;
  memcpy(page_data,&(hidden_pages_data[0][tmp]), err);

 out:
  print_exit_status(err);
  return(err);
}