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2 pj 1
 
1063 tullio 2
/*
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 *
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 */
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2 pj 19
#include <fs/types.h>
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#include <fs/errno.h>
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#include <fs/task.h>
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#include <fs/maccess.h>
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#include <fs/stat.h>
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#include <fs/fcntl.h>
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#include <fs/mount.h>
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#include "fsconst.h"
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#include "file.h"
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#include "dentry.h"
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#include "inode.h"
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#include "fileop.h"
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#include "inodeop.h"
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#include "super.h"
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#include "fs.h"
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#include "debug.h"
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/*
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  Example of how the code is expanded in system with/without
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  memory protection.
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  If DUMMY_MACCESS is defined:
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  char *pathname;
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  int len;
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  len=1;
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  if ((!len)||len>MAXSIZE) return -EVERIFY;
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  pathname=userpathname;
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  ...
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  if DUMMY_MACCESS is NOT defined:
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  char pathname[MAXSIZE];
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  int len;
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  len=verifyreadnolen(userpathanme);
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  if ((!len)||len>MAXSIZE) return -EVERIFY;
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  memcpyfromuser(pathname,userpathname);
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  ...
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*/
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/* PS: open() e opendir() potrebbero condividere codice! */
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int k_open(char *upathname, int oflag, int mode)
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{
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  declare_buffer(char,pathname,MAXPATHNAME);
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  int len;
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  struct file   *f;
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  struct dentry *d;
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  int           ret,res,createflag;
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  __pid_t       pid;
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  call_to_fs();
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  printk0("k_open: START");
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  pid=__get_pid();
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  len=__verify_read_nolen((char*)upathname);
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  if ((!len)||(len>MAXPATHNAMELEN)) return_from_fs(-EVERIFY);
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  __copy_from_user(pathname,upathname,len+1);
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  printk0("k_open: verifing memory... done");
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  /* flags not supported */
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  /* O_NOCTTY is ignored */
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  if (oflag&O_DSYNC||
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      oflag&O_NOCTTY||
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      oflag&O_NONBLOCK||
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      oflag&O_RSYNC||
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      oflag&O_SYNC) {
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    return_from_fs(-EACCES);
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  }
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98
  /* O_TRUNC wiht O_RDONLY not permitted! */
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  if ((oflag&O_RDONLY)&&(oflag&O_TRUNC)) return_from_fs(-EACCES);
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101
  printk0("k_open: checking flags... done");
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  if (oflag&O_CREAT) {
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    if (oflag&O_EXCL) createflag=DENTRY_MUSTCREATE;
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    else createflag=DENTRY_CANCREATE;
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  } else createflag=DENTRY_NOCREATE;
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  d=find_dentry_from_ext(cwden_ptr(pid),(char *)pathname,&createflag);
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  if (d==NULL) {
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    printk0("k_open: can't find/create directory entry");
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    if (createflag&DENTRY_EXIST) return_from_fs(-EEXIST);
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    return_from_fs(-ENOENT);
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  }
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  if (__S_ISDIR(d->d_inode->i_st.st_mode)) {
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    if (oflag&O_WRONLY||oflag&O_RDWR)
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      /* can't write on a directory */
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      return_from_fs(-EISDIR);
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  }
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  /* check for read-only filesystem */
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  if (!(d->d_sb->sb_mopts.flags&MOUNT_FLAG_RW)) {
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    if (oflag&O_WRONLY||oflag&O_RDWR||oflag&O_TRUNC) {
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      /* NB: O_CREAT va testata prima della find_dentry() */
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      unlock_dentry(d);      
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      return_from_fs(-EROFS);
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    }
129
  }
130
 
131
  printk0("k_open: find dir entry... done");
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  f=get_file(d->d_inode);
134
  if (f==NULL) {
135
    unlock_dentry(d);
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    return_from_fs(-ENFILE);
137
  }
138
 
139
  printk0("k_open: getting system file entry... done");
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141
  if (createflag&DENTRY_CREATED)
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    d->d_inode->i_st.st_mode=(mode&__ALLPERMS)|__S_IFREG;
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144
  f->f_dentry=d;
145
  f->f_op=d->d_inode->i_op->default_file_ops;
146
  f->f_pos=0;
147
  f->f_flag_isdir=__S_ISDIR(d->d_inode->i_st.st_mode);
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149
  ret=get_fd(pid,f);
150
  if (ret==-1) {
151
    free_file(f);
152
    unlock_dentry(d);
153
    return_from_fs(-EMFILE);
154
  }
155
  *fildesfflags_ptr(pid,ret)=oflag;
156
 
157
  printk0("k_open: getting file descriptor... done");
158
 
159
  if (oflag&O_TRUNC&&!(createflag&DENTRY_CREATED)) {
160
    struct inode *in=file_ptr(pid,ret)->f_dentry->d_inode;
161
    /* acquire write lock on inode's file */
162
    __rwlock_wrlock(&in->i_lock);
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    /* truncate the file */
164
    in->i_op->truncate(in,0);      
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    /* release write lock on inode's file */
166
    __rwlock_wrunlock(&in->i_lock);
167
    printk0("k_open: file truncation... done");
168
  }
169
 
170
  res=f->f_op->open(f->f_dentry->d_inode,f);
171
  if (res!=0) {
172
    free_fd(pid,ret);
173
    free_file(f);
174
    unlock_dentry(d);
175
    return_from_fs(res);
176
  }
177
 
178
  printk0("k_open: called proper filesystem open... done");
179
 
180
  printk0("k_open: END");
181
  return_from_fs(ret);
182
}
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