fs/ext2/dir.c

/* */
This source file includes following definitions.
ext2_dir_read
ext2_check_dir_entry
ext2_readdir
   1 /*
   2  *  linux/fs/ext2/dir.c
   3  *
   4  *  Copyright (C) 1992, 1993  Remy Card (card@masi.ibp.fr)
   5  *
   6  *  from
   7  *
   8  *  linux/fs/minix/dir.c
   9  *
  10  *  Copyright (C) 1991, 1992  Linus Torvalds
  11  *
  12  *  ext2 directory handling functions
  13  */
  14 
  15 #include <asm/segment.h>
  16 
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/ext2_fs.h>
  20 #include <linux/stat.h>
  21 #include <linux/sched.h>
  22 
  23 #if 0
  24 static int ext2_dir_read (struct inode * inode, struct file * filp,
     /*  */
  25                             char * buf, int count)
  26 {
  27         return -EISDIR;
  28 }
  29 #endif
  30 
  31 /* static */ int ext2_file_read (struct inode *, struct file *, char *, int);
  32 static int ext2_readdir (struct inode *, struct file *, struct dirent *, int);
  33 
  34 static struct file_operations ext2_dir_operations = {
  35         NULL,                   /* lseek - default */
  36         ext2_file_read,         /* read */
  37         NULL,                   /* write - bad */
  38         ext2_readdir,           /* readdir */
  39         NULL,                   /* select - default */
  40         ext2_ioctl,             /* ioctl */
  41         NULL,                   /* mmap */
  42         NULL,                   /* no special open code */
  43         NULL,                   /* no special release code */
  44         NULL                    /* fsync */
  45 };
  46 
  47 /*
  48  * directories can handle most operations...
  49  */
  50 struct inode_operations ext2_dir_inode_operations = {
  51         &ext2_dir_operations,   /* default directory file-ops */
  52         ext2_create,            /* create */
  53         ext2_lookup,            /* lookup */
  54         ext2_link,              /* link */
  55         ext2_unlink,            /* unlink */
  56         ext2_symlink,           /* symlink */
  57         ext2_mkdir,             /* mkdir */
  58         ext2_rmdir,             /* rmdir */
  59         ext2_mknod,             /* mknod */
  60         ext2_rename,            /* rename */
  61         NULL,                   /* readlink */
  62         NULL,                   /* follow_link */
  63         NULL,                   /* bmap */
  64         ext2_truncate,          /* truncate */
  65         ext2_permission         /* permission */
  66 };
  67 
  68 int ext2_check_dir_entry (char * function, struct inode * dir,
     /*  */
  69                           struct ext2_dir_entry * de, struct buffer_head * bh,
  70                           unsigned int offset)
  71 {
  72         char * error_msg = NULL;
  73 
  74         if (de->rec_len < EXT2_DIR_REC_LEN(1))
  75                 error_msg = "rec_len is smaller than minimal";
  76         else if (de->rec_len % 4 != 0)
  77                 error_msg = "rec_len % 4 != 0";
  78         else if (de->rec_len < EXT2_DIR_REC_LEN(de->name_len))
  79                 error_msg = "rec_len is too small for name_len";
  80         else if (((char *) de - bh->b_data) + de->rec_len >
  81                  dir->i_sb->s_blocksize)
  82                 error_msg = "directory entry accross blocks";
  83 
  84         if (error_msg != NULL) {
  85                 printk ("%s: bad directory entry (dev %04x, dir %d): %s\n",
  86                         function, dir->i_dev, dir->i_ino, error_msg);
  87                 printk ("offset=%d, inode=%d, rec_len=%d, name_len=%d\n",
  88                         offset, de->inode, de->rec_len, de->name_len);
  89         }
  90         return error_msg == NULL ? 1 : 0;
  91 }
  92 
  93 static int ext2_readdir (struct inode * inode, struct file * filp,
     /*  */
  94                          struct dirent * dirent, int count)
  95 {
  96         unsigned int offset, i, err;
  97         struct buffer_head * bh;
  98         struct ext2_dir_entry * de;
  99         struct super_block * sb;
 100         
 101         if (!inode || !S_ISDIR(inode->i_mode))
 102                 return -EBADF;
 103         sb = inode->i_sb;
 104         while (filp->f_pos < inode->i_size) {
 105                 offset = filp->f_pos & (sb->s_blocksize - 1);
 106                 bh = ext2_bread (inode, (filp->f_pos) >> EXT2_BLOCK_SIZE_BITS(sb), 0, &err);
 107                 if (!bh) {
 108                         filp->f_pos += sb->s_blocksize - offset;
 109                         continue;
 110                 }
 111                 de = (struct ext2_dir_entry *) (offset + bh->b_data);
 112                 while (offset < sb->s_blocksize && filp->f_pos < inode->i_size) {
 113                         if (! ext2_check_dir_entry ("ext2_readdir", inode, de,
 114                                                     bh, offset)) {
 115                                 brelse (bh);
 116                                 return 0;
 117                         }
 118                         offset += de->rec_len;
 119                         filp->f_pos += de->rec_len;
 120                         if (de->inode) {
 121                                 memcpy_tofs (dirent->d_name, de->name,
 122                                              de->name_len);
 123                                 put_fs_long (de->inode, &dirent->d_ino);
 124                                 put_fs_byte (0, de->name_len + dirent->d_name);
 125                                 put_fs_word (de->name_len, &dirent->d_reclen);
 126 #ifndef DONT_USE_DCACHE
 127                                 ext2_dcache_add (inode->i_dev, inode->i_ino,
 128                                                  de->name, de->name_len,
 129                                                  de->inode);
 130 #endif
 131                                 i = de->name_len;
 132                                 brelse (bh);
 133                                 return i;
 134                         }
 135                         de = (struct ext2_dir_entry *) ((char *) de +
 136                                                         de->rec_len);
 137                 }
 138                 brelse (bh);
 139         }
 140         return 0;
 141 }
/* */
root/fs/ext2/dir.c

DEFINITIONS
