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, 1994  Remy Card (card@masi.ibp.fr)
   5  *                                  Laboratoire MASI - Institut Blaise Pascal
   6  *                                  Universite Pierre et Marie Curie (Paris VI)
   7  *
   8  *  from
   9  *
  10  *  linux/fs/minix/dir.c
  11  *
  12  *  Copyright (C) 1991, 1992  Linus Torvalds
  13  *
  14  *  ext2 directory handling functions
  15  */
  16 
  17 #include <asm/segment.h>
  18 
  19 #include <linux/errno.h>
  20 #include <linux/fs.h>
  21 #include <linux/ext2_fs.h>
  22 #include <linux/sched.h>
  23 #include <linux/stat.h>
  24 
  25 static int ext2_dir_read (struct inode * inode, struct file * filp,
     /*  */
  26                             char * buf, int count)
  27 {
  28         return -EISDIR;
  29 }
  30 
  31 static int ext2_readdir (struct inode *, struct file *, struct dirent *, int);
  32 
  33 static struct file_operations ext2_dir_operations = {
  34         NULL,                   /* lseek - default */
  35         ext2_dir_read,          /* read */
  36         NULL,                   /* write - bad */
  37         ext2_readdir,           /* readdir */
  38         NULL,                   /* select - default */
  39         ext2_ioctl,             /* ioctl */
  40         NULL,                   /* mmap */
  41         NULL,                   /* no special open code */
  42         NULL,                   /* no special release code */
  43         file_fsync,             /* fsync */
  44         NULL,                   /* fasync */
  45         NULL,                   /* check_media_change */
  46         NULL                    /* revalidate */
  47 };
  48 
  49 /*
  50  * directories can handle most operations...
  51  */
  52 struct inode_operations ext2_dir_inode_operations = {
  53         &ext2_dir_operations,   /* default directory file-ops */
  54         ext2_create,            /* create */
  55         ext2_lookup,            /* lookup */
  56         ext2_link,              /* link */
  57         ext2_unlink,            /* unlink */
  58         ext2_symlink,           /* symlink */
  59         ext2_mkdir,             /* mkdir */
  60         ext2_rmdir,             /* rmdir */
  61         ext2_mknod,             /* mknod */
  62         ext2_rename,            /* rename */
  63         NULL,                   /* readlink */
  64         NULL,                   /* follow_link */
  65         NULL,                   /* bmap */
  66         ext2_truncate,          /* truncate */
  67         ext2_permission,        /* permission */
  68         NULL                    /* smap */
  69 };
  70 
  71 int ext2_check_dir_entry (char * function, struct inode * dir,
     /*  */
  72                           struct ext2_dir_entry * de, struct buffer_head * bh,
  73                           unsigned long offset)
  74 {
  75         char * error_msg = NULL;
  76 
  77         if (de->rec_len < EXT2_DIR_REC_LEN(1))
  78                 error_msg = "rec_len is smaller than minimal";
  79         else if (de->rec_len % 4 != 0)
  80                 error_msg = "rec_len % 4 != 0";
  81         else if (de->rec_len < EXT2_DIR_REC_LEN(de->name_len))
  82                 error_msg = "rec_len is too small for name_len";
  83         else if (dir && ((char *) de - bh->b_data) + de->rec_len >
  84                  dir->i_sb->s_blocksize)
  85                 error_msg = "directory entry across blocks";
  86         else if (dir && de->inode > dir->i_sb->u.ext2_sb.s_es->s_inodes_count)
  87                 error_msg = "inode out of bounds";
  88 
  89         if (error_msg != NULL)
  90                 ext2_error (dir->i_sb, function, "bad directory entry: %s\n"
  91                             "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
  92                             error_msg, offset, de->inode, de->rec_len,
  93                             de->name_len);
  94         return error_msg == NULL ? 1 : 0;
  95 }
  96 
  97 static int ext2_readdir (struct inode * inode, struct file * filp,
     /*  */
  98                          struct dirent * dirent, int count)
  99 {
 100         unsigned long offset, blk;
 101         int i, num;
 102         struct buffer_head * bh, * tmp, * bha[16];
 103         struct ext2_dir_entry * de;
 104         struct super_block * sb;
 105         int err;
 106         
 107         if (!inode || !S_ISDIR(inode->i_mode))
 108                 return -EBADF;
 109         sb = inode->i_sb;
 110         while (filp->f_pos < inode->i_size) {
 111                 offset = filp->f_pos & (sb->s_blocksize - 1);
 112                 blk = (filp->f_pos) >> EXT2_BLOCK_SIZE_BITS(sb);
 113                 bh = ext2_bread (inode, blk, 0, &err);
 114                 if (!bh) {
 115                         filp->f_pos += sb->s_blocksize - offset;
 116                         continue;
 117                 }
 118 
 119                 /*
 120                  * Do the readahead
 121                  */
 122                 if (!offset) {
 123                         for (i = 16 >> (EXT2_BLOCK_SIZE_BITS(sb) - 9), num = 0;
 124                              i > 0; i--) {
 125                                 tmp = ext2_getblk (inode, ++blk, 0, &err);
 126                                 if (tmp && !tmp->b_uptodate && !tmp->b_lock)
 127                                         bha[num++] = tmp;
 128                                 else
 129                                         brelse (tmp);
 130                         }
 131                         if (num) {
 132                                 ll_rw_block (READA, num, bha);
 133                                 for (i = 0; i < num; i++)
 134                                         brelse (bha[i]);
 135                         }
 136                 }
 137                 
 138                 de = (struct ext2_dir_entry *) (offset + bh->b_data);
 139                 while (offset < sb->s_blocksize && filp->f_pos < inode->i_size) {
 140                         if (!ext2_check_dir_entry ("ext2_readdir", inode, de,
 141                                                    bh, offset)) {
 142                                 brelse (bh);
 143                                 return 0;
 144                         }
 145                         offset += de->rec_len;
 146                         filp->f_pos += de->rec_len;
 147                         if (de->inode) {
 148                                 memcpy_tofs (dirent->d_name, de->name,
 149                                              de->name_len);
 150                                 put_fs_long (de->inode, &dirent->d_ino);
 151                                 put_fs_byte (0, de->name_len + dirent->d_name);
 152                                 put_fs_word (de->name_len, &dirent->d_reclen);
 153                                 dcache_add(inode, de->name, de->name_len,
 154                                                  de->inode);
 155                                 i = de->name_len;
 156                                 brelse (bh);
 157                                 if (!IS_RDONLY(inode)) {
 158                                         inode->i_atime = CURRENT_TIME;
 159                                         inode->i_dirt = 1;
 160                                 }
 161                                 return i;
 162                         }
 163                         de = (struct ext2_dir_entry *) ((char *) de +
 164                                                         de->rec_len);
 165                 }
 166                 brelse (bh);
 167         }
 168         if (!IS_RDONLY(inode)) {
 169                 inode->i_atime = CURRENT_TIME;
 170                 inode->i_dirt = 1;
 171         }
 172         return 0;
 173 }
/* */
root/fs/ext2/dir.c

DEFINITIONS
