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https://github.com/torvalds/linux
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7aa123a0dc
* sanity checks belong before risky operation, not after it * don't quit as soon as we'd found an entry Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
/*
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* dir.c
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*
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* Copyright (c) 1999 Al Smith
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*/
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#include <linux/buffer_head.h>
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#include "efs.h"
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static int efs_readdir(struct file *, struct dir_context *);
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const struct file_operations efs_dir_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.iterate = efs_readdir,
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};
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const struct inode_operations efs_dir_inode_operations = {
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.lookup = efs_lookup,
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};
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static int efs_readdir(struct file *file, struct dir_context *ctx)
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{
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struct inode *inode = file_inode(file);
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efs_block_t block;
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int slot;
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if (inode->i_size & (EFS_DIRBSIZE-1))
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printk(KERN_WARNING "EFS: WARNING: readdir(): directory size not a multiple of EFS_DIRBSIZE\n");
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/* work out where this entry can be found */
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block = ctx->pos >> EFS_DIRBSIZE_BITS;
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/* each block contains at most 256 slots */
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slot = ctx->pos & 0xff;
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/* look at all blocks */
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while (block < inode->i_blocks) {
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struct efs_dir *dirblock;
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struct buffer_head *bh;
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/* read the dir block */
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bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
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if (!bh) {
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printk(KERN_ERR "EFS: readdir(): failed to read dir block %d\n", block);
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break;
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}
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dirblock = (struct efs_dir *) bh->b_data;
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if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
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printk(KERN_ERR "EFS: readdir(): invalid directory block\n");
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brelse(bh);
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break;
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}
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for (; slot < dirblock->slots; slot++) {
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struct efs_dentry *dirslot;
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efs_ino_t inodenum;
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const char *nameptr;
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int namelen;
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if (dirblock->space[slot] == 0)
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continue;
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dirslot = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
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inodenum = be32_to_cpu(dirslot->inode);
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namelen = dirslot->namelen;
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nameptr = dirslot->name;
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#ifdef DEBUG
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printk(KERN_DEBUG "EFS: readdir(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u\n", block, slot, dirblock->slots-1, inodenum, nameptr, namelen);
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#endif
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if (!namelen)
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continue;
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/* found the next entry */
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ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
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/* sanity check */
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if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
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printk(KERN_WARNING "EFS: directory entry %d exceeds directory block\n", slot);
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continue;
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}
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/* copy filename and data in dirslot */
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if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {
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brelse(bh);
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return 0;
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}
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}
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brelse(bh);
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slot = 0;
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block++;
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}
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ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
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return 0;
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}
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