cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dir.c (3276B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * QNX4 file system, Linux implementation.
      4 *
      5 * Version : 0.2.1
      6 *
      7 * Using parts of the xiafs filesystem.
      8 *
      9 * History :
     10 *
     11 * 28-05-1998 by Richard Frowijn : first release.
     12 * 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
     13 */
     14
     15#include <linux/buffer_head.h>
     16#include "qnx4.h"
     17
     18/*
     19 * A qnx4 directory entry is an inode entry or link info
     20 * depending on the status field in the last byte. The
     21 * first byte is where the name start either way, and a
     22 * zero means it's empty.
     23 *
     24 * Also, due to a bug in gcc, we don't want to use the
     25 * real (differently sized) name arrays in the inode and
     26 * link entries, but always the 'de_name[]' one in the
     27 * fake struct entry.
     28 *
     29 * See
     30 *
     31 *   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
     32 *
     33 * for details, but basically gcc will take the size of the
     34 * 'name' array from one of the used union entries randomly.
     35 *
     36 * This use of 'de_name[]' (48 bytes) avoids the false positive
     37 * warnings that would happen if gcc decides to use 'inode.di_name'
     38 * (16 bytes) even when the pointer and size were to come from
     39 * 'link.dl_name' (48 bytes).
     40 *
     41 * In all cases the actual name pointer itself is the same, it's
     42 * only the gcc internal 'what is the size of this field' logic
     43 * that can get confused.
     44 */
     45union qnx4_directory_entry {
     46	struct {
     47		const char de_name[48];
     48		u8 de_pad[15];
     49		u8 de_status;
     50	};
     51	struct qnx4_inode_entry inode;
     52	struct qnx4_link_info link;
     53};
     54
     55static int qnx4_readdir(struct file *file, struct dir_context *ctx)
     56{
     57	struct inode *inode = file_inode(file);
     58	unsigned int offset;
     59	struct buffer_head *bh;
     60	unsigned long blknum;
     61	int ix, ino;
     62	int size;
     63
     64	QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
     65	QNX4DEBUG((KERN_INFO "pos                 = %ld\n", (long) ctx->pos));
     66
     67	while (ctx->pos < inode->i_size) {
     68		blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
     69		bh = sb_bread(inode->i_sb, blknum);
     70		if (bh == NULL) {
     71			printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
     72			return 0;
     73		}
     74		ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
     75		for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
     76			union qnx4_directory_entry *de;
     77
     78			offset = ix * QNX4_DIR_ENTRY_SIZE;
     79			de = (union qnx4_directory_entry *) (bh->b_data + offset);
     80
     81			if (!de->de_name[0])
     82				continue;
     83			if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
     84				continue;
     85			if (!(de->de_status & QNX4_FILE_LINK)) {
     86				size = sizeof(de->inode.di_fname);
     87				ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
     88			} else {
     89				size = sizeof(de->link.dl_fname);
     90				ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
     91					QNX4_INODES_PER_BLOCK +
     92					de->link.dl_inode_ndx;
     93			}
     94			size = strnlen(de->de_name, size);
     95			QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
     96			if (!dir_emit(ctx, de->de_name, size, ino, DT_UNKNOWN)) {
     97				brelse(bh);
     98				return 0;
     99			}
    100		}
    101		brelse(bh);
    102	}
    103	return 0;
    104}
    105
    106const struct file_operations qnx4_dir_operations =
    107{
    108	.llseek		= generic_file_llseek,
    109	.read		= generic_read_dir,
    110	.iterate_shared	= qnx4_readdir,
    111	.fsync		= generic_file_fsync,
    112};
    113
    114const struct inode_operations qnx4_dir_inode_operations =
    115{
    116	.lookup		= qnx4_lookup,
    117};