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// SPDX-License-Identifier: GPL-2.0
/*
* QNX4 file system, Linux implementation.
*
* Version : 0.2.1
*
* Using parts of the xiafs filesystem.
*
* History :
*
* 28-05-1998 by Richard Frowijn : first release.
* 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
*/
#include <linux/buffer_head.h>
#include "qnx4.h"
/*
* A qnx4 directory entry is an inode entry or link info
* depending on the status field in the last byte. The
* first byte is where the name start either way, and a
* zero means it's empty.
*
* Also, due to a bug in gcc, we don't want to use the
* real (differently sized) name arrays in the inode and
* link entries, but always the 'de_name[]' one in the
* fake struct entry.
*
* See
*
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
*
* for details, but basically gcc will take the size of the
* 'name' array from one of the used union entries randomly.
*
* This use of 'de_name[]' (48 bytes) avoids the false positive
* warnings that would happen if gcc decides to use 'inode.di_name'
* (16 bytes) even when the pointer and size were to come from
* 'link.dl_name' (48 bytes).
*
* In all cases the actual name pointer itself is the same, it's
* only the gcc internal 'what is the size of this field' logic
* that can get confused.
*/
union qnx4_directory_entry {
struct {
const char de_name[48];
u8 de_pad[15];
u8 de_status;
};
struct qnx4_inode_entry inode;
struct qnx4_link_info link;
};
static int qnx4_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
unsigned int offset;
struct buffer_head *bh;
unsigned long blknum;
int ix, ino;
int size;
QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
QNX4DEBUG((KERN_INFO "pos = %ld\n", (long) ctx->pos));
while (ctx->pos < inode->i_size) {
blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
bh = sb_bread(inode->i_sb, blknum);
if (bh == NULL) {
printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
return 0;
}
ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
union qnx4_directory_entry *de;
offset = ix * QNX4_DIR_ENTRY_SIZE;
de = (union qnx4_directory_entry *) (bh->b_data + offset);
if (!de->de_name[0])
continue;
if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
continue;
if (!(de->de_status & QNX4_FILE_LINK)) {
size = sizeof(de->inode.di_fname);
ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
} else {
size = sizeof(de->link.dl_fname);
ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
QNX4_INODES_PER_BLOCK +
de->link.dl_inode_ndx;
}
size = strnlen(de->de_name, size);
QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
if (!dir_emit(ctx, de->de_name, size, ino, DT_UNKNOWN)) {
brelse(bh);
return 0;
}
}
brelse(bh);
}
return 0;
}
const struct file_operations qnx4_dir_operations =
{
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = qnx4_readdir,
.fsync = generic_file_fsync,
};
const struct inode_operations qnx4_dir_inode_operations =
{
.lookup = qnx4_lookup,
};
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