// SPDX-License-Identifier: GPL-2.0
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/*
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* QNX4 file system, Linux implementation.
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*
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* Version : 0.2.1
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*
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* Using parts of the xiafs filesystem.
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*
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* History :
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*
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* 28-05-1998 by Richard Frowijn : first release.
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* 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
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*/
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#include <linux/buffer_head.h>
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#include "qnx4.h"
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/*
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* A qnx4 directory entry is an inode entry or link info
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* depending on the status field in the last byte. The
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* first byte is where the name start either way, and a
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* zero means it's empty.
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*
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* Also, due to a bug in gcc, we don't want to use the
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* real (differently sized) name arrays in the inode and
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* link entries, but always the 'de_name[]' one in the
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* fake struct entry.
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*
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* See
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*
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* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
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*
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* for details, but basically gcc will take the size of the
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* 'name' array from one of the used union entries randomly.
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*
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* This use of 'de_name[]' (48 bytes) avoids the false positive
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* warnings that would happen if gcc decides to use 'inode.di_name'
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* (16 bytes) even when the pointer and size were to come from
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* 'link.dl_name' (48 bytes).
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*
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* In all cases the actual name pointer itself is the same, it's
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* only the gcc internal 'what is the size of this field' logic
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* that can get confused.
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*/
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union qnx4_directory_entry {
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struct {
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const char de_name[48];
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u8 de_pad[15];
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u8 de_status;
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};
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struct qnx4_inode_entry inode;
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struct qnx4_link_info link;
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};
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static int qnx4_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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unsigned int offset;
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struct buffer_head *bh;
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unsigned long blknum;
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int ix, ino;
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int size;
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QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
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QNX4DEBUG((KERN_INFO "pos = %ld\n", (long) ctx->pos));
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while (ctx->pos < inode->i_size) {
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blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
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bh = sb_bread(inode->i_sb, blknum);
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if (bh == NULL) {
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printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
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return 0;
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}
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ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
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for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
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union qnx4_directory_entry *de;
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offset = ix * QNX4_DIR_ENTRY_SIZE;
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de = (union qnx4_directory_entry *) (bh->b_data + offset);
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if (!de->de_name[0])
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continue;
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if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
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continue;
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if (!(de->de_status & QNX4_FILE_LINK)) {
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size = sizeof(de->inode.di_fname);
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ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
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} else {
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size = sizeof(de->link.dl_fname);
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ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
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QNX4_INODES_PER_BLOCK +
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de->link.dl_inode_ndx;
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}
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size = strnlen(de->de_name, size);
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QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
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if (!dir_emit(ctx, de->de_name, size, ino, 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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}
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return 0;
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}
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const struct file_operations qnx4_dir_operations =
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{
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.iterate_shared = qnx4_readdir,
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.fsync = generic_file_fsync,
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};
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const struct inode_operations qnx4_dir_inode_operations =
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{
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.lookup = qnx4_lookup,
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};
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