1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
21da177e4SLinus Torvalds /*
31da177e4SLinus Torvalds * QNX4 file system, Linux implementation.
41da177e4SLinus Torvalds *
51da177e4SLinus Torvalds * Version : 0.2.1
61da177e4SLinus Torvalds *
71da177e4SLinus Torvalds * Using parts of the xiafs filesystem.
81da177e4SLinus Torvalds *
91da177e4SLinus Torvalds * History :
101da177e4SLinus Torvalds *
111da177e4SLinus Torvalds * 28-05-1998 by Richard Frowijn : first release.
121da177e4SLinus Torvalds * 20-06-1998 by Frank Denis : Linux 2.1.99+ & dcache support.
131da177e4SLinus Torvalds */
141da177e4SLinus Torvalds
151da177e4SLinus Torvalds #include <linux/buffer_head.h>
16964f5369SAl Viro #include "qnx4.h"
171da177e4SLinus Torvalds
18b7213ffaSLinus Torvalds /*
19b7213ffaSLinus Torvalds * A qnx4 directory entry is an inode entry or link info
20b7213ffaSLinus Torvalds * depending on the status field in the last byte. The
21b7213ffaSLinus Torvalds * first byte is where the name start either way, and a
22b7213ffaSLinus Torvalds * zero means it's empty.
23*d5f65459SLinus Torvalds *
24*d5f65459SLinus Torvalds * Also, due to a bug in gcc, we don't want to use the
25*d5f65459SLinus Torvalds * real (differently sized) name arrays in the inode and
26*d5f65459SLinus Torvalds * link entries, but always the 'de_name[]' one in the
27*d5f65459SLinus Torvalds * fake struct entry.
28*d5f65459SLinus Torvalds *
29*d5f65459SLinus Torvalds * See
30*d5f65459SLinus Torvalds *
31*d5f65459SLinus Torvalds * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
32*d5f65459SLinus Torvalds *
33*d5f65459SLinus Torvalds * for details, but basically gcc will take the size of the
34*d5f65459SLinus Torvalds * 'name' array from one of the used union entries randomly.
35*d5f65459SLinus Torvalds *
36*d5f65459SLinus Torvalds * This use of 'de_name[]' (48 bytes) avoids the false positive
37*d5f65459SLinus Torvalds * warnings that would happen if gcc decides to use 'inode.di_name'
38*d5f65459SLinus Torvalds * (16 bytes) even when the pointer and size were to come from
39*d5f65459SLinus Torvalds * 'link.dl_name' (48 bytes).
40*d5f65459SLinus Torvalds *
41*d5f65459SLinus Torvalds * In all cases the actual name pointer itself is the same, it's
42*d5f65459SLinus Torvalds * only the gcc internal 'what is the size of this field' logic
43*d5f65459SLinus Torvalds * that can get confused.
44b7213ffaSLinus Torvalds */
45b7213ffaSLinus Torvalds union qnx4_directory_entry {
46b7213ffaSLinus Torvalds struct {
47*d5f65459SLinus Torvalds const char de_name[48];
48*d5f65459SLinus Torvalds u8 de_pad[15];
49*d5f65459SLinus Torvalds u8 de_status;
50b7213ffaSLinus Torvalds };
51b7213ffaSLinus Torvalds struct qnx4_inode_entry inode;
52b7213ffaSLinus Torvalds struct qnx4_link_info link;
53b7213ffaSLinus Torvalds };
54b7213ffaSLinus Torvalds
qnx4_readdir(struct file * file,struct dir_context * ctx)55663f4decSAl Viro static int qnx4_readdir(struct file *file, struct dir_context *ctx)
561da177e4SLinus Torvalds {
57663f4decSAl Viro struct inode *inode = file_inode(file);
581da177e4SLinus Torvalds unsigned int offset;
591da177e4SLinus Torvalds struct buffer_head *bh;
601da177e4SLinus Torvalds unsigned long blknum;
611da177e4SLinus Torvalds int ix, ino;
621da177e4SLinus Torvalds int size;
631da177e4SLinus Torvalds
64891ddb95SAnders Larsen QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) inode->i_size));
65663f4decSAl Viro QNX4DEBUG((KERN_INFO "pos = %ld\n", (long) ctx->pos));
661da177e4SLinus Torvalds
67663f4decSAl Viro while (ctx->pos < inode->i_size) {
68663f4decSAl Viro blknum = qnx4_block_map(inode, ctx->pos >> QNX4_BLOCK_SIZE_BITS);
691da177e4SLinus Torvalds bh = sb_bread(inode->i_sb, blknum);
701da177e4SLinus Torvalds if (bh == NULL) {
711da177e4SLinus Torvalds printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", blknum);
72663f4decSAl Viro return 0;
731da177e4SLinus Torvalds }
74663f4decSAl Viro ix = (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK;
75663f4decSAl Viro for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos += QNX4_DIR_ENTRY_SIZE) {
76b7213ffaSLinus Torvalds union qnx4_directory_entry *de;
77b7213ffaSLinus Torvalds
781da177e4SLinus Torvalds offset = ix * QNX4_DIR_ENTRY_SIZE;
79b7213ffaSLinus Torvalds de = (union qnx4_directory_entry *) (bh->b_data + offset);
80b7213ffaSLinus Torvalds
81*d5f65459SLinus Torvalds if (!de->de_name[0])
82663f4decSAl Viro continue;
83b7213ffaSLinus Torvalds if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
84663f4decSAl Viro continue;
85b7213ffaSLinus Torvalds if (!(de->de_status & QNX4_FILE_LINK)) {
86b7213ffaSLinus Torvalds size = sizeof(de->inode.di_fname);
871da177e4SLinus Torvalds ino = blknum * QNX4_INODES_PER_BLOCK + ix - 1;
88b7213ffaSLinus Torvalds } else {
89b7213ffaSLinus Torvalds size = sizeof(de->link.dl_fname);
90b7213ffaSLinus Torvalds ino = ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) *
911da177e4SLinus Torvalds QNX4_INODES_PER_BLOCK +
92b7213ffaSLinus Torvalds de->link.dl_inode_ndx;
931da177e4SLinus Torvalds }
94*d5f65459SLinus Torvalds size = strnlen(de->de_name, size);
95b7213ffaSLinus Torvalds QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name));
96*d5f65459SLinus Torvalds if (!dir_emit(ctx, de->de_name, size, ino, DT_UNKNOWN)) {
971da177e4SLinus Torvalds brelse(bh);
98663f4decSAl Viro return 0;
991da177e4SLinus Torvalds }
1001da177e4SLinus Torvalds }
1011da177e4SLinus Torvalds brelse(bh);
1021da177e4SLinus Torvalds }
1031da177e4SLinus Torvalds return 0;
1041da177e4SLinus Torvalds }
1051da177e4SLinus Torvalds
1064b6f5d20SArjan van de Ven const struct file_operations qnx4_dir_operations =
1071da177e4SLinus Torvalds {
108ca572727Sjan Blunck .llseek = generic_file_llseek,
1091da177e4SLinus Torvalds .read = generic_read_dir,
110c51da20cSAl Viro .iterate_shared = qnx4_readdir,
1111b061d92SChristoph Hellwig .fsync = generic_file_fsync,
1121da177e4SLinus Torvalds };
1131da177e4SLinus Torvalds
114c5ef1c42SArjan van de Ven const struct inode_operations qnx4_dir_inode_operations =
1151da177e4SLinus Torvalds {
1161da177e4SLinus Torvalds .lookup = qnx4_lookup,
1171da177e4SLinus Torvalds };
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