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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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