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-rw-r--r--fs/qnx4/dir.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c
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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,
+};