1 files changed, 117 insertions, 0 deletions
diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c
new file mode 100644
index 0000000000..66645a5a35
--- /dev/null
+++ b/fs/qnx4/dir.c
@@ -0,0 +1,117 @@
+// 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,
+};