1 files changed, 111 insertions, 0 deletions
diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
new file mode 100644
index 0000000000..b80abec053
--- /dev/null
+++ b/fs/erofs/dir.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ * Copyright (C) 2022, Alibaba Cloud
+ */
+#include "internal.h"
+
+static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
+			       void *dentry_blk, struct erofs_dirent *de,
+			       unsigned int nameoff, unsigned int maxsize)
+{
+	const struct erofs_dirent *end = dentry_blk + nameoff;
+
+	while (de < end) {
+		const char *de_name;
+		unsigned int de_namelen;
+		unsigned char d_type;
+
+		d_type = fs_ftype_to_dtype(de->file_type);
+
+		nameoff = le16_to_cpu(de->nameoff);
+		de_name = (char *)dentry_blk + nameoff;
+
+		/* the last dirent in the block? */
+		if (de + 1 >= end)
+			de_namelen = strnlen(de_name, maxsize - nameoff);
+		else
+			de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
+
+		/* a corrupted entry is found */
+		if (nameoff + de_namelen > maxsize ||
+		    de_namelen > EROFS_NAME_LEN) {
+			erofs_err(dir->i_sb, "bogus dirent @ nid %llu",
+				  EROFS_I(dir)->nid);
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+
+		if (!dir_emit(ctx, de_name, de_namelen,
+			      le64_to_cpu(de->nid), d_type))
+			return 1;
+		++de;
+		ctx->pos += sizeof(struct erofs_dirent);
+	}
+	return 0;
+}
+
+static int erofs_readdir(struct file *f, struct dir_context *ctx)
+{
+	struct inode *dir = file_inode(f);
+	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+	struct super_block *sb = dir->i_sb;
+	unsigned long bsz = sb->s_blocksize;
+	const size_t dirsize = i_size_read(dir);
+	unsigned int i = erofs_blknr(sb, ctx->pos);
+	unsigned int ofs = erofs_blkoff(sb, ctx->pos);
+	int err = 0;
+	bool initial = true;
+
+	buf.inode = dir;
+	while (ctx->pos < dirsize) {
+		struct erofs_dirent *de;
+		unsigned int nameoff, maxsize;
+
+		de = erofs_bread(&buf, i, EROFS_KMAP);
+		if (IS_ERR(de)) {
+			erofs_err(sb, "fail to readdir of logical block %u of nid %llu",
+				  i, EROFS_I(dir)->nid);
+			err = PTR_ERR(de);
+			break;
+		}
+
+		nameoff = le16_to_cpu(de->nameoff);
+		if (nameoff < sizeof(struct erofs_dirent) || nameoff >= bsz) {
+			erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu",
+				  nameoff, EROFS_I(dir)->nid);
+			err = -EFSCORRUPTED;
+			break;
+		}
+
+		maxsize = min_t(unsigned int, dirsize - ctx->pos + ofs, bsz);
+
+		/* search dirents at the arbitrary position */
+		if (initial) {
+			initial = false;
+
+			ofs = roundup(ofs, sizeof(struct erofs_dirent));
+			ctx->pos = erofs_pos(sb, i) + ofs;
+			if (ofs >= nameoff)
+				goto skip_this;
+		}
+
+		err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
+					  nameoff, maxsize);
+		if (err)
+			break;
+skip_this:
+		ctx->pos = erofs_pos(sb, i) + maxsize;
+		++i;
+		ofs = 0;
+	}
+	erofs_put_metabuf(&buf);
+	return err < 0 ? err : 0;
+}
+
+const struct file_operations erofs_dir_fops = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= erofs_readdir,
+};