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-rw-r--r--fs/erofs/dir.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
new file mode 100644
index 000000000000..d28c623dfef9
--- /dev/null
+++ b/fs/erofs/dir.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#include "internal.h"
+
+static void debug_one_dentry(unsigned char d_type, const char *de_name,
+ unsigned int de_namelen)
+{
+#ifdef CONFIG_EROFS_FS_DEBUG
+ /* since the on-disk name could not have the trailing '\0' */
+ unsigned char dbg_namebuf[EROFS_NAME_LEN + 1];
+
+ memcpy(dbg_namebuf, de_name, de_namelen);
+ dbg_namebuf[de_namelen] = '\0';
+
+ erofs_dbg("found dirent %s de_len %u d_type %d", dbg_namebuf,
+ de_namelen, d_type);
+#endif
+}
+
+static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
+ void *dentry_blk, unsigned int *ofs,
+ unsigned int nameoff, unsigned int maxsize)
+{
+ struct erofs_dirent *de = dentry_blk + *ofs;
+ 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;
+ }
+
+ debug_one_dentry(d_type, de_name, de_namelen);
+ if (!dir_emit(ctx, de_name, de_namelen,
+ le64_to_cpu(de->nid), d_type))
+ /* stopped by some reason */
+ return 1;
+ ++de;
+ *ofs += sizeof(struct erofs_dirent);
+ }
+ *ofs = maxsize;
+ return 0;
+}
+
+static int erofs_readdir(struct file *f, struct dir_context *ctx)
+{
+ struct inode *dir = file_inode(f);
+ struct address_space *mapping = dir->i_mapping;
+ const size_t dirsize = i_size_read(dir);
+ unsigned int i = ctx->pos / EROFS_BLKSIZ;
+ unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
+ int err = 0;
+ bool initial = true;
+
+ while (ctx->pos < dirsize) {
+ struct page *dentry_page;
+ struct erofs_dirent *de;
+ unsigned int nameoff, maxsize;
+
+ dentry_page = read_mapping_page(mapping, i, NULL);
+ if (dentry_page == ERR_PTR(-ENOMEM)) {
+ err = -ENOMEM;
+ break;
+ } else if (IS_ERR(dentry_page)) {
+ erofs_err(dir->i_sb,
+ "fail to readdir of logical block %u of nid %llu",
+ i, EROFS_I(dir)->nid);
+ err = -EFSCORRUPTED;
+ break;
+ }
+
+ de = (struct erofs_dirent *)kmap(dentry_page);
+
+ nameoff = le16_to_cpu(de->nameoff);
+
+ if (nameoff < sizeof(struct erofs_dirent) ||
+ nameoff >= PAGE_SIZE) {
+ erofs_err(dir->i_sb,
+ "invalid de[0].nameoff %u @ nid %llu",
+ nameoff, EROFS_I(dir)->nid);
+ err = -EFSCORRUPTED;
+ goto skip_this;
+ }
+
+ maxsize = min_t(unsigned int,
+ dirsize - ctx->pos + ofs, PAGE_SIZE);
+
+ /* search dirents at the arbitrary position */
+ if (initial) {
+ initial = false;
+
+ ofs = roundup(ofs, sizeof(struct erofs_dirent));
+ if (ofs >= nameoff)
+ goto skip_this;
+ }
+
+ err = erofs_fill_dentries(dir, ctx, de, &ofs,
+ nameoff, maxsize);
+skip_this:
+ kunmap(dentry_page);
+
+ put_page(dentry_page);
+
+ ctx->pos = blknr_to_addr(i) + ofs;
+
+ if (err)
+ break;
+ ++i;
+ ofs = 0;
+ }
+ return err < 0 ? err : 0;
+}
+
+const struct file_operations erofs_dir_fops = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .iterate_shared = erofs_readdir,
+};
+