1 files changed, 139 insertions, 0 deletions

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
new file mode 100644
index 000000000000..1976e60e5174
--- /dev/null
+++ b/fs/erofs/dir.c
@@ -0,0 +1,139 @@
+// 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';
+
+        debugln("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 (unlikely(nameoff + de_namelen > maxsize ||
+                             de_namelen > EROFS_NAME_LEN)) {
+                        errln("bogus dirent @ nid %llu", EROFS_V(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)) {
+                        errln("fail to readdir of logical block %u of nid %llu",
+                              i, EROFS_V(dir)->nid);
+                        err = -EFSCORRUPTED;
+                        break;
+                }
+
+                de = (struct erofs_dirent *)kmap(dentry_page);
+
+                nameoff = le16_to_cpu(de->nameoff);
+
+                if (unlikely(nameoff < sizeof(struct erofs_dirent) ||
+                             nameoff >= PAGE_SIZE)) {
+                        errln("%s, invalid de[0].nameoff %u @ nid %llu",
+                              __func__, nameoff, EROFS_V(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 (unlikely(initial)) {
+                        initial = false;
+
+                        ofs = roundup(ofs, sizeof(struct erofs_dirent));
+                        if (unlikely(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 (unlikely(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,
+};
+