namei: introduce nameidata->link
shares space with nameidata->next, walk_component() et.al. store the struct path of symlink instead of returning it into a variable passed by caller. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
Родитель
d4dee48bad
Коммит
caa8563443
62
fs/namei.c
62
fs/namei.c
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@ -494,7 +494,10 @@ EXPORT_SYMBOL(path_put);
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struct nameidata {
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struct path path;
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struct qstr last;
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union {
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struct qstr last;
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struct path link;
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};
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struct path root;
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struct inode *inode; /* path.dentry.d_inode */
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unsigned int flags;
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@ -1559,8 +1562,9 @@ static inline int should_follow_link(struct dentry *dentry, int follow)
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return unlikely(d_is_symlink(dentry)) ? follow : 0;
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}
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static int walk_component(struct nameidata *nd, struct path *path, int follow)
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static int walk_component(struct nameidata *nd, int follow)
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{
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struct path path;
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struct inode *inode;
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int err;
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/*
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@ -1570,38 +1574,39 @@ static int walk_component(struct nameidata *nd, struct path *path, int follow)
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*/
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if (unlikely(nd->last_type != LAST_NORM))
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return handle_dots(nd, nd->last_type);
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err = lookup_fast(nd, path, &inode);
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err = lookup_fast(nd, &path, &inode);
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if (unlikely(err)) {
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if (err < 0)
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goto out_err;
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err = lookup_slow(nd, path);
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err = lookup_slow(nd, &path);
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if (err < 0)
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goto out_err;
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inode = path->dentry->d_inode;
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inode = path.dentry->d_inode;
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err = -ENOENT;
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if (d_is_negative(path->dentry))
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if (d_is_negative(path.dentry))
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goto out_path_put;
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}
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if (should_follow_link(path->dentry, follow)) {
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if (should_follow_link(path.dentry, follow)) {
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if (nd->flags & LOOKUP_RCU) {
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if (unlikely(nd->path.mnt != path->mnt ||
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unlazy_walk(nd, path->dentry))) {
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if (unlikely(nd->path.mnt != path.mnt ||
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unlazy_walk(nd, path.dentry))) {
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err = -ECHILD;
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goto out_err;
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}
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}
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BUG_ON(inode != path->dentry->d_inode);
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BUG_ON(inode != path.dentry->d_inode);
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nd->link = path;
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return 1;
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}
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path_to_nameidata(path, nd);
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path_to_nameidata(&path, nd);
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nd->inode = inode;
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return 0;
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out_path_put:
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path_to_nameidata(path, nd);
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path_to_nameidata(&path, nd);
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out_err:
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terminate_walk(nd);
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return err;
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@ -1614,12 +1619,12 @@ out_err:
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* Without that kind of total limit, nasty chains of consecutive
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* symlinks can cause almost arbitrarily long lookups.
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*/
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static inline int nested_symlink(struct path *path, struct nameidata *nd)
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static inline int nested_symlink(struct nameidata *nd)
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{
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int res;
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if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
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path_put_conditional(path, nd);
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path_put_conditional(&nd->link, nd);
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path_put(&nd->path);
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return -ELOOP;
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}
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@ -1629,13 +1634,13 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
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current->link_count++;
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do {
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struct path link = *path;
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struct path link = nd->link;
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void *cookie;
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res = follow_link(&link, nd, &cookie);
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if (res)
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break;
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res = walk_component(nd, path, LOOKUP_FOLLOW);
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res = walk_component(nd, LOOKUP_FOLLOW);
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put_link(nd, &link, cookie);
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} while (res > 0);
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@ -1770,7 +1775,6 @@ static inline u64 hash_name(const char *name)
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*/
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static int link_path_walk(const char *name, struct nameidata *nd)
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{
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struct path next;
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int err;
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while (*name=='/')
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@ -1830,17 +1834,17 @@ static int link_path_walk(const char *name, struct nameidata *nd)
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if (!*name)
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return 0;
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err = walk_component(nd, &next, LOOKUP_FOLLOW);
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err = walk_component(nd, LOOKUP_FOLLOW);
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if (err < 0)
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return err;
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if (err) {
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err = nested_symlink(&next, nd);
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err = nested_symlink(nd);
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if (err)
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return err;
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}
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if (!d_can_lookup(nd->path.dentry)) {
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err = -ENOTDIR;
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err = -ENOTDIR;
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break;
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}
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}
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@ -1960,20 +1964,19 @@ static void path_cleanup(struct nameidata *nd)
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fput(nd->base);
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}
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static inline int lookup_last(struct nameidata *nd, struct path *path)
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static inline int lookup_last(struct nameidata *nd)
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{
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if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
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nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
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nd->flags &= ~LOOKUP_PARENT;
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return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW);
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return walk_component(nd, nd->flags & LOOKUP_FOLLOW);
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}
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/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
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static int path_lookupat(int dfd, const struct filename *name,
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unsigned int flags, struct nameidata *nd)
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{
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struct path path;
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int err;
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/*
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@ -1992,10 +1995,10 @@ static int path_lookupat(int dfd, const struct filename *name,
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*/
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err = path_init(dfd, name, flags, nd);
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if (!err && !(flags & LOOKUP_PARENT)) {
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err = lookup_last(nd, &path);
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err = lookup_last(nd);
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while (err > 0) {
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void *cookie;
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struct path link = path;
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struct path link = nd->link;
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err = may_follow_link(&link, nd);
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if (unlikely(err))
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break;
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@ -2003,7 +2006,7 @@ static int path_lookupat(int dfd, const struct filename *name,
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err = follow_link(&link, nd, &cookie);
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if (err)
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break;
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err = lookup_last(nd, &path);
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err = lookup_last(nd);
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put_link(nd, &link, cookie);
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}
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}
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@ -2312,8 +2315,10 @@ done:
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}
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path->dentry = dentry;
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path->mnt = nd->path.mnt;
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if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW))
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if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) {
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nd->link = *path;
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return 1;
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}
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mntget(path->mnt);
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follow_mount(path);
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error = 0;
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@ -3040,6 +3045,7 @@ finish_lookup:
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}
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}
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BUG_ON(inode != path->dentry->d_inode);
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nd->link = *path;
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return 1;
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}
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@ -3228,7 +3234,7 @@ static struct file *path_openat(int dfd, struct filename *pathname,
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error = do_last(nd, &path, file, op, &opened, pathname);
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while (unlikely(error > 0)) { /* trailing symlink */
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struct path link = path;
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struct path link = nd->link;
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void *cookie;
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error = may_follow_link(&link, nd);
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if (unlikely(error))
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