1 files changed, 245 insertions, 0 deletions
diff --git a/lib/sqfs/src/io/dir_hl.c b/lib/sqfs/src/io/dir_hl.c
new file mode 100644
index 0000000..08efaaf
--- /dev/null
+++ b/lib/sqfs/src/io/dir_hl.c
@@ -0,0 +1,245 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * dir_hl.c
+ *
+ * Copyright (C) 2023 David Oberhollenzer <goliath@infraroot.at>
+ */
+#define SQFS_BUILDING_DLL
+#include "config.h"
+
+#include "util/util.h"
+#include "util/rbtree.h"
+#include "compat.h"
+
+#include "sqfs/dir_entry.h"
+#include "sqfs/error.h"
+#include "sqfs/inode.h"
+#include "sqfs/io.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+	sqfs_u64 dev;
+	sqfs_u64 inum;
+} inumtree_key_t;
+
+typedef struct {
+	sqfs_dir_iterator_t base;
+
+	int state;
+	const char *link_target;
+	sqfs_dir_iterator_t *src;
+	rbtree_t inumtree;
+} hl_iterator_t;
+
+static int compare_inum(const void *ctx, const void *lhs, const void *rhs)
+{
+	const inumtree_key_t *l = (const inumtree_key_t *)lhs;
+	const inumtree_key_t *r = (const inumtree_key_t *)rhs;
+	(void)ctx;
+
+	if (l->dev != r->dev)
+		return l->dev < r->dev ? -1 : 1;
+
+	return l->inum < r->inum ? -1 : (l->inum > r->inum ? 1 : 0);
+}
+
+static const char *detect_hard_link(const hl_iterator_t *it,
+				    const sqfs_dir_entry_t *ent)
+{
+	inumtree_key_t key = { ent->dev, ent->inode };
+	rbtree_node_t *tn;
+
+	if (S_ISDIR(ent->mode))
+		return NULL;
+
+	tn = rbtree_lookup(&(it->inumtree), &key);
+	if (tn == NULL)
+		return NULL;
+
+	return *((const char **)rbtree_node_value(tn));
+}
+
+static int store_hard_link(hl_iterator_t *it,
+			   const sqfs_dir_entry_t *ent)
+{
+	inumtree_key_t key = { ent->dev, ent->inode };
+	char *target;
+	int ret;
+
+	if (S_ISDIR(ent->mode) || (ent->flags & SQFS_DIR_ENTRY_FLAG_HARD_LINK))
+		return 0;
+
+	target = strdup(ent->name);
+	if (target == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	ret = rbtree_insert(&(it->inumtree), &key, &target);
+	if (ret != 0)
+		free(target);
+
+	return ret;
+}
+
+static void remove_links(rbtree_node_t *n)
+{
+	if (n != NULL) {
+		char **lnk = rbtree_node_value(n);
+		free(*lnk);
+		*lnk = NULL;
+
+		remove_links(n->left);
+		remove_links(n->right);
+	}
+}
+
+/*****************************************************************************/
+
+static void destroy(sqfs_object_t *obj)
+{
+	hl_iterator_t *it = (hl_iterator_t *)obj;
+
+	remove_links(it->inumtree.root);
+	rbtree_cleanup(&it->inumtree);
+	sqfs_drop(it->src);
+	free(it);
+}
+
+static int next(sqfs_dir_iterator_t *base, sqfs_dir_entry_t **out)
+{
+	hl_iterator_t *it = (hl_iterator_t *)base;
+	int ret;
+
+	if (it->state != 0) {
+		*out = NULL;
+		return it->state;
+	}
+
+	ret = it->src->next(it->src, out);
+	if (ret != 0) {
+		*out = NULL;
+		it->link_target = NULL;
+		it->state = ret;
+		return ret;
+	}
+
+	it->link_target = detect_hard_link(it, *out);
+
+	if (it->link_target == NULL) {
+		ret = store_hard_link(it, *out);
+		if (ret != 0) {
+			it->state = ret;
+			sqfs_free(*out);
+			*out = NULL;
+		}
+	} else {
+		(*out)->mode = SQFS_INODE_MODE_LNK | 0777;
+		(*out)->flags |= SQFS_DIR_ENTRY_FLAG_HARD_LINK;
+	}
+
+	return ret;
+}
+
+static int read_link(sqfs_dir_iterator_t *base, char **out)
+{
+	hl_iterator_t *it = (hl_iterator_t *)base;
+
+	if (it->link_target != NULL) {
+		*out = strdup(it->link_target);
+		if (*out == NULL)
+			return SQFS_ERROR_ALLOC;
+		return 0;
+	}
+
+	if (it->state != 0)
+		return SQFS_ERROR_NO_ENTRY;
+
+	return it->src->read_link(it->src, out);
+}
+
+static int open_subdir(sqfs_dir_iterator_t *base, sqfs_dir_iterator_t **out)
+{
+	hl_iterator_t *it = (hl_iterator_t *)base;
+
+	if (it->link_target != NULL) {
+		*out = NULL;
+		return SQFS_ERROR_NOT_DIR;
+	}
+
+	if (it->state != 0)
+		return SQFS_ERROR_NO_ENTRY;
+
+	return it->src->open_subdir(it->src, out);
+}
+
+static void ignore_subdir(sqfs_dir_iterator_t *base)
+{
+	hl_iterator_t *it = (hl_iterator_t *)base;
+
+	if (it->link_target == NULL && it->state == 0)
+		it->src->ignore_subdir(it->src);
+}
+
+static int open_file_ro(sqfs_dir_iterator_t *base, sqfs_istream_t **out)
+{
+	hl_iterator_t *it = (hl_iterator_t *)base;
+
+	if (it->link_target != NULL) {
+		*out = NULL;
+		return SQFS_ERROR_NOT_FILE;
+	}
+
+	if (it->state != 0)
+		return SQFS_ERROR_NO_ENTRY;
+
+	return it->src->open_file_ro(it->src, out);
+}
+
+static int read_xattr(sqfs_dir_iterator_t *base, sqfs_xattr_t **out)
+{
+	hl_iterator_t *it = (hl_iterator_t *)base;
+
+	if (it->link_target != NULL) {
+		*out = NULL;
+		return 0;
+	}
+
+	if (it->state != 0)
+		return SQFS_ERROR_NO_ENTRY;
+
+	return it->src->read_xattr(it->src, out);
+}
+
+int sqfs_hard_link_filter_create(sqfs_dir_iterator_t **out,
+				 sqfs_dir_iterator_t *base)
+{
+	hl_iterator_t *it;
+	int ret;
+
+	*out = NULL;
+
+	it = calloc(1, sizeof(*it));
+	if (it == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	ret = rbtree_init(&it->inumtree, sizeof(inumtree_key_t),
+			  sizeof(char *), compare_inum);
+	if (ret != 0) {
+		free(it);
+		return ret;
+	}
+
+	sqfs_object_init(it, destroy, NULL);
+	((sqfs_dir_iterator_t *)it)->next = next;
+	((sqfs_dir_iterator_t *)it)->read_link = read_link;
+	((sqfs_dir_iterator_t *)it)->open_subdir = open_subdir;
+	((sqfs_dir_iterator_t *)it)->ignore_subdir = ignore_subdir;
+	((sqfs_dir_iterator_t *)it)->open_file_ro = open_file_ro;
+	((sqfs_dir_iterator_t *)it)->read_xattr = read_xattr;
+
+	it->src = sqfs_grab(base);
+
+	*out = (sqfs_dir_iterator_t *)it;
+	return 0;
+}