1 files changed, 309 insertions, 0 deletions
diff --git a/lib/xattr.c b/lib/xattr.c
new file mode 100644
index 0000000..d07d325
--- /dev/null
+++ b/lib/xattr.c
@@ -0,0 +1,309 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * erofs_utils/lib/xattr.c
+ *
+ * Originally contributed by an anonymous person,
+ * heavily changed by Li Guifu <blucerlee@gmail.com>
+ *                and Gao Xiang <hsiangkao@aol.com>
+ */
+#include <stdlib.h>
+#include <sys/xattr.h>
+#ifdef HAVE_LINUX_XATTR_H
+#include <linux/xattr.h>
+#endif
+#include "erofs/print.h"
+#include "erofs/hashtable.h"
+#include "erofs/xattr.h"
+
+#define EA_HASHTABLE_BITS 16
+
+struct xattr_item {
+	const char *kvbuf;
+	unsigned int hash[2], len[2], count;
+	u8 prefix;
+	struct hlist_node node;
+};
+
+struct inode_xattr_node {
+	struct list_head list;
+	struct xattr_item *item;
+};
+
+static DECLARE_HASHTABLE(ea_hashtable, EA_HASHTABLE_BITS);
+
+static struct xattr_prefix {
+	const char *prefix;
+	u16 prefix_len;
+} xattr_types[] = {
+	[EROFS_XATTR_INDEX_USER] = {
+		XATTR_USER_PREFIX,
+		XATTR_USER_PREFIX_LEN
+	}, [EROFS_XATTR_INDEX_POSIX_ACL_ACCESS] = {
+		XATTR_NAME_POSIX_ACL_ACCESS,
+		sizeof(XATTR_NAME_POSIX_ACL_ACCESS) - 1
+	}, [EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT] = {
+		XATTR_NAME_POSIX_ACL_DEFAULT,
+		sizeof(XATTR_NAME_POSIX_ACL_DEFAULT) - 1
+	}, [EROFS_XATTR_INDEX_TRUSTED] = {
+		XATTR_TRUSTED_PREFIX,
+		XATTR_TRUSTED_PREFIX_LEN
+	}, [EROFS_XATTR_INDEX_SECURITY] = {
+		XATTR_SECURITY_PREFIX,
+		XATTR_SECURITY_PREFIX_LEN
+	}
+};
+
+static unsigned int BKDRHash(char *str, unsigned int len)
+{
+	const unsigned int seed = 131313;
+	unsigned int hash = 0;
+
+	while (len) {
+		hash = hash * seed + (*str++);
+		--len;
+	}
+	return hash;
+}
+
+static unsigned int xattr_item_hash(u8 prefix, char *buf,
+				    unsigned int len[2], unsigned int hash[2])
+{
+	hash[0] = BKDRHash(buf, len[0]);	/* key */
+	hash[1] = BKDRHash(buf + len[0], len[1]);	/* value */
+
+	return prefix ^ hash[0] ^ hash[1];
+}
+
+static unsigned int put_xattritem(struct xattr_item *item)
+{
+	if (item->count > 1)
+		return --item->count;
+	free(item);
+	return 0;
+}
+
+static struct xattr_item *get_xattritem(u8 prefix, char *kvbuf,
+					unsigned int len[2])
+{
+	struct xattr_item *item;
+	unsigned int hash[2], hkey;
+
+	hkey = xattr_item_hash(prefix, kvbuf, len, hash);
+
+	hash_for_each_possible(ea_hashtable, item, node, hkey) {
+		if (prefix == item->prefix &&
+		    item->len[0] == len[0] && item->len[1] == len[1] &&
+		    item->hash[0] == hash[0] && item->hash[1] == hash[1] &&
+		    !memcmp(kvbuf, item->kvbuf, len[0] + len[1])) {
+			free(kvbuf);
+			++item->count;
+			return item;
+		}
+	}
+
+	item = malloc(sizeof(*item));
+	if (!item) {
+		free(kvbuf);
+		return ERR_PTR(-ENOMEM);
+	}
+	INIT_HLIST_NODE(&item->node);
+	item->count = 1;
+	item->kvbuf = kvbuf;
+	item->len[0] = len[0];
+	item->len[1] = len[1];
+	item->hash[0] = hash[0];
+	item->hash[1] = hash[1];
+	item->prefix = prefix;
+	hash_add(ea_hashtable, &item->node, hkey);
+	return item;
+}
+
+static bool match_prefix(const char *key, u8 *index, u16 *len)
+{
+	struct xattr_prefix *p;
+
+	for (p = xattr_types; p < xattr_types + ARRAY_SIZE(xattr_types); ++p) {
+		if (p->prefix && !strncmp(p->prefix, key, p->prefix_len)) {
+			*len = p->prefix_len;
+			*index = p - xattr_types;
+			return true;
+		}
+	}
+	return false;
+}
+
+static struct xattr_item *parse_one_xattr(const char *path, const char *key,
+					  unsigned int keylen)
+{
+	ssize_t ret;
+	u8 prefix;
+	u16 prefixlen;
+	unsigned int len[2];
+	char *kvbuf;
+
+	erofs_dbg("parse xattr [%s] of %s", path, key);
+
+	if (!match_prefix(key, &prefix, &prefixlen))
+		return ERR_PTR(-ENODATA);
+
+	DBG_BUGON(keylen < prefixlen);
+
+	/* determine length of the value */
+	ret = lgetxattr(path, key, NULL, 0);
+	if (ret < 0)
+		return ERR_PTR(-errno);
+	len[1] = ret;
+
+	/* allocate key-value buffer */
+	len[0] = keylen - prefixlen;
+
+	kvbuf = malloc(len[0] + len[1]);
+	if (!kvbuf)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(kvbuf, key + prefixlen, len[0]);
+	if (len[1]) {
+		/* copy value to buffer */
+		ret = lgetxattr(path, key, kvbuf + len[0], len[1]);
+		if (ret < 0) {
+			free(kvbuf);
+			return ERR_PTR(-errno);
+		}
+		if (len[1] != ret) {
+			erofs_err("size of xattr value got changed just now (%u-> %ld)",
+				  len[1], (long)ret);
+			len[1] = ret;
+		}
+	}
+	return get_xattritem(prefix, kvbuf, len);
+}
+
+static int inode_xattr_add(struct list_head *hlist, struct xattr_item *item)
+{
+	struct inode_xattr_node *node = malloc(sizeof(*node));
+
+	if (!node)
+		return -ENOMEM;
+	init_list_head(&node->list);
+	node->item = item;
+	list_add(&node->list, hlist);
+	return 0;
+}
+
+static int read_xattrs_from_file(const char *path, struct list_head *ixattrs)
+{
+	int ret = 0;
+	char *keylst, *key;
+	ssize_t kllen = llistxattr(path, NULL, 0);
+
+	if (kllen < 0 && errno != ENODATA) {
+		erofs_err("llistxattr to get the size of names for %s failed",
+			  path);
+		return -errno;
+	}
+	if (kllen <= 1)
+		return 0;
+
+	keylst = malloc(kllen);
+	if (!keylst)
+		return -ENOMEM;
+
+	/* copy the list of attribute keys to the buffer.*/
+	kllen = llistxattr(path, keylst, kllen);
+	if (kllen < 0) {
+		erofs_err("llistxattr to get names for %s failed", path);
+		ret = -errno;
+		goto err;
+	}
+
+	/*
+	 * loop over the list of zero terminated strings with the
+	 * attribute keys. Use the remaining buffer length to determine
+	 * the end of the list.
+	 */
+	key = keylst;
+	while (kllen > 0) {
+		unsigned int keylen = strlen(key);
+		struct xattr_item *item = parse_one_xattr(path, key, keylen);
+
+		if (IS_ERR(item)) {
+			ret = PTR_ERR(item);
+			goto err;
+		}
+
+		if (ixattrs) {
+			ret = inode_xattr_add(ixattrs, item);
+			if (ret < 0)
+				goto err;
+		}
+		kllen -= keylen + 1;
+		key += keylen + 1;
+	}
+err:
+	free(keylst);
+	return ret;
+
+}
+
+int erofs_prepare_xattr_ibody(const char *path, struct list_head *ixattrs)
+{
+	int ret;
+	struct inode_xattr_node *node;
+
+	/* check if xattr is disabled */
+	if (cfg.c_inline_xattr_tolerance < 0)
+		return 0;
+
+	ret = read_xattrs_from_file(path, ixattrs);
+	if (ret < 0)
+		return ret;
+
+	if (list_empty(ixattrs))
+		return 0;
+
+	/* get xattr ibody size */
+	ret = sizeof(struct erofs_xattr_ibody_header);
+	list_for_each_entry(node, ixattrs, list) {
+		const struct xattr_item *item = node->item;
+
+		ret += sizeof(struct erofs_xattr_entry);
+		ret = EROFS_XATTR_ALIGN(ret + item->len[0] + item->len[1]);
+	}
+	return ret;
+}
+
+char *erofs_export_xattr_ibody(struct list_head *ixattrs, unsigned int size)
+{
+	struct inode_xattr_node *node, *n;
+	struct erofs_xattr_ibody_header *header;
+	unsigned int p;
+	char *buf = calloc(1, size);
+
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	header = (struct erofs_xattr_ibody_header *)buf;
+	header->h_shared_count = 0;
+
+	p = sizeof(struct erofs_xattr_ibody_header);
+	list_for_each_entry_safe(node, n, ixattrs, list) {
+		struct xattr_item *const item = node->item;
+		const struct erofs_xattr_entry entry = {
+			.e_name_index = item->prefix,
+			.e_name_len = item->len[0],
+			.e_value_size = cpu_to_le16(item->len[1])
+		};
+
+		memcpy(buf + p, &entry, sizeof(entry));
+		p += sizeof(struct erofs_xattr_entry);
+		memcpy(buf + p, item->kvbuf, item->len[0] + item->len[1]);
+		p = EROFS_XATTR_ALIGN(p + item->len[0] + item->len[1]);
+
+		list_del(&node->list);
+		free(node);
+		put_xattritem(item);
+	}
+	DBG_BUGON(p > size);
+	return buf;
+}
+