libsquashfs: Add utility functions to read xattrs into list

The common pattern is used in rdsquashfs and sqfs2tar, move the code
to libsquashfs.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

8 files changed, 236 insertions, 166 deletions

diff --git a/bin/rdsquashfs/src/dump_xattrs.c b/bin/rdsquashfs/src/dump_xattrs.c
index 9dbe437..93f3635 100644
--- a/bin/rdsquashfs/src/dump_xattrs.c
+++ b/bin/rdsquashfs/src/dump_xattrs.c
@@ -63,58 +63,37 @@ static bool is_printable(const sqfs_u8 *value, size_t len)
 
 int dump_xattrs(sqfs_xattr_reader_t *xattr, const sqfs_inode_generic_t *inode)
 {
-	sqfs_xattr_value_t *value;
-	sqfs_xattr_entry_t *key;
-	sqfs_xattr_id_t desc;
+	sqfs_xattr_t *list;
 	sqfs_u32 index;
-	size_t i;
 
 	if (xattr == NULL)
 		return 0;
 
 	sqfs_inode_get_xattr_index(inode, &index);
 
-	if (index == 0xFFFFFFFF)
-		return 0;
-
-	if (sqfs_xattr_reader_get_desc(xattr, index, &desc)) {
-		fputs("Error resolving xattr index\n", stderr);
+	if (sqfs_xattr_reader_read_all(xattr, index, &list)) {
+		fprintf(stderr, "Error loading xattr entries list #%08X\n",
+			index);
 		return -1;
 	}
 
-	if (sqfs_xattr_reader_seek_kv(xattr, &desc)) {
-		fputs("Error locating xattr key-value pairs\n", stderr);
-		return -1;
-	}
+	for (const sqfs_xattr_t *ent = list; ent != NULL; ent = ent->next) {
+		size_t key_len = strlen(ent->key);
 
-	for (i = 0; i < desc.count; ++i) {
-		if (sqfs_xattr_reader_read_key(xattr, &key)) {
-			fputs("Error reading xattr key\n", stderr);
-			return -1;
-		}
-
-		if (sqfs_xattr_reader_read_value(xattr, key, &value)) {
-			fputs("Error reading xattr value\n", stderr);
-			sqfs_free(key);
-			return -1;
-		}
-
-		if (is_printable(key->key, key->size)) {
-			printf("%s=", key->key);
+		if (is_printable((const sqfs_u8 *)ent->key, key_len)) {
+			printf("%s=", ent->key);
 		} else {
-			print_hex(key->key, key->size);
+			print_hex((const sqfs_u8 *)ent->key, key_len);
 		}
 
-		if (is_printable(value->value, value->size)) {
-			printf("%s\n", value->value);
+		if (is_printable(ent->value, ent->value_len)) {
+			printf("%s\n", ent->value);
 		} else {
-			print_hex(value->value, value->size);
+			print_hex(ent->value, ent->value_len);
 			printf("\n");
 		}
-
-		sqfs_free(key);
-		sqfs_free(value);
 	}
 
+	sqfs_xattr_list_free(list);
 	return 0;
 }
diff --git a/bin/rdsquashfs/src/rdsquashfs.h b/bin/rdsquashfs/src/rdsquashfs.h
index f9f75e9..364af14 100644
--- a/bin/rdsquashfs/src/rdsquashfs.h
+++ b/bin/rdsquashfs/src/rdsquashfs.h
@@ -10,6 +10,7 @@
 #include "config.h"
 #include "common.h"
 #include "util/util.h"
+#include "sqfs/xattr.h"
 
 #ifdef _WIN32
 #define WIN32_LEAN_AND_MEAN
diff --git a/bin/sqfs2tar/Makemodule.am b/bin/sqfs2tar/Makemodule.am
index 2e6c411..9f7abf9 100644
--- a/bin/sqfs2tar/Makemodule.am
+++ b/bin/sqfs2tar/Makemodule.am
@@ -1,6 +1,5 @@
 sqfs2tar_SOURCES = bin/sqfs2tar/src/sqfs2tar.c bin/sqfs2tar/src/sqfs2tar.h \
-	bin/sqfs2tar/src/options.c bin/sqfs2tar/src/write_tree.c \
-	bin/sqfs2tar/src/xattr.c
+	bin/sqfs2tar/src/options.c bin/sqfs2tar/src/write_tree.c
 sqfs2tar_CFLAGS = $(AM_CFLAGS) $(PTHREAD_CFLAGS)
 sqfs2tar_LDADD = libcommon.a libutil.a libsquashfs.la libtar.a
 sqfs2tar_LDADD += libio.a libxfrm.a libcompat.a libfstree.a
diff --git a/bin/sqfs2tar/src/sqfs2tar.h b/bin/sqfs2tar/src/sqfs2tar.h
index 3c7b3d1..e176008 100644
--- a/bin/sqfs2tar/src/sqfs2tar.h
+++ b/bin/sqfs2tar/src/sqfs2tar.h
@@ -46,10 +46,6 @@ extern ostream_t *out_file;
 
 char *assemble_tar_path(char *name, bool is_dir);
 
-/* xattr.c */
-int get_xattrs(const char *name, const sqfs_inode_generic_t *inode,
-	       sqfs_xattr_t **out);
-
 /* write_tree.c */
 int write_tree(const sqfs_tree_node_t *n);
 
diff --git a/bin/sqfs2tar/src/write_tree.c b/bin/sqfs2tar/src/write_tree.c
index 71eb249..e578a9f 100644
--- a/bin/sqfs2tar/src/write_tree.c
+++ b/bin/sqfs2tar/src/write_tree.c
@@ -124,8 +124,15 @@ static int write_tree_dfs(const sqfs_tree_node_t *n)
 		}
 	}
 
-	if (!no_xattr) {
-		if (get_xattrs(name, n->inode, &xattr)) {
+	if (!no_xattr && xr != NULL) {
+		sqfs_u32 index;
+		int ret;
+
+		sqfs_inode_get_xattr_index(n->inode, &index);
+
+		ret = sqfs_xattr_reader_read_all(xr, index, &xattr);
+		if (ret) {
+			sqfs_perror(name, "resolving xattr index", ret);
 			sqfs_free(name);
 			return -1;
 		}
diff --git a/bin/sqfs2tar/src/xattr.c b/bin/sqfs2tar/src/xattr.c
deleted file mode 100644
index 2af856d..0000000
--- a/bin/sqfs2tar/src/xattr.c
+++ /dev/null
@@ -1,84 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * xattr.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "sqfs2tar.h"
-
-static sqfs_xattr_t *mkxattr(const sqfs_xattr_entry_t *key,
-			     const sqfs_xattr_value_t *value)
-{
-	sqfs_xattr_t *ent;
-
-	ent = sqfs_xattr_create((const char *)key->key,
-				value->value, value->size);
-	if (ent == NULL) {
-		perror("creating xattr entry");
-		return NULL;
-	}
-
-	return ent;
-}
-
-int get_xattrs(const char *name, const sqfs_inode_generic_t *inode,
-	       sqfs_xattr_t **out)
-{
-	sqfs_xattr_t *list = NULL, *ent;
-	sqfs_xattr_value_t *value;
-	sqfs_xattr_entry_t *key;
-	sqfs_xattr_id_t desc;
-	sqfs_u32 index;
-	size_t i;
-	int ret;
-
-	if (xr == NULL)
-		return 0;
-
-	sqfs_inode_get_xattr_index(inode, &index);
-	if (index == 0xFFFFFFFF)
-		return 0;
-
-	ret = sqfs_xattr_reader_get_desc(xr, index, &desc);
-	if (ret) {
-		sqfs_perror(name, "resolving xattr index", ret);
-		return -1;
-	}
-
-	ret = sqfs_xattr_reader_seek_kv(xr, &desc);
-	if (ret) {
-		sqfs_perror(name, "locating xattr key-value pairs", ret);
-		return -1;
-	}
-
-	for (i = 0; i < desc.count; ++i) {
-		ret = sqfs_xattr_reader_read_key(xr, &key);
-		if (ret) {
-			sqfs_perror(name, "reading xattr key", ret);
-			goto fail;
-		}
-
-		ret = sqfs_xattr_reader_read_value(xr, key, &value);
-		if (ret) {
-			sqfs_perror(name, "reading xattr value", ret);
-			sqfs_free(key);
-			goto fail;
-		}
-
-		ent = mkxattr(key, value);
-		sqfs_free(key);
-		sqfs_free(value);
-
-		if (ent == NULL)
-			goto fail;
-
-		ent->next = list;
-		list = ent;
-	}
-
-	*out = list;
-	return 0;
-fail:
-	sqfs_xattr_list_free(list);
-	return -1;
-}
diff --git a/include/sqfs/xattr_reader.h b/include/sqfs/xattr_reader.h
index a0242fb..2c65afa 100644
--- a/include/sqfs/xattr_reader.h
+++ b/include/sqfs/xattr_reader.h
@@ -190,6 +190,42 @@ int sqfs_xattr_reader_read_value(sqfs_xattr_reader_t *xr,
 				 const sqfs_xattr_entry_t *key,
 				 sqfs_xattr_value_t **val_out);
 
+/**
+ * @brief Read a combined key-value pair into an @ref sqfs_xattr_t struct
+ *
+ * @memberof sqfs_xattr_reader_t
+ *
+ * @param xr A pointer to an xattr reader instance.
+ * @param out Returns a pointer to a combined key-value struct.
+ *
+ * @return Zero on success, a negative @ref SQFS_ERROR value on failure.
+ */
+SQFS_API
+int sqfs_xattr_reader_read(sqfs_xattr_reader_t *xr, sqfs_xattr_t **out);
+
+/**
+ * @brief Read all xattrs associated with an ID into memory
+ *
+ * @memberof sqfs_xattr_reader_t
+ *
+ * This is a convenience function that internally resolves the xattr index
+ * using @ref sqfs_xattr_reader_get_desc, seeks to the key-value list using
+ * @ref sqfs_xattr_reader_seek_kv and reads all the entries into a liked
+ * list of @ref sqfs_xattr_t structs.
+ *
+ * If the index is the special value 0xFFFFFFFF, the function successfully
+ * returns an empty list.
+ *
+ * @param xr A pointer to an xattr reader instance.
+ * @param idx An xattr index.
+ * @param out Returns a linked list to key-value pairs on success.
+ *
+ * @return Zero on success, a negative @ref SQFS_ERROR value on failure.
+ */
+SQFS_API int sqfs_xattr_reader_read_all(sqfs_xattr_reader_t *xr, sqfs_u32 idx,
+					sqfs_xattr_t **out);
+
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/sqfs/src/xattr/xattr_reader.c b/lib/sqfs/src/xattr/xattr_reader.c
index 9e3ea76..1c8ea37 100644
--- a/lib/sqfs/src/xattr/xattr_reader.c
+++ b/lib/sqfs/src/xattr/xattr_reader.c
@@ -166,6 +166,66 @@ fail_blocks:
 	return err;
 }
 
+static int read_key_hdr(sqfs_xattr_reader_t *xr, sqfs_xattr_entry_t *key,
+			const char **prefix)
+{
+	int ret;
+
+	ret = sqfs_meta_reader_read(xr->kvrd, key, sizeof(*key));
+	if (ret)
+		return ret;
+
+	key->type = le16toh(key->type);
+	key->size = le16toh(key->size);
+
+	*prefix = sqfs_get_xattr_prefix(key->type & SQFS_XATTR_PREFIX_MASK);
+	if ((*prefix) == NULL)
+		return SQFS_ERROR_UNSUPPORTED;
+
+	return 0;
+}
+
+static int read_value_hdr(sqfs_xattr_reader_t *xr,
+			  const sqfs_xattr_entry_t *key, sqfs_u64 *start,
+			  size_t *offset, sqfs_xattr_value_t *value)
+{
+	sqfs_u64 ref, new_start;
+	size_t new_offset;
+	int ret;
+
+	ret = sqfs_meta_reader_read(xr->kvrd, value, sizeof(*value));
+	if (ret)
+		return ret;
+
+	if (key->type & SQFS_XATTR_FLAG_OOL) {
+		ret = sqfs_meta_reader_read(xr->kvrd, &ref, sizeof(ref));
+		if (ret)
+			return ret;
+
+		ref = le64toh(ref);
+		new_start = xr->xattr_start + (ref >> 16);
+		new_offset = ref & 0xFFFF;
+
+		if (new_start >= xr->xattr_end ||
+		    new_offset >= SQFS_META_BLOCK_SIZE) {
+			return SQFS_ERROR_OUT_OF_BOUNDS;
+		}
+
+		sqfs_meta_reader_get_position(xr->kvrd, start, offset);
+
+		ret = sqfs_meta_reader_seek(xr->kvrd, new_start, new_offset);
+		if (ret)
+			return ret;
+
+		ret = sqfs_meta_reader_read(xr->kvrd, value, sizeof(*value));
+		if (ret)
+			return ret;
+	}
+
+	value->size = le32toh(value->size);
+	return 0;
+}
+
 int sqfs_xattr_reader_read_key(sqfs_xattr_reader_t *xr,
 			       sqfs_xattr_entry_t **key_out)
 {
@@ -174,17 +234,10 @@ int sqfs_xattr_reader_read_key(sqfs_xattr_reader_t *xr,
 	size_t plen, total;
 	int ret;
 
-	ret = sqfs_meta_reader_read(xr->kvrd, &key, sizeof(key));
+	ret = read_key_hdr(xr, &key, &prefix);
 	if (ret)
 		return ret;
 
-	key.type = le16toh(key.type);
-	key.size = le16toh(key.size);
-
-	prefix = sqfs_get_xattr_prefix(key.type & SQFS_XATTR_PREFIX_MASK);
-	if (prefix == NULL)
-		return SQFS_ERROR_UNSUPPORTED;
-
 	plen = strlen(prefix);
 
 	if (SZ_ADD_OV(plen, key.size, &total) || SZ_ADD_OV(total, 1, &total) ||
@@ -213,66 +266,107 @@ int sqfs_xattr_reader_read_value(sqfs_xattr_reader_t *xr,
 				 const sqfs_xattr_entry_t *key,
 				 sqfs_xattr_value_t **val_out)
 {
-	size_t offset, new_offset, size;
-	sqfs_xattr_value_t value, *out;
-	sqfs_u64 ref, start, new_start;
+	sqfs_xattr_value_t value, *out = NULL;
+	size_t size, offset = 0;
+	sqfs_u64 start = 0;
 	int ret;
 
-	ret = sqfs_meta_reader_read(xr->kvrd, &value, sizeof(value));
+	ret = read_value_hdr(xr, key, &start, &offset, &value);
 	if (ret)
 		return ret;
 
-	if (key->type & SQFS_XATTR_FLAG_OOL) {
-		ret = sqfs_meta_reader_read(xr->kvrd, &ref, sizeof(ref));
-		if (ret)
-			return ret;
-
-		sqfs_meta_reader_get_position(xr->kvrd, &start, &offset);
+	size = sizeof(*out) + 1;
+	if (SZ_ADD_OV(size, value.size, &size))
+		return SQFS_ERROR_OVERFLOW;
 
-		new_start = xr->xattr_start + (ref >> 16);
-		if (new_start >= xr->xattr_end)
-			return SQFS_ERROR_OUT_OF_BOUNDS;
+	out = calloc(1, size);
+	if (out == NULL)
+		return SQFS_ERROR_ALLOC;
 
-		new_offset = ref & 0xFFFF;
-		if (new_offset >= SQFS_META_BLOCK_SIZE)
-			return SQFS_ERROR_OUT_OF_BOUNDS;
+	*out = value;
 
-		ret = sqfs_meta_reader_seek(xr->kvrd, new_start, new_offset);
-		if (ret)
-			return ret;
+	ret = sqfs_meta_reader_read(xr->kvrd, out->value, value.size);
+	if (ret)
+		goto fail;
 
-		ret = sqfs_meta_reader_read(xr->kvrd, &value, sizeof(value));
+	if (key->type & SQFS_XATTR_FLAG_OOL) {
+		ret = sqfs_meta_reader_seek(xr->kvrd, start, offset);
 		if (ret)
-			return ret;
+			goto fail;
 	}
 
-	value.size = le32toh(value.size);
+	*val_out = out;
+	return 0;
+fail:
+	free(out);
+	return ret;
+}
+
+int sqfs_xattr_reader_read(sqfs_xattr_reader_t *xr, sqfs_xattr_t **out)
+{
+	sqfs_xattr_t *kv = NULL, *new = NULL;
+	size_t plen, total = 0, offset = 0;
+	sqfs_xattr_value_t value;
+	sqfs_xattr_entry_t key;
+	const char *prefix;
+	sqfs_u64 start = 0;
+	int ret;
 
-	if (SZ_ADD_OV(sizeof(*out), value.size, &size) ||
-	    SZ_ADD_OV(size, 1, &size)) {
+	/* read and decode the key */
+	ret = read_key_hdr(xr, &key, &prefix);
+	if (ret)
+		return ret;
+
+	plen = strlen(prefix);
+	total = sizeof(*kv) + plen + 1;
+
+	if (SZ_ADD_OV(total, key.size, &total))
 		return SQFS_ERROR_OVERFLOW;
-	}
 
-	out = calloc(1, size);
-	if (out == NULL)
+	kv = calloc(1, total);
+	if (kv == NULL)
 		return SQFS_ERROR_ALLOC;
 
-	*out = value;
+	memcpy(kv->data, prefix, plen);
+	ret = sqfs_meta_reader_read(xr->kvrd, kv->data + plen, key.size);
+	if (ret)
+		goto fail;
 
-	ret = sqfs_meta_reader_read(xr->kvrd, out->value, value.size);
+	/* read and decode the value */
+	ret = read_value_hdr(xr, &key, &start, &offset, &value);
 	if (ret)
 		goto fail;
 
-	if (key->type & SQFS_XATTR_FLAG_OOL) {
+	ret = SQFS_ERROR_OVERFLOW;
+	if (SZ_ADD_OV(total, value.size, &total) || SZ_ADD_OV(total, 1, &total))
+		goto fail;
+
+	ret = SQFS_ERROR_ALLOC;
+	new = realloc(kv, total);
+	if (new == NULL)
+		goto fail;
+	kv = new;
+
+	ret = sqfs_meta_reader_read(xr->kvrd, kv->data + plen + key.size + 1,
+				    value.size);
+	if (ret)
+		goto fail;
+
+	if (key.type & SQFS_XATTR_FLAG_OOL) {
 		ret = sqfs_meta_reader_seek(xr->kvrd, start, offset);
 		if (ret)
 			goto fail;
 	}
 
-	*val_out = out;
+	/* prefix with the kv struct */
+	kv->value_len = value.size;
+	kv->key = (const char *)kv->data;
+	kv->value = kv->data + plen + key.size + 1;
+	kv->data[plen + key.size + 1 + value.size] = '\0';
+	*out = kv;
 	return 0;
 fail:
-	free(out);
+	free(kv);
 	return ret;
 }
 
@@ -320,6 +414,48 @@ int sqfs_xattr_reader_get_desc(sqfs_xattr_reader_t *xr, sqfs_u32 idx,
 	return 0;
 }
 
+int sqfs_xattr_reader_read_all(sqfs_xattr_reader_t *xr, sqfs_u32 idx,
+			       sqfs_xattr_t **out)
+{
+	sqfs_xattr_t *head = NULL, *tail = NULL;
+	sqfs_xattr_id_t desc;
+	int ret;
+
+	*out = NULL;
+	if (idx == 0xFFFFFFFF)
+		return 0;
+
+	ret = sqfs_xattr_reader_get_desc(xr, idx, &desc);
+	if (ret)
+		return ret;
+
+	ret = sqfs_xattr_reader_seek_kv(xr, &desc);
+	if (ret)
+		return ret;
+
+	for (size_t i = 0; i < desc.count; ++i) {
+		sqfs_xattr_t *ent;
+
+		ret = sqfs_xattr_reader_read(xr, &ent);
+		if (ret)
+			goto fail;
+
+		if (tail == NULL) {
+			head = ent;
+			tail = ent;
+		} else {
+			tail->next = ent;
+			tail = ent;
+		}
+	}
+
+	*out = head;
+	return 0;
+fail:
+	sqfs_xattr_list_free(head);
+	return ret;
+}
+
 sqfs_xattr_reader_t *sqfs_xattr_reader_create(sqfs_u32 flags)
 {
 	sqfs_xattr_reader_t *xr;