Generate extended attribute table

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

1 files changed, 198 insertions, 0 deletions

diff --git a/mkfs/xattr.c b/mkfs/xattr.c
new file mode 100644
index 0000000..8f1a816
--- /dev/null
+++ b/mkfs/xattr.c
@@ -0,0 +1,198 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "meta_writer.h"
+#include "mkfs.h"
+#include "util.h"
+
+#include <assert.h>
+
+static const struct {
+	const char *prefix;
+	E_SQFS_XATTR_TYPE type;
+} xattr_types[] = {
+	{ "user.", SQUASHFS_XATTR_USER },
+	{ "trusted.", SQUASHFS_XATTR_TRUSTED },
+	{ "security.", SQUASHFS_XATTR_SECURITY },
+};
+
+static int get_prefix(const char *key)
+{
+	size_t i, len;
+
+	for (i = 0; i < sizeof(xattr_types) / sizeof(xattr_types[0]); ++i) {
+		len = strlen(xattr_types[i].prefix);
+
+		if (strncmp(key, xattr_types[i].prefix, len) == 0 &&
+		    strlen(key) > len) {
+			return xattr_types[i].type;
+		}
+	}
+
+	fprintf(stderr, "unknown xattr key '%s'\n", key);
+	return -1;
+}
+
+static int write_pair(meta_writer_t *mw, const char *key, const char *value)
+{
+	sqfs_xattr_entry_t kent;
+	sqfs_xattr_value_t vent;
+	int type;
+
+	type = get_prefix(key);
+	if (type < 0)
+		return -1;
+
+	key = strchr(key, '.');
+	assert(key != NULL);
+	++key;
+
+	kent.type = htole16(type);
+	kent.size = htole16(strlen(key));
+
+	if (meta_writer_append(mw, &kent, sizeof(kent)))
+		return -1;
+	if (meta_writer_append(mw, key, strlen(key)))
+		return -1;
+
+	vent.size = htole32(strlen(value));
+
+	if (meta_writer_append(mw, &vent, sizeof(vent)))
+		return -1;
+	if (meta_writer_append(mw, value, strlen(value)))
+		return -1;
+
+	return 0;
+}
+
+static int write_kv_pairs(sqfs_info_t *info, meta_writer_t *mw,
+			  tree_xattr_t *xattr)
+{
+	uint32_t key_idx, val_idx;
+	const char *key, *value;
+	size_t i;
+
+	for (i = 0; i < xattr->num_attr; ++i) {
+		key_idx = (xattr->ref[i] >> 32) & 0xFFFFFFFF;
+		val_idx = xattr->ref[i] & 0xFFFFFFFF;
+
+		key = str_table_get_string(&info->fs.xattr_keys, key_idx);
+		value = str_table_get_string(&info->fs.xattr_values, val_idx);
+
+		if (write_pair(mw, key, value))
+			return -1;
+
+		xattr->size += sizeof(sqfs_xattr_entry_t) + strlen(key);
+		xattr->size += sizeof(sqfs_xattr_value_t) + strlen(value);
+	}
+
+	return 0;
+}
+
+int write_xattr(sqfs_info_t *info)
+{
+	uint64_t kv_start, id_start, *tbl;
+	size_t i = 0, count = 0, blocks;
+	sqfs_xattr_id_table_t idtbl;
+	sqfs_xattr_id_t id_ent;
+	meta_writer_t *mw;
+	tree_xattr_t *it;
+	ssize_t ret;
+
+	if (info->fs.xattr == NULL)
+		return 0;
+
+	mw = meta_writer_create(info->outfd, info->cmp);
+	if (mw == NULL)
+		return -1;
+
+	/* write xattr key-value pairs */
+	kv_start = info->super.bytes_used;
+
+	for (it = info->fs.xattr; it != NULL; it = it->next) {
+		it->block = mw->block_offset;
+		it->offset = mw->offset;
+		it->size = 0;
+
+		if (write_kv_pairs(info, mw, it))
+			goto fail_mw;
+
+		++count;
+	}
+
+	if (meta_writer_flush(mw))
+		goto fail_mw;
+
+	info->super.bytes_used += mw->block_offset;
+	mw->block_offset = 0;
+
+	/* allocate location table */
+	blocks = (count * sizeof(id_ent)) / SQFS_META_BLOCK_SIZE;
+
+	if ((count * sizeof(id_ent)) % SQFS_META_BLOCK_SIZE)
+		++blocks;
+
+	tbl = calloc(sizeof(uint64_t), blocks);
+
+	if (tbl == NULL) {
+		perror("generating xattr ID table");
+		goto fail_mw;
+	}
+
+	/* write ID table referring to key value pairs, record offsets */
+	id_start = mw->block_offset;
+	tbl[i++] = htole64(info->super.bytes_used + id_start);
+
+	for (it = info->fs.xattr; it != NULL; it = it->next) {
+		id_ent.xattr = htole64((it->block << 16) | it->offset);
+		id_ent.count = htole32(it->num_attr);
+		id_ent.size = htole32(it->size);
+
+		if (meta_writer_append(mw, &id_ent, sizeof(id_ent)))
+			goto fail_tbl;
+
+		if (mw->block_offset != id_start) {
+			id_start = mw->block_offset;
+			tbl[i++] = htole64(info->super.bytes_used + id_start);
+		}
+	}
+
+	if (meta_writer_flush(mw))
+		goto fail_tbl;
+
+	info->super.bytes_used += mw->block_offset;
+	mw->block_offset = 0;
+
+	/* write offset table */
+	idtbl.xattr_table_start = htole64(kv_start);
+	idtbl.xattr_ids = htole32(count);
+	idtbl.unused = 0;
+
+	ret = write_retry(info->outfd, &idtbl, sizeof(idtbl));
+	if (ret < 0)
+		goto fail_wr;
+	if ((size_t)ret < sizeof(idtbl))
+		goto fail_trunc;
+
+	write_retry(info->outfd, tbl, sizeof(tbl[0]) * blocks);
+	if (ret < 0)
+		goto fail_wr;
+	if ((size_t)ret < sizeof(tbl[0]) * blocks)
+		goto fail_trunc;
+
+	info->super.xattr_id_table_start = info->super.bytes_used;
+	info->super.bytes_used += sizeof(idtbl) + sizeof(tbl[0]) * blocks;
+
+	free(tbl);
+	meta_writer_destroy(mw);
+	return 0;
+fail_wr:
+	perror("writing xattr ID table");
+	goto fail_tbl;
+fail_trunc:
+	fputs("writing xattr ID table: truncated write\n", stderr);
+	goto fail_tbl;
+fail_tbl:
+	free(tbl);
+fail_mw:
+	meta_writer_destroy(mw);
+	return -1;
+}