1 files changed, 57 insertions, 12 deletions

diff --git a/src/shared/btrfs-util.c b/src/shared/btrfs-util.c
index 2ed6bf2..f6055a8 100644
--- a/src/shared/btrfs-util.c
+++ b/src/shared/btrfs-util.c
@@ -262,24 +262,49 @@ static int btrfs_ioctl_search_args_compare(const struct btrfs_ioctl_search_args
 }
 
 typedef struct BtrfsForeachIterator {
-        const void *p;
-        size_t i;
+        const struct btrfs_ioctl_search_args *args;
+        size_t offset;
+        unsigned index;
+        struct btrfs_ioctl_search_header *header;
+        const void **body;
 } BtrfsForeachIterator;
 
+static int btrfs_iterate(BtrfsForeachIterator *i) {
+        assert(i);
+        assert(i->args);
+        assert(i->header);
+        assert(i->body);
+
+        if (i->index >= i->args->key.nr_items)
+                return 0; /* end */
+
+        assert_cc(BTRFS_SEARCH_ARGS_BUFSIZE >= sizeof(struct btrfs_ioctl_search_header));
+        if (i->offset > BTRFS_SEARCH_ARGS_BUFSIZE - sizeof(struct btrfs_ioctl_search_header))
+                return -EBADMSG;
+
+        struct btrfs_ioctl_search_header h;
+        memcpy(&h, (const uint8_t*) i->args->buf + i->offset, sizeof(struct btrfs_ioctl_search_header));
+
+        if (i->offset > BTRFS_SEARCH_ARGS_BUFSIZE - sizeof(struct btrfs_ioctl_search_header) - h.len)
+                return -EBADMSG;
+
+        *i->body = (const uint8_t*) i->args->buf + i->offset + sizeof(struct btrfs_ioctl_search_header);
+        *i->header = h;
+        i->offset += sizeof(struct btrfs_ioctl_search_header) + h.len;
+        i->index++;
+
+        return 1;
+}
+
 /* Iterates through a series of struct btrfs_file_extent_item elements. They are unfortunately not aligned,
  * hence we copy out the header from them */
-#define FOREACH_BTRFS_IOCTL_SEARCH_HEADER(sh, body, args)               \
+#define FOREACH_BTRFS_IOCTL_SEARCH_HEADER(_sh, _body, _args)            \
         for (BtrfsForeachIterator iterator = {                          \
-                        .p = ({                                         \
-                               memcpy(&(sh), (args).buf, sizeof(struct btrfs_ioctl_search_header)); \
-                               (body) = (const void*) ((const uint8_t*) (args).buf + sizeof(struct btrfs_ioctl_search_header)); \
-                               (args).buf;                              \
-                        }),                                             \
+                        .args = &(_args),                               \
+                        .header = &(_sh),                               \
+                        .body = &(_body),                               \
              };                                                         \
-             iterator.i < (args).key.nr_items;                          \
-             iterator.i++,                                              \
-             memcpy(&(sh), iterator.p = (const uint8_t*) iterator.p + sizeof(struct btrfs_ioctl_search_header) + (sh).len, sizeof(struct btrfs_ioctl_search_header)), \
-             (body) = (const void*) ((const uint8_t*) iterator.p + sizeof(struct btrfs_ioctl_search_header)))
+             btrfs_iterate(&iterator) > 0; )
 
 int btrfs_subvol_get_info_fd(int fd, uint64_t subvol_id, BtrfsSubvolInfo *ret) {
         struct btrfs_ioctl_search_args args = {
@@ -1162,6 +1187,8 @@ static int copy_quota_hierarchy(int fd, uint64_t old_subvol_id, uint64_t new_sub
         if (n_old_qgroups <= 0) /* Nothing to copy */
                 return n_old_qgroups;
 
+        assert(old_qgroups); /* Coverity gets confused by the macro iterator allocating this, add a hint */
+
         r = btrfs_subvol_get_parent(fd, old_subvol_id, &old_parent_id);
         if (r == -ENXIO)
                 /* We have no parent, hence nothing to copy. */
@@ -1785,6 +1812,24 @@ int btrfs_subvol_auto_qgroup(const char *path, uint64_t subvol_id, bool create_i
         return btrfs_subvol_auto_qgroup_fd(fd, subvol_id, create_intermediary_qgroup);
 }
 
+int btrfs_subvol_make_default(const char *path) {
+        _cleanup_close_ int fd = -EBADF;
+        uint64_t id;
+        int r;
+
+        assert(path);
+
+        fd = open(path, O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
+        if (fd < 0)
+                return -errno;
+
+        r = btrfs_subvol_get_id_fd(fd, &id);
+        if (r < 0)
+                return r;
+
+        return RET_NERRNO(ioctl(fd, BTRFS_IOC_DEFAULT_SUBVOL, &id));
+}
+
 int btrfs_subvol_get_parent(int fd, uint64_t subvol_id, uint64_t *ret) {
 
         struct btrfs_ioctl_search_args args = {