diff options
| -rw-r--r-- | sdcard/sdcard.c | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/sdcard/sdcard.c b/sdcard/sdcard.c index a48906a..4d50bf0 100644 --- a/sdcard/sdcard.c +++ b/sdcard/sdcard.c @@ -169,6 +169,11 @@ struct node { __u32 refcount; __u64 nid; __u64 gen; + /* + * The inode number for this FUSE node. Note that this isn't stable across + * multiple invocations of the FUSE daemon. + */ + __u32 ino; /* State derived based on current position in hierarchy. */ perm_t perm; @@ -225,6 +230,25 @@ struct fuse { struct node root; char obbpath[PATH_MAX]; + /* Used to allocate unique inode numbers for fuse nodes. We use + * a simple counter based scheme where inode numbers from deleted + * nodes aren't reused. Note that inode allocations are not stable + * across multiple invocation of the sdcard daemon, but that shouldn't + * be a huge problem in practice. + * + * Note that we restrict inodes to 32 bit unsigned integers to prevent + * truncation on 32 bit processes when unsigned long long stat.st_ino is + * assigned to an unsigned long ino_t type in an LP32 process. + * + * Also note that fuse_attr and fuse_dirent inode values are 64 bits wide + * on both LP32 and LP64, but the fuse kernel code doesn't squash 64 bit + * inode numbers into 32 bit values on 64 bit kernels (see fuse_squash_ino + * in fs/fuse/inode.c). + * + * Accesses must be guarded by |lock|. + */ + __u32 inode_ctr; + Hashmap* package_to_appid; Hashmap* appid_with_rw; }; @@ -388,7 +412,7 @@ static char* find_file_within(const char* path, const char* name, static void attr_from_stat(struct fuse_attr *attr, const struct stat *s, const struct node* node) { - attr->ino = node->nid; + attr->ino = node->ino; attr->size = s->st_size; attr->blocks = s->st_blocks; attr->atime = s->st_atim.tv_sec; @@ -576,6 +600,13 @@ struct node *create_node_locked(struct fuse* fuse, struct node *node; size_t namelen = strlen(name); + // Detect overflows in the inode counter. "4 billion nodes should be enough + // for everybody". + if (fuse->inode_ctr == 0) { + ERROR("No more inode numbers available"); + return NULL; + } + node = calloc(1, sizeof(struct node)); if (!node) { return NULL; @@ -597,6 +628,7 @@ struct node *create_node_locked(struct fuse* fuse, } node->namelen = namelen; node->nid = ptr_to_id(node); + node->ino = fuse->inode_ctr++; node->gen = fuse->next_generation++; derive_permissions_locked(fuse, parent, node); @@ -701,6 +733,7 @@ static void fuse_init(struct fuse *fuse, int fd, const char *source_path, fuse->derive = derive; fuse->split_perms = split_perms; fuse->write_gid = write_gid; + fuse->inode_ctr = 1; memset(&fuse->root, 0, sizeof(fuse->root)); fuse->root.nid = FUSE_ROOT_ID; /* 1 */ |