fuse.c

FUSE文件系统开发工具,将内核层面的文件系统开发过程平移到应用层面上来。

	do {
		pthread_mutex_lock(&f->lock);
		node = lookup_node(f, dir, oldname);
		if (node == NULL) {
			pthread_mutex_unlock(&f->lock);
			return NULL;
		}
		do {
			f->hidectr ++;
			snprintf(newname, bufsize, ".fuse_hidden%08x%08x",
				 (unsigned int) node->nodeid, f->hidectr);
			newnode = lookup_node(f, dir, newname);
		} while(newnode);
		pthread_mutex_unlock(&f->lock);

		newpath = get_path_name(f, dir, newname);
		if (!newpath)
			break;

		res = fuse_fs_getattr(f->fs, newpath, &buf);
		if (res == -ENOENT)
			break;
		free(newpath);
		newpath = NULL;
	} while(res == 0 && --failctr);

	return newpath;
}

static int hide_node(struct fuse *f, const char *oldpath,
		     fuse_ino_t dir, const char *oldname)
{
	char newname[64];
	char *newpath;
	int err = -EBUSY;

	newpath = hidden_name(f, dir, oldname, newname, sizeof(newname));
	if (newpath) {
		err = fuse_fs_rename(f->fs, oldpath, newpath);
		if (!err)
			err = rename_node(f, dir, oldname, dir, newname, 1);
		free(newpath);
	}
	return err;
}

static int mtime_eq(const struct stat *stbuf, const struct timespec *ts)
{
	return stbuf->st_mtime == ts->tv_sec &&
		ST_MTIM_NSEC(stbuf) == ts->tv_nsec;
}

#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC CLOCK_REALTIME
#endif

static void curr_time(struct timespec *now)
{
	static clockid_t clockid = CLOCK_MONOTONIC;
	int res = clock_gettime(clockid, now);
	if (res == -1 && errno == EINVAL) {
		clockid = CLOCK_REALTIME;
		res = clock_gettime(clockid, now);
	}
	if (res == -1) {
		perror("fuse: clock_gettime");
		abort();
	}
}

static void update_stat(struct node *node, const struct stat *stbuf)
{
	if (node->cache_valid && (!mtime_eq(stbuf, &node->mtime) ||
				  stbuf->st_size != node->size))
		node->cache_valid = 0;
	node->mtime.tv_sec = stbuf->st_mtime;
	node->mtime.tv_nsec = ST_MTIM_NSEC(stbuf);
	node->size = stbuf->st_size;
	curr_time(&node->stat_updated);
}

static int lookup_path(struct fuse *f, fuse_ino_t nodeid,
		       const char *name, const char *path,
		       struct fuse_entry_param *e, struct fuse_file_info *fi)
{
	int res;

	memset(e, 0, sizeof(struct fuse_entry_param));
	if (fi)
		res = fuse_fs_fgetattr(f->fs, path, &e->attr, fi);
	else
		res = fuse_fs_getattr(f->fs, path, &e->attr);
	if (res == 0) {
		struct node *node;

		node = find_node(f, nodeid, name);
		if (node == NULL)
			res = -ENOMEM;
		else {
			e->ino = node->nodeid;
			e->generation = node->generation;
			e->entry_timeout = f->conf.entry_timeout;
			e->attr_timeout = f->conf.attr_timeout;
			if (f->conf.auto_cache) {
				pthread_mutex_lock(&f->lock);
				update_stat(node, &e->attr);
				pthread_mutex_unlock(&f->lock);
			}
			set_stat(f, e->ino, &e->attr);
			if (f->conf.debug)
				fprintf(stderr, "   NODEID: %lu\n",
					(unsigned long) e->ino);
		}
	}
	return res;
}

static struct fuse_context_i *fuse_get_context_internal(void)
{
	struct fuse_context_i *c;

	c = (struct fuse_context_i *) pthread_getspecific(fuse_context_key);
	if (c == NULL) {
		c = (struct fuse_context_i *)
			malloc(sizeof(struct fuse_context_i));
		if (c == NULL) {
			/* This is hard to deal with properly, so just
			   abort.  If memory is so low that the
			   context cannot be allocated, there's not
			   much hope for the filesystem anyway */
			fprintf(stderr, "fuse: failed to allocate thread specific data\n");
			abort();
		}
		pthread_setspecific(fuse_context_key, c);
	}
	return c;
}

static void fuse_freecontext(void *data)
{
	free(data);
}

static int fuse_create_context_key(void)
{
	int err = 0;
	pthread_mutex_lock(&fuse_context_lock);
	if (!fuse_context_ref) {
		err = pthread_key_create(&fuse_context_key, fuse_freecontext);
		if (err) {
			fprintf(stderr, "fuse: failed to create thread specific key: %s\n",
				strerror(err));
			pthread_mutex_unlock(&fuse_context_lock);
			return -1;
		}
	}
	fuse_context_ref++;
	pthread_mutex_unlock(&fuse_context_lock);
	return 0;
}

static void fuse_delete_context_key(void)
{
	pthread_mutex_lock(&fuse_context_lock);
	fuse_context_ref--;
	if (!fuse_context_ref) {
		free(pthread_getspecific(fuse_context_key));
		pthread_key_delete(fuse_context_key);
	}
	pthread_mutex_unlock(&fuse_context_lock);
}

static struct fuse *req_fuse_prepare(fuse_req_t req)
{
	struct fuse_context_i *c = fuse_get_context_internal();
	const struct fuse_ctx *ctx = fuse_req_ctx(req);
	c->req = req;
	c->ctx.fuse = req_fuse(req);
	c->ctx.uid = ctx->uid;
	c->ctx.gid = ctx->gid;
	c->ctx.pid = ctx->pid;
	return c->ctx.fuse;
}

static inline void reply_err(fuse_req_t req, int err)
{
	/* fuse_reply_err() uses non-negated errno values */
	fuse_reply_err(req, -err);
}

static void reply_entry(fuse_req_t req, const struct fuse_entry_param *e,
			int err)
{
	if (!err) {
		struct fuse *f = req_fuse(req);
		if (fuse_reply_entry(req, e) == -ENOENT)
			forget_node(f, e->ino, 1);
	} else
		reply_err(req, err);
}

void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn)
{
	fuse_get_context()->private_data = fs->user_data;
	if (fs->op.init)
		fs->user_data = fs->op.init(conn);
}

static void fuse_lib_init(void *data, struct fuse_conn_info *conn)
{
	struct fuse *f = (struct fuse *) data;
	struct fuse_context_i *c = fuse_get_context_internal();

	memset(c, 0, sizeof(*c));
	c->ctx.fuse = f;
	fuse_fs_init(f->fs, conn);
}

void fuse_fs_destroy(struct fuse_fs *fs)
{
	fuse_get_context()->private_data = fs->user_data;
	if (fs->op.destroy)
		fs->op.destroy(fs->user_data);
	if (fs->m)
		fuse_put_module(fs->m);
	free(fs);
}

static void fuse_lib_destroy(void *data)
{
	struct fuse *f = (struct fuse *) data;
	struct fuse_context_i *c = fuse_get_context_internal();

	memset(c, 0, sizeof(*c));
	c->ctx.fuse = f;
	fuse_fs_destroy(f->fs);
	f->fs = NULL;
}

static void fuse_lib_lookup(fuse_req_t req, fuse_ino_t parent,
			    const char *name)
{
	struct fuse *f = req_fuse_prepare(req);
	struct fuse_entry_param e;
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path_name(f, parent, name);
	if (path != NULL) {
		struct fuse_intr_data d;
		if (f->conf.debug)
			fprintf(stderr, "LOOKUP %s\n", path);
		fuse_prepare_interrupt(f, req, &d);
		err = lookup_path(f, parent, name, path, &e, NULL);
		if (err == -ENOENT && f->conf.negative_timeout != 0.0) {
			e.ino = 0;
			e.entry_timeout = f->conf.negative_timeout;
			err = 0;
		}
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	reply_entry(req, &e, err);
}

static void fuse_lib_forget(fuse_req_t req, fuse_ino_t ino,
			    unsigned long nlookup)
{
	struct fuse *f = req_fuse(req);
	if (f->conf.debug)
		fprintf(stderr, "FORGET %llu/%lu\n", (unsigned long long)ino,
			nlookup);
	forget_node(f, ino, nlookup);
	fuse_reply_none(req);
}

static void fuse_lib_getattr(fuse_req_t req, fuse_ino_t ino,
			     struct fuse_file_info *fi)
{
	struct fuse *f = req_fuse_prepare(req);
	struct stat buf;
	char *path;
	int err;

	(void) fi;
	memset(&buf, 0, sizeof(buf));

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path(f, ino);
	if (path != NULL) {
		struct fuse_intr_data d;
		fuse_prepare_interrupt(f, req, &d);
		err = fuse_fs_getattr(f->fs, path, &buf);
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	if (!err) {
		if (f->conf.auto_cache) {
			pthread_mutex_lock(&f->lock);
			update_stat(get_node(f, ino), &buf);
			pthread_mutex_unlock(&f->lock);
		}
		set_stat(f, ino, &buf);
		fuse_reply_attr(req, &buf, f->conf.attr_timeout);
	} else
		reply_err(req, err);
}

int fuse_fs_chmod(struct fuse_fs *fs, const char *path, mode_t mode)
{
	fuse_get_context()->private_data = fs->user_data;
	if (fs->op.chmod)
		return fs->op.chmod(path, mode);
	else
		return -ENOSYS;
}

static void fuse_lib_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
			     int valid, struct fuse_file_info *fi)
{
	struct fuse *f = req_fuse_prepare(req);
	struct stat buf;
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path(f, ino);
	if (path != NULL) {
		struct fuse_intr_data d;
		fuse_prepare_interrupt(f, req, &d);
		err = 0;
		if (!err && (valid & FUSE_SET_ATTR_MODE))
			err = fuse_fs_chmod(f->fs, path, attr->st_mode);
		if (!err && (valid & (FUSE_SET_ATTR_UID | FUSE_SET_ATTR_GID))) {
			uid_t uid = (valid & FUSE_SET_ATTR_UID) ?
				attr->st_uid : (uid_t) -1;
			gid_t gid = (valid & FUSE_SET_ATTR_GID) ?
				attr->st_gid : (gid_t) -1;
			err = fuse_fs_chown(f->fs, path, uid, gid);
		}
		if (!err && (valid & FUSE_SET_ATTR_SIZE)) {
			if (fi)
				err = fuse_fs_ftruncate(f->fs, path,
							attr->st_size, fi);
			else
				err = fuse_fs_truncate(f->fs, path,
						       attr->st_size);
		}
		if (!err &&
		    (valid & (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) ==
		    (FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME)) {
			struct timespec tv[2];
			tv[0].tv_sec = attr->st_atime;
			tv[0].tv_nsec = ST_ATIM_NSEC(attr);
			tv[1].tv_sec = attr->st_mtime;
			tv[1].tv_nsec = ST_MTIM_NSEC(attr);
			err = fuse_fs_utimens(f->fs, path, tv);
		}
		if (!err)
			err = fuse_fs_getattr(f->fs,  path, &buf);
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	if (!err) {
		if (f->conf.auto_cache) {
			pthread_mutex_lock(&f->lock);
			update_stat(get_node(f, ino), &buf);
			pthread_mutex_unlock(&f->lock);
		}
		set_stat(f, ino, &buf);
		fuse_reply_attr(req, &buf, f->conf.attr_timeout);
	} else
		reply_err(req, err);
}

static void fuse_lib_access(fuse_req_t req, fuse_ino_t ino, int mask)
{
	struct fuse *f = req_fuse_prepare(req);
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path(f, ino);
	if (path != NULL) {
		struct fuse_intr_data d;
		if (f->conf.debug)
			fprintf(stderr, "ACCESS %s 0%o\n", path, mask);
		fuse_prepare_interrupt(f, req, &d);
		err = fuse_fs_access(f->fs, path, mask);
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	reply_err(req, err);
}

static void fuse_lib_readlink(fuse_req_t req, fuse_ino_t ino)
{
	struct fuse *f = req_fuse_prepare(req);
	char linkname[PATH_MAX + 1];
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path(f, ino);
	if (path != NULL) {
		struct fuse_intr_data d;
		fuse_prepare_interrupt(f, req, &d);
		err = fuse_fs_readlink(f->fs, path, linkname, sizeof(linkname));
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	if (!err) {
		linkname[PATH_MAX] = '\0';
		fuse_reply_readlink(req, linkname);
	} else
		reply_err(req, err);
}

static void fuse_lib_mknod(fuse_req_t req, fuse_ino_t parent, const char *name,
			   mode_t mode, dev_t rdev)
{
	struct fuse *f = req_fuse_prepare(req);
	struct fuse_entry_param e;
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path_name(f, parent, name);
	if (path) {
		struct fuse_intr_data d;
		if (f->conf.debug)
			fprintf(stderr, "MKNOD %s\n", path);
		fuse_prepare_interrupt(f, req, &d);
		err = -ENOSYS;
		if (S_ISREG(mode)) {
			struct fuse_file_info fi;

			memset(&fi, 0, sizeof(fi));
			fi.flags = O_CREAT | O_EXCL | O_WRONLY;
			err = fuse_fs_create(f->fs, path, mode, &fi);
			if (!err) {
				err = lookup_path(f, parent, name, path, &e,
						  &fi);
				fuse_fs_release(f->fs, path, &fi);
			}
		}
		if (err == -ENOSYS) {
			err = fuse_fs_mknod(f->fs, path, mode, rdev);
			if (!err)
				err = lookup_path(f, parent, name, path, &e,
						  NULL);
		}
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	reply_entry(req, &e, err);
}

static void fuse_lib_mkdir(fuse_req_t req, fuse_ino_t parent, const char *name,
			   mode_t mode)
{
	struct fuse *f = req_fuse_prepare(req);
	struct fuse_entry_param e;
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path_name(f, parent, name);
	if (path != NULL) {
		struct fuse_intr_data d;
		if (f->conf.debug)
			fprintf(stderr, "MKDIR %s\n", path);
		fuse_prepare_interrupt(f, req, &d);
		err = fuse_fs_mkdir(f->fs, path, mode);
		if (!err)
			err = lookup_path(f, parent, name, path, &e, NULL);
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	reply_entry(req, &e, err);
}

static void fuse_lib_unlink(fuse_req_t req, fuse_ino_t parent,
			    const char *name)
{
	struct fuse *f = req_fuse_prepare(req);
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_wrlock(&f->tree_lock);
	path = get_path_name(f, parent, name);
	if (path != NULL) {
		struct fuse_intr_data d;
		if (f->conf.debug)
			fprintf(stderr, "UNLINK %s\n", path);
		fuse_prepare_interrupt(f, req, &d);
		if (!f->conf.hard_remove && is_open(f, parent, name))
			err = hide_node(f, path, parent, name);
		else {
			err = fuse_fs_unlink(f->fs, path);
			if (!err)
				remove_node(f, parent, name);
		}
		fuse_finish_interrupt(f, req, &d);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	reply_err(req, err);
}

static void fuse_lib_rmdir(fuse_req_t req, fuse_ino_t parent, const char *name)
{
	struct fuse *f = req_fuse_prepare(req);
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_wrlock(&f->tree_lock);
	path = get_path_name(f, parent, name);
	if (path != NULL) {
		struct fuse_intr_data d;
		if (f->conf.debug)
			fprintf(stderr, "RMDIR %s\n", path);
		fuse_prepare_interrupt(f, req, &d);
		err = fuse_fs_rmdir(f->fs, path);
		fuse_finish_interrupt(f, req, &d);
		if (!err)
			remove_node(f, parent, name);
		free(path);
	}
	pthread_rwlock_unlock(&f->tree_lock);
	reply_err(req, err);
}

static void fuse_lib_symlink(fuse_req_t req, const char *linkname,
			     fuse_ino_t parent, const char *name)
{
	struct fuse *f = req_fuse_prepare(req);
	struct fuse_entry_param e;
	char *path;
	int err;

	err = -ENOENT;
	pthread_rwlock_rdlock(&f->tree_lock);
	path = get_path_name(f, parent, name);
	if (path != NULL) {