fuse_lowlevel.c

来自「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。」· C语言 代码 · 共 1,449 行 · 第 1/3 页

	size_t bufsize = fuse_chan_bufsize(req->ch);

	(void) nodeid;
	if (f->debug) {
		fprintf(stderr, "INIT: %u.%u\n", arg->major, arg->minor);
		if (arg->major > 7 || (arg->major == 7 && arg->minor >= 6)) {
			fprintf(stderr, "flags=0x%08x\n", arg->flags);
			fprintf(stderr, "max_readahead=0x%08x\n",
				arg->max_readahead);
		}
	}
	f->conn.proto_major = arg->major;
	f->conn.proto_minor = arg->minor;

	if (arg->major < 7) {
		fprintf(stderr, "fuse: unsupported protocol version: %u.%u\n",
			arg->major, arg->minor);
		fuse_reply_err(req, EPROTO);
		return;
	}

	if (arg->major > 7 || (arg->major == 7 && arg->minor >= 6)) {
		if (f->conn.async_read)
			f->conn.async_read = arg->flags & FUSE_ASYNC_READ;
		if (arg->max_readahead < f->conn.max_readahead)
			f->conn.max_readahead = arg->max_readahead;
	} else {
		f->conn.async_read = 0;
		f->conn.max_readahead = 0;
	}

	if (bufsize < FUSE_MIN_READ_BUFFER) {
		fprintf(stderr, "fuse: warning: buffer size too small: %zu\n",
			bufsize);
		bufsize = FUSE_MIN_READ_BUFFER;
	}

	bufsize -= 4096;
	if (bufsize < f->conn.max_write)
		f->conn.max_write = bufsize;

	f->got_init = 1;
	if (f->op.init)
		f->op.init(f->userdata, &f->conn);

	memset(&outarg, 0, sizeof(outarg));
	outarg.major = FUSE_KERNEL_VERSION;
	outarg.minor = FUSE_KERNEL_MINOR_VERSION;
	if (f->conn.async_read)
		outarg.flags |= FUSE_ASYNC_READ;
	if (f->op.getlk && f->op.setlk)
		outarg.flags |= FUSE_POSIX_LOCKS;
	outarg.max_readahead = f->conn.max_readahead;
	outarg.max_write = f->conn.max_write;

	if (f->debug) {
		fprintf(stderr, "   INIT: %u.%u\n", outarg.major, outarg.minor);
		fprintf(stderr, "   flags=0x%08x\n", outarg.flags);
		fprintf(stderr, "   max_readahead=0x%08x\n",
			outarg.max_readahead);
		fprintf(stderr, "   max_write=0x%08x\n", outarg.max_write);
	}

	send_reply_ok(req, &outarg, arg->minor < 5 ? 8 : sizeof(outarg));
}

static void do_destroy(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
{
	struct fuse_ll *f = req->f;

	(void) nodeid;
	(void) inarg;

	f->got_destroy = 1;
	if (f->op.destroy)
		f->op.destroy(f->userdata);

	send_reply_ok(req, NULL, 0);
}

void *fuse_req_userdata(fuse_req_t req)
{
	return req->f->userdata;
}

const struct fuse_ctx *fuse_req_ctx(fuse_req_t req)
{
	return &req->ctx;
}

void fuse_req_interrupt_func(fuse_req_t req, fuse_interrupt_func_t func,
			     void *data)
{
	pthread_mutex_lock(&req->lock);
	req->u.ni.func = func;
	req->u.ni.data = data;
	if (req->interrupted && func)
		func(req, data);
	pthread_mutex_unlock(&req->lock);
}

int fuse_req_interrupted(fuse_req_t req)
{
	int interrupted;

	pthread_mutex_lock(&req->f->lock);
	interrupted = req->interrupted;
	pthread_mutex_unlock(&req->f->lock);

	return interrupted;
}

static struct {
	void (*func)(fuse_req_t, fuse_ino_t, const void *);
	const char *name;
} fuse_ll_ops[] = {
	[FUSE_LOOKUP]	   = { do_lookup,      "LOOKUP"	     },
	[FUSE_FORGET]	   = { do_forget,      "FORGET"	     },
	[FUSE_GETATTR]	   = { do_getattr,     "GETATTR"     },
	[FUSE_SETATTR]	   = { do_setattr,     "SETATTR"     },
	[FUSE_READLINK]	   = { do_readlink,    "READLINK"    },
	[FUSE_SYMLINK]	   = { do_symlink,     "SYMLINK"     },
	[FUSE_MKNOD]	   = { do_mknod,       "MKNOD"	     },
	[FUSE_MKDIR]	   = { do_mkdir,       "MKDIR"	     },
	[FUSE_UNLINK]	   = { do_unlink,      "UNLINK"	     },
	[FUSE_RMDIR]	   = { do_rmdir,       "RMDIR"	     },
	[FUSE_RENAME]	   = { do_rename,      "RENAME"	     },
	[FUSE_LINK]	   = { do_link,	       "LINK"	     },
	[FUSE_OPEN]	   = { do_open,	       "OPEN"	     },
	[FUSE_READ]	   = { do_read,	       "READ"	     },
	[FUSE_WRITE]	   = { do_write,       "WRITE"	     },
	[FUSE_STATFS]	   = { do_statfs,      "STATFS"	     },
	[FUSE_RELEASE]	   = { do_release,     "RELEASE"     },
	[FUSE_FSYNC]	   = { do_fsync,       "FSYNC"	     },
	[FUSE_SETXATTR]	   = { do_setxattr,    "SETXATTR"    },
	[FUSE_GETXATTR]	   = { do_getxattr,    "GETXATTR"    },
	[FUSE_LISTXATTR]   = { do_listxattr,   "LISTXATTR"   },
	[FUSE_REMOVEXATTR] = { do_removexattr, "REMOVEXATTR" },
	[FUSE_FLUSH]	   = { do_flush,       "FLUSH"	     },
	[FUSE_INIT]	   = { do_init,	       "INIT"	     },
	[FUSE_OPENDIR]	   = { do_opendir,     "OPENDIR"     },
	[FUSE_READDIR]	   = { do_readdir,     "READDIR"     },
	[FUSE_RELEASEDIR]  = { do_releasedir,  "RELEASEDIR"  },
	[FUSE_FSYNCDIR]	   = { do_fsyncdir,    "FSYNCDIR"    },
	[FUSE_GETLK]	   = { do_getlk,       "GETLK"	     },
	[FUSE_SETLK]	   = { do_setlk,       "SETLK"	     },
	[FUSE_SETLKW]	   = { do_setlkw,      "SETLKW"	     },
	[FUSE_ACCESS]	   = { do_access,      "ACCESS"	     },
	[FUSE_CREATE]	   = { do_create,      "CREATE"	     },
	[FUSE_INTERRUPT]   = { do_interrupt,   "INTERRUPT"   },
	[FUSE_BMAP]	   = { do_bmap,	       "BMAP"	     },
	[FUSE_DESTROY]	   = { do_destroy,     "DESTROY"     },
};

#define FUSE_MAXOP (sizeof(fuse_ll_ops) / sizeof(fuse_ll_ops[0]))

static const char *opname(enum fuse_opcode opcode)
{
	if (opcode >= FUSE_MAXOP || !fuse_ll_ops[opcode].name)
		return "???";
	else
		return fuse_ll_ops[opcode].name;
}

static void fuse_ll_process(void *data, const char *buf, size_t len,
			    struct fuse_chan *ch)
{
	struct fuse_ll *f = (struct fuse_ll *) data;
	struct fuse_in_header *in = (struct fuse_in_header *) buf;
	const void *inarg = buf + sizeof(struct fuse_in_header);
	struct fuse_req *req;

	if (f->debug)
		fprintf(stderr,
			"unique: %llu, opcode: %s (%i), nodeid: %lu, insize: %zu\n",
			(unsigned long long) in->unique,
			opname((enum fuse_opcode) in->opcode), in->opcode,
			(unsigned long) in->nodeid, len);

	req = (struct fuse_req *) calloc(1, sizeof(struct fuse_req));
	if (req == NULL) {
		fprintf(stderr, "fuse: failed to allocate request\n");
		return;
	}

	req->f = f;
	req->unique = in->unique;
	req->ctx.uid = in->uid;
	req->ctx.gid = in->gid;
	req->ctx.pid = in->pid;
	req->ch = ch;
	req->ctr = 1;
	list_init_req(req);
	fuse_mutex_init(&req->lock);

	if (!f->got_init && in->opcode != FUSE_INIT)
		fuse_reply_err(req, EIO);
	else if (f->allow_root && in->uid != f->owner && in->uid != 0 &&
		 in->opcode != FUSE_INIT && in->opcode != FUSE_READ &&
		 in->opcode != FUSE_WRITE && in->opcode != FUSE_FSYNC &&
		 in->opcode != FUSE_RELEASE && in->opcode != FUSE_READDIR &&
		 in->opcode != FUSE_FSYNCDIR && in->opcode != FUSE_RELEASEDIR) {
		fuse_reply_err(req, EACCES);
	} else if (in->opcode >= FUSE_MAXOP || !fuse_ll_ops[in->opcode].func)
		fuse_reply_err(req, ENOSYS);
	else {
		if (in->opcode != FUSE_INTERRUPT) {
			struct fuse_req *intr;
			pthread_mutex_lock(&f->lock);
			intr = check_interrupt(f, req);
			list_add_req(req, &f->list);
			pthread_mutex_unlock(&f->lock);
			if (intr)
				fuse_reply_err(intr, EAGAIN);
		}
		fuse_ll_ops[in->opcode].func(req, in->nodeid, inarg);
	}
}

enum {
	KEY_HELP,
	KEY_VERSION,
};

static struct fuse_opt fuse_ll_opts[] = {
	{ "debug", offsetof(struct fuse_ll, debug), 1 },
	{ "-d", offsetof(struct fuse_ll, debug), 1 },
	{ "allow_root", offsetof(struct fuse_ll, allow_root), 1 },
	{ "max_write=%u", offsetof(struct fuse_ll, conn.max_write), 0 },
	{ "max_readahead=%u", offsetof(struct fuse_ll, conn.max_readahead), 0 },
	{ "async_read", offsetof(struct fuse_ll, conn.async_read), 1 },
	{ "sync_read", offsetof(struct fuse_ll, conn.async_read), 0 },
	FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_DISCARD),
	FUSE_OPT_KEY("-h", KEY_HELP),
	FUSE_OPT_KEY("--help", KEY_HELP),
	FUSE_OPT_KEY("-V", KEY_VERSION),
	FUSE_OPT_KEY("--version", KEY_VERSION),
	FUSE_OPT_END
};

static void fuse_ll_version(void)
{
	fprintf(stderr, "using FUSE kernel interface version %i.%i\n",
		FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
}

static void fuse_ll_help(void)
{
	fprintf(stderr,
"    -o max_write=N         set maximum size of write requests\n"
"    -o max_readahead=N     set maximum readahead\n"
"    -o async_read          perform reads asynchronously (default)\n"
"    -o sync_read           perform reads synchronously\n"
"    -o atomic_o_trunc      enable atomic open+truncate support\n");
}

static int fuse_ll_opt_proc(void *data, const char *arg, int key,
			    struct fuse_args *outargs)
{
	(void) data; (void) outargs;

	switch (key) {
	case KEY_HELP:
		fuse_ll_help();
		break;

	case KEY_VERSION:
		fuse_ll_version();
		break;

	default:
		fprintf(stderr, "fuse: unknown option `%s'\n", arg);
	}

	return -1;
}

int fuse_lowlevel_is_lib_option(const char *opt)
{
	return fuse_opt_match(fuse_ll_opts, opt);
}

static void fuse_ll_destroy(void *data)
{
	struct fuse_ll *f = (struct fuse_ll *) data;

	if (f->got_init && !f->got_destroy) {
		if (f->op.destroy)
			f->op.destroy(f->userdata);
	}

	pthread_mutex_destroy(&f->lock);
	free(f);
}

/*
 * always call fuse_lowlevel_new_common() internally, to work around a
 * misfeature in the FreeBSD runtime linker, which links the old
 * version of a symbol to internal references.
 */
struct fuse_session *fuse_lowlevel_new_common(struct fuse_args *args,
					      const struct fuse_lowlevel_ops *op,
					      size_t op_size, void *userdata)
{
	struct fuse_ll *f;
	struct fuse_session *se;
	struct fuse_session_ops sop = {
		.process = fuse_ll_process,
		.destroy = fuse_ll_destroy,
	};

	if (sizeof(struct fuse_lowlevel_ops) < op_size) {
		fprintf(stderr, "fuse: warning: library too old, some operations may not work\n");
		op_size = sizeof(struct fuse_lowlevel_ops);
	}

	f = (struct fuse_ll *) calloc(1, sizeof(struct fuse_ll));
	if (f == NULL) {
		fprintf(stderr, "fuse: failed to allocate fuse object\n");
		goto out;
	}

	f->conn.async_read = 1;
	f->conn.max_write = UINT_MAX;
	f->conn.max_readahead = UINT_MAX;
	list_init_req(&f->list);
	list_init_req(&f->interrupts);
	fuse_mutex_init(&f->lock);

	if (fuse_opt_parse(args, f, fuse_ll_opts, fuse_ll_opt_proc) == -1)
		goto out_free;

	memcpy(&f->op, op, op_size);
	f->owner = getuid();
	f->userdata = userdata;

	se = fuse_session_new(&sop, f);
	if (!se)
		goto out_free;

	return se;

out_free:
	free(f);
out:
	return NULL;
}


struct fuse_session *fuse_lowlevel_new(struct fuse_args *args,
				       const struct fuse_lowlevel_ops *op,
				       size_t op_size, void *userdata)
{
	return fuse_lowlevel_new_common(args, op, op_size, userdata);
}


#ifndef __FreeBSD__

static void fill_open_compat(struct fuse_open_out *arg,
			     const struct fuse_file_info_compat *f)
{
	arg->fh = f->fh;
	if (f->direct_io)
		arg->open_flags |= FOPEN_DIRECT_IO;
	if (f->keep_cache)
		arg->open_flags |= FOPEN_KEEP_CACHE;
}

static void convert_statfs_compat(const struct statfs *compatbuf,
				  struct statvfs *buf)
{
	buf->f_bsize	= compatbuf->f_bsize;
	buf->f_blocks	= compatbuf->f_blocks;
	buf->f_bfree	= compatbuf->f_bfree;
	buf->f_bavail	= compatbuf->f_bavail;
	buf->f_files	= compatbuf->f_files;
	buf->f_ffree	= compatbuf->f_ffree;
	buf->f_namemax	= compatbuf->f_namelen;
}

int fuse_reply_open_compat(fuse_req_t req,
			   const struct fuse_file_info_compat *f)
{
	struct fuse_open_out arg;

	memset(&arg, 0, sizeof(arg));
	fill_open_compat(&arg, f);
	return send_reply_ok(req, &arg, sizeof(arg));
}

int fuse_reply_statfs_compat(fuse_req_t req, const struct statfs *stbuf)
{
	struct statvfs newbuf;

	memset(&newbuf, 0, sizeof(newbuf));
	convert_statfs_compat(stbuf, &newbuf);

	return fuse_reply_statfs(req, &newbuf);
}

struct fuse_session *fuse_lowlevel_new_compat(const char *opts,
				const struct fuse_lowlevel_ops_compat *op,
				size_t op_size, void *userdata)
{
	struct fuse_session *se;
	struct fuse_args args = FUSE_ARGS_INIT(0, NULL);

	if (opts &&
	    (fuse_opt_add_arg(&args, "") == -1 ||
	     fuse_opt_add_arg(&args, "-o") == -1 ||
	     fuse_opt_add_arg(&args, opts) == -1)) {
		fuse_opt_free_args(&args);
		return NULL;
	}
	se = fuse_lowlevel_new(&args, (const struct fuse_lowlevel_ops *) op,
			       op_size, userdata);
	fuse_opt_free_args(&args);

	return se;
}

struct fuse_ll_compat_conf {
	unsigned max_read;
	int set_max_read;
};

static const struct fuse_opt fuse_ll_opts_compat[] = {
	{ "max_read=", offsetof(struct fuse_ll_compat_conf, set_max_read), 1 },
	{ "max_read=%u", offsetof(struct fuse_ll_compat_conf, max_read), 0 },
	FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_KEEP),
	FUSE_OPT_END
};

int fuse_sync_compat_args(struct fuse_args *args)
{
	struct fuse_ll_compat_conf conf;

	memset(&conf, 0, sizeof(conf));
	if (fuse_opt_parse(args, &conf, fuse_ll_opts_compat, NULL) == -1)
		return -1;

	if (fuse_opt_insert_arg(args, 1, "-osync_read"))
		return -1;

	if (conf.set_max_read) {
		char tmpbuf[64];

		sprintf(tmpbuf, "-omax_readahead=%u", conf.max_read);
		if (fuse_opt_insert_arg(args, 1, tmpbuf) == -1)
			return -1;
	}
	return 0;
}

FUSE_SYMVER(".symver fuse_reply_statfs_compat,fuse_reply_statfs@FUSE_2.4");
FUSE_SYMVER(".symver fuse_reply_open_compat,fuse_reply_open@FUSE_2.4");
FUSE_SYMVER(".symver fuse_lowlevel_new_compat,fuse_lowlevel_new@FUSE_2.4");

#else /* __FreeBSD__ */

int fuse_sync_compat_args(struct fuse_args *args)
{
	(void) args;
	return 0;
}

#endif /* __FreeBSD__ */

struct fuse_session *fuse_lowlevel_new_compat25(struct fuse_args *args,
				const struct fuse_lowlevel_ops_compat25 *op,
				size_t op_size, void *userdata)
{
	if (fuse_sync_compat_args(args) == -1)
		return NULL;

	return fuse_lowlevel_new_common(args,
					(const struct fuse_lowlevel_ops *) op,
					op_size, userdata);
}

FUSE_SYMVER(".symver fuse_lowlevel_new_compat25,fuse_lowlevel_new@FUSE_2.5");