mount_service: create high level fuse helpers

Create a fuse_main wrapper for fuse services.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Bernd Schubert <bernd@bsbernd.com>

include/fuse.h

@@ -1008,6 +1008,40 @@ static inline int fuse_main_fn(int argc, char *argv[],
 #define fuse_main(argc, argv, op, user_data) \
 	fuse_main_fn(argc, argv, op, user_data)
 
+#if FUSE_MAKE_VERSION(3, 19) <= FUSE_USE_VERSION
+struct fuse_service;
+int fuse_service_main_real_versioned(struct fuse_service *service,
+				     struct fuse_args *args,
+				     const struct fuse_operations *op,
+				     size_t op_size,
+				     struct libfuse_version *version,
+				     void *user_data);
+
+/**
+ * Same as fuse_service_main_fn, but takes its information from the mount
+ * service context and an fuse_args that has already had fuse_service_append_args
+ * applied to it.
+ */
+static inline int fuse_service_main_fn(struct fuse_service *service,
+				       struct fuse_args *args,
+				       const struct fuse_operations *op,
+				       void *user_data)
+{
+	struct libfuse_version version = {
+		.major  = FUSE_MAJOR_VERSION,
+		.minor  = FUSE_MINOR_VERSION,
+		.hotfix = FUSE_HOTFIX_VERSION,
+		.padding = FUSE_USE_VERSION,
+	};
+
+	return fuse_service_main_real_versioned(service, args, op,
+						sizeof(*(op)), &version,
+						user_data);
+}
+#define fuse_service_main(s, args, op, user_data) \
+	fuse_service_main_fn(s, args, op, user_data)
+#endif /* FUSE_USE_VERSION >= FUSE_MAKE_VERSION(3, 19) */
+
 /* ----------------------------------------------------------- *
  * More detailed API					       *
  * ----------------------------------------------------------- */

lib/fuse_versionscript

@@ -240,6 +240,7 @@ FUSE_3.19 {
 		fuse_service_exit;
 		fuse_service_expect_mount_format;
 		fuse_service_finish_file_requests;
+		fuse_service_main_real_versioned;
 		fuse_service_parse_cmdline_opts;
 		fuse_service_receive_file;
 		fuse_service_release;

lib/helper.c

@@ -16,6 +16,7 @@
 #include "fuse_opt.h"
 #include "fuse_lowlevel.h"
 #include "fuse_daemonize.h"
+#include "fuse_service.h"
 #include "mount_util.h"
 
 #include <stdio.h>
@@ -302,6 +303,110 @@ int fuse_parse_cmdline_30(struct fuse_args *args,
 	return rc;
 }
 
+struct fuse *_fuse_new_31(struct fuse_args *args,
+		       const struct fuse_operations *op, size_t op_size,
+		       struct libfuse_version *version,
+		       void *user_data);
+
+int fuse_service_main_real_versioned(struct fuse_service *service,
+				     struct fuse_args *args,
+				     const struct fuse_operations *op,
+				     size_t op_size,
+				     struct libfuse_version *version,
+				     void *user_data)
+{
+	struct fuse *fuse;
+	struct fuse_cmdline_opts opts;
+	struct fuse_loop_config *loop_config = NULL;
+	int res;
+
+	if (fuse_service_parse_cmdline_opts(args, &opts) != 0) {
+		res = 1;
+		goto out0;
+	}
+
+	if (opts.show_version) {
+		printf("FUSE library version %s\n", PACKAGE_VERSION);
+		fuse_lowlevel_version();
+		res = 0;
+		goto out1;
+	}
+
+	if (opts.show_help) {
+		if (args->argv[0][0] != '\0')
+			printf("usage: %s [options] <mountpoint>\n\n",
+			       args->argv[0]);
+		printf("FUSE options:\n");
+		fuse_cmdline_help();
+		fuse_lib_help(args);
+		res = 0;
+		goto out1;
+	}
+
+	if (!opts.show_help &&
+	    !opts.mountpoint) {
+		fuse_log(FUSE_LOG_ERR, "error: no mountpoint specified\n");
+		res = 2;
+		goto out1;
+	}
+
+	fuse = _fuse_new_31(args, op, op_size, version, user_data);
+	if (fuse == NULL) {
+		res = 3;
+		goto out1;
+	}
+	struct fuse_session *se = fuse_get_session(fuse);
+
+	if (!opts.singlethread) {
+		loop_config = fuse_loop_cfg_create();
+		if (loop_config == NULL) {
+			res = 7;
+			goto out2;
+		}
+	}
+
+	if (fuse_set_signal_handlers(se) != 0) {
+		res = 6;
+		goto out3;
+	}
+
+	if (fuse_service_session_mount(service, se, 0, &opts) != 0) {
+		res = 4;
+		goto out4;
+	}
+
+	if (opts.singlethread) {
+		fuse_service_send_goodbye(service, 0);
+		fuse_service_release(service);
+
+		res = fuse_loop(fuse);
+	} else {
+		fuse_loop_cfg_set_clone_fd(loop_config, opts.clone_fd);
+		fuse_loop_cfg_set_idle_threads(loop_config, opts.max_idle_threads);
+		fuse_loop_cfg_set_max_threads(loop_config, opts.max_threads);
+
+		fuse_service_send_goodbye(service, 0);
+		fuse_service_release(service);
+
+		res = fuse_loop_mt(fuse, loop_config);
+	}
+	if (res)
+		res = 8;
+
+out4:
+	fuse_remove_signal_handlers(se);
+out3:
+	fuse_loop_cfg_destroy(loop_config);
+out2:
+	fuse_destroy(fuse);
+out1:
+	free(opts.mountpoint);
+out0:
+	fuse_service_send_goodbye(service, res);
+	fuse_service_release(service);
+	return res;
+}
+
 int fuse_main_real_versioned(int argc, char *argv[],
 			     const struct fuse_operations *op, size_t op_size,
 			     struct libfuse_version *version, void *user_data)
@@ -340,10 +445,6 @@ int fuse_main_real_versioned(int argc, char *argv[],
 		goto out1;
 	}
 
-	struct fuse *_fuse_new_31(struct fuse_args *args,
-			       const struct fuse_operations *op, size_t op_size,
-			       struct libfuse_version *version,
-			       void *user_data);
 	fuse = _fuse_new_31(&args, op, op_size, version, user_data);
 	if (fuse == NULL) {
 		res = 3;