libc: remove global watch() function

This patch replaces the function with a 'Watch' interface to be
explicitly passed to the caller (currently only time.cc).

Issue #3497

repos/libports/src/lib/libc/internal/init.h

@@ -34,6 +34,7 @@ namespace Libc {
 	struct Current_time;
 	struct Clone_connection;
 	struct Kernel_routine_scheduler;
+	struct Watch;
 
 	/**
 	 * Support for shared libraries
@@ -98,7 +99,7 @@ namespace Libc {
 	 * Init timing facilities
 	 */
 	void init_sleep(Suspend &);
-	void init_time(Current_time &, Rtc_path const &);
+	void init_time(Current_time &, Rtc_path const &, Watch &);
 
 	/**
 	 * Socket fs

repos/libports/src/lib/libc/internal/kernel.h

@@ -37,6 +37,7 @@
 #include <internal/kernel_routine.h>
 #include <internal/current_time.h>
 #include <internal/kernel_timer_accessor.h>
+#include <internal/watch.h>
 
 namespace Libc { class Kernel; }
 
@@ -58,7 +59,8 @@ struct Libc::Kernel final : Vfs::Io_response_handler,
                             Suspend,
                             Select,
                             Kernel_routine_scheduler,
-                            Current_time
+                            Current_time,
+                            Watch
 {
 	private:
 
@@ -513,9 +515,9 @@ struct Libc::Kernel final : Vfs::Io_response_handler,
 		}
 
 		/**
-		 * Alloc new watch handler for given path
+		 * Watch interface
 		 */
-		Vfs::Vfs_watch_handle *alloc_watch_handle(char const *path)
+		Vfs::Vfs_watch_handle *alloc_watch_handle(char const *path) override
 		{
 			Vfs::Vfs_watch_handle *watch_handle { nullptr };
 			typedef Vfs::Directory_service::Watch_result Result;

repos/libports/src/lib/libc/internal/legacy.h

@@ -27,18 +27,6 @@ namespace Libc {
 	 */
 	void dispatch_pending_io_signals();
 
-	/**
-	 * Get watch handle for given path
-	 *
-	 * \param path  path that should be be watched
-	 *
-	 * \return      point to the watch handle object or a nullptr
-	 *              when the watch operation failed
-	 *
-	 * XXX  only needed by time.cc
-	 */
-	Vfs::Vfs_watch_handle *watch(char const *path);
-
 	/*
 	 * XXX  this function is solely needed to support noux fork mechanism
 	 */

repos/libports/src/lib/libc/internal/watch.h

@@ -0,0 +1,31 @@
+/*
+ * \brief  Interface for watching files
+ * \author Norman Feske
+ * \date   2019-09-20
+ */
+
+/*
+ * Copyright (C) 2019 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _LIBC__INTERNAL__WATCH_H_
+#define _LIBC__INTERNAL__WATCH_H_
+
+/* libc-internal includes */
+#include <internal/types.h>
+
+namespace Libc {
+
+	struct Watch : Interface
+	{
+		/**
+		 * Alloc new watch handler for given path
+		 */
+		virtual Vfs::Vfs_watch_handle *alloc_watch_handle(char const *path) = 0;
+	};
+}
+
+#endif /* _LIBC__INTERNAL__WATCH_H_ */

repos/libports/src/lib/libc/kernel.cc

@@ -322,7 +322,7 @@ Libc::Kernel::Kernel(Genode::Env &env, Genode::Allocator &heap)
 	init_plugin(*this);
 	init_sleep(*this);
 	init_vfs_plugin(*this);
-	init_time(*this, _rtc_path);
+	init_time(*this, _rtc_path, *this);
 	init_poll(*this);
 	init_select(*this, *this, *this);
 	init_socket_fs(*this);

repos/libports/src/lib/libc/legacy.cc

@@ -25,12 +25,6 @@ void Libc::dispatch_pending_io_signals()
 }
 
 
-Vfs::Vfs_watch_handle *Libc::watch(char const *path)
-{
-	return Kernel::kernel().alloc_watch_handle(path);
-}
-
-
 void Libc::schedule_suspend(void (*suspended) ())
 {
 	Kernel::kernel().schedule_suspend(suspended);

repos/libports/src/lib/libc/time.cc

@@ -28,17 +28,22 @@
 #include <internal/errno.h>
 #include <internal/init.h>
 #include <internal/current_time.h>
+#include <internal/watch.h>
 
 static Libc::Current_time *_current_time_ptr;
 static char const         *_rtc_path;
+static Libc::Watch        *_watch_ptr;
 
 
-void Libc::init_time(Current_time &current_time, Rtc_path const &rtc_path)
+void Libc::init_time(Current_time   &current_time,
+                     Rtc_path const &rtc_path,
+                     Watch          &watch)
 {
 	static Rtc_path rtc_path_inst = rtc_path;
 
 	_current_time_ptr = &current_time;
 	_rtc_path         =  rtc_path_inst.string();
+	_watch_ptr        = &watch;
 }
 
 
@@ -51,21 +56,23 @@ struct Libc::Rtc : Vfs::Watch_response_handler
 
 	Rtc_path const _rtc_path;
 
+	Watch &_watch;
+
 	bool   _read_file { true };
 	time_t _rtc_value { 0 };
 
 	bool const _rtc_path_valid = (_rtc_path != "");
 
-	Rtc(Rtc_path const &rtc_path)
+	Rtc(Rtc_path const &rtc_path, Watch &watch)
 	:
-		_rtc_path(rtc_path)
+		_rtc_path(rtc_path), _watch(watch)
 	{
 		if (!_rtc_path_valid) {
 			warning("rtc not configured, returning ", _rtc_value);
 			return;
 		}
 
-		_watch_handle = watch(_rtc_path.string());
+		_watch_handle = _watch.alloc_watch_handle(_rtc_path.string());
 		if (_watch_handle) {
 			_watch_handle->handler(this);
 		}
@@ -134,15 +141,17 @@ int clock_gettime(clockid_t clk_id, struct timespec *ts)
 
 	if (!ts) return Errno(EFAULT);
 
+	struct Missing_call_of_init_time : Exception { };
+
 	auto current_time = [&] ()
 	{
-		struct Missing_call_of_init_time : Exception { };
 		if (!_current_time_ptr)
 			throw Missing_call_of_init_time();
 
 		return _current_time_ptr->current_time();
 	};
 
+
 	/* initialize timespec just in case users do not check for errors */
 	ts->tv_sec  = 0;
 	ts->tv_nsec = 0;
@@ -153,10 +162,13 @@ int clock_gettime(clockid_t clk_id, struct timespec *ts)
 	case CLOCK_REALTIME:
 	case CLOCK_SECOND: /* FreeBSD specific */
 	{
+		if (!_watch_ptr)
+			throw Missing_call_of_init_time();
+
 		/*
 		 * XXX move instance to Libc::Kernel
 		 */
-		static Rtc rtc(_rtc_path);
+		static Rtc rtc(_rtc_path, *_watch_ptr);
 
 		time_t const rtc_value = rtc.read();
 		if (!rtc_value) return Errno(EINVAL);