noux: add SYSCALL_SYNC

File systems using the File_system_session interface can now be
synchronized by using this syscall. This is needed for file system
that maintain an internal cache, which should be flushed.

Fixes #1008.

ports/include/noux_session/noux_session.h

@@ -75,6 +75,7 @@ namespace Noux {
 			SYSCALL_GETTIMEOFDAY,
 			SYSCALL_CLOCK_GETTIME,
 			SYSCALL_UTIMES,
+			SYSCALL_SYNC,
 			SYSCALL_INVALID = -1
 		};
 
@@ -122,6 +123,7 @@ namespace Noux {
 			NOUX_DECL_SYSCALL_NAME(GETTIMEOFDAY)
 			NOUX_DECL_SYSCALL_NAME(CLOCK_GETTIME)
 			NOUX_DECL_SYSCALL_NAME(UTIMES)
+			NOUX_DECL_SYSCALL_NAME(SYNC)
 			case SYSCALL_INVALID: return 0;
 			}
 			return 0;

ports/include/noux_session/sysio.h

@@ -494,6 +494,8 @@ namespace Noux {
 
 			SYSIO_DECL(utimes,      { Path path; unsigned long sec; unsigned long usec; },
 			                        { });
+
+			SYSIO_DECL(sync,        { }, { });
 		};
 	};
 };

ports/src/lib/libc_noux/plugin.cc

@@ -550,6 +550,12 @@ void endpwent(void)
 }
 
 
+extern "C" void sync(void)
+{
+	noux_syscall(Noux::Session::SYSCALL_SYNC);
+}
+
+
 /********************
  ** Time functions **
  ********************/

ports/src/noux/dir_file_system.h

@@ -652,6 +652,30 @@ namespace Noux {
 
 			char const *name() const { return "dir"; }
 
+			/**
+			 * Synchronize all file systems
+			 *
+			 * Only file system using the File_system_session interface are
+			 * synchronized.
+			 */
+			void sync()
+			{
+				for (File_system *fs = _first_file_system; fs; fs = fs->next) {
+					Fs_file_system *fs_fs = dynamic_cast<Fs_file_system *>(fs);
+					if (fs_fs) {
+						fs_fs->sync();
+						continue;
+					}
+
+					/* the directory might contain Fs_file_systems */
+					Dir_file_system *dir_fs = dynamic_cast<Dir_file_system *>(fs);
+					if (dir_fs) {
+						dir_fs->sync();
+						continue;
+					}
+				}
+			}
+
 
 			/********************************
 			 ** File I/O service interface **

ports/src/noux/file_system.h

@@ -42,6 +42,15 @@ namespace Noux {
 		 * This function is used for debugging only.
 		 */
 		virtual char const *name() const = 0;
+
+		/**
+		 * Synchronize file system
+		 *
+		 * This function is only used by a Fs_file_system because such a
+		 * file system may employ a backend, which maintains a internal
+		 * cache, that needs to be flushed.
+		 */
+		virtual void sync() { }
 	};
 }
 

ports/src/noux/fs_file_system.h

@@ -576,6 +576,11 @@ namespace Noux {
 
 			char const *name() const { return "fs"; }
 
+			void sync()
+			{
+				_fs.sync();
+			}
+
 
 			/********************************
 			 ** File I/O service interface **

ports/src/noux/main.cc

@@ -789,6 +789,12 @@ bool Noux::Child::syscall(Noux::Session::Syscall sc)
 				return true;
 			}
 
+		case SYSCALL_SYNC:
+			{
+				root_dir()->sync();
+				return true;
+			}
+
 		case SYSCALL_SOCKET:
 		case SYSCALL_GETSOCKOPT:
 		case SYSCALL_SETSOCKOPT:

ports/src/noux/net/net.cc

@@ -111,6 +111,7 @@ bool Noux::Child::_syscall_net(Noux::Session::Syscall sc)
 		case SYSCALL_GETTIMEOFDAY:
 		case SYSCALL_CLOCK_GETTIME:
 		case SYSCALL_UTIMES:
+		case SYSCALL_SYNC:
 			break;
 		case SYSCALL_SOCKET:
 			{