Stacked file systems for Noux

This patch introduces support for stacked file systems alongside new
glue for accessing file-system implementations provided via Genode's
new file-system-session interface.

Using stacked file systems, an arbitrary number of file systems (such
as tar archives or file systems implemented as separate Genode
components) can be composed to form one merged virtual file system.

An example is given via the 'ports/run/noux_bash.run' script. This run
script creates a virtual file system out of multiple tar archives each
containing the content of a particular GNU package. In addition, one
'ram_fs' is mounted, which enables Noux to perform write operations.
This way, the shell output can be redirected to a file, or files can
be saved in VIM.

Fixes #103.

ports/include/noux_session/noux_session.h

@@ -44,6 +44,7 @@ namespace Noux {
 			SYSCALL_OPEN,
 			SYSCALL_CLOSE,
 			SYSCALL_IOCTL,
+			SYSCALL_LSEEK,
 			SYSCALL_DIRENT,
 			SYSCALL_FCHDIR,
 			SYSCALL_EXECVE,
@@ -53,6 +54,9 @@ namespace Noux {
 			SYSCALL_WAIT4,
 			SYSCALL_PIPE,
 			SYSCALL_DUP2,
+			SYSCALL_UNLINK,
+			SYSCALL_RENAME,
+			SYSCALL_MKDIR,
 			SYSCALL_INVALID = -1
 		};
 
@@ -69,6 +73,7 @@ namespace Noux {
 			NOUX_DECL_SYSCALL_NAME(OPEN)
 			NOUX_DECL_SYSCALL_NAME(CLOSE)
 			NOUX_DECL_SYSCALL_NAME(IOCTL)
+			NOUX_DECL_SYSCALL_NAME(LSEEK)
 			NOUX_DECL_SYSCALL_NAME(DIRENT)
 			NOUX_DECL_SYSCALL_NAME(FCHDIR)
 			NOUX_DECL_SYSCALL_NAME(EXECVE)
@@ -78,6 +83,9 @@ namespace Noux {
 			NOUX_DECL_SYSCALL_NAME(WAIT4)
 			NOUX_DECL_SYSCALL_NAME(PIPE)
 			NOUX_DECL_SYSCALL_NAME(DUP2)
+			NOUX_DECL_SYSCALL_NAME(UNLINK)
+			NOUX_DECL_SYSCALL_NAME(RENAME)
+			NOUX_DECL_SYSCALL_NAME(MKDIR)
 			case SYSCALL_INVALID: return 0;
 			}
 			return 0;

ports/include/noux_session/sysio.h

@@ -58,6 +58,17 @@ namespace Noux {
 
 		typedef __SIZE_TYPE__ size_t;
 
+		/**
+		 * Flags of 'mode' argument of open syscall
+		 */
+		enum {
+			OPEN_MODE_RDONLY  = 0,
+			OPEN_MODE_WRONLY  = 1,
+			OPEN_MODE_RDWR    = 2,
+			OPEN_MODE_ACCMODE = 3,
+			OPEN_MODE_CREATE  = 0x0200,
+		};
+
 		enum {
 			STAT_MODE_SYMLINK   = 0120000,
 			STAT_MODE_FILE      = 0100000,
@@ -100,6 +111,8 @@ namespace Noux {
 			};
 		};
 
+		enum Lseek_whence { LSEEK_SET, LSEEK_CUR, LSEEK_END };
+
 		enum { DIRENT_MAX_NAME_LEN = 128 };
 
 		enum Dirent_type {
@@ -208,8 +221,14 @@ namespace Noux {
 		enum General_error { ERR_FD_INVALID, NUM_GENERAL_ERRORS };
 		enum Stat_error    { STAT_ERR_NO_ENTRY     = NUM_GENERAL_ERRORS };
 		enum Fcntl_error   { FCNTL_ERR_CMD_INVALID = NUM_GENERAL_ERRORS };
-		enum Open_error    { OPEN_ERR_UNACCESSIBLE = NUM_GENERAL_ERRORS };
+		enum Open_error    { OPEN_ERR_UNACCESSIBLE, OPEN_ERR_NO_PERM };
 		enum Execve_error  { EXECVE_NONEXISTENT    = NUM_GENERAL_ERRORS };
+		enum Unlink_error  { UNLINK_ERR_NO_ENTRY, UNLINK_ERR_NO_PERM };
+		enum Rename_error  { RENAME_ERR_NO_ENTRY, RENAME_ERR_CROSS_FS,
+		                     RENAME_ERR_NO_PERM };
+		enum Mkdir_error   { MKDIR_ERR_EXISTS,   MKDIR_ERR_NO_ENTRY,
+		                     MKDIR_ERR_NO_SPACE, MKDIR_ERR_NO_PERM,
+		                     MKDIR_ERR_NAME_TOO_LONG};
 
 		union {
 			General_error general;
@@ -217,13 +236,17 @@ namespace Noux {
 			Fcntl_error   fcntl;
 			Open_error    open;
 			Execve_error  execve;
+			Unlink_error  unlink;
+			Rename_error  rename;
+			Mkdir_error   mkdir;
 		} error;
 
 		union {
 
 			SYSIO_DECL(getcwd, { }, { Path path; });
 
-			SYSIO_DECL(write,  { int fd; size_t count; Chunk chunk; }, { });
+			SYSIO_DECL(write,  { int fd; size_t count; Chunk chunk; },
+			                   { size_t count; });
 
 			SYSIO_DECL(stat,   { Path path; }, { Stat st; });
 
@@ -238,7 +261,10 @@ namespace Noux {
 
 			SYSIO_DECL(ioctl,  : Ioctl_in { int fd; }, : Ioctl_out { });
 
-			SYSIO_DECL(dirent, { int fd; int index; }, { Dirent entry; });
+			SYSIO_DECL(lseek,  { int fd; off_t offset; Lseek_whence whence; },
+			                   { off_t offset; });
+
+			SYSIO_DECL(dirent, { int fd; }, { Dirent entry; });
 
 			SYSIO_DECL(fchdir, { int fd; }, { });
 
@@ -261,6 +287,12 @@ namespace Noux {
 			SYSIO_DECL(pipe,   { }, { int fd[2]; });
 
 			SYSIO_DECL(dup2,   { int fd; int to_fd; }, { });
+
+			SYSIO_DECL(unlink, { Path path; }, { });
+
+			SYSIO_DECL(rename, { Path from_path; Path to_path; }, { });
+
+			SYSIO_DECL(mkdir, { Path path; int mode; }, { });
 		};
 	};
 };