Add openat(2).

This is a rather hacky implementation.

libc/Makefile

@@ -173,6 +173,7 @@ mkdir.o \
 mktemp.o \
 on_exit.o \
 open.o \
+openat.o \
 pipe.o \
 print.o \
 putc.o \

libc/open.cpp

@@ -17,8 +17,8 @@
 	You should have received a copy of the GNU Lesser General Public License
 	along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
 
-	dup.cpp
-	Duplicates a file descriptor.
+	open.cpp
+	Open a file.
 
 *******************************************************************************/
 
@@ -26,11 +26,11 @@
 #include <fcntl.h>
 #include <stdarg.h>
 
-DEFN_SYSCALL3(int, SysOpen, SYSCALL_OPEN, const char*, int, mode_t);
+DEFN_SYSCALL3(int, sys_open, SYSCALL_OPEN, const char*, int, mode_t);
 
 extern "C" int open(const char* path, int flags, ...)
 {
-	int mode = 0;
+	mode_t mode = 0;
 	if ( flags & O_CREAT )
 	{
 		va_list ap;
@@ -38,5 +38,5 @@ extern "C" int open(const char* path, int flags, ...)
 		mode = va_arg(ap, mode_t);
 		va_end(ap);
 	}
-	return SysOpen(path, flags, mode);
+	return sys_open(path, flags, mode);
 }

libc/openat.cpp

@@ -0,0 +1,42 @@
+/*******************************************************************************
+
+	Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
+
+	This file is part of the Sortix C Library.
+
+	The Sortix C Library is free software: you can redistribute it and/or modify
+	it under the terms of the GNU Lesser General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or (at your
+	option) any later version.
+
+	The Sortix C Library is distributed in the hope that it will be useful, but
+	WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+	or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+	License for more details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+	openat.cpp
+	Open a file relative to directory.
+
+*******************************************************************************/
+
+#include <sys/syscall.h>
+#include <fcntl.h>
+#include <stdarg.h>
+
+DEFN_SYSCALL4(int, sys_openat, SYSCALL_OPENAT, int, const char*, int, mode_t);
+
+extern "C" int openat(int dirfd, const char* path, int flags, ...)
+{
+	mode_t mode = 0;
+	if ( flags & O_CREAT )
+	{
+		va_list ap;
+		va_start(ap, flags);
+		mode = va_arg(ap, mode_t);
+		va_end(ap);
+	}
+	return sys_openat(dirfd, path, flags, mode);
+}

sortix/filesystem.cpp

@@ -1,6 +1,6 @@
-/******************************************************************************
+/*******************************************************************************
 
-	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
+	Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
 
 	This file is part of Sortix.
 
@@ -14,13 +14,13 @@
 	FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 	details.
 
-	You should have received a copy of the GNU General Public License along
-	with Sortix. If not, see <http://www.gnu.org/licenses/>.
+	You should have received a copy of the GNU General Public License along with
+	Sortix. If not, see <http://www.gnu.org/licenses/>.
 
 	filesystem.cpp
 	Allows access to stored sequences of bytes in an orderly fashion.
 
-******************************************************************************/
+*******************************************************************************/
 
 #include <sortix/kernel/platform.h>
 #include <sortix/kernel/string.h>
@@ -86,6 +86,22 @@ namespace Sortix
 			return fd;
 		}
 
+		int SysOpenAt(int dirfd, const char* pathname, int flags, mode_t mode)
+		{
+			if ( pathname[0] == '/' )
+				return SysOpen(pathname, flags, mode);
+			Process* process = CurrentProcess();
+			Device* dir = process->descriptors.Get(dirfd);
+			if ( !dir ) { errno = EBADF; return -1; }
+			const char* path = process->descriptors.GetPath(dirfd);
+			char* fullpath = String::Combine(3, path, "/", pathname);
+			if ( !fullpath )
+				return -1;
+			int ret = SysOpen(fullpath, flags, mode);
+			delete[] fullpath;
+			return ret;
+		}
+
 		int SysAccess(const char* pathname, int mode)
 		{
 			int oflags = 0;
@@ -216,6 +232,7 @@ namespace Sortix
 		void Init()
 		{
 			Syscall::Register(SYSCALL_OPEN, (void*) SysOpen);
+			Syscall::Register(SYSCALL_OPENAT, (void*) SysOpenAt);
 			Syscall::Register(SYSCALL_UNLINK, (void*) SysUnlink);
 			Syscall::Register(SYSCALL_MKDIR, (void*) SysMkDir);
 			Syscall::Register(SYSCALL_RMDIR, (void*) SysRmDir);

sortix/include/sortix/syscallnum.h

@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011, 2012.
+	Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
 
 	This file is part of Sortix.
 
@@ -16,6 +16,7 @@
 
 	You should have received a copy of the GNU General Public License along with
 	Sortix. If not, see <http://www.gnu.org/licenses/>.
+
 	syscallnum.h
 	Stores numerical constants for each available system call on this kernel.
 
@@ -75,7 +76,7 @@
 #define SYSCALL_TFORK 51
 #define SYSCALL_TCGETWINSIZE 52
 #define SYSCALL_RAISE 53
-#define SYSCALL_MAX_NUM 54 /* index of highest constant + 1 */
+#define SYSCALL_OPENAT 54
+#define SYSCALL_MAX_NUM 55 /* index of highest constant + 1 */
 
 #endif
-