From 43b89665dc3ec83ccfc292d6bc65dce75fdad9b3 Mon Sep 17 00:00:00 2001
From: Lubos Dolezel <lubos@dolezel.info>
Date: Wed, 1 Feb 2017 23:39:55 +0100
Subject: [PATCH] Implement sys_openat()

---
 src/kernel/emulation/linux/CMakeLists.txt |  1 +
 src/kernel/emulation/linux/fcntl/open.h   |  2 +
 src/kernel/emulation/linux/fcntl/openat.c | 46 +++++++++++++++++++++++
 src/kernel/emulation/linux/fcntl/openat.h |  8 ++++
 src/kernel/emulation/linux/syscalls.c     |  3 ++
 5 files changed, 60 insertions(+)
 create mode 100644 src/kernel/emulation/linux/fcntl/openat.c
 create mode 100644 src/kernel/emulation/linux/fcntl/openat.h

diff --git a/src/kernel/emulation/linux/CMakeLists.txt b/src/kernel/emulation/linux/CMakeLists.txt
index 8cbfbffb3..32a23cc67 100644
--- a/src/kernel/emulation/linux/CMakeLists.txt
+++ b/src/kernel/emulation/linux/CMakeLists.txt
@@ -114,6 +114,7 @@ set(emulation_sources
 	misc/getrusage.c
 	misc/getlogin.c
 	fcntl/open.c
+	fcntl/openat.c
 	fcntl/fcntl.c
 	network/socket.c
 	network/socketpair.c
diff --git a/src/kernel/emulation/linux/fcntl/open.h b/src/kernel/emulation/linux/fcntl/open.h
index 0e6ab1cf2..b5164cdd7 100644
--- a/src/kernel/emulation/linux/fcntl/open.h
+++ b/src/kernel/emulation/linux/fcntl/open.h
@@ -37,5 +37,7 @@ long sys_open_nocancel(const char* filename, int flags, unsigned int mode);
 #define BSD_O_SYMLINK 0x200000
 #define BSD_O_CLOEXEC 0x1000000
 
+int oflags_bsd_to_linux(int flags);
+
 #endif
 
diff --git a/src/kernel/emulation/linux/fcntl/openat.c b/src/kernel/emulation/linux/fcntl/openat.c
new file mode 100644
index 000000000..a55b300bb
--- /dev/null
+++ b/src/kernel/emulation/linux/fcntl/openat.c
@@ -0,0 +1,46 @@
+#include "openat.h"
+#include "open.h"
+#include "../base.h"
+#include "../errno.h"
+#include <linux-syscalls/linux.h>
+#include "../../../../libc/include/fcntl.h"
+#include "../common_at.h"
+
+#ifndef O_NOFOLLOW
+#	define O_NOFOLLOW 0x0100
+#endif
+#ifndef O_CLOEXEC
+#	define O_CLOEXEC 0x1000000
+#endif
+#ifndef O_DIRECTORY
+#	define O_DIRECTORY 0x100000
+#endif
+
+extern int strcmp(const char *s1, const char *s2);
+
+long sys_openat(int fd, const char* filename, int flags, unsigned int mode)
+{
+	return sys_openat_nocancel(fd, filename, flags, mode);
+}
+
+long sys_openat_nocancel(int fd, const char* filename, int flags, unsigned int mode)
+{
+	int ret, linux_flags;
+
+	linux_flags = oflags_bsd_to_linux(flags);
+
+	if (sizeof(void*) == 4)
+	{
+		linux_flags |= LINUX_O_LARGEFILE;
+	}
+
+	// XNU /dev/random behaves like Linux /dev/urandom
+	if (strcmp(filename, "/dev/random") == 0)
+		filename = "/dev/urandom";
+
+	ret = LINUX_SYSCALL(__NR_openat, atfd(fd), filename, linux_flags, mode);
+	if (ret < 0)
+		ret = errno_linux_to_bsd(ret);
+
+	return ret;
+}
diff --git a/src/kernel/emulation/linux/fcntl/openat.h b/src/kernel/emulation/linux/fcntl/openat.h
new file mode 100644
index 000000000..b323a235d
--- /dev/null
+++ b/src/kernel/emulation/linux/fcntl/openat.h
@@ -0,0 +1,8 @@
+#ifndef LINUX_OPENAT_H
+#define LINUX_OPENAT_H
+
+long sys_openat(int fd, const char* filename, int flags, unsigned int mode);
+long sys_openat_nocancel(int fd, const char* filename, int flags, unsigned int mode);
+
+#endif
+
diff --git a/src/kernel/emulation/linux/syscalls.c b/src/kernel/emulation/linux/syscalls.c
index 707e9611e..d396a3021 100644
--- a/src/kernel/emulation/linux/syscalls.c
+++ b/src/kernel/emulation/linux/syscalls.c
@@ -82,6 +82,7 @@
 #include "misc/syscall.h"
 #include "synch/semwait_signal.h"
 #include "fcntl/open.h"
+#include "fcntl/openat.h"
 #include "fcntl/fcntl.h"
 #include "network/socket.h"
 #include "network/connect.h"
@@ -335,6 +336,8 @@ void* __bsd_syscall_table[600] = {
 	[417] = sys_poll_nocancel,
 	[423] = sys_semwait_signal_nocancel,
 	[461] = sys_getattrlistbulk,
+	[463] = sys_openat,
+	[464] = sys_openat_nocancel,
 	[469] = sys_fstatat,
 	[470] = sys_fstatat64,
 	[500] = sys_getentropy,
-- 
2.51.2