[PATCH liburing v3 02/10] arch: syscall: Add `__sys_open()` syscall

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

A prep patch to support aarch64 nolibc. We will use this to get the
page size by reading /proc/self/auxv. For some reason __NR_open is
not defined, so also define it in aarch64 syscall specific file.

v3:
  - Use __NR_openat if __NR_open is not defined.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/arch/generic/syscall.h |  9 +++++++++
 src/arch/syscall-defs.h    | 14 ++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/arch/generic/syscall.h b/src/arch/generic/syscall.h
index fa93064..71b2234 100644
--- a/src/arch/generic/syscall.h
+++ b/src/arch/generic/syscall.h
@@ -7,6 +7,8 @@
 #ifndef LIBURING_ARCH_GENERIC_SYSCALL_H
 #define LIBURING_ARCH_GENERIC_SYSCALL_H
 
+#include <fcntl.h>
+
 static inline int ____sys_io_uring_register(int fd, unsigned opcode,
 					    const void *arg, unsigned nr_args)
 {
@@ -41,6 +43,13 @@ static inline int ____sys_io_uring_enter(int fd, unsigned to_submit,
 				       _NSIG / 8);
 }
 
+static inline int __sys_open(const char *pathname, int flags, mode_t mode)
+{
+	int ret;
+	ret = open(pathname, flags, mode);
+	return (ret < 0) ? -errno : ret;
+}
+
 static inline void *__sys_mmap(void *addr, size_t length, int prot, int flags,
 			       int fd, off_t offset)
 {
diff --git a/src/arch/syscall-defs.h b/src/arch/syscall-defs.h
index 1e8ae1b..9d4424d 100644
--- a/src/arch/syscall-defs.h
+++ b/src/arch/syscall-defs.h
@@ -3,6 +3,20 @@
 #ifndef LIBURING_ARCH_SYSCALL_DEFS_H
 #define LIBURING_ARCH_SYSCALL_DEFS_H
 
+#include <fcntl.h>
+
+static inline int __sys_open(const char *pathname, int flags, mode_t mode)
+{
+	/*
+ 	 * Some architectures don't have __NR_open, but __NR_openat.
+ 	 */
+#ifdef __NR_open
+	return __do_syscall3(__NR_open, pathname, flags, mode);
+#else
+	return __do_syscall4(__NR_openat, AT_FDCWD, pathname, flags, mode);
+#endif
+}
+
 static inline void *__sys_mmap(void *addr, size_t length, int prot, int flags,
 			       int fd, off_t offset)
 {
-- 
Ammar Faizi