unix: add Faccessat2 and use it in Faccessat if available
Linux kernel 5.8 added the faccessat2 syscall taking a flags argument.
Attempt to use it in Faccessat and fall back to the existing
implementation mimicking glibc faccessat.
Tested on Debian Buster with manually built Linux kernel 5.8
Suggested by Ian Lance Taylor.
Change-Id: Ia14f744a63dde7ff2dea34935cabc62937de9cb5
Reviewed-on: https://go-review.googlesource.com/c/sys/+/246537
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/unix/syscall_linux.go b/unix/syscall_linux.go
index fad483b..ab16736 100644
--- a/unix/syscall_linux.go
+++ b/unix/syscall_linux.go
@@ -1965,10 +1965,15 @@
}
//sys faccessat(dirfd int, path string, mode uint32) (err error)
+//sys Faccessat2(dirfd int, path string, mode uint32, flags int) (err error)
func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
- if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
- return EINVAL
+ if flags == 0 {
+ return faccessat(dirfd, path, mode)
+ }
+
+ if err := Faccessat2(dirfd, path, mode, flags); err != ENOSYS {
+ return err
}
// The Linux kernel faccessat system call does not take any flags.
@@ -1977,8 +1982,8 @@
// Because people naturally expect syscall.Faccessat to act
// like C faccessat, we do the same.
- if flags == 0 {
- return faccessat(dirfd, path, mode)
+ if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
+ return EINVAL
}
var st Stat_t
diff --git a/unix/zsyscall_linux.go b/unix/zsyscall_linux.go
index f6603de..4eec7a7 100644
--- a/unix/zsyscall_linux.go
+++ b/unix/zsyscall_linux.go
@@ -1821,6 +1821,21 @@
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+func Faccessat2(dirfd int, path string, mode uint32, flags int) (err error) {
+ var _p0 *byte
+ _p0, err = BytePtrFromString(path)
+ if err != nil {
+ return
+ }
+ _, _, e1 := Syscall6(SYS_FACCESSAT2, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode), uintptr(flags), 0, 0)
+ if e1 != 0 {
+ err = errnoErr(e1)
+ }
+ return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
func nameToHandleAt(dirFD int, pathname string, fh *fileHandle, mountID *_C_int, flags int) (err error) {
var _p0 *byte
_p0, err = BytePtrFromString(pathname)
