unix: call gettimeofday libc function directly

This also works when invoking the raw syscall on Go ≤ 1.11

Fixes golang/go#38925

Change-Id: I137532da92b457a6853ed1be87c0aa72d2b2c886
Reviewed-on: https://go-review.googlesource.com/c/sys/+/232803
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/unix/syscall_darwin.go b/unix/syscall_darwin.go
index 9a5a6ee..0cf31ac 100644
--- a/unix/syscall_darwin.go
+++ b/unix/syscall_darwin.go
@@ -423,6 +423,7 @@
 //sysnb	Getrlimit(which int, lim *Rlimit) (err error)
 //sysnb	Getrusage(who int, rusage *Rusage) (err error)
 //sysnb	Getsid(pid int) (sid int, err error)
+//sysnb	Gettimeofday(tp *Timeval) (err error)
 //sysnb	Getuid() (uid int)
 //sysnb	Issetugid() (tainted bool)
 //sys	Kqueue() (fd int, err error)
diff --git a/unix/syscall_darwin_386.go b/unix/syscall_darwin_386.go
index 707ba4f..2724e3a 100644
--- a/unix/syscall_darwin_386.go
+++ b/unix/syscall_darwin_386.go
@@ -20,17 +20,6 @@
 	return Timeval{Sec: int32(sec), Usec: int32(usec)}
 }
 
-//sysnb	gettimeofday(tp *Timeval) (sec int32, usec int32, err error)
-func Gettimeofday(tv *Timeval) (err error) {
-	// The tv passed to gettimeofday must be non-nil
-	// but is otherwise unused. The answers come back
-	// in the two registers.
-	sec, usec, err := gettimeofday(tv)
-	tv.Sec = int32(sec)
-	tv.Usec = int32(usec)
-	return err
-}
-
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint32(fd)
 	k.Filter = int16(mode)
diff --git a/unix/syscall_darwin_amd64.go b/unix/syscall_darwin_amd64.go
index fdbfb59..ce2e0d2 100644
--- a/unix/syscall_darwin_amd64.go
+++ b/unix/syscall_darwin_amd64.go
@@ -20,17 +20,6 @@
 	return Timeval{Sec: sec, Usec: int32(usec)}
 }
 
-//sysnb	gettimeofday(tp *Timeval) (sec int64, usec int32, err error)
-func Gettimeofday(tv *Timeval) (err error) {
-	// The tv passed to gettimeofday must be non-nil
-	// but is otherwise unused. The answers come back
-	// in the two registers.
-	sec, usec, err := gettimeofday(tv)
-	tv.Sec = sec
-	tv.Usec = usec
-	return err
-}
-
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint64(fd)
 	k.Filter = int16(mode)
diff --git a/unix/syscall_darwin_arm.go b/unix/syscall_darwin_arm.go
index f8bc4cf..fc17a3f 100644
--- a/unix/syscall_darwin_arm.go
+++ b/unix/syscall_darwin_arm.go
@@ -20,17 +20,6 @@
 	return Timeval{Sec: int32(sec), Usec: int32(usec)}
 }
 
-//sysnb	gettimeofday(tp *Timeval) (sec int32, usec int32, err error)
-func Gettimeofday(tv *Timeval) (err error) {
-	// The tv passed to gettimeofday must be non-nil
-	// but is otherwise unused. The answers come back
-	// in the two registers.
-	sec, usec, err := gettimeofday(tv)
-	tv.Sec = int32(sec)
-	tv.Usec = int32(usec)
-	return err
-}
-
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint32(fd)
 	k.Filter = int16(mode)
diff --git a/unix/syscall_darwin_arm64.go b/unix/syscall_darwin_arm64.go
index 5ede3ac..1e91ddf 100644
--- a/unix/syscall_darwin_arm64.go
+++ b/unix/syscall_darwin_arm64.go
@@ -22,17 +22,6 @@
 	return Timeval{Sec: sec, Usec: int32(usec)}
 }
 
-//sysnb	gettimeofday(tp *Timeval) (sec int64, usec int32, err error)
-func Gettimeofday(tv *Timeval) (err error) {
-	// The tv passed to gettimeofday must be non-nil
-	// but is otherwise unused. The answers come back
-	// in the two registers.
-	sec, usec, err := gettimeofday(tv)
-	tv.Sec = sec
-	tv.Usec = usec
-	return err
-}
-
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint64(fd)
 	k.Filter = int16(mode)
diff --git a/unix/zsyscall_darwin_386.1_11.go b/unix/zsyscall_darwin_386.1_11.go
index c1cc0a4..23e94d3 100644
--- a/unix/zsyscall_darwin_386.1_11.go
+++ b/unix/zsyscall_darwin_386.1_11.go
@@ -966,6 +966,16 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
@@ -1709,18 +1719,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int32, usec int32, err error) {
-	r0, r1, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int32(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := Syscall(SYS_FSTAT64, uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_386.go b/unix/zsyscall_darwin_386.go
index a3fc490..e2ffb3b 100644
--- a/unix/zsyscall_darwin_386.go
+++ b/unix/zsyscall_darwin_386.go
@@ -1376,6 +1376,21 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc_gettimeofday_trampoline()
+
+//go:linkname libc_gettimeofday libc_gettimeofday
+//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := syscall_rawSyscall(funcPC(libc_getuid_trampoline), 0, 0, 0)
 	uid = int(r0)
@@ -2357,23 +2372,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int32, usec int32, err error) {
-	r0, r1, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int32(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-func libc_gettimeofday_trampoline()
-
-//go:linkname libc_gettimeofday libc_gettimeofday
-//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := syscall_syscall(funcPC(libc_fstat64_trampoline), uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_amd64.1_11.go b/unix/zsyscall_darwin_amd64.1_11.go
index f8e5c37..1025617 100644
--- a/unix/zsyscall_darwin_amd64.1_11.go
+++ b/unix/zsyscall_darwin_amd64.1_11.go
@@ -966,6 +966,16 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
@@ -1709,18 +1719,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int64, usec int32, err error) {
-	r0, r1, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int64(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := Syscall(SYS_FSTAT64, uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_amd64.go b/unix/zsyscall_darwin_amd64.go
index 50d6437..c67e336 100644
--- a/unix/zsyscall_darwin_amd64.go
+++ b/unix/zsyscall_darwin_amd64.go
@@ -1376,6 +1376,21 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc_gettimeofday_trampoline()
+
+//go:linkname libc_gettimeofday libc_gettimeofday
+//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := syscall_rawSyscall(funcPC(libc_getuid_trampoline), 0, 0, 0)
 	uid = int(r0)
@@ -2357,23 +2372,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int64, usec int32, err error) {
-	r0, r1, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int64(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-func libc_gettimeofday_trampoline()
-
-//go:linkname libc_gettimeofday libc_gettimeofday
-//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := syscall_syscall(funcPC(libc_fstat64_trampoline), uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_arm.1_11.go b/unix/zsyscall_darwin_arm.1_11.go
index cea04e0..d34e6df 100644
--- a/unix/zsyscall_darwin_arm.1_11.go
+++ b/unix/zsyscall_darwin_arm.1_11.go
@@ -966,6 +966,16 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
@@ -1682,18 +1692,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int32, usec int32, err error) {
-	r0, r1, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int32(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := Syscall(SYS_FSTAT, uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_arm.go b/unix/zsyscall_darwin_arm.go
index 6310395..b759757 100644
--- a/unix/zsyscall_darwin_arm.go
+++ b/unix/zsyscall_darwin_arm.go
@@ -1376,6 +1376,21 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc_gettimeofday_trampoline()
+
+//go:linkname libc_gettimeofday libc_gettimeofday
+//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := syscall_rawSyscall(funcPC(libc_getuid_trampoline), 0, 0, 0)
 	uid = int(r0)
@@ -2342,23 +2357,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int32, usec int32, err error) {
-	r0, r1, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int32(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-func libc_gettimeofday_trampoline()
-
-//go:linkname libc_gettimeofday libc_gettimeofday
-//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := syscall_syscall(funcPC(libc_fstat_trampoline), uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_arm64.1_11.go b/unix/zsyscall_darwin_arm64.1_11.go
index 8c3bb3a..8d39a09 100644
--- a/unix/zsyscall_darwin_arm64.1_11.go
+++ b/unix/zsyscall_darwin_arm64.1_11.go
@@ -966,6 +966,16 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
@@ -1682,18 +1692,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int64, usec int32, err error) {
-	r0, r1, e1 := RawSyscall(SYS_GETTIMEOFDAY, uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int64(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := Syscall(SYS_FSTAT, uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {
diff --git a/unix/zsyscall_darwin_arm64.go b/unix/zsyscall_darwin_arm64.go
index a8709f7..b288612 100644
--- a/unix/zsyscall_darwin_arm64.go
+++ b/unix/zsyscall_darwin_arm64.go
@@ -1376,6 +1376,21 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func Gettimeofday(tp *Timeval) (err error) {
+	_, _, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc_gettimeofday_trampoline()
+
+//go:linkname libc_gettimeofday libc_gettimeofday
+//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func Getuid() (uid int) {
 	r0, _, _ := syscall_rawSyscall(funcPC(libc_getuid_trampoline), 0, 0, 0)
 	uid = int(r0)
@@ -2342,23 +2357,6 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func gettimeofday(tp *Timeval) (sec int64, usec int32, err error) {
-	r0, r1, e1 := syscall_rawSyscall(funcPC(libc_gettimeofday_trampoline), uintptr(unsafe.Pointer(tp)), 0, 0)
-	sec = int64(r0)
-	usec = int32(r1)
-	if e1 != 0 {
-		err = errnoErr(e1)
-	}
-	return
-}
-
-func libc_gettimeofday_trampoline()
-
-//go:linkname libc_gettimeofday libc_gettimeofday
-//go:cgo_import_dynamic libc_gettimeofday gettimeofday "/usr/lib/libSystem.B.dylib"
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func Fstat(fd int, stat *Stat_t) (err error) {
 	_, _, e1 := syscall_syscall(funcPC(libc_fstat_trampoline), uintptr(fd), uintptr(unsafe.Pointer(stat)), 0)
 	if e1 != 0 {