syscall: support syscalls without error return on Linux

Add the rawSyscallNoError wrapper function which is used for Linux
syscalls that don't return an error and convert all applicable
occurences of RawSyscall to use it instead.

Fixes #22924

Change-Id: Iff1eddb54573d459faa01471f10398b3d38528dd
Reviewed-on: https://go-review.googlesource.com/84485
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/syscall/asm_linux_386.s

@@ -9,21 +9,20 @@
 // System calls for 386, Linux
 //
 
-// func Syscall(trap uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr);
-// Trap # in AX, args in BX CX DX SI DI, return in AX
-
 // See ../runtime/sys_linux_386.s for the reason why we always use int 0x80
 // instead of the glibc-specific "CALL 0x10(GS)".
 #define INVOKE_SYSCALL	INT	$0x80
 
-TEXT	·Syscall(SB),NOSPLIT,$0-28
+// func Syscall(trap uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr);
+// Trap # in AX, args in BX CX DX SI DI, return in AX
+TEXT ·Syscall(SB),NOSPLIT,$0-28
 	CALL	runtime·entersyscall(SB)
 	MOVL	trap+0(FP), AX	// syscall entry
 	MOVL	a1+4(FP), BX
 	MOVL	a2+8(FP), CX
 	MOVL	a3+12(FP), DX
 	MOVL	$0, SI
-	MOVL	$0,  DI
+	MOVL	$0, DI
 	INVOKE_SYSCALL
 	CMPL	AX, $0xfffff001
 	JLS	ok
@@ -41,7 +40,7 @@ ok:
 	RET
 
 // func Syscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
-TEXT	·Syscall6(SB),NOSPLIT,$0-40
+TEXT ·Syscall6(SB),NOSPLIT,$0-40
 	CALL	runtime·entersyscall(SB)
 	MOVL	trap+0(FP), AX	// syscall entry
 	MOVL	a1+4(FP), BX
@@ -73,7 +72,7 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-28
 	MOVL	a2+8(FP), CX
 	MOVL	a3+12(FP), DX
 	MOVL	$0, SI
-	MOVL	$0,  DI
+	MOVL	$0, DI
 	INVOKE_SYSCALL
 	CMPL	AX, $0xfffff001
 	JLS	ok1
@@ -89,7 +88,7 @@ ok1:
 	RET
 
 // func RawSyscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
-TEXT	·RawSyscall6(SB),NOSPLIT,$0-40
+TEXT ·RawSyscall6(SB),NOSPLIT,$0-40
 	MOVL	trap+0(FP), AX	// syscall entry
 	MOVL	a1+4(FP), BX
 	MOVL	a2+8(FP), CX
@@ -111,6 +110,19 @@ ok2:
 	MOVL	$0, err+36(FP)
 	RET
 
+// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-24
+	MOVL	trap+0(FP), AX	// syscall entry
+	MOVL	a1+4(FP), BX
+	MOVL	a2+8(FP), CX
+	MOVL	a3+12(FP), DX
+	MOVL	$0, SI
+	MOVL	$0, DI
+	INVOKE_SYSCALL
+	MOVL	AX, r1+16(FP)
+	MOVL	DX, r2+20(FP)
+	RET
+
 #define SYS_SOCKETCALL 102	/* from zsysnum_linux_386.go */
 
 // func socketcall(call int, a0, a1, a2, a3, a4, a5 uintptr) (n int, err int)
@@ -119,10 +131,10 @@ TEXT ·socketcall(SB),NOSPLIT,$0-36
 	CALL	runtime·entersyscall(SB)
 	MOVL	$SYS_SOCKETCALL, AX	// syscall entry
 	MOVL	call+0(FP), BX	// socket call number
-	LEAL		a0+4(FP), CX	// pointer to call arguments
+	LEAL	a0+4(FP), CX	// pointer to call arguments
 	MOVL	$0, DX
 	MOVL	$0, SI
-	MOVL	$0,  DI
+	MOVL	$0, DI
 	INVOKE_SYSCALL
 	CMPL	AX, $0xfffff001
 	JLS	oksock
@@ -145,7 +157,7 @@ TEXT ·rawsocketcall(SB),NOSPLIT,$0-36
 	LEAL		a0+4(FP), CX	// pointer to call arguments
 	MOVL	$0, DX
 	MOVL	$0, SI
-	MOVL	$0,  DI
+	MOVL	$0, DI
 	INVOKE_SYSCALL
 	CMPL	AX, $0xfffff001
 	JLS	oksock1
@@ -171,7 +183,7 @@ TEXT ·seek(SB),NOSPLIT,$0-28
 	MOVL	offset_hi+8(FP), CX
 	MOVL	offset_lo+4(FP), DX
 	LEAL	newoffset_lo+16(FP), SI	// result pointer
-	MOVL	whence+12(FP),  DI
+	MOVL	whence+12(FP), DI
 	INVOKE_SYSCALL
 	CMPL	AX, $0xfffff001
 	JLS	okseek

src/syscall/asm_linux_amd64.s

@@ -9,12 +9,12 @@
 // System calls for AMD64, Linux
 //
 
-// func Syscall(trap int64, a1, a2, a3 int64) (r1, r2, err int64);
+// func Syscall(trap int64, a1, a2, a3 uintptr) (r1, r2, err uintptr);
 // Trap # in AX, args in DI SI DX R10 R8 R9, return in AX DX
 // Note that this differs from "standard" ABI convention, which
 // would pass 4th arg in CX, not R10.
 
-TEXT	·Syscall(SB),NOSPLIT,$0-56
+TEXT ·Syscall(SB),NOSPLIT,$0-56
 	CALL	runtime·entersyscall(SB)
 	MOVQ	a1+8(FP), DI
 	MOVQ	a2+16(FP), SI
@@ -134,6 +134,20 @@ ok2:
 	MOVQ	$0, err+24(FP)
 	RET
 
+// func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
+	MOVQ	a1+8(FP), DI
+	MOVQ	a2+16(FP), SI
+	MOVQ	a3+24(FP), DX
+	MOVQ	$0, R10
+	MOVQ	$0, R8
+	MOVQ	$0, R9
+	MOVQ	trap+0(FP), AX	// syscall entry
+	SYSCALL
+	MOVQ	AX, r1+32(FP)
+	MOVQ	DX, r2+40(FP)
+	RET
+
 // func gettimeofday(tv *Timeval) (err uintptr)
 TEXT ·gettimeofday(SB),NOSPLIT,$0-16
 	MOVQ	tv+0(FP), DI

src/syscall/asm_linux_arm.s

@@ -12,9 +12,8 @@
 // TODO(kaib): handle error returns
 
 // func Syscall(syscall uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr);
-
-TEXT	·Syscall(SB),NOSPLIT,$0-28
-	BL		runtime·entersyscall(SB)
+TEXT ·Syscall(SB),NOSPLIT,$0-28
+	BL	runtime·entersyscall(SB)
 	MOVW	trap+0(FP), R7
 	MOVW	a1+4(FP), R0
 	MOVW	a2+8(FP), R1
@@ -22,30 +21,30 @@ TEXT	·Syscall(SB),NOSPLIT,$0-28
 	MOVW	$0, R3
 	MOVW	$0, R4
 	MOVW	$0, R5
-	SWI		$0
+	SWI	$0
 	MOVW	$0xfffff001, R1
-	CMP		R1, R0
-	BLS		ok
+	CMP	R1, R0
+	BLS	ok
 	MOVW	$-1, R1
 	MOVW	R1, r1+16(FP)
 	MOVW	$0, R2
 	MOVW	R2, r2+20(FP)
-	RSB		$0, R0, R0
+	RSB	$0, R0, R0
 	MOVW	R0, err+24(FP)
-	BL		runtime·exitsyscall(SB)
+	BL	runtime·exitsyscall(SB)
 	RET
 ok:
 	MOVW	R0, r1+16(FP)
 	MOVW	$0, R0
 	MOVW	R0, r2+20(FP)
 	MOVW	R0, err+24(FP)
-	BL		runtime·exitsyscall(SB)
+	BL	runtime·exitsyscall(SB)
 	RET
 
 // func Syscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
 // Actually Syscall5 but the rest of the code expects it to be named Syscall6.
-TEXT	·Syscall6(SB),NOSPLIT,$0-40
-	BL		runtime·entersyscall(SB)
+TEXT ·Syscall6(SB),NOSPLIT,$0-40
+	BL	runtime·entersyscall(SB)
 	MOVW	trap+0(FP), R7	// syscall entry
 	MOVW	a1+4(FP), R0
 	MOVW	a2+8(FP), R1
@@ -53,24 +52,24 @@ TEXT	·Syscall6(SB),NOSPLIT,$0-40
 	MOVW	a4+16(FP), R3
 	MOVW	a5+20(FP), R4
 	MOVW	a6+24(FP), R5
-	SWI		$0
+	SWI	$0
 	MOVW	$0xfffff001, R6
-	CMP		R6, R0
-	BLS		ok6
+	CMP	R6, R0
+	BLS	ok6
 	MOVW	$-1, R1
 	MOVW	R1, r1+28(FP)
 	MOVW	$0, R2
 	MOVW	R2, r2+32(FP)
-	RSB		$0, R0, R0
+	RSB	$0, R0, R0
 	MOVW	R0, err+36(FP)
-	BL		runtime·exitsyscall(SB)
+	BL	runtime·exitsyscall(SB)
 	RET
 ok6:
 	MOVW	R0, r1+28(FP)
 	MOVW	R1, r2+32(FP)
 	MOVW	$0, R0
 	MOVW	R0, err+36(FP)
-	BL		runtime·exitsyscall(SB)
+	BL	runtime·exitsyscall(SB)
 	RET
 
 // func RawSyscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
@@ -83,15 +82,15 @@ TEXT	·RawSyscall6(SB),NOSPLIT,$0-40
 	MOVW	a4+16(FP), R3
 	MOVW	a5+20(FP), R4
 	MOVW	a6+24(FP), R5
-	SWI		$0
+	SWI	$0
 	MOVW	$0xfffff001, R6
-	CMP		R6, R0
-	BLS		ok2
+	CMP	R6, R0
+	BLS	ok2
 	MOVW	$-1, R1
 	MOVW	R1, r1+28(FP)
 	MOVW	$0, R2
 	MOVW	R2, r2+32(FP)
-	RSB		$0, R0, R0
+	RSB	$0, R0, R0
 	MOVW	R0, err+36(FP)
 	RET
 ok2:
@@ -131,7 +130,7 @@ okseek:
 	MOVW	$0, R0
 	MOVW	R0, err+24(FP)
 	BL	runtime·exitsyscall(SB)
-	RET	
+	RET
 
 // func RawSyscall(trap uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr);
 TEXT ·RawSyscall(SB),NOSPLIT,$0-28
@@ -139,15 +138,15 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-28
 	MOVW	a1+4(FP), R0
 	MOVW	a2+8(FP), R1
 	MOVW	a3+12(FP), R2
-	SWI		$0
+	SWI	$0
 	MOVW	$0xfffff001, R1
-	CMP		R1, R0
-	BLS		ok1
+	CMP	R1, R0
+	BLS	ok1
 	MOVW	$-1, R1
 	MOVW	R1, r1+16(FP)
 	MOVW	$0, R2
 	MOVW	R2, r2+20(FP)
-	RSB		$0, R0, R0
+	RSB	$0, R0, R0
 	MOVW	R0, err+24(FP)
 	RET
 ok1:
@@ -157,3 +156,14 @@ ok1:
 	MOVW	R0, err+24(FP)
 	RET
 
+// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-24
+	MOVW	trap+0(FP), R7	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
+	SWI	$0
+	MOVW	R0, r1+16(FP)
+	MOVW	$0, R0
+	MOVW	R0, r2+20(FP)
+	RET

src/syscall/asm_linux_arm64.s

@@ -5,8 +5,7 @@
 #include "textflag.h"
 
 // func Syscall(trap int64, a1, a2, a3 int64) (r1, r2, err int64);
-
-TEXT	·Syscall(SB),NOSPLIT,$0-56
+TEXT ·Syscall(SB),NOSPLIT,$0-56
 	BL	runtime·entersyscall(SB)
 	MOVD	a1+8(FP), R0
 	MOVD	a2+16(FP), R1
@@ -103,3 +102,17 @@ ok:
 	MOVD	R1, r2+64(FP)	// r2
 	MOVD	ZR, err+72(FP)	// errno
 	RET
+
+// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
+	MOVD	a1+8(FP), R0
+	MOVD	a2+16(FP), R1
+	MOVD	a3+24(FP), R2
+	MOVD	$0, R3
+	MOVD	$0, R4
+	MOVD	$0, R5
+	MOVD	trap+0(FP), R8	// syscall entry
+	SVC
+	MOVD	R0, r1+32(FP)
+	MOVD	R1, r2+40(FP)
+	RET

src/syscall/asm_linux_mips64x.s

@@ -12,8 +12,7 @@
 //
 
 // func Syscall(trap int64, a1, a2, a3 int64) (r1, r2, err int64);
-
-TEXT	·Syscall(SB),NOSPLIT,$0-56
+TEXT ·Syscall(SB),NOSPLIT,$0-56
 	JAL	runtime·entersyscall(SB)
 	MOVV	a1+8(FP), R4
 	MOVV	a2+16(FP), R5
@@ -102,3 +101,16 @@ ok2:
 	MOVV	R3, r2+64(FP)	// r2
 	MOVV	R0, err+72(FP)	// errno
 	RET
+
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
+	MOVV	a1+8(FP), R4
+	MOVV	a2+16(FP), R5
+	MOVV	a3+24(FP), R6
+	MOVV	R0, R7
+	MOVV	R0, R8
+	MOVV	R0, R9
+	MOVV	trap+0(FP), R2	// syscall entry
+	SYSCALL
+	MOVV	R2, r1+32(FP)
+	MOVV	R3, r2+40(FP)
+	RET

src/syscall/asm_linux_mipsx.s

@@ -13,8 +13,7 @@
 //
 
 // func Syscall(trap uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr);
-
-TEXT	·Syscall(SB),NOSPLIT,$0-28
+TEXT ·Syscall(SB),NOSPLIT,$0-28
 	JAL	runtime·entersyscall(SB)
 	MOVW	a1+4(FP), R4
 	MOVW	a2+8(FP), R5
@@ -36,7 +35,6 @@ ok:
 	JAL	runtime·exitsyscall(SB)
 	RET
 
-
 // func Syscall6(trap trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
 // 5th and 6th arg go at sp+16, sp+20.
 // Note that frame size of 20 means that 24 bytes gets reserved on stack.
@@ -140,3 +138,13 @@ ok2:
 	MOVW	R3, r2+32(FP)	// r2
 	MOVW	R0, err+36(FP)	// errno
 	RET
+
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$20-24
+	MOVW	a1+4(FP), R4
+	MOVW	a2+8(FP), R5
+	MOVW	a3+12(FP), R6
+	MOVW	trap+0(FP), R2	// syscall entry
+	SYSCALL
+	MOVW	R2, r1+16(FP)	// r1
+	MOVW	R3, r2+20(FP)	// r2
+	RET

src/syscall/asm_linux_ppc64x.s

@@ -12,8 +12,7 @@
 //
 
 // func Syscall(trap int64, a1, a2, a3 int64) (r1, r2, err int64);
-
-TEXT	·Syscall(SB),NOSPLIT,$0-56
+TEXT ·Syscall(SB),NOSPLIT,$0-56
 	BL	runtime·entersyscall(SB)
 	MOVD	a1+8(FP), R3
 	MOVD	a2+16(FP), R4
@@ -102,3 +101,16 @@ ok2:
 	MOVD	R4, r2+64(FP)	// r2
 	MOVD	R0, err+72(FP)	// errno
 	RET
+
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
+	MOVD	a1+8(FP), R3
+	MOVD	a2+16(FP), R4
+	MOVD	a3+24(FP), R5
+	MOVD	R0, R6
+	MOVD	R0, R7
+	MOVD	R0, R8
+	MOVD	trap+0(FP), R9	// syscall entry
+	SYSCALL R9
+	MOVD	R3, r1+32(FP)
+	MOVD	R4, r2+40(FP)
+	RET

src/syscall/asm_linux_s390x.s

@@ -106,6 +106,20 @@ ok2:
 	MOVD	$0, err+72(FP)	// errno
 	RET
 
+// func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
+TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
+	MOVD	a1+8(FP), R2
+	MOVD	a2+16(FP), R3
+	MOVD	a3+24(FP), R4
+	MOVD	$0, R5
+	MOVD	$0, R6
+	MOVD	$0, R7
+	MOVD	trap+0(FP), R1	// syscall entry
+	SYSCALL
+	MOVD	R2, r1+32(FP)
+	MOVD	R3, r2+40(FP)
+	RET
+
 #define SYS_SOCKETCALL 102	/* from zsysnum_linux_s390x.go */
 
 // func socketcall(call int, a0, a1, a2, a3, a4, a5 uintptr) (n int, err int)

src/syscall/exec_linux.go

@@ -122,7 +122,7 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
 	)
 
 	// Record parent PID so child can test if it has died.
-	ppid, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	ppid, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 
 	// Guard against side effects of shuffling fds below.
 	// Make sure that nextfd is beyond any currently open files so
@@ -219,10 +219,7 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
 	if sys.Foreground {
 		pgrp := int32(sys.Pgid)
 		if pgrp == 0 {
-			r1, _, err1 = RawSyscall(SYS_GETPID, 0, 0, 0)
-			if err1 != 0 {
-				goto childerror
-			}
+			r1, _ = rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 
 			pgrp = int32(r1)
 		}
@@ -311,9 +308,9 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
 		// Signal self if parent is already dead. This might cause a
 		// duplicate signal in rare cases, but it won't matter when
 		// using SIGKILL.
-		r1, _, _ = RawSyscall(SYS_GETPPID, 0, 0, 0)
+		r1, _ = rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 		if r1 != ppid {
-			pid, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+			pid, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 			_, _, err1 := RawSyscall(SYS_KILL, pid, uintptr(sys.Pdeathsig), 0)
 			if err1 != 0 {
 				goto childerror

src/syscall/export_linux_test.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package syscall
+
+var RawSyscallNoError = rawSyscallNoError
+
+const Sys_GETEUID = sys_GETEUID

src/syscall/mksyscall.pl

@@ -205,7 +205,11 @@ while(<>) {
 	# Determine which form to use; pad args with zeros.
 	my $asm = "Syscall";
 	if ($nonblock) {
-		$asm = "RawSyscall";
+		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
+			$asm = "rawSyscallNoError";
+		} else {
+			$asm = "RawSyscall";
+		}
 	}
 	if(@args <= 3) {
 		while(@args < 3) {
@@ -282,7 +286,12 @@ while(<>) {
 	if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
 		$text .= "\t$call\n";
 	} else {
-		$text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
+		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
+			# raw syscall without error on Linux, see golang.org/issue/22924
+			$text .= "\t$ret[0], $ret[1] := $call\n";
+		} else {
+			$text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
+		}
 	}
 	$text .= $body;
 

src/syscall/setuidgid_32_linux.go

@@ -8,6 +8,8 @@
 package syscall
 
 const (
+	sys_GETEUID = SYS_GETEUID32
+
 	sys_SETGID = SYS_SETGID32
 	sys_SETUID = SYS_SETUID32
 )

src/syscall/setuidgid_linux.go

@@ -8,6 +8,8 @@
 package syscall
 
 const (
+	sys_GETEUID = SYS_GETEUID
+
 	sys_SETGID = SYS_SETGID
 	sys_SETUID = SYS_SETUID
 )

src/syscall/syscall_linux.go

@@ -13,6 +13,8 @@ package syscall
 
 import "unsafe"
 
+func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
+
 /*
  * Wrapped
  */

src/syscall/syscall_linux_test.go

@@ -13,6 +13,9 @@ import (
 	"os/exec"
 	"os/signal"
 	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
 	"syscall"
 	"testing"
 	"time"
@@ -23,6 +26,8 @@ func TestMain(m *testing.M) {
 		deathSignalParent()
 	} else if os.Getenv("GO_DEATHSIG_CHILD") == "1" {
 		deathSignalChild()
+	} else if os.Getenv("GO_SYSCALL_NOERROR") == "1" {
+		syscallNoError()
 	}
 
 	os.Exit(m.Run())
@@ -166,3 +171,84 @@ func TestParseNetlinkMessage(t *testing.T) {
 		}
 	}
 }
+
+func TestSyscallNoError(t *testing.T) {
+	// On Linux there are currently no syscalls which don't fail and return
+	// a value larger than 0xfffffffffffff001 so we could test RawSyscall
+	// vs. RawSyscallNoError on 64bit architectures.
+	if runtime.GOARCH != "386" && runtime.GOARCH != "arm" {
+		t.Skip("skipping on non-32bit architecture")
+	}
+
+	// TODO(tklauser) is this check enough? Otherwise test for being in a non-k8s
+	// Linux VM via testenv.Builder().
+	if os.Getuid() != 0 {
+		t.Skip("skipping root only test")
+	}
+
+	// Copy the test binary to a location that a non-root user can read/execute
+	// after we drop privileges
+	tempDir, err := ioutil.TempDir("", "TestSyscallNoError")
+	if err != nil {
+		t.Fatalf("cannot create temporary directory: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+	os.Chmod(tempDir, 0755)
+
+	tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
+
+	src, err := os.Open(os.Args[0])
+	if err != nil {
+		t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
+	}
+	defer src.Close()
+
+	dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
+	if err != nil {
+		t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
+	}
+	if _, err := io.Copy(dst, src); err != nil {
+		t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
+	}
+	err = dst.Close()
+	if err != nil {
+		t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
+	}
+
+	uid := uint32(0xfffffffe)
+	err = os.Chown(tmpBinary, int(uid), -1)
+	if err != nil {
+		t.Fatalf("failed to chown test binary %q, %v", tmpBinary, err)
+	}
+
+	err = os.Chmod(tmpBinary, 0755|os.ModeSetuid)
+	if err != nil {
+		t.Fatalf("failed to set setuid bit on test binary %q, %v", tmpBinary, err)
+	}
+
+	cmd := exec.Command(tmpBinary)
+	cmd.Env = []string{"GO_SYSCALL_NOERROR=1"}
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed to start first child process: %v", err)
+	}
+
+	got := strings.TrimSpace(string(out))
+	want := strconv.FormatUint(uint64(uid)+1, 10) + " / " +
+		strconv.FormatUint(uint64(-uid), 10) + " / " +
+		strconv.FormatUint(uint64(uid), 10)
+	if got != want {
+		t.Errorf("expected %s, got %s", want, got)
+	}
+}
+
+func syscallNoError() {
+	// Test that the return value from SYS_GETEUID32 (which cannot fail)
+	// doesn't get treated as an error (see https://golang.org/issue/22924)
+	euid1, _, e := syscall.RawSyscall(syscall.Sys_GETEUID, 0, 0, 0)
+	euid2, _ := syscall.RawSyscallNoError(syscall.Sys_GETEUID, 0, 0, 0)
+
+	fmt.Println(uintptr(euid1), "/", int(e), "/", uintptr(euid2))
+	os.Exit(0)
+}

src/syscall/zsyscall_linux_386.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1216,7 +1216,7 @@ func Ftruncate(fd int, length int64) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID32, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1224,7 +1224,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID32, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1232,7 +1232,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID32, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1240,7 +1240,7 @@ func Getgid() (gid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID32, 0, 0, 0)
 	uid = int(r0)
 	return
 }

src/syscall/zsyscall_linux_amd64.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1206,7 +1206,7 @@ func Ftruncate(fd int, length int64) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1214,7 +1214,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1222,7 +1222,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1240,7 +1240,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
 	return
 }

src/syscall/zsyscall_linux_arm.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1375,7 +1375,7 @@ func Fstat(fd int, stat *Stat_t) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID32, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1383,7 +1383,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID32, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1391,7 +1391,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID32, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1399,7 +1399,7 @@ func Getgid() (gid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID32, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID32, 0, 0, 0)
 	uid = int(r0)
 	return
 }

src/syscall/zsyscall_linux_arm64.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1211,7 +1211,7 @@ func Ftruncate(fd int, length int64) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1219,7 +1219,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1227,7 +1227,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1245,7 +1245,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
 	return
 }

src/syscall/zsyscall_linux_ppc64.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1206,7 +1206,7 @@ func Ftruncate(fd int, length int64) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1214,7 +1214,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1222,7 +1222,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1240,7 +1240,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
 	return
 }

src/syscall/zsyscall_linux_ppc64le.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1206,7 +1206,7 @@ func Ftruncate(fd int, length int64) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1214,7 +1214,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1222,7 +1222,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1240,7 +1240,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
 	return
 }

src/syscall/zsyscall_linux_s390x.go

@@ -501,7 +501,7 @@ func Getpgid(pid int) (pgid int, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getpid() (pid int) {
-	r0, _, _ := RawSyscall(SYS_GETPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPID, 0, 0, 0)
 	pid = int(r0)
 	return
 }
@@ -509,7 +509,7 @@ func Getpid() (pid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getppid() (ppid int) {
-	r0, _, _ := RawSyscall(SYS_GETPPID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETPPID, 0, 0, 0)
 	ppid = int(r0)
 	return
 }
@@ -538,7 +538,7 @@ func Getrusage(who int, rusage *Rusage) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Gettid() (tid int) {
-	r0, _, _ := RawSyscall(SYS_GETTID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETTID, 0, 0, 0)
 	tid = int(r0)
 	return
 }
@@ -945,7 +945,7 @@ func Times(tms *Tms) (ticks uintptr, err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Umask(mask int) (oldmask int) {
-	r0, _, _ := RawSyscall(SYS_UMASK, uintptr(mask), 0, 0)
+	r0, _ := rawSyscallNoError(SYS_UMASK, uintptr(mask), 0, 0)
 	oldmask = int(r0)
 	return
 }
@@ -1206,7 +1206,7 @@ func Ftruncate(fd int, length int64) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getegid() (egid int) {
-	r0, _, _ := RawSyscall(SYS_GETEGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEGID, 0, 0, 0)
 	egid = int(r0)
 	return
 }
@@ -1214,7 +1214,7 @@ func Getegid() (egid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Geteuid() (euid int) {
-	r0, _, _ := RawSyscall(SYS_GETEUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETEUID, 0, 0, 0)
 	euid = int(r0)
 	return
 }
@@ -1222,7 +1222,7 @@ func Geteuid() (euid int) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getgid() (gid int) {
-	r0, _, _ := RawSyscall(SYS_GETGID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETGID, 0, 0, 0)
 	gid = int(r0)
 	return
 }
@@ -1240,7 +1240,7 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
 func Getuid() (uid int) {
-	r0, _, _ := RawSyscall(SYS_GETUID, 0, 0, 0)
+	r0, _ := rawSyscallNoError(SYS_GETUID, 0, 0, 0)
 	uid = int(r0)
 	return
 }