runtime: Update open/close/read/write to return -1 on error.

Error detection code copied from syscall, where presumably
we actually do it right.

Note that we throw the errno away.  The runtime doesn't use it.

Fixes #10052

Change-Id: I8de77dda6bf287276b137646c26b84fa61554ec8
Reviewed-on: https://go-review.googlesource.com/6571
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/runtime/export_test.go

@@ -117,3 +117,8 @@ var Gostringnocopy = gostringnocopy
 var Maxstring = &maxstring
 
 type Uintreg uintreg
+
+var Open = open
+var Close = close
+var Read = read
+var Write = write

src/runtime/os_nacl.go

@@ -52,3 +52,8 @@ func sigpanic() {
 
 func raiseproc(sig int32) {
 }
+
+// Stubs so tests can link correctly.  These should never be called.
+func open(name *byte, mode, perm int32) int32
+func close(fd int32) int32
+func read(fd int32, p unsafe.Pointer, n int32) int32

src/runtime/os_windows.go

@@ -4,7 +4,7 @@
 
 package runtime
 
-import _ "unsafe" // for go:linkname
+import "unsafe"
 
 type stdFunction *byte
 
@@ -39,3 +39,17 @@ func sigpanic() {
 	}
 	throw("fault")
 }
+
+// Stubs so tests can link correctly.  These should never be called.
+func open(name *byte, mode, perm int32) int32 {
+	throw("unimplemented")
+	return -1
+}
+func close(fd int32) int32 {
+	throw("unimplemented")
+	return -1
+}
+func read(fd int32, p unsafe.Pointer, n int32) int32 {
+	throw("unimplemented")
+	return -1
+}

src/runtime/runtime_test.go

@@ -292,3 +292,29 @@ func TestTrailingZero(t *testing.T) {
 		t.Errorf("sizeof(%#v)==%d, want 0", T5{}, unsafe.Sizeof(T5{}))
 	}
 }
+
+func TestBadOpen(t *testing.T) {
+	if GOOS == "windows" || GOOS == "nacl" {
+		t.Skip("skipping OS that doesn't have open/read/write/close")
+	}
+	// make sure we get the correct error code if open fails.  Same for
+	// read/write/close on the resulting -1 fd.  See issue 10052.
+	nonfile := []byte("/notreallyafile")
+	fd := Open(&nonfile[0], 0, 0)
+	if fd != -1 {
+		t.Errorf("open(\"%s\")=%d, want -1", string(nonfile), fd)
+	}
+	var buf [32]byte
+	r := Read(-1, unsafe.Pointer(&buf[0]), int32(len(buf)))
+	if r != -1 {
+		t.Errorf("read()=%d, want -1", r)
+	}
+	w := Write(^uintptr(0), unsafe.Pointer(&buf[0]), int32(len(buf)))
+	if w != -1 {
+		t.Errorf("write()=%d, want -1", w)
+	}
+	c := Close(-1)
+	if c != -1 {
+		t.Errorf("close()=%d, want -1", c)
+	}
+}

src/runtime/sys_darwin_386.s

@@ -29,24 +29,32 @@ TEXT runtime·exit1(SB),NOSPLIT,$0
 TEXT runtime·open(SB),NOSPLIT,$0
 	MOVL	$5, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·close(SB),NOSPLIT,$0
 	MOVL	$6, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·read(SB),NOSPLIT,$0
 	MOVL	$3, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·write(SB),NOSPLIT,$0
 	MOVL	$4, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 

src/runtime/sys_darwin_amd64.s

@@ -38,6 +38,8 @@ TEXT runtime·open(SB),NOSPLIT,$0
 	MOVL	perm+12(FP), DX		// arg 3 mode
 	MOVL	$(0x2000000+5), AX	// syscall entry
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -45,6 +47,8 @@ TEXT runtime·close(SB),NOSPLIT,$0
 	MOVL	fd+0(FP), DI		// arg 1 fd
 	MOVL	$(0x2000000+6), AX	// syscall entry
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -54,6 +58,8 @@ TEXT runtime·read(SB),NOSPLIT,$0
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$(0x2000000+3), AX	// syscall entry
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 
@@ -63,6 +69,8 @@ TEXT runtime·write(SB),NOSPLIT,$0
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$(0x2000000+4), AX	// syscall entry
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 

src/runtime/sys_darwin_arm.s

@@ -48,6 +48,7 @@ TEXT runtime·open(SB),NOSPLIT,$0
 	MOVW	perm+8(FP), R2
 	MOVW	$SYS_open, R12
 	SWI	$0x80
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -55,6 +56,7 @@ TEXT runtime·close(SB),NOSPLIT,$0
 	MOVW	fd+0(FP), R0
 	MOVW	$SYS_close, R12
 	SWI	$0x80
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+4(FP)
 	RET
 
@@ -64,6 +66,7 @@ TEXT runtime·write(SB),NOSPLIT,$0
 	MOVW	n+8(FP), R2
 	MOVW	$SYS_write, R12
 	SWI	$0x80
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -73,6 +76,7 @@ TEXT runtime·read(SB),NOSPLIT,$0
 	MOVW	n+8(FP), R2
 	MOVW	$SYS_read, R12
 	SWI	$0x80
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 

src/runtime/sys_dragonfly_386.s

@@ -85,24 +85,32 @@ TEXT runtime·exit1(SB),NOSPLIT,$16
 TEXT runtime·open(SB),NOSPLIT,$-4
 	MOVL	$5, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·close(SB),NOSPLIT,$-4
 	MOVL	$6, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·read(SB),NOSPLIT,$-4
 	MOVL	$3, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·write(SB),NOSPLIT,$-4
 	MOVL	$4, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 

src/runtime/sys_dragonfly_amd64.s

@@ -77,6 +77,8 @@ TEXT runtime·open(SB),NOSPLIT,$-8
 	MOVL	perm+12(FP), DX		// arg 3 mode
 	MOVL	$5, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -84,6 +86,8 @@ TEXT runtime·close(SB),NOSPLIT,$-8
 	MOVL	fd+0(FP), DI		// arg 1 fd
 	MOVL	$6, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -93,6 +97,8 @@ TEXT runtime·read(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$3, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 
@@ -102,6 +108,8 @@ TEXT runtime·write(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$4, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 

src/runtime/sys_freebsd_386.s

@@ -62,24 +62,32 @@ TEXT runtime·exit1(SB),NOSPLIT,$-4
 TEXT runtime·open(SB),NOSPLIT,$-4
 	MOVL	$5, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·close(SB),NOSPLIT,$-4
 	MOVL	$6, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·read(SB),NOSPLIT,$-4
 	MOVL	$3, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·write(SB),NOSPLIT,$-4
 	MOVL	$4, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 

src/runtime/sys_freebsd_amd64.s

@@ -67,6 +67,8 @@ TEXT runtime·open(SB),NOSPLIT,$-8
 	MOVL	perm+12(FP), DX		// arg 3 mode
 	MOVL	$5, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -74,6 +76,8 @@ TEXT runtime·close(SB),NOSPLIT,$-8
 	MOVL	fd+0(FP), DI		// arg 1 fd
 	MOVL	$6, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -83,6 +87,8 @@ TEXT runtime·read(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$3, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 
@@ -92,6 +98,8 @@ TEXT runtime·write(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$4, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 

src/runtime/sys_freebsd_arm.s

@@ -93,6 +93,7 @@ TEXT runtime·open(SB),NOSPLIT,$-8
 	MOVW perm+8(FP), R2	// arg 3 perm
 	MOVW $SYS_open, R7
 	SWI $0
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -102,6 +103,7 @@ TEXT runtime·read(SB),NOSPLIT,$-8
 	MOVW n+8(FP), R2	// arg 3 count
 	MOVW $SYS_read, R7
 	SWI $0
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -111,6 +113,7 @@ TEXT runtime·write(SB),NOSPLIT,$-8
 	MOVW n+8(FP), R2	// arg 3 count
 	MOVW $SYS_write, R7
 	SWI $0
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -118,6 +121,7 @@ TEXT runtime·close(SB),NOSPLIT,$-8
 	MOVW fd+0(FP), R0	// arg 1 fd
 	MOVW $SYS_close, R7
 	SWI $0
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+4(FP)
 	RET
 

src/runtime/sys_linux_386.s

@@ -30,6 +30,9 @@ TEXT runtime·open(SB),NOSPLIT,$0
 	MOVL	mode+4(FP), CX
 	MOVL	perm+8(FP), DX
 	CALL	*runtime·_vdso(SB)
+	CMPL	AX, $0xfffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
@@ -37,6 +40,9 @@ TEXT runtime·close(SB),NOSPLIT,$0
 	MOVL	$6, AX		// syscall - close
 	MOVL	fd+0(FP), BX
 	CALL	*runtime·_vdso(SB)
+	CMPL	AX, $0xfffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+4(FP)
 	RET
 
@@ -46,6 +52,9 @@ TEXT runtime·write(SB),NOSPLIT,$0
 	MOVL	p+4(FP), CX
 	MOVL	n+8(FP), DX
 	CALL	*runtime·_vdso(SB)
+	CMPL	AX, $0xfffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
@@ -55,6 +64,9 @@ TEXT runtime·read(SB),NOSPLIT,$0
 	MOVL	p+4(FP), CX
 	MOVL	n+8(FP), DX
 	CALL	*runtime·_vdso(SB)
+	CMPL	AX, $0xfffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 

src/runtime/sys_linux_amd64.s

@@ -28,6 +28,9 @@ TEXT runtime·open(SB),NOSPLIT,$0-20
 	MOVL	perm+12(FP), DX
 	MOVL	$2, AX			// syscall entry
 	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -35,6 +38,9 @@ TEXT runtime·close(SB),NOSPLIT,$0-12
 	MOVL	fd+0(FP), DI
 	MOVL	$3, AX			// syscall entry
 	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -44,6 +50,9 @@ TEXT runtime·write(SB),NOSPLIT,$0-28
 	MOVL	n+16(FP), DX
 	MOVL	$1, AX			// syscall entry
 	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 
@@ -53,6 +62,9 @@ TEXT runtime·read(SB),NOSPLIT,$0-28
 	MOVL	n+16(FP), DX
 	MOVL	$0, AX			// syscall entry
 	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 

src/runtime/sys_linux_arm.s

@@ -57,6 +57,9 @@ TEXT runtime·open(SB),NOSPLIT,$0
 	MOVW	perm+8(FP), R2
 	MOVW	$SYS_open, R7
 	SWI	$0
+	MOVW	$0xfffff001, R1
+	CMP	R1, R0
+	MOVW.HI	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -64,6 +67,9 @@ TEXT runtime·close(SB),NOSPLIT,$0
 	MOVW	fd+0(FP), R0
 	MOVW	$SYS_close, R7
 	SWI	$0
+	MOVW	$0xfffff001, R1
+	CMP	R1, R0
+	MOVW.HI	$-1, R0
 	MOVW	R0, ret+4(FP)
 	RET
 
@@ -73,6 +79,9 @@ TEXT runtime·write(SB),NOSPLIT,$0
 	MOVW	n+8(FP), R2
 	MOVW	$SYS_write, R7
 	SWI	$0
+	MOVW	$0xfffff001, R1
+	CMP	R1, R0
+	MOVW.HI	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -82,6 +91,9 @@ TEXT runtime·read(SB),NOSPLIT,$0
 	MOVW	n+8(FP), R2
 	MOVW	$SYS_read, R7
 	SWI	$0
+	MOVW	$0xfffff001, R1
+	CMP	R1, R0
+	MOVW.HI	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 

src/runtime/sys_linux_ppc64x.s

@@ -62,12 +62,16 @@ TEXT runtime·open(SB),NOSPLIT,$-8-20
 	MOVW	mode+8(FP), R4
 	MOVW	perm+12(FP), R5
 	SYSCALL	$SYS_open
+	BVC	2(PC)
+	MOVW	$-1, R3
 	MOVW	R3, ret+16(FP)
 	RETURN
 
 TEXT runtime·close(SB),NOSPLIT,$-8-12
 	MOVW	fd+0(FP), R3
 	SYSCALL	$SYS_close
+	BVC	2(PC)
+	MOVW	$-1, R3
 	MOVW	R3, ret+8(FP)
 	RETURN
 
@@ -76,6 +80,8 @@ TEXT runtime·write(SB),NOSPLIT,$-8-28
 	MOVD	p+8(FP), R4
 	MOVW	n+16(FP), R5
 	SYSCALL	$SYS_write
+	BVC	2(PC)
+	MOVW	$-1, R3
 	MOVW	R3, ret+24(FP)
 	RETURN
 
@@ -84,6 +90,8 @@ TEXT runtime·read(SB),NOSPLIT,$-8-28
 	MOVD	p+8(FP), R4
 	MOVW	n+16(FP), R5
 	SYSCALL	$SYS_read
+	BVC	2(PC)
+	MOVW	$-1, R3
 	MOVW	R3, ret+24(FP)
 	RETURN
 

src/runtime/sys_netbsd_386.s

@@ -27,24 +27,32 @@ TEXT runtime·exit1(SB),NOSPLIT,$-4
 TEXT runtime·open(SB),NOSPLIT,$-4
 	MOVL	$5, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·close(SB),NOSPLIT,$-4
 	MOVL	$6, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·read(SB),NOSPLIT,$-4
 	MOVL	$3, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·write(SB),NOSPLIT,$-4
 	MOVL	$4, AX			// sys_write
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 

src/runtime/sys_netbsd_amd64.s

@@ -91,6 +91,8 @@ TEXT runtime·open(SB),NOSPLIT,$-8
 	MOVL	perm+12(FP), DX		// arg 3 mode
 	MOVL	$5, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -98,6 +100,8 @@ TEXT runtime·close(SB),NOSPLIT,$-8
 	MOVL	fd+0(FP), DI		// arg 1 fd
 	MOVL	$6, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -107,6 +111,8 @@ TEXT runtime·read(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$3, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 
@@ -116,6 +122,8 @@ TEXT runtime·write(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 - nbyte
 	MOVL	$4, AX			// sys_write
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 

src/runtime/sys_netbsd_arm.s

@@ -29,12 +29,14 @@ TEXT runtime·open(SB),NOSPLIT,$-8
 	MOVW mode+4(FP), R1
 	MOVW perm+8(FP), R2
 	SWI $0xa00005
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
 TEXT runtime·close(SB),NOSPLIT,$-8
 	MOVW fd+0(FP), R0
 	SWI $0xa00006
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+4(FP)
 	RET
 
@@ -43,6 +45,7 @@ TEXT runtime·read(SB),NOSPLIT,$-8
 	MOVW p+4(FP), R1
 	MOVW n+8(FP), R2
 	SWI $0xa00003
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 
@@ -51,6 +54,7 @@ TEXT runtime·write(SB),NOSPLIT,$-4
 	MOVW	p+4(FP), R1	// arg 2 - buf
 	MOVW	n+8(FP), R2	// arg 3 - nbyte
 	SWI $0xa00004	// sys_write
+	MOVW.CS	$-1, R0
 	MOVW	R0, ret+12(FP)
 	RET
 

src/runtime/sys_openbsd_386.s

@@ -31,24 +31,32 @@ TEXT runtime·exit1(SB),NOSPLIT,$8
 TEXT runtime·open(SB),NOSPLIT,$-4
 	MOVL	$5, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·close(SB),NOSPLIT,$-4
 	MOVL	$6, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·read(SB),NOSPLIT,$-4
 	MOVL	$3, AX
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 
 TEXT runtime·write(SB),NOSPLIT,$-4
 	MOVL	$4, AX			// sys_write
 	INT	$0x80
+	JAE	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+12(FP)
 	RET
 

src/runtime/sys_openbsd_amd64.s

@@ -101,6 +101,8 @@ TEXT runtime·open(SB),NOSPLIT,$-8
 	MOVL	perm+12(FP), DX		// arg 3 mode
 	MOVL	$5, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+16(FP)
 	RET
 
@@ -108,6 +110,8 @@ TEXT runtime·close(SB),NOSPLIT,$-8
 	MOVL	fd+0(FP), DI		// arg 1 fd
 	MOVL	$6, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+8(FP)
 	RET
 
@@ -117,6 +121,8 @@ TEXT runtime·read(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 count
 	MOVL	$3, AX
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET
 
@@ -126,6 +132,8 @@ TEXT runtime·write(SB),NOSPLIT,$-8
 	MOVL	n+16(FP), DX		// arg 3 - nbyte
 	MOVL	$4, AX			// sys_write
 	SYSCALL
+	JCC	2(PC)
+	MOVL	$-1, AX
 	MOVL	AX, ret+24(FP)
 	RET