x/sys/windows: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 #41001

dbellavista · 2020-08-24T11:03:43Z

Hi! I'm trying to call the windows.SetInformationJobObject function which requires the size of the input structure of type windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION. To my understanding I can use unsafe.Sizeof to achieve the same result of the C sizeof operator.

When compiling on amd64 arch, the sizeof is correct, but on 386 there is a 4 bytes difference.

What version of Go are you using (`go version`)?

$ go version
go version go1.14.6 windows/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (`go env`)?

go env Output

$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\danie\AppData\Local\go-build
set GOENV=C:\Users\danie\AppData\Roaming\go\env
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\danie\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=c:\go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=c:\go\pkg\tool\windows_amd64
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=Y:\Agent\windows-service-wrapper\go.mod
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\danie\AppData\Local\Temp\go-build389674314=/tmp/go-build -gno-record-gcc-switches

What did you do?

package main

// #include <windows.h>
//
// int SizeOfJob() {
//     JOBOBJECT_EXTENDED_LIMIT_INFORMATION test;
//     test.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
//     return sizeof(test);
// }
import "C"

import (
	"fmt"
	"unsafe"

	"golang.org/x/sys/windows"
)

func main() {
	info := windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION{
		BasicLimitInformation: windows.JOBOBJECT_BASIC_LIMIT_INFORMATION{
			LimitFlags: windows.JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE,
		},
	}

	fmt.Printf("Go Size %d\nC Size %d", unsafe.Sizeof(info), C.SizeOfJob())
}

What did you expect to see?

Compiled on windows with environment GOARCH=386

Go Size 112
C Size 112

Compiled on windows with environment GOARCH="amd64"

Go Size 144
C Size 144

What did you see instead?

Compiled on windows with environment GOARCH=386

Go Size 108
C Size 112

The text was updated successfully, but these errors were encountered:

networkimprov · 2020-08-25T06:07:29Z

cc @alexbrainman

@gopherbot add OS-Windows

cagedmantis · 2020-08-26T21:31:25Z

/cc @ianlancetaylor @griesemer

ianlancetaylor · 2020-08-26T22:35:02Z

My first guess would be an alignment difference. Can you print the C offsetof and the Go unsafe.Offsetof for each field in the struct? So that we can find out exactly where the difference happens? Thanks.

dbellavista · 2020-08-27T07:40:32Z

@ianlancetaylor You are right. It seems to be a size difference in JOBOBJECT_BASIC_LIMIT_INFORMATION. The C size is greater (48 bytes) than the sum of the field sizes.

Offset and sizes of JOBOBJECT_EXTENDED_LIMIT_INFORMATION

Field	GO Offset	C Offset	GO Size	C Size
BasicLimitInformation	0	0	44	48
IoInfo	44	48	48	48
ProcessMemoryLimit	92	96	4	4
JobMemoryLimit	96	100	4	4
PeakProcessMemoryUsed	100	104	4	4
PeakJobMemoryUsed	104	108	4	4

Offset and sizes of JOBOBJECT_BASIC_LIMIT_INFORMATION (type of BasicLimitInformation)

Field	GO Offset	C Offset	GO Size	C Size
PerProcessUserTimeLimit	0	0	8	8
PerJobUserTimeLimit	8	8	8	8
LimitFlags	16	16	4	4
MinimumWorkingSetSize	20	20	4	4
MaximumWorkingSetSize	24	24	4	4
ActiveProcessLimit	28	28	4	4
Affinity	32	32	4	4
PriorityClass	36	36	4	4
SchedulingClass	40	40	4	4

Code

package main

// #include <windows.h>
//
// int SizeOfJob() {
//     JOBOBJECT_EXTENDED_LIMIT_INFORMATION test;
//     return sizeof(test);
// }
// int SizeOfBasicJob() {
//     JOBOBJECT_EXTENDED_LIMIT_INFORMATION test;
//     return sizeof(test.BasicLimitInformation);
// }
// int SizeOfBasicStructJob() {
//     JOBOBJECT_BASIC_LIMIT_INFORMATION test;
//     return sizeof(test);
// }
// int SizeOfBasicLimitInformation() { JOBOBJECT_EXTENDED_LIMIT_INFORMATION test; return sizeof(test.BasicLimitInformation); };
// int SizeOfIoInfo() { JOBOBJECT_EXTENDED_LIMIT_INFORMATION test; return sizeof(test.IoInfo); };
// int SizeOfProcessMemoryLimit() { JOBOBJECT_EXTENDED_LIMIT_INFORMATION test; return sizeof(test.ProcessMemoryLimit); };
// int SizeOfJobMemoryLimit() { JOBOBJECT_EXTENDED_LIMIT_INFORMATION test; return sizeof(test.JobMemoryLimit); };
// int SizeOfPeakProcessMemoryUsed() { JOBOBJECT_EXTENDED_LIMIT_INFORMATION test; return sizeof(test.PeakProcessMemoryUsed); };
// int SizeOfPeakJobMemoryUsed() { JOBOBJECT_EXTENDED_LIMIT_INFORMATION test; return sizeof(test.PeakJobMemoryUsed); };
//
// int OffsetOfBasicLimitInformation() { return offsetof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION, BasicLimitInformation); };
// int OffsetOfIoInfo() { return offsetof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION, IoInfo); };
// int OffsetOfProcessMemoryLimit() { return offsetof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION, ProcessMemoryLimit); };
// int OffsetOfJobMemoryLimit() { return offsetof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION, JobMemoryLimit); };
// int OffsetOfPeakProcessMemoryUsed() { return offsetof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION, PeakProcessMemoryUsed); };
// int OffsetOfPeakJobMemoryUsed() { return offsetof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION, PeakJobMemoryUsed); };
//
// int SizeOfPerProcessUserTimeLimit() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.PerProcessUserTimeLimit); }
// int SizeOfPerJobUserTimeLimit() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.PerJobUserTimeLimit); }
// int SizeOfLimitFlags() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.LimitFlags); }
// int SizeOfMinimumWorkingSetSize() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.MinimumWorkingSetSize); }
// int SizeOfMaximumWorkingSetSize() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.MaximumWorkingSetSize); }
// int SizeOfActiveProcessLimit() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.ActiveProcessLimit); }
// int SizeOfAffinity() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.Affinity); }
// int SizeOfPriorityClass() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.PriorityClass); }
// int SizeOfSchedulingClass() { JOBOBJECT_BASIC_LIMIT_INFORMATION test; return sizeof(test.SchedulingClass); }
//
// int OffsetOfPerProcessUserTimeLimit() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, PerProcessUserTimeLimit); }
// int OffsetOfPerJobUserTimeLimit() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, PerJobUserTimeLimit); }
// int OffsetOfLimitFlags() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, LimitFlags); }
// int OffsetOfMinimumWorkingSetSize() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, MinimumWorkingSetSize); }
// int OffsetOfMaximumWorkingSetSize() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, MaximumWorkingSetSize); }
// int OffsetOfActiveProcessLimit() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, ActiveProcessLimit); }
// int OffsetOfAffinity() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, Affinity); }
// int OffsetOfPriorityClass() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, PriorityClass); }
// int OffsetOfSchedulingClass() { return offsetof(JOBOBJECT_BASIC_LIMIT_INFORMATION, SchedulingClass); }
import "C"

import (
	"fmt"
	"unsafe"

	"golang.org/x/sys/windows"
)

func main() {
	info := windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION{}

	fmt.Printf("|Field | GO Offset | C Offset | GO Size | C Size|\n|-|-|-|-|-|\n")

	fmt.Printf("|BasicLimitInformation | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation), C.OffsetOfBasicLimitInformation(), unsafe.Sizeof(info.BasicLimitInformation), C.SizeOfBasicLimitInformation())
	fmt.Printf("|IoInfo | %d | %d | %d | %d|\n", unsafe.Offsetof(info.IoInfo), C.OffsetOfIoInfo(), unsafe.Sizeof(info.IoInfo), C.SizeOfIoInfo())
	fmt.Printf("|ProcessMemoryLimit | %d | %d | %d | %d|\n", unsafe.Offsetof(info.ProcessMemoryLimit), C.OffsetOfProcessMemoryLimit(), unsafe.Sizeof(info.ProcessMemoryLimit), C.SizeOfProcessMemoryLimit())
	fmt.Printf("|JobMemoryLimit | %d | %d | %d | %d|\n", unsafe.Offsetof(info.JobMemoryLimit), C.OffsetOfJobMemoryLimit(), unsafe.Sizeof(info.JobMemoryLimit), C.SizeOfJobMemoryLimit())
	fmt.Printf("|PeakProcessMemoryUsed | %d | %d | %d | %d|\n", unsafe.Offsetof(info.PeakProcessMemoryUsed), C.OffsetOfPeakProcessMemoryUsed(), unsafe.Sizeof(info.PeakProcessMemoryUsed), C.SizeOfPeakProcessMemoryUsed())
	fmt.Printf("|PeakJobMemoryUsed | %d | %d | %d | %d|\n", unsafe.Offsetof(info.PeakJobMemoryUsed), C.OffsetOfPeakJobMemoryUsed(), unsafe.Sizeof(info.PeakJobMemoryUsed), C.SizeOfPeakJobMemoryUsed())

	fmt.Printf("\n")
	fmt.Printf("|Field | GO Offset | C Offset | GO Size | C Size|\n|-|-|-|-|-|\n")
	fmt.Printf("|PerProcessUserTimeLimit | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.PerProcessUserTimeLimit), C.OffsetOfPerProcessUserTimeLimit(), unsafe.Sizeof(info.BasicLimitInformation.PerProcessUserTimeLimit), C.SizeOfPerProcessUserTimeLimit())
	fmt.Printf("|PerJobUserTimeLimit | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.PerJobUserTimeLimit), C.OffsetOfPerJobUserTimeLimit(), unsafe.Sizeof(info.BasicLimitInformation.PerJobUserTimeLimit), C.SizeOfPerJobUserTimeLimit())
	fmt.Printf("|LimitFlags | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.LimitFlags), C.OffsetOfLimitFlags(), unsafe.Sizeof(info.BasicLimitInformation.LimitFlags), C.SizeOfLimitFlags())
	fmt.Printf("|MinimumWorkingSetSize | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.MinimumWorkingSetSize), C.OffsetOfMinimumWorkingSetSize(), unsafe.Sizeof(info.BasicLimitInformation.MinimumWorkingSetSize), C.SizeOfMinimumWorkingSetSize())
	fmt.Printf("|MaximumWorkingSetSize | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.MaximumWorkingSetSize), C.OffsetOfMaximumWorkingSetSize(), unsafe.Sizeof(info.BasicLimitInformation.MaximumWorkingSetSize), C.SizeOfMaximumWorkingSetSize())
	fmt.Printf("|ActiveProcessLimit | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.ActiveProcessLimit), C.OffsetOfActiveProcessLimit(), unsafe.Sizeof(info.BasicLimitInformation.ActiveProcessLimit), C.SizeOfActiveProcessLimit())
	fmt.Printf("|Affinity | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.Affinity), C.OffsetOfAffinity(), unsafe.Sizeof(info.BasicLimitInformation.Affinity), C.SizeOfAffinity())
	fmt.Printf("|PriorityClass | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.PriorityClass), C.OffsetOfPriorityClass(), unsafe.Sizeof(info.BasicLimitInformation.PriorityClass), C.SizeOfPriorityClass())
	fmt.Printf("|SchedulingClass | %d | %d | %d | %d|\n", unsafe.Offsetof(info.BasicLimitInformation.SchedulingClass), C.OffsetOfSchedulingClass(), unsafe.Sizeof(info.BasicLimitInformation.SchedulingClass), C.SizeOfSchedulingClass())
	fmt.Printf("\n")
}

gopherbot · 2020-08-27T21:38:04Z

Change https://golang.org/cl/251197 mentions this issue: windows: use GOARCH-specific JOBOBJECT_BASIC_LIMIT_INFORMATION

ianlancetaylor · 2020-08-27T21:38:09Z

@dbellavista Thanks! Looks like for Windows the alignment of JOBOBJECT_BASIC_LIMIT_INFORMATION is 8 bytes, but for Go it is 4 bytes. Sounds like we need to pad the 32-bit versions of the struct.

Can you see whether https://golang.org/cl/251197 fixes the problem? Thanks.

dbellavista · 2020-08-28T07:15:01Z

@ianlancetaylor thanks! The sizes are now equal

gopherbot · 2020-09-04T08:16:42Z

Change https://golang.org/cl/253097 mentions this issue: windows: add TestJobObjectInfo

Add test for CL 251197. Updates golang/go#41001 Change-Id: I6317678057eb8b18a1f7564842a92682c0c9930f Reviewed-on: https://go-review.googlesource.com/c/sys/+/253097 Run-TryBot: Alex Brainman <alex.brainman@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>

gopherbot added the OS-Windows label Aug 25, 2020

cagedmantis changed the title ~~Wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386~~ cmd/cgo: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 Aug 26, 2020

cagedmantis added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Aug 26, 2020

cagedmantis added this to the Backlog milestone Aug 26, 2020

ianlancetaylor changed the title ~~cmd/cgo: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386~~ x/sys/windows: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 Aug 26, 2020

ianlancetaylor modified the milestones: Backlog, Unreleased Aug 26, 2020

gopherbot closed this as completed in golang/sys@e0c6998 Sep 5, 2020

golang locked and limited conversation to collaborators Sep 5, 2021

gopherbot added the FrozenDueToAge label Sep 5, 2021

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x/sys/windows: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 #41001

x/sys/windows: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 #41001

dbellavista commented Aug 24, 2020

networkimprov commented Aug 25, 2020 •

edited

cagedmantis commented Aug 26, 2020

ianlancetaylor commented Aug 26, 2020

dbellavista commented Aug 27, 2020

gopherbot commented Aug 27, 2020

ianlancetaylor commented Aug 27, 2020

dbellavista commented Aug 28, 2020

gopherbot commented Sep 4, 2020

x/sys/windows: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 #41001

x/sys/windows: wrong Sizeof result on struct windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION on ARCH 386 #41001

Comments

dbellavista commented Aug 24, 2020

What version of Go are you using (go version)?

Does this issue reproduce with the latest release?

What operating system and processor architecture are you using (go env)?

What did you do?

What did you expect to see?

What did you see instead?

networkimprov commented Aug 25, 2020 • edited

cagedmantis commented Aug 26, 2020

ianlancetaylor commented Aug 26, 2020

dbellavista commented Aug 27, 2020

gopherbot commented Aug 27, 2020

ianlancetaylor commented Aug 27, 2020

dbellavista commented Aug 28, 2020

gopherbot commented Sep 4, 2020

What version of Go are you using (`go version`)?

What operating system and processor architecture are you using (`go env`)?

networkimprov commented Aug 25, 2020 •

edited