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os/user: Lookup fails to find users when running as root on darwin-arm64 cross compiled from darwin-amd64 #43543

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JBirdVegas opened this issue Jan 6, 2021 · 4 comments
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NeedsInvestigation OS-Darwin
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@JBirdVegas
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@JBirdVegas JBirdVegas commented Jan 6, 2021

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

$ go version
go version go1.16beta1 darwin/amd64

Does this issue reproduce with the latest release?

Yes

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

Compiled using darwin, amd64. Executed on darwin, arm64

Build env:

go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/user-js/Library/Caches/go-build"
GOENV="/Users/user-js/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/user-js/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/user-js/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/user-js/go/go1.16beta1"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/user-js/go/go1.16beta1/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.16beta1"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/s6/fv1xpj4n7j9c9l1flw1j4lxr0000gn/T/go-build580121957=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version go1.16beta1 darwin/amd64
GOROOT/bin/go tool compile -V: compile version go1.16beta1
uname -v: Darwin Kernel Version 19.6.0: Thu Oct 29 22:56:45 PDT 2020; root:xnu-6153.141.2.2~1/RELEASE_X86_64
ProductName:	Mac OS X
ProductVersion:	10.15.7
BuildVersion:	19H15
lldb --version: lldb-1200.0.41
Apple Swift version 5.3.1 (swiftlang-1200.0.41 clang-1200.0.32.8)
gdb --version: GNU gdb (GDB) 8.3

Execution env:

go env Output
$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/user-es/Library/Caches/go-build"
GOENV="/Users/user-es/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/user-es/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/user-es/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/opt/homebrew/Cellar/go/1.15.6/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/opt/homebrew/Cellar/go/1.15.6/libexec/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.16beta1"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/v1/1y48b2yx6tndh56_yn2fqx4c0000gn/T/go-build161273293=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version go1.16beta1 darwin/arm64
GOROOT/bin/go tool compile -V: compile version go1.16beta1
uname -v: Darwin Kernel Version 20.1.0: Sat Oct 31 00:07:10 PDT 2020; root:xnu-7195.50.7~2/RELEASE_ARM64_T8101
ProductName:	macOS
ProductVersion:	11.0.1
BuildVersion:	20B29
lldb --version: lldb-1200.0.44.2
Apple Swift version 5.3.2 (swiftlang-1200.0.45 clang-1200.0.32.28)
### What did you do?

cross compile code on darwin amd64 then execute on darwin arm64.

% cat main.go
package main

import (
	"log"
	"os"
	"os/user"
	"runtime"
)

func main() {
	log.Printf("GOOS: %s, GOARCH: %s", runtime.GOOS, runtime.GOARCH)
	lookup, err := user.Lookup(os.Args[1])
	if err != nil {
		log.Panic(err)
	}
	log.Printf("User: %v\n", lookup)
}

Compile on darwin amd64 for arm64
GOOS=darwin GOARCH=arm64 go build main.go

Download to darwin arm64 computer then execute without and with sudo.

% whoami
user-es
% ./main $(whoami)
2021/01/06 09:08:50 GOOS: darwin, GOARCH: arm64
2021/01/06 09:08:50 User: &{501 20 user-es  /Users/user-es}
% sudo ./main $(whoami)
2021/01/06 09:08:50 GOOS: darwin, GOARCH: arm64
2021/01/06 09:08:50 user: unknown user user-es
panic: user: unknown user user-es

goroutine 1 [running]:
log.Panic(0x1400010ff38, 0x1, 0x1)
	/Users/user-js/go/go1.16beta1/src/log/log.go:354 +0x98
main.main()
	/Users/user-js/dev/go1.16beta1-maybebug/main.go:14 +0xe8

What did you expect to see?

I expected the user user-es found by the function user.Lookup(string) when running as root, same as it does without root.

I also expected the same error when the code is compiled on darwin-arm64 and executed on darwin-arm64. However if compiled on the target machine the function user.Lookup(string) works as expected when ran as both user and root.

What did you see instead?

The function user.Lookup(string) fails to find the user user-es when running as root, when cross compiled from darwin-amd64.

@bcmills bcmills changed the title func user.Lookup(string) fails to find users when running as root on darwin-arm64 cross compiled from darwin-amd64. os/user: Lookup fails to find users when running as root on darwin-arm64 cross compiled from darwin-amd64. Jan 6, 2021
@bcmills bcmills changed the title os/user: Lookup fails to find users when running as root on darwin-arm64 cross compiled from darwin-amd64. os/user: Lookup fails to find users when running as root on darwin-arm64 cross compiled from darwin-amd64 Jan 6, 2021
@bcmills bcmills added OS-Darwin NeedsInvestigation labels Jan 6, 2021
@bcmills bcmills added this to the Backlog milestone Jan 6, 2021
@bcmills
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@bcmills bcmills commented Jan 6, 2021

CC @cherrymui

@ianlancetaylor
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@ianlancetaylor ianlancetaylor commented Jan 6, 2021

You probably have to set CGO_ENABLED=1. But that may fail due to #43476.

@JBirdVegas
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@JBirdVegas JBirdVegas commented Jan 7, 2021

Yes @ianlancetaylor that is correct however building with CGO_ENABLED=0 produces the same error.

#43476 refers to building on arm64 and executing on amd64. My error is the opposite, GOHOSTARCH=amd64 GOARCH=arm64

@ianlancetaylor
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@ianlancetaylor ianlancetaylor commented Jan 8, 2021

To be clear, I'm suggesting that you need to build with CGO_ENABLED=1. The default is CGO_ENABLED=0.

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