cmd/go: `go install` with CGO_ENABLED=0 tries to install standard packages, which can fail

[glycerine]

Please answer these questions before submitting your issue. Thanks!

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

[jaten@biggie tmp]$ go version
go version go1.8rc3 linux/amd64 ## also happens on go1.7.4
[jaten@biggie tmp]$

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

[jaten@biggie tmp]$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/jaten/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build885638224=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="0"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
[jaten@biggie tmp]$

What did you do?

I ran make for https://github.com/glycerine/vhaline
Makefile does go install on the library github.com/glycerine/vhaline/vhaline and then on a test executable; github.com/glycerine/vhaline/cmd/vhaline

What did you expect to see?

successful build. build is successful without CGO_ENABLED=0

What did you see instead?

[jaten@biggie vhaline]$ make                                                                                                  
cd vhaline && go install && cd ../cmd/vhaline && go install                                                                   
go install net: open /usr/local/go/pkg/linux_amd64/net.a: permission denied                  ### problem!                                 
make: *** [build] Error 1                                                                                                     
[jaten@biggie vhaline]$ go version                                                                                            
go version go1.8rc3 linux/amd64                                                                                               
[jaten@biggie vhaline]$ env|grep GO                                                                                           
CGO_ENABLED=0                                                                                                                 
GOROOT=/usr/local/go                                                                                                          
GODEBUG=netdns=go                                                                                                             
GOPATH=/home/jaten/go                                                                                                         
[jaten@biggie vhaline]$ ls -al /usr/local/go/pkg/linux_amd64/net.a                                                            
-rw-r--r-- 1 root root 1209910 Jan 26 18:55 /usr/local/go/pkg/linux_amd64/net.a                                               
[jaten@biggie vhaline]$ file /usr/local/go/pkg/linux_amd64/net.a                                                              
/usr/local/go/pkg/linux_amd64/net.a: current ar archive                                                                       
[jaten@biggie vhaline]$ mkdir tmp                                                                                             
[jaten@biggie vhaline]$ cd tmp                                                                                                
[jaten@biggie tmp]$ ar x /usr/local/go/pkg/linux_amd64/net.a                                                                  
[jaten@biggie tmp]$ ls -al                                                                                                    
total 1192                                                                                                                    
drwxrwxr-x 2 jaten jaten      48 Feb  7 16:57 .                                                                               
drwxrwxr-x 7 jaten jaten    4096 Feb  7 16:57 ..                                                                              
-rw-r--r-- 1 jaten jaten   19172 Feb  7 16:57 _all.o                                                                          
-rw-r--r-- 1 jaten jaten 1169185 Feb  7 16:57 _go_.o                                                                          
-rw-r--r-- 1 jaten jaten   21364 Feb  7 16:57 __.PKGDEF                                                                       
[jaten@biggie tmp]$ go env    
GOARCH="amd64"                                                                                                                
GOBIN=""                                                                                                                      
GOEXE=""                                                                                                                      
GOHOSTARCH="amd64"                                                                                                            
GOHOSTOS="linux"                                                                                                              
GOOS="linux"                                                                                                                  
GOPATH="/home/jaten/go"                                                                                                       
GORACE=""                                                                                                                     
GOROOT="/usr/local/go"                                                                                                        
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"                                                                                
GCCGO="gccgo"                                                                                                                 
CC="gcc"                                                                                                                      
GOGCCFLAGS="-fPIC -m64 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build885638224=/tmp/go-build -gno-record-gcc-switches"   
CXX="g++"                                                                                                                     
CGO_ENABLED="0"                                                                                                               
PKG_CONFIG="pkg-config"                                                                                                       
CGO_CFLAGS="-g -O2"                                                                                                           
CGO_CPPFLAGS=""                                                                                                               
CGO_CXXFLAGS="-g -O2"                                                                                                         
CGO_FFLAGS="-g -O2"                                                                                                           
CGO_LDFLAGS="-g -O2"                                                                                                          
[jaten@biggie tmp]$ go version                                                                                                
go version go1.8rc3 linux/amd64                                                                                               
[jaten@biggie tmp]$ unset CGO_ENABLED                                                                                         
[jaten@biggie tmp]$ cd ..                                                                                                     
[jaten@biggie vhaline]$ make                                                                                                  
cd vhaline && go install && cd ../cmd/vhaline && go install                                                                   
[jaten@biggie vhaline]$ #successful build  

[davecheney]

Your makefile is calling go install, which fails because your user does not have permission to write to that directory.

Either use go build to skip writing stdlib packages to a directory the user doesn't own, or build go from source in a directory you don't own. I recommend the second option.

https://dave.cheney.net/2014/04/20/how-to-install-multiple-versions-of-go

[glycerine]

Your makefile is calling go install, which fails because your user does not have permission to write to that directory.

wait.... go install is trying to write to $GOROOT, i.e. /usr/local/go? really? I thought go install would write only to $GOPATH, which is ~/go here.

[ianlancetaylor]

I agree that a simple go install for 1.8rc3 should not write to $GOROOT. Can you reproduce this without running make? What does go install -x print?

[davecheney]

wait.... go install is trying to write to $GOROOT, i.e. /usr/local/go? really? I thought go install would write only to $GOPATH, which is ~/go here.

If you set CGO_ENABLED=0 then the go tool has to rebuild all the standard lib packages, and because you used go install, it will try to write them back to their original locations. This is the same as cross compilation using the binary install of Go.

https://dave.cheney.net/2015/08/22/cross-compilation-with-go-1-5, see comparison of go build vs go install.

[glycerine]

What does go install -x print?

[jaten@biggie vhaline]$ export CGO_ENABLED=0                                                                                                    
[jaten@biggie vhaline]$ env|grep GO                                                                                                             
CGO_ENABLED=0                                                                                                                                   
GOPATH=/home/jaten/go                                                                                                                           
[jaten@biggie vhaline]$ go build                                                                                                                  
[jaten@biggie vhaline]$ go install -x                                                                                                           
WORK=/tmp/go-build958770575                                                                                                                     
mkdir -p $WORK/net/_obj/                                                                                                                        
mkdir -p $WORK/                                                                                                                                 
cd /usr/local/go/src/net                                                                                                                        
/usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/net.a -trimpath $WORK -p net -buildid 9b4851ad605915a6fa99ce0ea2840f1da29dd007 -D _/usr/loc\
al/go/src/net -I $WORK -pack ./addrselect.go ./cgo_stub.go ./conf.go ./dial.go ./dnsclient.go ./dnsclient_unix.go ./dnsconfig_unix.go ./dnsmsg.\
go ./fd_mutex.go ./fd_poll_runtime.go ./fd_posix.go ./fd_unix.go ./file.go ./file_unix.go ./hook.go ./hook_cloexec.go ./hook_unix.go ./hosts.go\
 ./interface.go ./interface_linux.go ./ip.go ./iprawsock.go ./iprawsock_posix.go ./ipsock.go ./ipsock_posix.go ./lookup.go ./lookup_unix.go ./m\
ac.go ./net.go ./nss.go ./parse.go ./pipe.go ./port.go ./port_unix.go ./sendfile_linux.go ./sock_cloexec.go ./sock_linux.go ./sock_posix.go ./s\
ockopt_linux.go ./sockopt_posix.go ./sockoptip_linux.go ./sockoptip_posix.go ./tcpsock.go ./tcpsock_posix.go ./tcpsockopt_posix.go ./tcpsockopt\
_unix.go ./udpsock.go ./udpsock_posix.go ./unixsock.go ./unixsock_posix.go ./writev_unix.go                                                     
mkdir -p /usr/local/go/pkg/linux_amd64/                                                                                                         
cp $WORK/net.a /usr/local/go/pkg/linux_amd64/net.a                                                                                              
go install net: open /usr/local/go/pkg/linux_amd64/net.a: permission denied                                                                     
[jaten@biggie vhaline]$ cd ../cmd/vhaline/                                                                                                      
[jaten@biggie vhaline]$ go build                                                                                                                
[jaten@biggie vhaline]$ ldd ./vhaline                                                                                                           
    not a dynamic executable                                                                                                                    
[jaten@biggie vhaline]$   ##yeah! successfully built without cgo

Okay, then. So my immediately problem is solved. Thank you, Dave, for pointing the surprising difference between go build and go install under CGO_ENABLED=0.

@ianlancetaylor This is really pretty surprising behavior; I wouldn't have expected that CGO_ENABLED=0 would require a rebuild of the entire standard lib. If you want to leave the ticket open as a bug, that's okay with me. I'm also okay with closing it, at your discretion. Dave's cross-compilation post makes it clear for cross-compilation, but its not clear to me that setting CGO_ENABLED=0 is, or should be thought of, the same as cross-compiling.

Using go build vs go install

When cross compiling, you should use go build, not go install. This is the one of the few cases where go build is preferable to go install.

The reason for this is go install always caches compiled packages, .a files, into the pkg/ directory that matches the root of the source code.

For example, if you are building $GOPATH/src/github.com/lib/pq, then the compiled package will be >installed into $GOPATH/pkg/$GOOS_$GOARCH/github.com/lib/pq.a.

This logic also holds true for the standard library, which lives in /usr/local/go/src, so will be compiled to /usr/local/go/pkg/$GOOS_$GOARCH. This is a problem, because when cross compiling the go tool needs to rebuild the standard library for your target, but the binary distribution expects that /usr/local/go is not writeable.

Using go build rather that go install is the solution here, because go build builds, then throws away most of the result (rather than caching it for later), leaving you with the final binary in the current directory, which is most likely writeable by you.
-- from https://dave.cheney.net/2015/08/22/cross-compilation-with-go-1-5

[rakyll]

Standard library builds (e.g. go install std) are going under GOROOT, wished it was somewhere under GOPATH at the cost of not being able to share prebuilt standard libraries (for various combinations of GOOS, GOARCH, CGO_ENABLED) between different GOPATHs.

[glycerine]

(tongue in cheek...) perhaps $GOROOT==$GOPATH could mean "write my standard libs" under GOPATH.

[ianlancetaylor]

Setting CGO_ENABLED=0 does not require rebuilding the entire standard library, but it does require rebuilding the standard library packages that use cgo. Those packages are: net, os/user, crypto/x509.

That said, it does seem wrong that go install tries to install a standard library package in this case. If the package is not mentioned on the command line, it seems to me that it should be built but not installed.

[davecheney]

Ian, does that argument extend to cross compilation? That's the place most users hit this issue.

…

On Wed, 8 Feb 2017, 07:33 Ian Lance Taylor ***@***.***> wrote: Setting CGO_ENABLED=0 does not require rebuilding the entire standard library, but it does require rebuilding the standard library packages that use cgo. Those packages are: net, os/user, crypto/x509. That said, it does seem wrong that go install tries to install a standard library package in this case. If the package is not mentioned on the command line, it seems to me that it should be built but not installed. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#18981 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAcA2W8umf9_BB9Pfh2H8x1CIPIYzvUks5raNUUgaJpZM4L5xMh> .

[ianlancetaylor]

My feeling right now is that if you are using a release, then running go install without explicitly mentioning any standard library package should not attempt to install any standard library package. Clearly if you run go install std or go install net then it should install the standard library package (if it is out of date). But if you don't do that, I don't think go install should be trying to write files into GOROOT.

Happy to hear counter-arguments.

[davecheney]

That would be wonderful if that was the outcome of this ticket, the "official binary + cross compile + go install" story is the last remaining hurdle to Go developers having a seamless cross compilation experience with our official builds.

…

On Wed, Feb 8, 2017 at 7:51 AM, Ian Lance Taylor ***@***.***> wrote: My feeling right now is that if you are using a release, then running go install without explicitly mentioning any standard library package should not attempt to install any standard library package. Clearly if you run go install std or go install net then it should install the standard library package (if it is out of date). But if you don't do that, I don't think go install should be trying to write files into GOROOT. Happy to hear counter-arguments. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#18981 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAcAys1VIUMFRjtrCS5AQseaeynhzgNks5raNlngaJpZM4L5xMh> .