cmd/go: flag modcacherw does not take effect in the target package

[marjus45]

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

$ go version
go version go1.21.4 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

I tested this on a clean Debian container.

go env Output

$ go env
GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/root/.cache/go-build'
GOENV='/root/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/root/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/root/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.4'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='0'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build392749006=/tmp/go-build -gno-record-gcc-switches'

What did you do?

1. Install a package using the modcacherw flag with go install:

   $ GOPATH=$(pwd)/_go go install -modcacherw github.com/google/go-containerregistry/cmd/crane@v0.16.1
   go: downloading github.com/google/go-containerregistry v0.16.1
   go: downloading github.com/docker/cli v24.0.0+incompatible
   go: downloading github.com/opencontainers/image-spec v1.1.0-rc3
   go: downloading github.com/spf13/cobra v1.7.0
   go: downloading github.com/opencontainers/go-digest v1.0.0
   go: downloading golang.org/x/sync v0.2.0
   go: downloading github.com/docker/distribution v2.8.2+incompatible
   go: downloading github.com/containerd/stargz-snapshotter/estargz v0.14.3
   go: downloading github.com/google/go-cmp v0.5.9
   go: downloading github.com/mitchellh/go-homedir v1.1.0
   go: downloading github.com/klauspost/compress v1.16.5
   go: downloading github.com/spf13/pflag v1.0.5
   go: downloading github.com/vbatts/tar-split v0.11.3
   go: downloading github.com/pkg/errors v0.9.1
   go: downloading golang.org/x/sys v0.8.0
   go: downloading github.com/docker/docker-credential-helpers v0.7.0
   go: downloading github.com/docker/docker v24.0.0+incompatible
   go: downloading github.com/sirupsen/logrus v1.9.1
   

2. List the directories:

   $ ls _go/pkg/mod/github.com/google/ -la
   total 16
   drwxr-xr-x  4 root root 4096 Nov 20 13:49 .
   drwxr-xr-x 12 root root 4096 Nov 20 13:49 ..
   drwxr-xr-x  4 root root 4096 Nov 20 13:49 go-cmp@v0.5.9
   dr-xr-xr-x 10 root root 4096 Nov 20 13:49 go-containerregistry@v0.16.1
   

3. Notice that go-containerregistry@v0.16.1 has read only permissions while their dependencies (go-cmp) has read-write permissions, as expected.

What did you expect to see?

I expected to see the directory go-containerregistry@v0.16.1 to have read-write permissions, since I have set the flag modcacherw.

	-modcacherw
		leave newly-created directories in the module cache read-write
		instead of making them read-only.

What did you see instead?

Instead go-containerregistry@v0.16.1 has read only permissions.

I thinks this is a regression, since up to v1.20 I confirmed that it worked as expected.

[mknyszek]

CC @bcmills @matloob per https://dev.golang.org/owners

[bcmills]

@marjus45, I'm not able to reproduce the behavior you report:

$ go1.21.4 install -modcacherw github.com/google/go-containerregistry/cmd/crane@v0.16.1
go: downloading github.com/google/go-containerregistry v0.16.1
go: downloading github.com/opencontainers/image-spec v1.1.0-rc3
go: downloading github.com/docker/cli v24.0.0+incompatible
go: downloading golang.org/x/sync v0.2.0
go: downloading github.com/spf13/cobra v1.7.0
go: downloading github.com/docker/distribution v2.8.2+incompatible
go: downloading github.com/containerd/stargz-snapshotter/estargz v0.14.3
go: downloading github.com/google/go-cmp v0.5.9
go: downloading github.com/opencontainers/go-digest v1.0.0
go: downloading github.com/mitchellh/go-homedir v1.1.0
go: downloading github.com/klauspost/compress v1.16.5
go: downloading github.com/vbatts/tar-split v0.11.3
go: downloading github.com/spf13/pflag v1.0.5
go: downloading github.com/pkg/errors v0.9.1
go: downloading github.com/docker/docker v24.0.0+incompatible
go: downloading github.com/sirupsen/logrus v1.9.1
go: downloading golang.org/x/sys v0.8.0
go: downloading github.com/docker/docker-credential-helpers v0.7.0

$ ls -la $(go1.21.4 env GOMODCACHE)/github.com/google
total 16
drwxr-x---  4 bcmills primarygroup 4096 Dec  1 09:27 .
drwxr-x--- 12 bcmills primarygroup 4096 Dec  1 09:27 ..
drwxr-x---  4 bcmills primarygroup 4096 Dec  1 09:27 go-cmp@v0.5.9
drwxr-x--- 10 bcmills primarygroup 4096 Dec  1 09:27 go-containerregistry@v0.16.1

Did you run any other commands before or after the go install command?

[bcmills]

Huh. Apparently it has something to do with running as root:

$ sudo $(which go1.21.4) install -modcacherw github.com/google/go-containerregistry/cmd/crane@v0.16.1
go: downloading github.com/google/go-containerregistry v0.16.1
go: downloading github.com/docker/cli v24.0.0+incompatible
go: downloading github.com/opencontainers/image-spec v1.1.0-rc3
go: downloading github.com/spf13/cobra v1.7.0
go: downloading golang.org/x/sync v0.2.0
go: downloading github.com/opencontainers/go-digest v1.0.0
go: downloading github.com/mitchellh/go-homedir v1.1.0
go: downloading github.com/google/go-cmp v0.5.9
go: downloading github.com/docker/distribution v2.8.2+incompatible
go: downloading github.com/containerd/stargz-snapshotter/estargz v0.14.3
go: downloading github.com/klauspost/compress v1.16.5
go: downloading github.com/vbatts/tar-split v0.11.3
go: downloading github.com/spf13/pflag v1.0.5
go: downloading github.com/pkg/errors v0.9.1
go: downloading github.com/sirupsen/logrus v1.9.1
go: downloading github.com/docker/docker v24.0.0+incompatible
go: downloading golang.org/x/sys v0.8.0
go: downloading github.com/docker/docker-credential-helpers v0.7.0

$ sudo ls -la $(sudo $(which go1.21.4) env GOMODCACHE)/github.com/google
total 16
drwxr-xr-x  4 root root 4096 Dec  1 09:33 .
drwxr-xr-x 12 root root 4096 Dec  1 09:33 ..
drwxr-xr-x  4 root root 4096 Dec  1 09:33 go-cmp@v0.5.9
dr-xr-xr-x 10 root root 4096 Dec  1 09:33 go-containerregistry@v0.16.1

[bcmills]

Bisecting now.

[bcmills]

aa99c4d2925e3628460482db8657765880e6836c is the first bad commit
commit aa99c4d2925e3628460482db8657765880e6836c
Author: Russ Cox <rsc@golang.org>
Date:   Wed May 24 07:10:17 2023 -0400

    cmd/go: handle queries properly in go install m@v

    The original code only handled go install m@v1.0.0
    but not queries like go install m@v1 or m@master.
    Handle those by invoking more of the module machinery.

    For #57001.

    Change-Id: I7d54fc3dd65072e5906a17ff95b407b0f7feac69
    Reviewed-on: https://go-review.googlesource.com/c/go/+/497879
    Run-TryBot: Russ Cox <rsc@golang.org>
    Reviewed-by: Bryan Mills <bcmills@google.com>
    Auto-Submit: Russ Cox <rsc@golang.org>
    TryBot-Result: Gopher Robot <gobot@golang.org>

 src/cmd/go/gotoolchain.go                         | 62 +++++++----------------
 src/cmd/go/internal/modload/init.go               | 14 +++++
 src/cmd/go/testdata/mod/rsc.io_fortune_v0.0.1.txt |  4 ++
 src/cmd/go/testdata/script/gotoolchain.txt        | 13 +++++
 4 files changed, 50 insertions(+), 43 deletions(-)

[bcmills]

@gopherbot, please backport to Go 1.21. This was a regression in Go 1.21 and has no clear workaround.

[gopherbot]

Backport issue(s) opened: #64497 (for 1.21).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[gopherbot]

Change https://go.dev/cl/546635 mentions this issue: cmd/go/internal/toolchain: make a best effort to parse 'go run' and 'go install' flags