cmd/go: reject relative paths in GOMODCACHE environment

Go already rejects relative paths in a couple environment variables,
It should reject relative paths in GOMODCACHE.

Fixes #43715

Change-Id: Id1ceff839c7ab21c00cf4ace45ce48324733a526
Reviewed-on: https://go-review.googlesource.com/c/go/+/284432
Run-TryBot: Baokun Lee <bk@golangcn.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Trust: Jay Conrod <jayconrod@google.com>
Trust: Baokun Lee <bk@golangcn.org>

diff --git a/src/cmd/go/internal/envcmd/env.go b/src/cmd/go/internal/envcmd/env.go
index 6937187522bd237fbefac0c13727754af40fcb86..aad5d704e58e8fa713d1f7220449551dd5271d38 100644 (file)
--- a/src/cmd/go/internal/envcmd/env.go
+++ b/src/cmd/go/internal/envcmd/env.go
@@ -428,7 +428,7 @@ func checkEnvWrite(key, val string) error {
                        return fmt.Errorf("GOPATH entry is relative; must be absolute path: %q", val)
                }
        // Make sure CC and CXX are absolute paths
-       case "CC", "CXX":
+       case "CC", "CXX", "GOMODCACHE":
                if !filepath.IsAbs(val) && val != "" && val != filepath.Base(val) {
                        return fmt.Errorf("%s entry is relative; must be absolute path: %q", key, val)
                }

diff --git a/src/cmd/go/internal/modfetch/cache.go b/src/cmd/go/internal/modfetch/cache.go
index 3a2ff63721cb368e4b0825a8d75ae8fbee8eafc5..9e751931a0ba07211cb00ec9a7dad9da0df13dec 100644 (file)
--- a/src/cmd/go/internal/modfetch/cache.go
+++ b/src/cmd/go/internal/modfetch/cache.go
@@ -28,10 +28,8 @@ import (
 )
 
 func cacheDir(path string) (string, error) {
-       if cfg.GOMODCACHE == "" {
-               // modload.Init exits if GOPATH[0] is empty, and cfg.GOMODCACHE
-               // is set to GOPATH[0]/pkg/mod if GOMODCACHE is empty, so this should never happen.
-               return "", fmt.Errorf("internal error: cfg.GOMODCACHE not set")
+       if err := checkCacheDir(); err != nil {
+               return "", err
        }
        enc, err := module.EscapePath(path)
        if err != nil {
@@ -64,10 +62,8 @@ func CachePath(m module.Version, suffix string) (string, error) {
 // along with the directory if the directory does not exist or if the directory
 // is not completely populated.
 func DownloadDir(m module.Version) (string, error) {
-       if cfg.GOMODCACHE == "" {
-               // modload.Init exits if GOPATH[0] is empty, and cfg.GOMODCACHE
-               // is set to GOPATH[0]/pkg/mod if GOMODCACHE is empty, so this should never happen.
-               return "", fmt.Errorf("internal error: cfg.GOMODCACHE not set")
+       if err := checkCacheDir(); err != nil {
+               return "", err
        }
        enc, err := module.EscapePath(m.Path)
        if err != nil {
@@ -134,10 +130,8 @@ func lockVersion(mod module.Version) (unlock func(), err error) {
 // user's working directory.
 // If err is nil, the caller MUST eventually call the unlock function.
 func SideLock() (unlock func(), err error) {
-       if cfg.GOMODCACHE == "" {
-               // modload.Init exits if GOPATH[0] is empty, and cfg.GOMODCACHE
-               // is set to GOPATH[0]/pkg/mod if GOMODCACHE is empty, so this should never happen.
-               base.Fatalf("go: internal error: cfg.GOMODCACHE not set")
+       if err := checkCacheDir(); err != nil {
+               base.Fatalf("go: %v", err)
        }
 
        path := filepath.Join(cfg.GOMODCACHE, "cache", "lock")
@@ -633,3 +627,16 @@ func rewriteVersionList(dir string) {
                base.Fatalf("go: failed to write version list: %v", err)
        }
 }
+
+func checkCacheDir() error {
+       if cfg.GOMODCACHE == "" {
+               // modload.Init exits if GOPATH[0] is empty, and cfg.GOMODCACHE
+               // is set to GOPATH[0]/pkg/mod if GOMODCACHE is empty, so this should never happen.
+               return fmt.Errorf("internal error: cfg.GOMODCACHE not set")
+       }
+
+       if !filepath.IsAbs(cfg.GOMODCACHE) {
+               return fmt.Errorf("GOMODCACHE entry is relative; must be absolute path: %q.\n", cfg.GOMODCACHE)
+       }
+       return nil
+}

diff --git a/src/cmd/go/internal/modfetch/fetch.go b/src/cmd/go/internal/modfetch/fetch.go
index c55c3cf2534bfe116f3005231b002e56e6959a0f..d5ad277dd00ab773e93f88f3e5ec23d72e066784 100644 (file)
--- a/src/cmd/go/internal/modfetch/fetch.go
+++ b/src/cmd/go/internal/modfetch/fetch.go
@@ -37,10 +37,8 @@ var downloadCache par.Cache
 // local download cache and returns the name of the directory
 // corresponding to the root of the module's file tree.
 func Download(ctx context.Context, mod module.Version) (dir string, err error) {
-       if cfg.GOMODCACHE == "" {
-               // modload.Init exits if GOPATH[0] is empty, and cfg.GOMODCACHE
-               // is set to GOPATH[0]/pkg/mod if GOMODCACHE is empty, so this should never happen.
-               base.Fatalf("go: internal error: cfg.GOMODCACHE not set")
+       if err := checkCacheDir(); err != nil {
+               base.Fatalf("go: %v", err)
        }
 
        // The par.Cache here avoids duplicate work.

diff --git a/src/cmd/go/testdata/script/env_write.txt b/src/cmd/go/testdata/script/env_write.txt
index bda1e57826ee1bb9dbea4cac1e3571f533fda501..4fa39df10447156b494b244a2074a6feff8632f1 100644 (file)
--- a/src/cmd/go/testdata/script/env_write.txt
+++ b/src/cmd/go/testdata/script/env_write.txt
@@ -173,3 +173,9 @@ go env -w GOOS=linux GOARCH=mips
 env GOOS=windows
 ! go env -u GOOS
 stderr 'unsupported GOOS/GOARCH.*windows/mips$'
+
+# go env -w should reject relative paths in GOMODCACHE environment.
+! go env -w GOMODCACHE=~/test
+stderr 'go env -w: GOMODCACHE entry is relative; must be absolute path: "~/test"'
+! go env -w GOMODCACHE=./test
+stderr 'go env -w: GOMODCACHE entry is relative; must be absolute path: "./test"'

diff --git a/src/cmd/go/testdata/script/mod_cache_dir.txt b/src/cmd/go/testdata/script/mod_cache_dir.txt
new file mode 100644 (file)
index 0000000..7284ccf
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_cache_dir.txt
@@ -0,0 +1,11 @@
+env GO111MODULE=on
+
+# Go should reject relative paths in GOMODCACHE environment.
+
+env GOMODCACHE="~/test"
+! go get example.com/tools/cmd/hello
+stderr 'must be absolute path'
+
+env GOMODCACHE="./test"
+! go get example.com/tools/cmd/hello
+stderr 'must be absolute path'