cmd/go: add "go env GOCACHE"

rsc · rsc · commit c604792d2833 · 2017-11-02T03:35:41.000Z
This lets users see the effective GOCACHE setting. Change-Id: I0b6dd2945d54611be89ed68fe2fd99110b9a25f6 Reviewed-on: https://go-review.googlesource.com/75293 Reviewed-by: David Crawshaw <crawshaw@golang.org>
diff --git a/src/cmd/dist/deps.go b/src/cmd/dist/deps.go
diff --git a/src/cmd/go/internal/cache/default.go b/src/cmd/go/internal/cache/default.go
@@ -26,52 +26,61 @@ var (
 // initDefaultCache does the work of finding the default cache
 // the first time Default is called.
 func initDefaultCache() {
-	dir := os.Getenv("GOCACHE")
+	dir := DefaultDir()
 	if dir == "off" {
 		return
 	}
-	if dir == "" {
-		// Compute default location.
-		// TODO(rsc): This code belongs somewhere else,
-		// like maybe ioutil.CacheDir or os.CacheDir.
-		switch runtime.GOOS {
-		case "windows":
-			dir = os.Getenv("LocalAppData")
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		base.Fatalf("initializing cache in $GOCACHE: %s", err)
+	}
+	c, err := Open(dir)
+	if err != nil {
+		base.Fatalf("initializing cache in $GOCACHE: %s", err)
+	}
+	defaultCache = c
+}
 
-		case "darwin":
-			dir = os.Getenv("HOME")
-			if dir == "" {
-				return
-			}
-			dir += "/Library/Caches"
+// DefaultDir returns the effective GOCACHE setting.
+// It returns "off" if the cache is disabled.
+func DefaultDir() string {
+	dir := os.Getenv("GOCACHE")
+	if dir != "" {
+		return dir
+	}
 
-		case "plan9":
-			dir = os.Getenv("home")
-			if dir == "" {
-				return
-			}
-			dir += "/lib/cache"
+	// Compute default location.
+	// TODO(rsc): This code belongs somewhere else,
+	// like maybe ioutil.CacheDir or os.CacheDir.
+	switch runtime.GOOS {
+	case "windows":
+		dir = os.Getenv("LocalAppData")
 
-		default: // Unix
-			// https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
-			dir = os.Getenv("XDG_CACHE_HOME")
-			if dir == "" {
-				dir = os.Getenv("HOME")
-				if dir == "" {
-					return
-				}
-				dir += "/.cache"
-			}
+	case "darwin":
+		dir = os.Getenv("HOME")
+		if dir == "" {
+			return "off"
 		}
-		dir = filepath.Join(dir, "go-build")
-		if err := os.MkdirAll(dir, 0777); err != nil {
-			return
+		dir += "/Library/Caches"
+
+	case "plan9":
+		dir = os.Getenv("home")
+		if dir == "" {
+			return "off"
 		}
-	}
+		// Plan 9 has no established per-user cache directory,
+		// but $home/lib/xyz is the usual equivalent of $HOME/.xyz on Unix.
+		dir += "/lib/cache"
 
-	c, err := Open(dir)
-	if err != nil {
-		base.Fatalf("initializing cache in $GOCACHE: %s", err)
+	default: // Unix
+		// https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
+		dir = os.Getenv("XDG_CACHE_HOME")
+		if dir == "" {
+			dir = os.Getenv("HOME")
+			if dir == "" {
+				return "off"
+			}
+			dir += "/.cache"
+		}
 	}
-	defaultCache = c
+	return filepath.Join(dir, "go-build")
 }
diff --git a/src/cmd/go/internal/envcmd/env.go b/src/cmd/go/internal/envcmd/env.go
@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"cmd/go/internal/base"
+	"cmd/go/internal/cache"
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
 	"cmd/go/internal/work"
@@ -55,6 +56,7 @@ func MkEnv() []cfg.EnvVar {
 		{Name: "GORACE", Value: os.Getenv("GORACE")},
 		{Name: "GOROOT", Value: cfg.GOROOT},
 		{Name: "GOTOOLDIR", Value: base.ToolDir},
+		{Name: "GOCACHE", Value: cache.DefaultDir()},
 
 		// disable escape codes in clang errors
 		{Name: "TERM", Value: "dumb"},
