cmd/go: make env -w and -u validate GOOS and GOARCH values

This change makes go env -w and -u check invalid GOOS and GOARCH values and abort if that's the case.

Fixes #34194

Change-Id: Idca8e93bb0b190fd273bf786c925be7993c24a2b
GitHub-Last-Rev: ee67f09d75f4552001cb8b6506bc4af0894c9b05
GitHub-Pull-Request: golang/go#34221
Reviewed-on: https://go-review.googlesource.com/c/go/+/194617
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/src/cmd/go/internal/envcmd/env.go b/src/cmd/go/internal/envcmd/env.go
index ff4a7e4a46..d2d5ed9507 100644
--- a/src/cmd/go/internal/envcmd/env.go
+++ b/src/cmd/go/internal/envcmd/env.go
@@ -8,6 +8,7 @@ package envcmd
 import (
 	"encoding/json"
 	"fmt"
+	"go/build"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -249,6 +250,21 @@ func runEnv(cmd *base.Command, args []string) {
 				fmt.Fprintf(os.Stderr, "warning: go env -w %s=... does not override conflicting OS environment variable\n", key)
 			}
 		}
+
+		goos, okGOOS := add["GOOS"]
+		goarch, okGOARCH := add["GOARCH"]
+		if okGOOS || okGOARCH {
+			if !okGOOS {
+				goos = cfg.Goos
+			}
+			if !okGOARCH {
+				goarch = cfg.Goarch
+			}
+			if err := work.CheckGOOSARCHPair(goos, goarch); err != nil {
+				base.Fatalf("go env -w: %v", err)
+			}
+		}
+
 		updateEnvFile(add, nil)
 		return
 	}
@@ -265,6 +281,24 @@ func runEnv(cmd *base.Command, args []string) {
 			}
 			del[arg] = true
 		}
+		if del["GOOS"] || del["GOARCH"] {
+			goos, goarch := cfg.Goos, cfg.Goarch
+			if del["GOOS"] {
+				goos = getOrigEnv("GOOS")
+				if goos == "" {
+					goos = build.Default.GOOS
+				}
+			}
+			if del["GOARCH"] {
+				goarch = getOrigEnv("GOARCH")
+				if goarch == "" {
+					goarch = build.Default.GOARCH
+				}
+			}
+			if err := work.CheckGOOSARCHPair(goos, goarch); err != nil {
+				base.Fatalf("go env -u: %v", err)
+			}
+		}
 		updateEnvFile(nil, del)
 		return
 	}
@@ -331,6 +365,15 @@ func printEnvAsJSON(env []cfg.EnvVar) {
 	}
 }
 
+func getOrigEnv(key string) string {
+	for _, v := range cfg.OrigEnv {
+		if strings.HasPrefix(v, key+"=") {
+			return strings.TrimPrefix(v, key+"=")
+		}
+	}
+	return ""
+}
+
 func checkEnvWrite(key, val string) error {
 	switch key {
 	case "GOEXE", "GOGCCFLAGS", "GOHOSTARCH", "GOHOSTOS", "GOMOD", "GOTOOLDIR":