internal/goenv: make goenv parsing robust across go versions and OSes (

#455)

internal/goenv/goenv.go

@@ -3,46 +3,24 @@ package goenv
 import (
 	"errors"
 	"os/exec"
-	"runtime"
-	"strconv"
 	"strings"
 )
 
-func Read() (map[string]string, error) {
-	out, err := exec.Command("go", "env").CombinedOutput()
+func Read(varNames []string) (map[string]string, error) {
+	out, err := exec.Command("go", append([]string{"env"}, varNames...)...).CombinedOutput()
 	if err != nil {
 		return nil, err
 	}
-	return parseGoEnv(out, runtime.GOOS)
+	return parseGoEnv(varNames, out)
 }
 
-func parseGoEnv(data []byte, goos string) (map[string]string, error) {
+func parseGoEnv(varNames []string, data []byte) (map[string]string, error) {
 	vars := make(map[string]string)
 
 	lines := strings.Split(strings.ReplaceAll(string(data), "\r\n", "\n"), "\n")
-
-	if goos == "windows" {
-		// Line format is: `set $name=$value`
-		for _, l := range lines {
-			l = strings.TrimPrefix(l, "set ")
-			parts := strings.Split(l, "=")
-			if len(parts) != 2 {
-				continue
-			}
-			vars[parts[0]] = parts[1]
-		}
-	} else {
-		// Line format is: `$name="$value"`
-		for _, l := range lines {
-			parts := strings.Split(strings.TrimSpace(l), "=")
-			if len(parts) != 2 {
-				continue
-			}
-			val, err := strconv.Unquote(parts[1])
-			if err != nil {
-				continue
-			}
-			vars[parts[0]] = val
+	for i, varName := range varNames {
+		if i < len(lines) && len(lines[i]) > 0 {
+			vars[varName] = lines[i]
 		}
 	}
 

internal/goenv/goenv_test.go

@@ -7,69 +7,83 @@ import (
 
 func TestParse(t *testing.T) {
 	tests := []struct {
-		goos   string
 		lines  []string
 		goroot string
 		gopath string
+		err    bool
 	}{
+		// handle windows line-endings
 		{
-			goos: "windows",
 			lines: []string{
-				"set GOROOT=C:\\Program Files\\Go\r\n",
-				"set GOPATH=C:\\Users\\me\\go\r\n",
+				"C:\\Program Files\\Go\r\n",
+				"C:\\Users\\me\\go\r\n",
 			},
 			goroot: "C:\\Program Files\\Go",
 			gopath: "C:\\Users\\me\\go",
 		},
 
-		// Don't do trim on Windows.
+		// preserve trailing spaces on windows
 		{
-			goos: "windows",
 			lines: []string{
-				"set GOROOT=C:\\Program Files\\Go \r\n",
-				"set GOPATH=C:\\Users\\me\\go  \r\n",
+				"C:\\Program Files\\Go \r\n",
+				"C:\\Users\\me\\go  \r\n",
 			},
 			goroot: "C:\\Program Files\\Go ",
 			gopath: "C:\\Users\\me\\go  ",
 		},
 
+		// handle linux line-endings
 		{
-			goos: "linux",
 			lines: []string{
-				"GOROOT=\"/usr/local/go\"\n",
-				"GOPATH=\"/home/me/go\"\n",
+				"/usr/local/go\n",
+				"/home/me/go\n",
 			},
 			goroot: "/usr/local/go",
 			gopath: "/home/me/go",
 		},
 
-		// Trim lines on Linux.
+		// preserve trailing spaces on linux
 		{
-			goos: "linux",
 			lines: []string{
-				" GOROOT=\"/usr/local/go\"  \n",
-				"GOPATH=\"/home/me/go\"  \n",
+				"/usr/local/go \n",
+				"/home/me/go \n",
 			},
-			goroot: "/usr/local/go",
+			goroot: "/usr/local/go ",
+			gopath: "/home/me/go ",
+		},
+
+		// handle empty value
+		{
+			lines: []string{
+				"\n",
+				"/home/me/go\n",
+			},
+			goroot: "",
 			gopath: "/home/me/go",
 		},
 
-		// Quotes preserve the whitespace.
+		// handle short output
 		{
-			goos: "linux",
 			lines: []string{
-				" GOROOT=\"/usr/local/go \"  \n",
-				"GOPATH=\"/home/me/go \"  \n",
+				"/usr/local/go",
 			},
-			goroot: "/usr/local/go ",
-			gopath: "/home/me/go ",
+			goroot: "/usr/local/go",
+			gopath: "",
+		},
+
+		// handle empty output
+		{
+			lines:  []string{},
+			goroot: "",
+			gopath: "",
+			err:    true,
 		},
 	}
 
 	for i, test := range tests {
 		data := []byte(strings.Join(test.lines, ""))
-		vars, err := parseGoEnv(data, test.goos)
-		if err != nil {
+		vars, err := parseGoEnv([]string{"GOROOT", "GOPATH"}, data)
+		if err != nil != test.err {
 			t.Fatalf("test %d failed: %v", i, err)
 		}
 		if vars["GOROOT"] != test.goroot {

ruleguard/engine.go

@@ -248,7 +248,7 @@ func inferBuildContext() *build.Context {
 	// Inherit most fields from the build.Default.
 	ctx := build.Default
 
-	env, err := goenv.Read()
+	env, err := goenv.Read([]string{"GOROOT", "GOPATH", "GOARCH", "GOOS", "CGO_ENABLED"})
 	if err != nil {
 		return &ctx
 	}