Convert soong_javac_filter to a wrapper

Piping the output of javac through a filter makes it hard to capture
the exit status.  Convert it to a wrapper that executes javac and
propagates the exit status.

Bug: 36666657
Test: javac_wrapper_test
Change-Id: I9b56cc3794023aabc9328138a68830e26e980f97

cmd/javac_wrapper/Android.bp

@@ -13,11 +13,11 @@
 // limitations under the License.
 
 blueprint_go_binary {
-    name: "soong_javac_filter",
+    name: "soong_javac_wrapper",
     srcs: [
-        "javac_filter.go",
+        "javac_wrapper.go",
     ],
     testSrcs: [
-        "javac_filter_test.go",
+        "javac_wrapper_test.go",
     ],
 }

cmd/javac_wrapper/javac_wrapper.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// soong_javac_filter expects the output of javac on stdin, and produces
-// an ANSI colorized version of the output on stdout.
+// soong_javac_wrapper expects a javac command line and argments, executes
+// it, and produces an ANSI colorized version of the output on stdout.
 //
 // It also hides the unhelpful and unhideable "warning there is a warning"
 // messages.
@@ -24,17 +24,19 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/exec"
 	"regexp"
+	"syscall"
 )
 
 // Regular expressions are based on
 // https://chromium.googlesource.com/chromium/src/+/master/build/android/gyp/javac.py
 // Colors are based on clang's output
 var (
-	filelinePrefix = `^[-.\w/\\]+.java:[0-9]+:`
-	warningRe      = regexp.MustCompile(filelinePrefix + ` (warning:) .*$`)
-	errorRe        = regexp.MustCompile(filelinePrefix + ` (.*?:) .*$`)
-	markerRe       = regexp.MustCompile(`\s*(\^)\s*$`)
+	filelinePrefix = `^([-.\w/\\]+.java:[0-9]+: )`
+	warningRe      = regexp.MustCompile(filelinePrefix + `?(warning:) .*$`)
+	errorRe        = regexp.MustCompile(filelinePrefix + `(.*?:) .*$`)
+	markerRe       = regexp.MustCompile(`()\s*(\^)\s*$`)
 
 	escape  = "\x1b"
 	reset   = escape + "[0m"
@@ -45,11 +47,69 @@ var (
 )
 
 func main() {
-	err := process(bufio.NewReader(os.Stdin), os.Stdout)
+	exitCode, err := Main(os.Args[0], os.Args[1:])
 	if err != nil {
-		fmt.Fprintln(os.Stderr, "reading standard input:", err)
-		os.Exit(-1)
+		fmt.Fprintln(os.Stderr, err.Error())
 	}
+	os.Exit(exitCode)
+}
+
+func Main(name string, args []string) (int, error) {
+	if len(args) < 1 {
+		return 1, fmt.Errorf("usage: %s javac ...", name)
+	}
+
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return 1, fmt.Errorf("creating output pipe: %s", err)
+	}
+
+	cmd := exec.Command(args[0], args[1:]...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = pw
+	cmd.Stderr = pw
+	err = cmd.Start()
+	if err != nil {
+		return 1, fmt.Errorf("starting subprocess: %s", err)
+	}
+
+	pw.Close()
+
+	// Process subprocess stdout asynchronously
+	errCh := make(chan error)
+	go func() {
+		errCh <- process(pr, os.Stdout)
+	}()
+
+	// Wait for subprocess to finish
+	cmdErr := cmd.Wait()
+
+	// Wait for asynchronous stdout processing to finish
+	err = <-errCh
+
+	// Check for subprocess exit code
+	if cmdErr != nil {
+		if exitErr, ok := cmdErr.(*exec.ExitError); ok {
+			if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
+				if status.Exited() {
+					return status.ExitStatus(), nil
+				} else if status.Signaled() {
+					exitCode := 128 + int(status.Signal())
+					return exitCode, nil
+				} else {
+					return 1, exitErr
+				}
+			} else {
+				return 1, nil
+			}
+		}
+	}
+
+	if err != nil {
+		return 1, err
+	}
+
+	return 0, nil
 }
 
 func process(r io.Reader, w io.Writer) error {
@@ -61,7 +121,11 @@ func process(r io.Reader, w io.Writer) error {
 	for scanner.Scan() {
 		processLine(w, scanner.Text())
 	}
-	return scanner.Err()
+	err := scanner.Err()
+	if err != nil {
+		return fmt.Errorf("scanning input: %s", err)
+	}
+	return nil
 }
 
 func processLine(w io.Writer, line string) {
@@ -83,7 +147,7 @@ func processLine(w io.Writer, line string) {
 // Returns line, modified if it matched, and true if it matched.
 func applyColor(line, color string, re *regexp.Regexp) (string, bool) {
 	if m := re.FindStringSubmatchIndex(line); m != nil {
-		tagStart, tagEnd := m[2], m[3]
+		tagStart, tagEnd := m[4], m[5]
 		line = bold + line[:tagStart] +
 			color + line[tagStart:tagEnd] + reset + bold +
 			line[tagEnd:] + reset

cmd/javac_wrapper/javac_wrapper_test.go

@@ -16,6 +16,7 @@ package main
 
 import (
 	"bytes"
+	"strconv"
 	"testing"
 )
 
@@ -38,6 +39,10 @@ var testCases = []struct {
 		in:  "File.java:398: warning: [RectIntersectReturnValueIgnored] Return value of com.blah.function() must be checked\n",
 		out: "\x1b[1mFile.java:398: \x1b[35mwarning:\x1b[0m\x1b[1m [RectIntersectReturnValueIgnored] Return value of com.blah.function() must be checked\x1b[0m\n",
 	},
+	{
+		in:  "warning: [options] bootstrap class path not set in conjunction with -source 1.7\n",
+		out: "\x1b[1m\x1b[35mwarning:\x1b[0m\x1b[1m [options] bootstrap class path not set in conjunction with -source 1.7\x1b[0m\n",
+	},
 	{
 		in:  "    (see http://go/errorprone/bugpattern/RectIntersectReturnValueIgnored.md)\n",
 		out: "    (see http://go/errorprone/bugpattern/RectIntersectReturnValueIgnored.md)\n",
@@ -60,7 +65,8 @@ Note: dir/file.java uses unchecked or unsafe operations.
 }
 
 func TestJavacColorize(t *testing.T) {
-	for _, test := range testCases {
+	for i, test := range testCases {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
 			buf := new(bytes.Buffer)
 			err := process(bytes.NewReader([]byte(test.in)), buf)
 			if err != nil {
@@ -70,5 +76,39 @@ func TestJavacColorize(t *testing.T) {
 			if got != test.out {
 				t.Errorf("expected %q got %q", test.out, got)
 			}
+		})
 	}
 }
+
+func TestSubprocess(t *testing.T) {
+	t.Run("failure", func(t *testing.T) {
+		exitCode, err := Main("test", []string{"sh", "-c", "exit 9"})
+		if err != nil {
+			t.Fatal("unexpected error", err)
+		}
+		if exitCode != 9 {
+			t.Fatal("expected exit code 9, got", exitCode)
+		}
+	})
+
+	t.Run("signal", func(t *testing.T) {
+		exitCode, err := Main("test", []string{"sh", "-c", "kill -9 $$"})
+		if err != nil {
+			t.Fatal("unexpected error", err)
+		}
+		if exitCode != 137 {
+			t.Fatal("expected exit code 137, got", exitCode)
+		}
+	})
+
+	t.Run("success", func(t *testing.T) {
+		exitCode, err := Main("test", []string{"echo"})
+		if err != nil {
+			t.Fatal("unexpected error", err)
+		}
+		if exitCode != 0 {
+			t.Fatal("expected exit code 0, got", exitCode)
+		}
+	})
+
+}