Improve flags for compliance tools.

Test: m droid dist reportmissinglicenses

Change-Id: I4090dae3d5d33d1908d67dff31aeee92d2b261da

tools/compliance/cmd/listshare/listshare.go

@@ -15,6 +15,7 @@
 package main
 
 import (
+	"bytes"
 	"flag"
 	"fmt"
 	"io"
@@ -24,12 +25,41 @@ import (
 	"sort"
 	"strings"
 
+	"android/soong/response"
 	"android/soong/tools/compliance"
 )
 
-func init() {
-	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, `Usage: %s file.meta_lic {file.meta_lic...}
+var (
+	failNoneRequested = fmt.Errorf("\nNo license metadata files requested")
+	failNoLicenses    = fmt.Errorf("No licenses found")
+)
+
+func main() {
+	var expandedArgs []string
+	for _, arg := range os.Args[1:] {
+		if strings.HasPrefix(arg, "@") {
+			f, err := os.Open(strings.TrimPrefix(arg, "@"))
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err.Error())
+				os.Exit(1)
+			}
+
+			respArgs, err := response.ReadRspFile(f)
+			f.Close()
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err.Error())
+				os.Exit(1)
+			}
+			expandedArgs = append(expandedArgs, respArgs...)
+		} else {
+			expandedArgs = append(expandedArgs, arg)
+		}
+	}
+
+	flags := flag.NewFlagSet("flags", flag.ExitOnError)
+
+	flags.Usage = func() {
+		fmt.Fprintf(os.Stderr, `Usage: %s {-o outfile} file.meta_lic {file.meta_lic...}
 
 Outputs a csv file with 1 project per line in the first field followed
 by target:condition pairs describing why the project must be shared.
@@ -39,30 +69,61 @@ Soong module or Make target, and the license condition is either
 restricted (e.g. GPL) or reciprocal (e.g. MPL).
 `, filepath.Base(os.Args[0]))
 	}
-}
 
-var (
-	failNoneRequested = fmt.Errorf("\nNo license metadata files requested")
-	failNoLicenses    = fmt.Errorf("No licenses found")
-)
+	outputFile := flags.String("o", "-", "Where to write the list of projects to share. (default stdout)")
 
-func main() {
-	flag.Parse()
+	flags.Parse(expandedArgs)
 
 	// Must specify at least one root target.
-	if flag.NArg() == 0 {
-		flag.Usage()
+	if flags.NArg() == 0 {
+		flags.Usage()
 		os.Exit(2)
 	}
 
-	err := listShare(os.Stdout, os.Stderr, compliance.FS, flag.Args()...)
+	if len(*outputFile) == 0 {
+		flags.Usage()
+		fmt.Fprintf(os.Stderr, "must specify file for -o; use - for stdout\n")
+		os.Exit(2)
+	} else {
+		dir, err := filepath.Abs(filepath.Dir(*outputFile))
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "cannot determine path to %q: %s\n", *outputFile, err)
+			os.Exit(1)
+		}
+		fi, err := os.Stat(dir)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "cannot read directory %q of %q: %s\n", dir, *outputFile, err)
+			os.Exit(1)
+		}
+		if !fi.IsDir() {
+			fmt.Fprintf(os.Stderr, "parent %q of %q is not a directory\n", dir, *outputFile)
+			os.Exit(1)
+		}
+	}
+
+	var ofile io.Writer
+	ofile = os.Stdout
+	var obuf *bytes.Buffer
+	if *outputFile != "-" {
+		obuf = &bytes.Buffer{}
+		ofile = obuf
+	}
+
+	err := listShare(ofile, os.Stderr, compliance.FS, flags.Args()...)
 	if err != nil {
 		if err == failNoneRequested {
-			flag.Usage()
+			flags.Usage()
 		}
 		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
 		os.Exit(1)
 	}
+	if *outputFile != "-" {
+		err := os.WriteFile(*outputFile, obuf.Bytes(), 0666)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "could not write output to %q from %q: %s\n", *outputFile, os.Getenv("PWD"), err)
+			os.Exit(1)
+		}
+	}
 	os.Exit(0)
 }
 
@@ -76,7 +137,7 @@ func listShare(stdout, stderr io.Writer, rootFS fs.FS, files ...string) error {
 	// Read the license graph from the license metadata files (*.meta_lic).
 	licenseGraph, err := compliance.ReadLicenseGraph(rootFS, stderr, files)
 	if err != nil {
-		return fmt.Errorf("Unable to read license metadata file(s) %q: %v\n", files, err)
+		return fmt.Errorf("Unable to read license metadata file(s) %q from %q: %v\n", files, os.Getenv("PWD"), err)
 	}
 	if licenseGraph == nil {
 		return failNoLicenses