Introduce the estimate command

related to issue #89

estimate.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/tools/go/vcs"
+)
+
+func get(gopath, repo string) error {
+	done := make(chan struct{})
+	defer close(done)
+	go progressSize("go get", filepath.Join(gopath, "src"), done)
+
+	// As per https://groups.google.com/forum/#!topic/golang-nuts/N5apfenE4m4,
+	// the arguments to “go get” are packages, not repositories. Hence, we
+	// specify “gopkg/...” in order to cover all packages.
+	// As a concrete example, github.com/jacobsa/util is a repository we want
+	// to package into a single Debian package, and using “go get -d
+	// github.com/jacobsa/util” fails because there are no buildable go files
+	// in the top level of that repository.
+	cmd := exec.Command("go", "get", "-d", "-t", repo+"/...")
+	cmd.Stderr = os.Stderr
+	cmd.Env = append([]string{
+		fmt.Sprintf("GOPATH=%s", gopath),
+	}, passthroughEnv()...)
+	return cmd.Run()
+}
+
+func estimate(importpath string) error {
+	// construct a separate GOPATH in a temporary directory
+	gopath, err := ioutil.TempDir("", "dh-make-golang")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(gopath)
+
+	if err := get(gopath, importpath); err != nil {
+		return err
+	}
+
+	// Use digraph(1) to obtain the forward transitive closure of the repo in
+	// question.
+	cmd := exec.Command("/bin/sh", "-c", "go list -f '{{.ImportPath}}{{.Imports}}' ... | tr '[]' ' ' | digraph forward $(go list "+importpath+"/...)")
+	cmd.Stderr = os.Stderr
+	cmd.Env = append([]string{
+		fmt.Sprintf("GOPATH=%s", gopath),
+	}, passthroughEnv()...)
+	out, err := cmd.Output()
+	if err != nil {
+		return fmt.Errorf("%v: %v", cmd.Args, err)
+	}
+
+	closure := make(map[string]bool)
+	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
+		closure[line] = true
+	}
+
+	// Remove standard lib packages
+	cmd = exec.Command("go", "list", "std")
+	cmd.Stderr = os.Stderr
+	cmd.Env = append([]string{
+		fmt.Sprintf("GOPATH=%s", gopath),
+	}, passthroughEnv()...)
+
+	out, err = cmd.Output()
+	if err != nil {
+		return fmt.Errorf("%v: %v", cmd.Args, err)
+	}
+	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
+		delete(closure, line)
+	}
+
+	delete(closure, "C") // would fail resolving anyway
+
+	// Resolve all packages to the root of their repository.
+	roots := make(map[string]bool)
+	for dep := range closure {
+		rr, err := vcs.RepoRootForImportPath(dep, false)
+		if err != nil {
+			log.Printf("Could not determine repo path for import path %q: %v\n", dep, err)
+			continue
+		}
+
+		roots[rr.Root] = true
+	}
+
+	// Filter out all already-packaged ones:
+	golangBinaries, err := getGolangBinaries()
+	if err != nil {
+		return nil
+	}
+
+	for importpath, binary := range golangBinaries {
+		if roots[importpath] {
+			log.Printf("found %s in Debian package %s", importpath, binary)
+			delete(roots, importpath)
+		}
+	}
+
+	if len(roots) == 0 {
+		log.Printf("%s is already fully packaged in Debian", importpath)
+		return nil
+	}
+	log.Printf("Bringing %s to Debian requires packaging the following Go packages:", importpath)
+	for importpath := range roots {
+		fmt.Println(importpath)
+	}
+
+	return nil
+}
+
+func execEstimate(args []string) {
+	fs := flag.NewFlagSet("search", flag.ExitOnError)
+
+	err := fs.Parse(args)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if fs.NArg() != 1 {
+		fmt.Fprintf(os.Stderr, "Usage: %s estimate <importpath>\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "Estimates the work necessary to bring <importpath> into Debian by printing all currently unpacked repositories\n")
+		fmt.Fprintf(os.Stderr, "Example: %s estimate github.com/Debian/dh-make-golang\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	// TODO: support the -git_revision flag
+
+	if err := estimate(fs.Arg(0)); err != nil {
+		log.Fatal(err)
+	}
+}

main.go

@@ -19,6 +19,8 @@ func main() {
 		execSearch(args[1:])
 	case "create-salsa-project":
 		execCreateSalsaProject(args[1:])
+	case "estimate":
+		execEstimate(args[1:])
 	default:
 		execMake(args)
 	}

make.go

@@ -197,6 +197,7 @@ func (u *upstream) findDependencies(gopath, repo string) error {
 		rr, err := vcs.RepoRootForImportPath(dep, false)
 		if err != nil {
 			log.Printf("Could not determine repo path for import path %q: %v\n", dep, err)
+			continue
 		}
 
 		roots[rr.Root] = true