Make it possible to specify --libs-dir multiple times

When looking for libraries, directories will be searched in the order they appear on the command line.

CL: mos: Make it possible to specify --libs-dir multiple times

PUBLISHED_FROM=edf703eb2f76edefb5fa1f6c8c0ab9151bfd3058

mos/build.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"io"
 	"io/ioutil"
@@ -12,8 +13,6 @@ import (
 	"time"
 	"unicode"
 
-	"context"
-
 	"cesanta.com/common/go/fwbundle"
 	"cesanta.com/common/go/ourutil"
 	"cesanta.com/mos/build"
@@ -27,6 +26,7 @@ import (
 	"cesanta.com/mos/update"
 	"cesanta.com/mos/version"
 	"github.com/cesanta/errors"
+	"github.com/golang/glog"
 	flag "github.com/spf13/pflag"
 	yaml "gopkg.in/yaml.v2"
 )
@@ -434,11 +434,17 @@ func (lpr *compProviderReal) GetLibLocalPath(
 	}
 
 	// If --libs-dir is set, this is where all the libs are.
-	if paths.LibsDirFlag != "" {
+	if len(paths.LibsDirFlag) > 0 {
 		name2, _ := m.GetName2()
-		libDirAbs := filepath.Join(paths.LibsDirFlag, name2)
-		ourutil.Freportf(lpr.logWriter, "%s: Using %q (--libs-dir) %s", name, libDirAbs, name2)
-		return libDirAbs, nil
+		for _, libsDir := range paths.LibsDirFlag {
+			libDir := filepath.Join(libsDir, name2)
+			glog.V(2).Infof("%s (%s): Trying %s...", name, name2, libDir)
+			if fi, err := os.Stat(libDir); err == nil && fi.IsDir() {
+				ourutil.Freportf(lpr.logWriter, "%s: Using %q (--libs-dir)", name, libDir)
+				return libDir, nil
+			}
+		}
+		return "", errors.Errorf("%s not found in --libs-dir", name2)
 	}
 
 	// Try to fetch

mos/common/paths/paths.go

@@ -1,7 +1,6 @@
 package paths
 
 import (
-	"flag"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -11,6 +10,7 @@ import (
 	"cesanta.com/mos/version"
 
 	"github.com/cesanta/errors"
+	flag "github.com/spf13/pflag"
 )
 
 var (
@@ -20,7 +20,7 @@ var (
 
 	TmpDir         = ""
 	depsDirFlag    = ""
-	LibsDirFlag    = ""
+	LibsDirFlag    = []string{}
 	AppsDir        = ""
 	modulesDirFlag = ""
 
@@ -31,7 +31,7 @@ var (
 func init() {
 	flag.StringVar(&TmpDir, "temp-dir", "~/.mos/tmp", "Directory to store temporary files")
 	flag.StringVar(&depsDirFlag, "deps-dir", "", "Directory to fetch libs, modules into")
-	flag.StringVar(&LibsDirFlag, "libs-dir", "", "Directory to find libs in")
+	flag.StringSliceVar(&LibsDirFlag, "libs-dir", []string{}, "Directory to find libs in. Can be used multiple times.")
 	flag.StringVar(&AppsDir, "apps-dir", AppsDirTpl, "Directory to store apps into")
 	flag.StringVar(&modulesDirFlag, "modules-dir", "", "Directory to store modules into")
 
@@ -52,9 +52,11 @@ func Init() error {
 		return errors.Trace(err)
 	}
 
-	LibsDirFlag, err = NormalizePath(LibsDirFlag, version.GetMosVersion())
-	if err != nil {
-		return errors.Trace(err)
+	for i, s := range LibsDirFlag {
+		LibsDirFlag[i], err = NormalizePath(s, version.GetMosVersion())
+		if err != nil {
+			return errors.Trace(err)
+		}
 	}
 
 	AppsDir, err = NormalizePath(AppsDir, version.GetMosVersion())