Fix HTTP getter subdir paths to work properly

The tests were actually turning `foo//bar` into `foo/bar` so we have
_never_ tested subdir access with HTTP. Turns out, it never worked!
There was a bug that caused it to never work. This fixes that bug, adds
more tests, and verifies globbing works, too.

client.go

@@ -305,19 +305,11 @@ func (c *Client) Get() error {
 			return err
 		}
 
-		// Subdir matching supports globs. This allows matching unknown
-		// subdirectory structures but where we know the general path.
-		// For example, for archives that have a root folder containing
-		// all the items, you can download it with the getter URL of:
-		// 'path//*'.
-		matches, err := filepath.Glob(filepath.Join(dst, subDir))
+		// Process any globs
+		subDir, err := SubdirGlob(dst, subDir)
 		if err != nil {
 			return err
 		}
-		if len(matches) > 1 {
-			return fmt.Errorf("subdir %q matches multiple paths", subDir)
-		}
-		subDir = matches[0]
 
 		return copyDir(realDst, subDir, false)
 	}

get_http.go

@@ -98,7 +98,6 @@ func (g *HttpGetter) Get(dst string, u *url.URL) error {
 }
 
 func (g *HttpGetter) GetFile(dst string, u *url.URL) error {
-
 	if g.Netrc {
 		// Add auth from netrc if we can
 		if err := addAuthFromNetrc(u); err != nil {
@@ -140,13 +139,22 @@ func (g *HttpGetter) getSubdir(dst, source, subDir string) error {
 	}
 	defer os.RemoveAll(td)
 
+	// We have to create a subdirectory that doesn't exist for the file
+	// getter to work.
+	td = filepath.Join(td, "data")
+
 	// Download that into the given directory
 	if err := Get(td, source); err != nil {
 		return err
 	}
 
+	// Process any globbing
+	sourcePath, err := SubdirGlob(td, subDir)
+	if err != nil {
+		return err
+	}
+
 	// Make sure the subdir path actually exists
-	sourcePath := filepath.Join(td, subDir)
 	if _, err := os.Stat(sourcePath); err != nil {
 		return fmt.Errorf(
 			"Error downloading %s: %s", source, err)

get_http_test.go

@@ -86,6 +86,30 @@ func TestHttpGetter_metaSubdir(t *testing.T) {
 	}
 }
 
+func TestHttpGetter_metaSubdirGlob(t *testing.T) {
+	ln := testHttpServer(t)
+	defer ln.Close()
+
+	g := new(HttpGetter)
+	dst := tempDir(t)
+
+	var u url.URL
+	u.Scheme = "http"
+	u.Host = ln.Addr().String()
+	u.Path = "/meta-subdir-glob"
+
+	// Get it!
+	if err := g.Get(dst, &u); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Verify the main file exists
+	mainPath := filepath.Join(dst, "sub.tf")
+	if _, err := os.Stat(mainPath); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}
+
 func TestHttpGetter_none(t *testing.T) {
 	ln := testHttpServer(t)
 	defer ln.Close()
@@ -194,6 +218,7 @@ func testHttpServer(t *testing.T) net.Listener {
 	mux.HandleFunc("/meta", testHttpHandlerMeta)
 	mux.HandleFunc("/meta-auth", testHttpHandlerMetaAuth)
 	mux.HandleFunc("/meta-subdir", testHttpHandlerMetaSubdir)
+	mux.HandleFunc("/meta-subdir-glob", testHttpHandlerMetaSubdirGlob)
 
 	var server http.Server
 	server.Handler = mux
@@ -234,6 +259,10 @@ func testHttpHandlerMetaSubdir(w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte(fmt.Sprintf(testHttpMetaStr, testModuleURL("basic//subdir").String())))
 }
 
+func testHttpHandlerMetaSubdirGlob(w http.ResponseWriter, r *http.Request) {
+	w.Write([]byte(fmt.Sprintf(testHttpMetaStr, testModuleURL("basic//sub*").String())))
+}
+
 func testHttpHandlerNone(w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte(testHttpNoneStr))
 }

module_test.go

@@ -40,10 +40,15 @@ func testModule(n string) string {
 }
 
 func testModuleURL(n string) *url.URL {
+	n, subDir := SourceDirSubdir(n)
 	u, err := urlhelper.Parse(testModule(n))
 	if err != nil {
 		panic(err)
 	}
+	if subDir != "" {
+		u.Path += "//" + subDir
+		u.RawPath = u.Path
+	}
 
 	return u
 }

source.go

@@ -1,6 +1,8 @@
 package getter
 
 import (
+	"fmt"
+	"path/filepath"
 	"strings"
 )
 
@@ -34,3 +36,22 @@ func SourceDirSubdir(src string) (string, string) {
 
 	return src, subdir
 }
+
+// SubdirGlob returns the actual subdir with globbing processed.
+//
+// dst should be a destination directory that is already populated (the
+// download is complete) and subDir should be the set subDir. If subDir
+// is an empty string, this returns an empty string.
+//
+// The returned path is the full absolute path.
+func SubdirGlob(dst, subDir string) (string, error) {
+	matches, err := filepath.Glob(filepath.Join(dst, subDir))
+	if err != nil {
+		return "", err
+	}
+	if len(matches) > 1 {
+		return "", fmt.Errorf("subdir %q matches multiple paths", subDir)
+	}
+
+	return matches[0], nil
+}