1 files changed, 79 insertions, 0 deletions
diff --git a/internal/proxydir/proxydir.go b/internal/proxydir/proxydir.go
new file mode 100644
index 000000000..52e5b586f
--- /dev/null
+++ b/internal/proxydir/proxydir.go
@@ -0,0 +1,79 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package proxydir provides functions for writing module data to a directory
+// in proxy format, so that it can be used as a module proxy by setting
+// GOPROXY="file://<dir>".
+package proxydir
+
+import (
+	"archive/zip"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// WriteModuleVersion creates a directory in the proxy dir for a module.
+func WriteModuleVersion(rootDir, module, ver string, files map[string][]byte) (rerr error) {
+	dir := filepath.Join(rootDir, module, "@v")
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+
+	// The go command checks for versions by looking at the "list" file.  Since
+	// we are supporting multiple versions, create this file if it does not exist
+	// or append the version number to the preexisting file.
+	f, err := os.OpenFile(filepath.Join(dir, "list"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer checkClose("list file", f, &rerr)
+	if _, err := f.WriteString(ver + "\n"); err != nil {
+		return err
+	}
+
+	// Serve the go.mod file on the <version>.mod url, if it exists. Otherwise,
+	// serve a stub.
+	modContents, ok := files["go.mod"]
+	if !ok {
+		modContents = []byte("module " + module)
+	}
+	if err := ioutil.WriteFile(filepath.Join(dir, ver+".mod"), modContents, 0644); err != nil {
+		return err
+	}
+
+	// info file, just the bare bones.
+	infoContents := []byte(fmt.Sprintf(`{"Version": "%v", "Time":"2017-12-14T13:08:43Z"}`, ver))
+	if err := ioutil.WriteFile(filepath.Join(dir, ver+".info"), infoContents, 0644); err != nil {
+		return err
+	}
+
+	// zip of all the source files.
+	f, err = os.OpenFile(filepath.Join(dir, ver+".zip"), os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer checkClose("zip file", f, &rerr)
+	z := zip.NewWriter(f)
+	defer checkClose("zip writer", z, &rerr)
+	for name, contents := range files {
+		zf, err := z.Create(module + "@" + ver + "/" + name)
+		if err != nil {
+			return err
+		}
+		if _, err := zf.Write(contents); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func checkClose(name string, closer io.Closer, err *error) {
+	if cerr := closer.Close(); cerr != nil && *err == nil {
+		*err = fmt.Errorf("closing %s: %v", name, cerr)
+	}
+}