1 files changed, 133 insertions, 0 deletions
diff --git a/libgo/go/cmd/go/internal/modcmd/download.go b/libgo/go/cmd/go/internal/modcmd/download.go
new file mode 100644
index 00000000000..cf42eff58a1
--- /dev/null
+++ b/libgo/go/cmd/go/internal/modcmd/download.go
@@ -0,0 +1,133 @@
+// Copyright 2018 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 modcmd
+
+import (
+	"cmd/go/internal/base"
+	"cmd/go/internal/modfetch"
+	"cmd/go/internal/modload"
+	"cmd/go/internal/module"
+	"cmd/go/internal/par"
+	"encoding/json"
+	"os"
+)
+
+var cmdDownload = &base.Command{
+	UsageLine: "go mod download [-dir] [-json] [modules]",
+	Short:     "download modules to local cache",
+	Long: `
+Download downloads the named modules, which can be module patterns selecting
+dependencies of the main module or module queries of the form path@version.
+With no arguments, download applies to all dependencies of the main module.
+
+The go command will automatically download modules as needed during ordinary
+execution. The "go mod download" command is useful mainly for pre-filling
+the local cache or to compute the answers for a Go module proxy.
+
+By default, download reports errors to standard error but is otherwise silent.
+The -json flag causes download to print a sequence of JSON objects
+to standard output, describing each downloaded module (or failure),
+corresponding to this Go struct:
+
+    type Module struct {
+        Path     string // module path
+        Version  string // module version
+        Error    string // error loading module
+        Info     string // absolute path to cached .info file
+        GoMod    string // absolute path to cached .mod file
+        Zip      string // absolute path to cached .zip file
+        Dir      string // absolute path to cached source root directory
+        Sum      string // checksum for path, version (as in go.sum)
+        GoModSum string // checksum for go.mod (as in go.sum)
+    }
+
+See 'go help modules' for more about module queries.
+	`,
+}
+
+var downloadJSON = cmdDownload.Flag.Bool("json", false, "")
+
+func init() {
+	cmdDownload.Run = runDownload // break init cycle
+}
+
+type moduleJSON struct {
+	Path     string `json:",omitempty"`
+	Version  string `json:",omitempty"`
+	Error    string `json:",omitempty"`
+	Info     string `json:",omitempty"`
+	GoMod    string `json:",omitempty"`
+	Zip      string `json:",omitempty"`
+	Dir      string `json:",omitempty"`
+	Sum      string `json:",omitempty"`
+	GoModSum string `json:",omitempty"`
+}
+
+func runDownload(cmd *base.Command, args []string) {
+	if len(args) == 0 {
+		args = []string{"all"}
+	}
+
+	var mods []*moduleJSON
+	var work par.Work
+	listU := false
+	listVersions := false
+	for _, info := range modload.ListModules(args, listU, listVersions) {
+		if info.Replace != nil {
+			info = info.Replace
+		}
+		if info.Version == "" {
+			continue
+		}
+		m := &moduleJSON{
+			Path:    info.Path,
+			Version: info.Version,
+		}
+		mods = append(mods, m)
+		work.Add(m)
+	}
+
+	work.Do(10, func(item interface{}) {
+		m := item.(*moduleJSON)
+		var err error
+		m.Info, err = modfetch.InfoFile(m.Path, m.Version)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		m.GoMod, err = modfetch.GoModFile(m.Path, m.Version)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		m.GoModSum, err = modfetch.GoModSum(m.Path, m.Version)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		mod := module.Version{Path: m.Path, Version: m.Version}
+		m.Zip, err = modfetch.DownloadZip(mod)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		m.Sum = modfetch.Sum(mod)
+		m.Dir, err = modfetch.Download(mod)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+	})
+
+	if *downloadJSON {
+		for _, m := range mods {
+			b, err := json.MarshalIndent(m, "", "\t")
+			if err != nil {
+				base.Fatalf("%v", err)
+			}
+			os.Stdout.Write(append(b, '\n'))
+		}
+	}
+}