cmd/go: add support for Fossil SCM to go get

Fixes #10010.

Change-Id: Ib13ac28eafed72c456d8b5b6549015cdf5fdda94
Reviewed-on: https://go-review.googlesource.com/56190
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/internal/get/get.go

@@ -452,12 +452,8 @@ func downloadPackage(p *load.Package) error {
 	// Check that this is an appropriate place for the repo to be checked out.
 	// The target directory must either not exist or have a repo checked out already.
 	meta := filepath.Join(root, "."+vcs.cmd)
-	st, err := os.Stat(meta)
-	if err == nil && !st.IsDir() {
-		return fmt.Errorf("%s exists but is not a directory", meta)
-	}
-	if err != nil {
-		// Metadata directory does not exist. Prepare to checkout new copy.
+	if _, err := os.Stat(meta); err != nil {
+		// Metadata file or directory does not exist. Prepare to checkout new copy.
 		// Some version control tools require the target directory not to exist.
 		// We require that too, just to avoid stepping on existing work.
 		if _, err := os.Stat(root); err == nil {

src/cmd/go/internal/get/vcs.go

@@ -93,6 +93,7 @@ var vcsList = []*vcsCmd{
 	vcsGit,
 	vcsSvn,
 	vcsBzr,
+	vcsFossil,
 }
 
 // vcsByCmd returns the version control system for the given
@@ -324,6 +325,34 @@ func svnRemoteRepo(vcsSvn *vcsCmd, rootDir string) (remoteRepo string, err error
 	return strings.TrimSpace(out), nil
 }
 
+// fossilRepoName is the name go get associates with a fossil repository. In the
+// real world the file can be named anything.
+const fossilRepoName = ".fossil"
+
+// vcsFossil describes how to use Fossil (fossil-scm.org)
+var vcsFossil = &vcsCmd{
+	name: "Fossil",
+	cmd:  "fossil",
+
+	createCmd:   []string{"-go-internal-mkdir {dir} clone {repo} " + filepath.Join("{dir}", fossilRepoName), "-go-internal-cd {dir} open .fossil"},
+	downloadCmd: []string{"up"},
+
+	tagCmd:         []tagCmd{{"tag ls", `(.*)`}},
+	tagSyncCmd:     []string{"up tag:{tag}"},
+	tagSyncDefault: []string{"up trunk"},
+
+	scheme:     []string{"https", "http"},
+	remoteRepo: fossilRemoteRepo,
+}
+
+func fossilRemoteRepo(vcsFossil *vcsCmd, rootDir string) (remoteRepo string, err error) {
+	out, err := vcsFossil.runOutput(rootDir, "remote-url")
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(out)), nil
+}
+
 func (v *vcsCmd) String() string {
 	return v.name
 }
@@ -362,6 +391,19 @@ func (v *vcsCmd) run1(dir string, cmdline string, keyval []string, verbose bool)
 		args[i] = expand(m, arg)
 	}
 
+	if len(args) >= 2 && args[0] == "-go-internal-mkdir" {
+		var err error
+		if filepath.IsAbs(args[1]) {
+			err = os.Mkdir(args[1], os.ModePerm)
+		} else {
+			err = os.Mkdir(filepath.Join(dir, args[1]), os.ModePerm)
+		}
+		if err != nil {
+			return nil, err
+		}
+		args = args[2:]
+	}
+
 	if len(args) >= 2 && args[0] == "-go-internal-cd" {
 		if filepath.IsAbs(args[1]) {
 			dir = args[1]
@@ -895,6 +937,14 @@ var vcsPaths = []*vcsPath{
 		repo:   "https://{root}",
 	},
 
+	// chiselapp.com for fossil
+	{
+		prefix: "chiselapp.com",
+		re:     `^(?P<root>chiselapp\.com/user/[A-Za-z0-9]+/repository/[A-za-z0-9_.\-]+)$`,
+		vcs:    "fossil",
+		repo:   "https://{root}",
+	},
+
 	// General syntax for any server.
 	// Must be last.
 	{

src/cmd/go/internal/get/vcs_test.go

@@ -154,6 +154,22 @@ func TestRepoRootForImportPath(t *testing.T) {
 				repo: "https://git.apache.org/package-name_2.x.git",
 			},
 		},
+		{
+			"chiselapp.com/user/kyle/repository/fossilgg",
+			&repoRoot{
+				vcs:  vcsFossil,
+				repo: "https://chiselapp.com/user/kyle/repository/fossilgg",
+			},
+		},
+		{
+			// must have a user/$name/repository/$repo path
+			"chiselapp.com/kyle/repository/fossilgg",
+			nil,
+		},
+		{
+			"chiselapp.com/user/kyle/fossilgg",
+			nil,
+		},
 	}
 
 	for _, test := range tests {
@@ -241,6 +257,8 @@ func TestIsSecure(t *testing.T) {
 		{vcsGit, "example.com:path/to/repo.git", false},
 		{vcsGit, "path/that/contains/a:colon/repo.git", false},
 		{vcsHg, "ssh://user@example.com/path/to/repo.hg", true},
+		{vcsFossil, "http://example.com/foo", false},
+		{vcsFossil, "https://example.com/foo", true},
 	}
 
 	for _, test := range tests {