cmd/fscrypt: setup, encrypt, unlock commands

This commit adds in the framework for adding commands and subcommands to
the fscrypt tool. This commit adds in the "setup", "encrypt", and
"unlock" commands. Additional information can be found by running:
    fscrypt <command> --help.

This commit defines how flags are parsed and errors are handled. It also
creates an extensible framework for prompting the user for information.

Change-Id: I159d7f44ee2b2bbc5e072f0802850e082d9a13ce

1 files changed, 143 insertions, 0 deletions

diff --git a/cmd/fscrypt/strings.go b/cmd/fscrypt/strings.go
new file mode 100644
index 0000000..b77389f
--- /dev/null
+++ b/cmd/fscrypt/strings.go
@@ -0,0 +1,143 @@
+/*
+ * strings.go - File which contains the specific strings used for output and
+ * formatting in fscrypt.
+ *
+ * Copyright 2017 Google Inc.
+ * Author: Joe Richey (joerichey@google.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Global application strings
+const (
+	shortUsage = "A tool for managing Linux filesystem encryption"
+
+	apache2GoogleCopyright = `Copyright 2017 Google, Inc.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.`
+)
+
+// Argument usage strings
+const (
+	directoryArg    = "DIRECTORY"
+	mountpointArg   = "MOUNTPOINT"
+	pathArg         = "PATH"
+	archiveArg      = "ARCHIVE_FILE"
+	recoveryCodeArg = "RECOVERY_CODE"
+	mountpointIDArg = mountpointArg + ":ID"
+)
+
+// Text Templates which format our command line output (using text/template)
+var (
+	// indent is the prefix for the output lines in each section
+	indent = strings.Repeat(" ", indentLength)
+	// Top level help output: what is printed for "fscrypt" or "fscrypt --help"
+	appHelpTemplate = `{{.HelpName}} - {{.Usage}}
+
+Usage:
+` + indent + `{{.HelpName}} COMMAND [arguments] [options]
+
+Commands:{{range .VisibleCommands}}
+` + indent + `{{join .Names ", "}}{{"\t- "}}{{.Usage}}{{end}}
+{{if .Description}}
+Description:
+` + indent + `{{.Description}}
+{{end}}
+Options:
+{{range .VisibleFlags}}{{.}}
+
+{{end}}`
+
+	// Command help output, used when a command has no subcommands
+	commandHelpTemplate = `{{.HelpName}} - {{.Usage}}
+
+Usage:
+` + indent + `{{.HelpName}}{{if .ArgsUsage}} {{.ArgsUsage}}{{end}}{{if .VisibleFlags}} [options]{{end}}
+{{if .Description}}
+Description:
+` + indent + `{{.Description}}
+{{end}}{{if .VisibleFlags}}
+Options:
+{{range .VisibleFlags}}{{.}}
+
+{{end}}{{end}}`
+
+	// Subcommand help output, used when a command has subcommands
+	subcommandHelpTemplate = `{{.HelpName}} - {{.Usage}}
+
+Usage:
+` + indent + `{{.HelpName}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}SUBCOMMAND [arguments]{{end}}{{if .VisibleFlags}} [options]{{end}}
+
+Subcommands:{{range .VisibleCommands}}
+` + indent + `{{join .Names ", "}}{{"\t- "}}{{.Usage}}{{end}}
+{{if .Description}}
+Description:
+` + indent + `{{.Description}}
+{{end}}{{if .VisibleFlags}}
+Options:
+{{range .VisibleFlags}}{{.}}
+
+{{end}}{{end}}`
+
+	// Additional info, used with "fscrypt version"
+	versionInfoTemplate = `{{.HelpName}} - {{.Usage}}
+
+{{if .Version}}Version:
+` + indent + `{{.Version}}
+
+{{end}}{{if .Compiled}}Compiled:
+` + indent + `{{.Compiled}}
+
+{{end}}{{if len .Authors}}Author{{with $length := len .Authors}}{{if ne 1 $length}}s{{end}}{{end}}:{{range .Authors}}
+` + indent + `{{.}}{{end}}
+
+{{end}}{{if .Copyright}}Copyright:
+` + indent + `{{.Copyright}}
+
+{{end}}`
+)
+
+// Add words to this map to have pluralize support them.
+var plurals = map[string]string{
+	"argument":   "arguments",
+	"filesystem": "filesystems",
+	"protector":  "protectors",
+	"policy":     "policies",
+}
+
+// pluralize prints our the correct pluralization of a work along with the
+// specified count. This means pluralize(1, "policy") = "1 policy" but
+// pluralize(2, "policy") = "2 policies"
+func pluralize(count int, word string) string {
+	if count != 1 {
+		word = plurals[word]
+	}
+	return fmt.Sprintf("%d %s", count, word)
+}