Fixes

1 files changed, 201 insertions, 0 deletions

diff --git a/cmd/output.go b/cmd/output.go
new file mode 100644
index 0000000..024705d
--- /dev/null
+++ b/cmd/output.go
@@ -0,0 +1,201 @@
+/*
+ * output.go - Functions for handling command line formatting and output.
+ *
+ * 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 cmd
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/google/fscrypt/util"
+	"golang.org/x/crypto/ssh/terminal"
+)
+
+var (
+	// TabWidth is the number of spaces used to display a tab.
+	TabWidth = 8
+	// LineLength is the maximum length of any output. If not set, the width
+	// of the terminal be detected and assigned to LineLength.
+	LineLength int
+	// FallbackLineLength is the LineLength used if detection fails. By
+	// default we fall back to punch cards.
+	FallbackLineLength = 80
+	// MaxLineLength is the maximum allowed detected value of LineLength.
+	MaxLineLength = 120
+	// Output is the io.Writer all commands should use for their normal
+	// output (errors should just return the appropriate error). If not set,
+	// it is automatically set based on the provided flags.
+	Output io.Writer
+	// HelpFlag writes help to Stdout
+	HelpFlag = &BoolFlag{
+		Name:  "help",
+		Usage: "Prints this 🧗help text for commands and subcommands",
+	}
+	// VerboseFlag indicates that all logging output should be printed.
+	VerboseFlag = &BoolFlag{
+		Name:  "verbose",
+		Usage: "Prints additional debug messages.",
+	}
+	// QuietFlag indicates that no normal output should be printed.
+	QuietFlag = &BoolFlag{
+		Name: "quiet",
+		Usage: `Prints nothing except for errors and uses any default
+		option instead of prompting the user.`,
+	}
+	// ForceFlag indicates that the operation should proceed if possible.
+	ForceFlag = &BoolFlag{
+		Name: "force",
+		Usage: `Print no confirmation prompts or warnings and
+		automatically proceed with the requested action.`,
+	}
+)
+
+// Suffixes for questions with a yes or no default
+const (
+	defaultYesSuffix = "[Y/n]"
+	defaultNoSuffix  = "[y/N]"
+)
+
+// We use the width of the terminal unless we cannot get the width.
+func init() {
+	if LineLength > 0 {
+		return
+	}
+	width, _, err := terminal.GetSize(int(os.Stdout.Fd()))
+	if err != nil {
+		LineLength = FallbackLineLength
+	} else {
+		LineLength = util.MinInt(width, MaxLineLength)
+	}
+}
+
+// Takes an input string text, and wraps the text so that each line begins with
+// numTabs tabs and ends with a newline (except the last line), and each line
+// has length less than lineLength. If the text contains a word which is too
+// long, that word gets its own line.
+func wrapText(text string, numTabs int) string {
+	// We use a buffer to format the wrapped text so we get O(n) runtime
+	var buffer bytes.Buffer
+	spaceLeft := 0
+	maxTextLen := LineLength - numTabs*TabWidth
+	delimiter := strings.Repeat("\t", numTabs)
+	for i, word := range strings.Fields(text) {
+		wordLen := utf8.RuneCountInString(word)
+		if wordLen >= spaceLeft {
+			// If no room left, write the word on the next line.
+			buffer.WriteString("\n")
+			buffer.WriteString(delimiter)
+			buffer.WriteString(word)
+			spaceLeft = maxTextLen - wordLen
+		} else {
+			// Write word on this line
+			buffer.WriteByte(' ')
+			buffer.WriteString(word)
+			spaceLeft -= 1 + wordLen
+		}
+	}
+
+	return buffer.String()
+}
+
+// Configures the Output and log output io.Writers. Called before running
+// commands but after processing flags.
+func setupOutput() {
+	if VerboseFlag.Value {
+		log.SetOutput(os.Stdout)
+	} else {
+		log.SetOutput(ioutil.Discard)
+	}
+	if Output != nil {
+		return
+	}
+	if QuietFlag.Value {
+		Output = ioutil.Discard
+	} else {
+		Output = os.Stdout
+	}
+}
+
+// AskQuestion asks the user a yes or no question. Returning a boolean on a
+// successful answer and an error if there was not a response from the user.
+// Returns the defaultChoice on empty input (or in quiet mode).
+func AskQuestion(question string, defaultChoice bool) (bool, error) {
+	// If in quiet mode, we just use the default.
+	if QuietFlag.Value {
+		return defaultChoice, nil
+	}
+	// Loop until failure or valid input.
+	for {
+		if defaultChoice {
+			fmt.Fprintf(Output, "%s %s ", question, defaultYesSuffix)
+		} else {
+			fmt.Fprintf(Output, "%s %s ", question, defaultNoSuffix)
+		}
+
+		input, err := util.ReadLine()
+		if err != nil {
+			return false, err
+		}
+
+		switch strings.ToLower(input) {
+		case "y", "yes":
+			return true, nil
+		case "n", "no":
+			return false, nil
+		case "":
+			return defaultChoice, nil
+		}
+	}
+}
+
+// AskConfirmation asks the user for confirmation before performing a specific
+// action. An error is returned if the user declines or IO fails.
+func AskConfirmation(question, warning string, defaultChoice bool) error {
+	// All confirmations are "yes" if we are forcing.
+	if ForceFlag.Value {
+		return nil
+	}
+
+	// Defaults of "no" require forcing.
+	if QuietFlag.Value {
+		if defaultChoice {
+			return nil
+		}
+		return ErrMustForce
+	}
+
+	if warning != "" {
+		fmt.Fprintln(Output, wrapText("WARNING: "+warning, 0))
+	}
+
+	confirmed, err := AskQuestion(question, defaultChoice)
+	if err != nil {
+		return err
+	}
+	if !confirmed {
+		return ErrCanceled
+	}
+	return nil
+}