vendor: add in external packages for use with CLI

crypto/ssh/terminal gets us information about the terminal, such as
its dimensions and state. It also allows us to manipulate the terminal.
For example, we can put the terminal in raw mode when a passphrase needs
to be entered.

This commit also add the github.com/urfave/cli package which we will use
to write the command line tool component of fscrypt. This tool allows
for us to easily use commands and subcommands.

Note that this is actually the upstream repository with two PRs applied:

https://github.com/urfave/cli/pull/629
https://github.com/urfave/cli/pull/630

They fix bugs in the handling of custom usage errors.

Change-Id: I2d3ba967b1bce8f73440e3a06df4eaba7ab96c19

1 files changed, 115 insertions, 0 deletions

diff --git a/vendor/github.com/urfave/cli/errors.go b/vendor/github.com/urfave/cli/errors.go
new file mode 100644
index 0000000..562b295
--- /dev/null
+++ b/vendor/github.com/urfave/cli/errors.go
@@ -0,0 +1,115 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+// OsExiter is the function used when the app exits. If not set defaults to os.Exit.
+var OsExiter = os.Exit
+
+// ErrWriter is used to write errors to the user. This can be anything
+// implementing the io.Writer interface and defaults to os.Stderr.
+var ErrWriter io.Writer = os.Stderr
+
+// MultiError is an error that wraps multiple errors.
+type MultiError struct {
+	Errors []error
+}
+
+// NewMultiError creates a new MultiError. Pass in one or more errors.
+func NewMultiError(err ...error) MultiError {
+	return MultiError{Errors: err}
+}
+
+// Error implements the error interface.
+func (m MultiError) Error() string {
+	errs := make([]string, len(m.Errors))
+	for i, err := range m.Errors {
+		errs[i] = err.Error()
+	}
+
+	return strings.Join(errs, "\n")
+}
+
+type ErrorFormatter interface {
+	Format(s fmt.State, verb rune)
+}
+
+// ExitCoder is the interface checked by `App` and `Command` for a custom exit
+// code
+type ExitCoder interface {
+	error
+	ExitCode() int
+}
+
+// ExitError fulfills both the builtin `error` interface and `ExitCoder`
+type ExitError struct {
+	exitCode int
+	message  interface{}
+}
+
+// NewExitError makes a new *ExitError
+func NewExitError(message interface{}, exitCode int) *ExitError {
+	return &ExitError{
+		exitCode: exitCode,
+		message:  message,
+	}
+}
+
+// Error returns the string message, fulfilling the interface required by
+// `error`
+func (ee *ExitError) Error() string {
+	return fmt.Sprintf("%v", ee.message)
+}
+
+// ExitCode returns the exit code, fulfilling the interface required by
+// `ExitCoder`
+func (ee *ExitError) ExitCode() int {
+	return ee.exitCode
+}
+
+// HandleExitCoder checks if the error fulfills the ExitCoder interface, and if
+// so prints the error to stderr (if it is non-empty) and calls OsExiter with the
+// given exit code.  If the given error is a MultiError, then this func is
+// called on all members of the Errors slice and calls OsExiter with the last exit code.
+func HandleExitCoder(err error) {
+	if err == nil {
+		return
+	}
+
+	if exitErr, ok := err.(ExitCoder); ok {
+		if err.Error() != "" {
+			if _, ok := exitErr.(ErrorFormatter); ok {
+				fmt.Fprintf(ErrWriter, "%+v\n", err)
+			} else {
+				fmt.Fprintln(ErrWriter, err)
+			}
+		}
+		OsExiter(exitErr.ExitCode())
+		return
+	}
+
+	if multiErr, ok := err.(MultiError); ok {
+		code := handleMultiError(multiErr)
+		OsExiter(code)
+		return
+	}
+}
+
+func handleMultiError(multiErr MultiError) int {
+	code := 1
+	for _, merr := range multiErr.Errors {
+		if multiErr2, ok := merr.(MultiError); ok {
+			code = handleMultiError(multiErr2)
+		} else {
+			fmt.Fprintln(ErrWriter, merr)
+			if exitErr, ok := merr.(ExitCoder); ok {
+				code = exitErr.ExitCode()
+			}
+		}
+	}
+	return code
+}