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, 276 insertions, 0 deletions

diff --git a/vendor/github.com/urfave/cli/context.go b/vendor/github.com/urfave/cli/context.go
new file mode 100644
index 0000000..cb89e92
--- /dev/null
+++ b/vendor/github.com/urfave/cli/context.go
@@ -0,0 +1,276 @@
+package cli
+
+import (
+	"errors"
+	"flag"
+	"reflect"
+	"strings"
+	"syscall"
+)
+
+// Context is a type that is passed through to
+// each Handler action in a cli application. Context
+// can be used to retrieve context-specific Args and
+// parsed command-line options.
+type Context struct {
+	App           *App
+	Command       Command
+	shellComplete bool
+	flagSet       *flag.FlagSet
+	setFlags      map[string]bool
+	parentContext *Context
+}
+
+// NewContext creates a new context. For use in when invoking an App or Command action.
+func NewContext(app *App, set *flag.FlagSet, parentCtx *Context) *Context {
+	c := &Context{App: app, flagSet: set, parentContext: parentCtx}
+
+	if parentCtx != nil {
+		c.shellComplete = parentCtx.shellComplete
+	}
+
+	return c
+}
+
+// NumFlags returns the number of flags set
+func (c *Context) NumFlags() int {
+	return c.flagSet.NFlag()
+}
+
+// Set sets a context flag to a value.
+func (c *Context) Set(name, value string) error {
+	return c.flagSet.Set(name, value)
+}
+
+// GlobalSet sets a context flag to a value on the global flagset
+func (c *Context) GlobalSet(name, value string) error {
+	return globalContext(c).flagSet.Set(name, value)
+}
+
+// IsSet determines if the flag was actually set
+func (c *Context) IsSet(name string) bool {
+	if c.setFlags == nil {
+		c.setFlags = make(map[string]bool)
+
+		c.flagSet.Visit(func(f *flag.Flag) {
+			c.setFlags[f.Name] = true
+		})
+
+		c.flagSet.VisitAll(func(f *flag.Flag) {
+			if _, ok := c.setFlags[f.Name]; ok {
+				return
+			}
+			c.setFlags[f.Name] = false
+		})
+
+		// XXX hack to support IsSet for flags with EnvVar
+		//
+		// There isn't an easy way to do this with the current implementation since
+		// whether a flag was set via an environment variable is very difficult to
+		// determine here. Instead, we intend to introduce a backwards incompatible
+		// change in version 2 to add `IsSet` to the Flag interface to push the
+		// responsibility closer to where the information required to determine
+		// whether a flag is set by non-standard means such as environment
+		// variables is avaliable.
+		//
+		// See https://github.com/urfave/cli/issues/294 for additional discussion
+		flags := c.Command.Flags
+		if c.Command.Name == "" { // cannot == Command{} since it contains slice types
+			if c.App != nil {
+				flags = c.App.Flags
+			}
+		}
+		for _, f := range flags {
+			eachName(f.GetName(), func(name string) {
+				if isSet, ok := c.setFlags[name]; isSet || !ok {
+					return
+				}
+
+				val := reflect.ValueOf(f)
+				if val.Kind() == reflect.Ptr {
+					val = val.Elem()
+				}
+
+				envVarValue := val.FieldByName("EnvVar")
+				if !envVarValue.IsValid() {
+					return
+				}
+
+				eachName(envVarValue.String(), func(envVar string) {
+					envVar = strings.TrimSpace(envVar)
+					if _, ok := syscall.Getenv(envVar); ok {
+						c.setFlags[name] = true
+						return
+					}
+				})
+			})
+		}
+	}
+
+	return c.setFlags[name]
+}
+
+// GlobalIsSet determines if the global flag was actually set
+func (c *Context) GlobalIsSet(name string) bool {
+	ctx := c
+	if ctx.parentContext != nil {
+		ctx = ctx.parentContext
+	}
+
+	for ; ctx != nil; ctx = ctx.parentContext {
+		if ctx.IsSet(name) {
+			return true
+		}
+	}
+	return false
+}
+
+// FlagNames returns a slice of flag names used in this context.
+func (c *Context) FlagNames() (names []string) {
+	for _, flag := range c.Command.Flags {
+		name := strings.Split(flag.GetName(), ",")[0]
+		if name == "help" {
+			continue
+		}
+		names = append(names, name)
+	}
+	return
+}
+
+// GlobalFlagNames returns a slice of global flag names used by the app.
+func (c *Context) GlobalFlagNames() (names []string) {
+	for _, flag := range c.App.Flags {
+		name := strings.Split(flag.GetName(), ",")[0]
+		if name == "help" || name == "version" {
+			continue
+		}
+		names = append(names, name)
+	}
+	return
+}
+
+// Parent returns the parent context, if any
+func (c *Context) Parent() *Context {
+	return c.parentContext
+}
+
+// value returns the value of the flag coressponding to `name`
+func (c *Context) value(name string) interface{} {
+	return c.flagSet.Lookup(name).Value.(flag.Getter).Get()
+}
+
+// Args contains apps console arguments
+type Args []string
+
+// Args returns the command line arguments associated with the context.
+func (c *Context) Args() Args {
+	args := Args(c.flagSet.Args())
+	return args
+}
+
+// NArg returns the number of the command line arguments.
+func (c *Context) NArg() int {
+	return len(c.Args())
+}
+
+// Get returns the nth argument, or else a blank string
+func (a Args) Get(n int) string {
+	if len(a) > n {
+		return a[n]
+	}
+	return ""
+}
+
+// First returns the first argument, or else a blank string
+func (a Args) First() string {
+	return a.Get(0)
+}
+
+// Tail returns the rest of the arguments (not the first one)
+// or else an empty string slice
+func (a Args) Tail() []string {
+	if len(a) >= 2 {
+		return []string(a)[1:]
+	}
+	return []string{}
+}
+
+// Present checks if there are any arguments present
+func (a Args) Present() bool {
+	return len(a) != 0
+}
+
+// Swap swaps arguments at the given indexes
+func (a Args) Swap(from, to int) error {
+	if from >= len(a) || to >= len(a) {
+		return errors.New("index out of range")
+	}
+	a[from], a[to] = a[to], a[from]
+	return nil
+}
+
+func globalContext(ctx *Context) *Context {
+	if ctx == nil {
+		return nil
+	}
+
+	for {
+		if ctx.parentContext == nil {
+			return ctx
+		}
+		ctx = ctx.parentContext
+	}
+}
+
+func lookupGlobalFlagSet(name string, ctx *Context) *flag.FlagSet {
+	if ctx.parentContext != nil {
+		ctx = ctx.parentContext
+	}
+	for ; ctx != nil; ctx = ctx.parentContext {
+		if f := ctx.flagSet.Lookup(name); f != nil {
+			return ctx.flagSet
+		}
+	}
+	return nil
+}
+
+func copyFlag(name string, ff *flag.Flag, set *flag.FlagSet) {
+	switch ff.Value.(type) {
+	case *StringSlice:
+	default:
+		set.Set(name, ff.Value.String())
+	}
+}
+
+func normalizeFlags(flags []Flag, set *flag.FlagSet) error {
+	visited := make(map[string]bool)
+	set.Visit(func(f *flag.Flag) {
+		visited[f.Name] = true
+	})
+	for _, f := range flags {
+		parts := strings.Split(f.GetName(), ",")
+		if len(parts) == 1 {
+			continue
+		}
+		var ff *flag.Flag
+		for _, name := range parts {
+			name = strings.Trim(name, " ")
+			if visited[name] {
+				if ff != nil {
+					return errors.New("Cannot use two forms of the same flag: " + name + " " + ff.Name)
+				}
+				ff = set.Lookup(name)
+			}
+		}
+		if ff == nil {
+			continue
+		}
+		for _, name := range parts {
+			name = strings.Trim(name, " ")
+			if !visited[name] {
+				copyFlag(name, ff, set)
+			}
+		}
+	}
+	return nil
+}