cmds

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 Go to latest Published: Jul 29, 2021 License: MIT Imports: 14 Imported by: 0

README

go-ipfs-cmds

standard-readme compliant

ipfs commands library

cmds offers tools for describing and calling commands both locally and remotely, as well as encoding, formatting and transferring the result. It is the successor of go-ipfs/commands and contains a legacy layer such that it can handle previously defined commands.

Lead Maintainer

Steven Allen

Documentation

https://godoc.org/github.com/ipfs/go-ipfs-cmds

Contribute

Feel free to join in. All welcome. Open an issue!

This repository falls under the IPFS Code of Conduct.

Want to hack on IPFS?

License

MIT

Documentation

Overview

Package cmds helps building both standalone and client-server applications.

Semantics

The basic building blocks are requests, commands, emitters and responses. A command consists of a description of the parameters and a function. The function is passed the request as well as an emitter as arguments. It does operations on the inputs and sends the results to the user by emitting them.

There are a number of emitters in this package and subpackages, but the user is free to create their own.

Commands

A command is a struct containing the commands help text, a description of the arguments and options, the command's processing function and a type to let the caller know what type will be emitted. Optionally one of the functions PostRun and Encoder may be defined that consumes the function's emitted values and generates a visual representation for e.g. the terminal. Encoders work on a value-by-value basis, while PostRun operates on the value stream.

Emitters

An emitter has the Emit method, that takes the command's function's output as an argument and passes it to the user. 

type ResponseEmitter interface {
	Close() error
	CloseWithError(error) error
	SetLength(length uint64)
	Emit(value interface{}) error
}

The command's function does not know what kind of emitter it works with, so the same function may run locally or on a server, using an rpc interface. Emitters can also send errors using the SetError method.

The user-facing emitter usually is the cli emitter. Values emitter here will be printed to the terminal using either the Encoders or the PostRun function.

Responses

A response is a value that the user can read emitted values from. 

type Response interface {
	Request() Request
	Error() *Error
	Length() uint64
	Next() (interface{}, error)
}

Responses have a method Next() that returns the next emitted value and an error value. If the last element has been received, the returned error value is io.EOF. If the application code has sent an error using SetError, the error ErrRcvdError is returned on next, indicating that the caller should call Error(). Depending on the reponse type, other errors may also occur.

Pipes

Pipes are pairs (emitter, response), such that a value emitted on the emitter can be received in the response value. Most builtin emitters are "pipe" emitters. The most prominent examples are the channel pipe and the http pipe.

The channel pipe is backed by a channel. The only error value returned by the response is io.EOF, which happens when the channel is closed.

The http pipe is backed by an http connection. The response can also return other errors, e.g. if there are errors on the network.

Examples

To get a better idea of what's going on, take a look at the examples at https://github.com/ipfs/go-ipfs-cmds/tree/master/examples.

Index

Constants

View Source 
const (
	// General purpose
	Undefined = ""

	// EncodingTypes
	JSON        = "json"
	XML         = "xml"
	Protobuf    = "protobuf"
	Text        = "text"
	TextNewline = "textnl"

	// PostRunTypes
	CLI = "cli"
)

Supported EncodingType constants.

View Source 
const (
	Invalid = reflect.Invalid
	Bool    = reflect.Bool
	Int     = reflect.Int
	Uint    = reflect.Uint
	Int64   = reflect.Int64
	Uint64  = reflect.Uint64
	Float   = reflect.Float64
	String  = reflect.String
	Strings = reflect.Array
)

Types of Command options

View Source 
const (
	EncShort     = "enc"
	EncLong      = "encoding"
	RecShort     = "r"
	RecLong      = "recursive"
	ChanOpt      = "stream-channels"
	TimeoutOpt   = "timeout"
	OptShortHelp = "h"
	OptLongHelp  = "help"
	DerefLong    = "dereference-args"
	StdinName    = "stdin-name"
	Hidden       = "hidden"
	HiddenShort  = "H"
	Ignore       = "ignore"
	IgnoreRules  = "ignore-rules-path"
)

Flag names

View Source 
const DefaultOutputEncoding = JSON

DefaultOutputEncoding defines the default API output encoding.

Variables

View Source 
var (
	// ErrNotCallable signals a command that cannot be called.
	ErrNotCallable = ClientError("this command cannot be called directly; try one of its subcommands.")

	// ErrNoFormatter signals that the command can not be formatted.
	ErrNoFormatter = ClientError("this command cannot be formatted to plain text")

	// ErrIncorrectType signales that the commands returned a value with unexpected type.
	ErrIncorrectType = errors.New("the command returned a value with a different type than expected")
)
View Source 
var (
	ErrClosedEmitter        = errors.New("cmds: emit on closed emitter")
	ErrClosingClosedEmitter = errors.New("cmds: closing closed emitter")
)
View Source 
var Decoders = map[EncodingType]func(w io.Reader) Decoder{
	XML: func(r io.Reader) Decoder {
		return xml.NewDecoder(r)
	},
	JSON: func(r io.Reader) Decoder {
		return json.NewDecoder(r)
	},
}
View Source 
var Encoders = EncoderMap{
	XML: func(req *Request) func(io.Writer) Encoder {
		return func(w io.Writer) Encoder { return xml.NewEncoder(w) }
	},
	JSON: func(req *Request) func(io.Writer) Encoder {
		return func(w io.Writer) Encoder { return json.NewEncoder(w) }
	},
	Text: func(req *Request) func(io.Writer) Encoder {
		return func(w io.Writer) Encoder { return TextEncoder{w: w} }
	},
	TextNewline: func(req *Request) func(io.Writer) Encoder {
		return func(w io.Writer) Encoder { return TextEncoder{w: w, suffix: "\n"} }
	},
}
View Source 
var OptionDerefArgs = BoolOption(DerefLong, "Symlinks supplied in arguments are dereferenced")
View Source 
var OptionEncodingType = StringOption(EncLong, EncShort, "The encoding type the output should be encoded with (json, xml, or text)").WithDefault("text")

options that are used by this package

View Source 
var OptionHidden = BoolOption(Hidden, HiddenShort, "Include files that are hidden. Only takes effect on recursive add.")
View Source 
var OptionIgnore = StringsOption(Ignore, "A rule (.gitignore-stype) defining which file(s) should be ignored (variadic, experimental)")
View Source 
var OptionIgnoreRules = StringOption(IgnoreRules, "A path to a file with .gitignore-style ignore rules (experimental)")
View Source 
var OptionRecursivePath = BoolOption(RecLong, RecShort, "Add directory paths recursively")
View Source 
var OptionStdinName = StringOption(StdinName, "Assign a name if the file source is stdin.")
View Source 
var OptionStreamChannels = BoolOption(ChanOpt, "Stream channel output")
View Source 
var OptionTimeout = StringOption(TimeoutOpt, "Set a global timeout on the command")

Functions

func ClientError 

func ClientError(msg string) error

func Copy 

func Copy(re ResponseEmitter, res Response) error

Copy sends all values received on res to re. If res is closed, it closes re.

func EmitChan 

func EmitChan(re ResponseEmitter, ch <-chan interface{}) error

func EmitOnce 

func EmitOnce(re ResponseEmitter, v interface{}) error

EmitOnce is a helper that emits a value wrapped in Single, to signal that this will be the only value sent.

func GetEncoder 

func GetEncoder(req *Request, w io.Writer, def EncodingType) (encType EncodingType, enc Encoder, err error)

GetEncoder takes a request and returns returns the encoding type and the encoder.

func MakeEncoder 

func MakeEncoder(f func(*Request, io.Writer, interface{}) error) func(*Request) func(io.Writer) Encoder

func MakeTypedEncoder 

func MakeTypedEncoder(f interface{}) func(*Request) func(io.Writer) Encoder

func NewChanResponsePair 

func NewChanResponsePair(req *Request) (ResponseEmitter, Response)

Types

type Argument 

type Argument struct {
	Name          string
	Type          ArgumentType
	Required      bool // error if no value is specified
	Variadic      bool // unlimited values can be specfied
	SupportsStdin bool // can accept stdin as a value
	Recursive     bool // supports recursive file adding (with '-r' flag)
	Description   string
}

func FileArg 

func FileArg(name string, required, variadic bool, description string) Argument

func StringArg 

func StringArg(name string, required, variadic bool, description string) Argument

func (Argument) EnableRecursive 

func (a Argument) EnableRecursive() Argument

func (Argument) EnableStdin 

func (a Argument) EnableStdin() Argument

type ArgumentType 

type ArgumentType int
const (
	ArgString ArgumentType = iota
	ArgFile
)

type Command 

type Command struct {
	// Options defines the flags accepted by the command. Flags on specified
	// on parent commands are inherited by sub commands.
	Options []Option

	// Arguments defines the positional arguments for the command. These
	// arguments can be strings and/or files.
	//
	// The rules for valid arguments are as follows:
	//
	// 1. No required arguments may follow optional arguments.
	// 2. There can be at most one STDIN argument.
	// 3. There can be at most one variadic argument, and it must be last.
	Arguments []Argument

	// PreRun is run before Run. When executing a command on a remote
	// daemon, PreRun is always run in the local process.
	PreRun func(req *Request, env Environment) error

	// Run is the function that processes the request to generate a response.
	// Note that when executing the command over the HTTP API you can only read
	// after writing when using multipart requests. The request body will not be
	// available for reading after the HTTP connection has been written to.
	Run Function

	// PostRun is run after Run, and can transform results returned by run.
	// When executing a command on a remote daemon, PostRun is always run in
	// the local process.
	PostRun PostRunMap

	// Encoders encode results from Run (and/or PostRun) in the desired
	// encoding.
	Encoders EncoderMap

	// Helptext is the command's help text.
	Helptext HelpText

	// External denotes that a command is actually an external binary.
	// fewer checks and validations will be performed on such commands.
	External bool

	// Type describes the type of the output of the Command's Run Function.
	// In precise terms, the value of Type is an instance of the return type of
	// the Run Function.
	//
	// ie. If command Run returns &Block{}, then Command.Type == &Block{}
	Type interface{}

	// Subcommands allow attaching sub commands to a command.
	//
	// Note: A command can specify both a Run function and Subcommands. If
	// invoked with no arguments, or an argument that matches no
	// sub commands, the Run function of the current command will be invoked.
	//
	// Take care when specifying both a Run function and Subcommands. A
	// simple typo in a sub command will invoke the parent command and may
	// end up returning a cryptic error to the user.
	Subcommands map[string]*Command

	// NoRemote denotes that a command cannot be executed in a remote environment
	NoRemote bool

	// NoLocal denotes that a command cannot be executed in a local environment
	NoLocal bool

	// Extra contains a set of other command-specific parameters
	Extra *Extra
}

Command is a runnable command, with input arguments and options (flags). It can also have Subcommands, to group units of work into sets.

func (*Command) Call 

func (c *Command) Call(req *Request, re ResponseEmitter, env Environment)

Call invokes the command for the given Request

func (*Command) CheckArguments 

func (c *Command) CheckArguments(req *Request) error

CheckArguments checks that we have all the required string arguments, loading any from stdin if necessary.

func (*Command) DebugValidate 

func (c *Command) DebugValidate() map[string][]error

DebugValidate checks if the command tree is well-formed.

This operation is slow and should be called from tests only.

func (*Command) Get 

func (c *Command) Get(path []string) (*Command, error)

Get resolves and returns the Command addressed by path

func (*Command) GetOptions 

func (c *Command) GetOptions(path []string) (map[string]Option, error)

GetOptions returns the options in the given path of commands

func (*Command) ProcessHelp 

func (c *Command) ProcessHelp()

func (*Command) Resolve 

func (c *Command) Resolve(pth []string) ([]*Command, error)

Resolve returns the subcommands at the given path The returned set of subcommands starts with this command and therefore is always at least size 1

func (*Command) Walk 

func (c *Command) Walk(visitor CommandVisitor)

Walks tree of all subcommands (including this one)

type CommandVisitor 

type CommandVisitor func(*Command)

type Decoder 

type Decoder interface {
	Decode(value interface{}) error
}

Decoder decodes values into value (which should be a pointer).

type Encoder 

type Encoder interface {
	Encode(value interface{}) error
}

Encoder encodes values onto e.g. an io.Writer. Examples are json.Encoder and xml.Encoder.

type EncoderFunc 

type EncoderFunc func(req *Request) func(w io.Writer) Encoder

type EncoderMap 

type EncoderMap map[EncodingType]EncoderFunc

type EncodingType 

type EncodingType string

EncodingType defines a supported encoding

func GetEncoding 

func GetEncoding(req *Request, def EncodingType) EncodingType

GetEncoding returns the EncodingType set in a request, falling back to JSON

type Environment 

type Environment interface{}

Environment is the environment passed to commands.

type Error 

type Error struct {
	Message string
	Code    ErrorType
}

Error is a struct for marshalling errors

func Errorf 

func Errorf(code ErrorType, format string, args ...interface{}) Error

Errorf returns an Error with the given code and format specification

func (Error) Error 

func (e Error) Error() string

func (Error) MarshalJSON 

func (e Error) MarshalJSON() ([]byte, error)

func (*Error) UnmarshalJSON 

func (e *Error) UnmarshalJSON(data []byte) error

func (Error) Unwrap 

func (e Error) Unwrap() error

Unwrap returns the base error (an ErrorType). Works with go 1.13 error helpers.

type ErrorType 

type ErrorType uint

ErrorType signfies a category of errors 

const (
	// ErrNormal is a normal error. The command failed for some reason that's not a bug.
	ErrNormal ErrorType = iota
	// ErrClient means the client made an invalid request.
	ErrClient
	// ErrImplementation means there's a bug in the implementation.
	ErrImplementation
	// ErrRateLimited is returned when the operation has been rate-limited.
	ErrRateLimited
	// ErrForbidden is returned when the client doesn't have permission to
	// perform the requested operation.
	ErrForbidden
)

ErrorTypes convey what category of error ocurred

func (ErrorType) Error 

func (e ErrorType) Error() string

func (ErrorType) String 

func (e ErrorType) String() string

type Executor 

type Executor interface {
	Execute(req *Request, re ResponseEmitter, env Environment) error
}

func NewExecutor 

func NewExecutor(root *Command) Executor

type Extra 

type Extra struct {
	// contains filtered or unexported fields
}

Extra is a set of tag information for a command

func (*Extra) GetValue 

func (e *Extra) GetValue(key interface{}) (interface{}, bool)

func (*Extra) SetValue 

func (e *Extra) SetValue(key, value interface{}) *Extra

type Flusher 

type Flusher interface {
	Flush() error
}

type Function 

type Function func(*Request, ResponseEmitter, Environment) error

Function is the type of function that Commands use. It reads from the Request, and writes results to the ResponseEmitter.

type HelpText 

type HelpText struct {
	// required
	Tagline               string            // used in <cmd usage>
	ShortDescription      string            // used in DESCRIPTION
	SynopsisOptionsValues map[string]string // mappings for synopsis generator

	// optional - whole section overrides
	Usage           string // overrides USAGE section
	LongDescription string // overrides DESCRIPTION section
	Options         string // overrides OPTIONS section
	Arguments       string // overrides ARGUMENTS section
	Subcommands     string // overrides SUBCOMMANDS section
	Synopsis        string // overrides SYNOPSIS field
}

HelpText is a set of strings used to generate command help text. The help text follows formats similar to man pages, but not exactly the same.

type MakeEnvironment 

type MakeEnvironment func(context.Context, *Request) (Environment, error)

MakeEnvironment takes a context and the request to construct the environment that is passed to the command's Run function. The user can define a function like this to pass it to cli.Run.

type MakeExecutor 

type MakeExecutor func(*Request, interface{}) (Executor, error)

MakeExecutor takes the request and environment variable to construct the executor that determines how to call the command - i.e. by calling Run or making an API request to a daemon. The user can define a function like this to pass it to cli.Run.

type MaybeError 

type MaybeError struct {
	Value interface{} // needs to be a pointer
	Error *Error
	// contains filtered or unexported fields
}

func (*MaybeError) Get 

func (m *MaybeError) Get() (interface{}, error)

func (*MaybeError) UnmarshalJSON 

func (m *MaybeError) UnmarshalJSON(data []byte) error

type OptMap 

type OptMap map[string]interface{}

type Option 

type Option interface {
	Name() string    // the main name of the option
	Names() []string // a list of unique names matched with user-provided flags

	Type() reflect.Kind  // value must be this type
	Description() string // a short string that describes this option

	WithDefault(interface{}) Option // sets the default value of the option
	Default() interface{}

	Parse(str string) (interface{}, error)
}

Option is used to specify a field that will be provided by a consumer

func BoolOption 

func BoolOption(names ...string) Option

func DelimitedStringsOption 

func DelimitedStringsOption(delimiter string, names ...string) Option

DelimitedStringsOption like StringsOption is a command option that can handle a slice of strings. However, DelimitedStringsOption will automatically break up the associated CLI inputs based on the delimiter. For example, instead of passing `command --option=val1 --option=val2` you can pass `command --option=val1,val2` or even `command --option=val1,val2 --option=val3,val4`.

A delimiter of "" is invalid

func FloatOption 

func FloatOption(names ...string) Option

func Int64Option 

func Int64Option(names ...string) Option

func IntOption 

func IntOption(names ...string) Option

func NewOption 

func NewOption(kind reflect.Kind, names ...string) Option

constructor helper functions

func StringOption 

func StringOption(names ...string) Option

func StringsOption 

func StringsOption(names ...string) Option

StringsOption is a command option that can handle a slice of strings

func Uint64Option 

func Uint64Option(names ...string) Option

func UintOption 

func UintOption(names ...string) Option

type PostRunMap 

type PostRunMap map[PostRunType]func(Response, ResponseEmitter) error

PostRunMap is the map used in Command.PostRun.

type PostRunType 

type PostRunType string

PostRunType defines which PostRunFunc should be used

type ReqLog 

type ReqLog struct {
	Requests []*ReqLogEntry
	// contains filtered or unexported fields
}

ReqLog represents a request log.

func (*ReqLog) Add 

func (rl *ReqLog) Add(req *Request) *ReqLogEntry

Add ads an entry to the log for the given request.

func (*ReqLog) AddEntry 

func (rl *ReqLog) AddEntry(rle *ReqLogEntry)

AddEntry adds an entry to the log.

func (*ReqLog) ClearInactive 

func (rl *ReqLog) ClearInactive()

ClearInactive clears any inactive requests from the log.

func (*ReqLog) Finish 

func (rl *ReqLog) Finish(rle *ReqLogEntry)

func (*ReqLog) Report 

func (rl *ReqLog) Report() []*ReqLogEntry

Report generates a copy of all the entries in the requestlog

func (*ReqLog) SetKeepTime 

func (rl *ReqLog) SetKeepTime(t time.Duration)

type ReqLogEntry 

type ReqLogEntry struct {
	StartTime time.Time
	EndTime   time.Time
	Active    bool
	Command   string
	Options   map[string]interface{}
	Args      []string
	ID        int
}

ReqLogEntry represent a log entry for a request.

func (*ReqLogEntry) Copy 

func (r *ReqLogEntry) Copy() *ReqLogEntry

Copy copies a log entry and returns a pointer to the copy.

type Request 

type Request struct {
	Context       context.Context
	Root, Command *Command

	Path      []string
	Arguments []string
	Options   OptMap

	Files files.Directory
	// contains filtered or unexported fields
}

Request represents a call to a command from a consumer

func NewRequest 

func NewRequest(ctx context.Context,
	path []string,
	opts OptMap,
	args []string,
	file files.Directory,
	root *Command,
) (*Request, error)

NewRequest returns a request initialized with given arguments An non-nil error will be returned if the provided option values are invalid

func (*Request) BodyArgs 

func (req *Request) BodyArgs() StdinArguments

BodyArgs returns a scanner that returns arguments passed in the body as tokens.

Returns nil if there are no arguments to be consumed via stdin.

func (*Request) FillDefaults 

func (req *Request) FillDefaults() error

FillDefaults fills in default values if option has not been set.

func (*Request) ParseBodyArgs 

func (req *Request) ParseBodyArgs() error

ParseBodyArgs parses arguments in the request body.

func (*Request) SetOption 

func (req *Request) SetOption(name string, value interface{})

SetOption sets a request option.

type Response 

type Response interface {
	Request() *Request

	Error() *Error
	Length() uint64

	// Next returns the next emitted value.
	// The returned error can be a network or decoding error.
	Next() (interface{}, error)
}

Response is the result of a command request. Response is returned to the client.

func NewReaderResponse 

func NewReaderResponse(r io.Reader, req *Request) (Response, error)

NewReaderResponse creates a Response from the given reader.

type ResponseEmitter 

type ResponseEmitter interface {
	// Close closes the underlying transport.
	Close() error

	// CloseWithError closes the underlying transport and makes subsequent read
	// calls return the passed error.
	CloseWithError(error) error

	// SetLength sets the length of the output
	// err is an interface{} so we don't have to manually convert to error.
	SetLength(length uint64)

	// Emit sends a value.
	// If value is io.Reader we just copy that to the connection
	// other values are marshalled.
	Emit(value interface{}) error
}

ResponseEmitter encodes and sends the command code's output to the client. It is all a command can write to.

func NewFlushForwarder 

func NewFlushForwarder(re ResponseEmitter, f Flusher) ResponseEmitter

func NewWriterResponseEmitter 

func NewWriterResponseEmitter(w io.WriteCloser, req *Request) (ResponseEmitter, error)

NewWriterResponseEmitter creates a response emitter that sends responses to the given WriterCloser.

type Single 

type Single struct {
	Value interface{}
}

Single can be used to signal to any ResponseEmitter that only one value will be emitted. This is important e.g. for the http.ResponseEmitter so it can set the HTTP headers appropriately.

func (Single) GoString 

func (s Single) GoString() string

func (Single) String 

func (s Single) String() string

type StdinArguments 

type StdinArguments interface {
	io.ReadCloser

	// Scan reads in the next argument and returns true if there is an
	// argument to read.
	Scan() bool

	// Argument returns the next argument.
	Argument() string

	// Err returns any errors encountered when reading in arguments.
	Err() error
}

StdinArguments is used to iterate through arguments piped through stdin.

It closely mimics the bufio.Scanner interface but also implements the ReadCloser interface.

type TextEncoder 

type TextEncoder struct {
	// contains filtered or unexported fields
}

func (TextEncoder) Encode 

func (e TextEncoder) Encode(v interface{}) error

Source Files

View all Source files

Directories

Path Synopsis
examples
adder
adder/local
adder/remote/client
adder/remote/server

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