/usr/share/gocode/src/github.com/hashicorp/go-plugin/client.go is in golang-github-hashicorp-go-plugin-dev 0.0~git20160212.0.cccb4a1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"bufio"
"errors"
"fmt"
"io"
"io/ioutil"
"log"
"net"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"unicode"
)
// If this is 1, then we've called CleanupClients. This can be used
// by plugin RPC implementations to change error behavior since you
// can expected network connection errors at this point. This should be
// read by using sync/atomic.
var Killed uint32 = 0
// This is a slice of the "managed" clients which are cleaned up when
// calling Cleanup
var managedClients = make([]*Client, 0, 5)
// Error types
var (
// ErrProcessNotFound is returned when a client is instantiated to
// reattach to an existing process and it isn't found.
ErrProcessNotFound = errors.New("Reattachment process not found")
)
// Client handles the lifecycle of a plugin application. It launches
// plugins, connects to them, dispenses interface implementations, and handles
// killing the process.
//
// Plugin hosts should use one Client for each plugin executable. To
// dispense a plugin type, use the `Client.Client` function, and then
// cal `Dispense`. This awkward API is mostly historical but is used to split
// the client that deals with subprocess management and the client that
// does RPC management.
//
// See NewClient and ClientConfig for using a Client.
type Client struct {
config *ClientConfig
exited bool
doneLogging chan struct{}
l sync.Mutex
address net.Addr
process *os.Process
client *RPCClient
}
// ClientConfig is the configuration used to initialize a new
// plugin client. After being used to initialize a plugin client,
// that configuration must not be modified again.
type ClientConfig struct {
// HandshakeConfig is the configuration that must match servers.
HandshakeConfig
// Plugins are the plugins that can be consumed.
Plugins map[string]Plugin
// One of the following must be set, but not both.
//
// Cmd is the unstarted subprocess for starting the plugin. If this is
// set, then the Client starts the plugin process on its own and connects
// to it.
//
// Reattach is configuration for reattaching to an existing plugin process
// that is already running. This isn't common.
Cmd *exec.Cmd
Reattach *ReattachConfig
// Managed represents if the client should be managed by the
// plugin package or not. If true, then by calling CleanupClients,
// it will automatically be cleaned up. Otherwise, the client
// user is fully responsible for making sure to Kill all plugin
// clients. By default the client is _not_ managed.
Managed bool
// The minimum and maximum port to use for communicating with
// the subprocess. If not set, this defaults to 10,000 and 25,000
// respectively.
MinPort, MaxPort uint
// StartTimeout is the timeout to wait for the plugin to say it
// has started successfully.
StartTimeout time.Duration
// If non-nil, then the stderr of the client will be written to here
// (as well as the log). This is the original os.Stderr of the subprocess.
// This isn't the output of synced stderr.
Stderr io.Writer
// SyncStdout, SyncStderr can be set to override the
// respective os.Std* values in the plugin. Care should be taken to
// avoid races here. If these are nil, then this will automatically be
// hooked up to os.Stdin, Stdout, and Stderr, respectively.
//
// If the default values (nil) are used, then this package will not
// sync any of these streams.
SyncStdout io.Writer
SyncStderr io.Writer
}
// ReattachConfig is used to configure a client to reattach to an
// already-running plugin process. You can retrieve this information by
// calling ReattachConfig on Client.
type ReattachConfig struct {
Addr net.Addr
Pid int
}
// This makes sure all the managed subprocesses are killed and properly
// logged. This should be called before the parent process running the
// plugins exits.
//
// This must only be called _once_.
func CleanupClients() {
// Set the killed to true so that we don't get unexpected panics
atomic.StoreUint32(&Killed, 1)
// Kill all the managed clients in parallel and use a WaitGroup
// to wait for them all to finish up.
var wg sync.WaitGroup
for _, client := range managedClients {
wg.Add(1)
go func(client *Client) {
client.Kill()
wg.Done()
}(client)
}
log.Println("[DEBUG] plugin: waiting for all plugin processes to complete...")
wg.Wait()
}
// Creates a new plugin client which manages the lifecycle of an external
// plugin and gets the address for the RPC connection.
//
// The client must be cleaned up at some point by calling Kill(). If
// the client is a managed client (created with NewManagedClient) you
// can just call CleanupClients at the end of your program and they will
// be properly cleaned.
func NewClient(config *ClientConfig) (c *Client) {
if config.MinPort == 0 && config.MaxPort == 0 {
config.MinPort = 10000
config.MaxPort = 25000
}
if config.StartTimeout == 0 {
config.StartTimeout = 1 * time.Minute
}
if config.Stderr == nil {
config.Stderr = ioutil.Discard
}
if config.SyncStdout == nil {
config.SyncStdout = ioutil.Discard
}
if config.SyncStderr == nil {
config.SyncStderr = ioutil.Discard
}
c = &Client{config: config}
if config.Managed {
managedClients = append(managedClients, c)
}
return
}
// Client returns an RPC client for the plugin.
//
// Subsequent calls to this will return the same RPC client.
func (c *Client) Client() (*RPCClient, error) {
addr, err := c.Start()
if err != nil {
return nil, err
}
c.l.Lock()
defer c.l.Unlock()
if c.client != nil {
return c.client, nil
}
// Connect to the client
conn, err := net.Dial(addr.Network(), addr.String())
if err != nil {
return nil, err
}
if tcpConn, ok := conn.(*net.TCPConn); ok {
// Make sure to set keep alive so that the connection doesn't die
tcpConn.SetKeepAlive(true)
}
// Create the actual RPC client
c.client, err = NewRPCClient(conn, c.config.Plugins)
if err != nil {
conn.Close()
return nil, err
}
// Begin the stream syncing so that stdin, out, err work properly
err = c.client.SyncStreams(
c.config.SyncStdout,
c.config.SyncStderr)
if err != nil {
c.client.Close()
c.client = nil
return nil, err
}
return c.client, nil
}
// Tells whether or not the underlying process has exited.
func (c *Client) Exited() bool {
c.l.Lock()
defer c.l.Unlock()
return c.exited
}
// End the executing subprocess (if it is running) and perform any cleanup
// tasks necessary such as capturing any remaining logs and so on.
//
// This method blocks until the process successfully exits.
//
// This method can safely be called multiple times.
func (c *Client) Kill() {
if c.process == nil {
return
}
// Kill the process
c.process.Kill()
// Wait for the client to finish logging so we have a complete log
<-c.doneLogging
}
// Starts the underlying subprocess, communicating with it to negotiate
// a port for RPC connections, and returning the address to connect via RPC.
//
// This method is safe to call multiple times. Subsequent calls have no effect.
// Once a client has been started once, it cannot be started again, even if
// it was killed.
func (c *Client) Start() (addr net.Addr, err error) {
c.l.Lock()
defer c.l.Unlock()
if c.address != nil {
return c.address, nil
}
// If one of cmd or reattach isn't set, then it is an error. We wrap
// this in a {} for scoping reasons, and hopeful that the escape
// analysis will pop the stock here.
{
cmdSet := c.config.Cmd != nil
attachSet := c.config.Reattach != nil
if cmdSet == attachSet {
return nil, fmt.Errorf("Only one of Cmd or Reattach must be set")
}
}
// Create the logging channel for when we kill
c.doneLogging = make(chan struct{})
if c.config.Reattach != nil {
// Verify the process still exists. If not, then it is an error
p, err := os.FindProcess(c.config.Reattach.Pid)
if err != nil {
return nil, err
}
// Attempt to connect to the addr since on Unix systems FindProcess
// doesn't actually return an error if it can't find the process.
conn, err := net.Dial(
c.config.Reattach.Addr.Network(),
c.config.Reattach.Addr.String())
if err != nil {
p.Kill()
return nil, ErrProcessNotFound
}
conn.Close()
// Goroutine to mark exit status
go func(pid int) {
// Wait for the process to die
pidWait(pid)
// Log so we can see it
log.Printf("[DEBUG] plugin: reattached plugin process exited\n")
// Mark it
c.l.Lock()
defer c.l.Unlock()
c.exited = true
// Close the logging channel since that doesn't work on reattach
close(c.doneLogging)
}(p.Pid)
// Set the address and process
c.address = c.config.Reattach.Addr
c.process = p
return c.address, nil
}
env := []string{
fmt.Sprintf("%s=%s", c.config.MagicCookieKey, c.config.MagicCookieValue),
fmt.Sprintf("PLUGIN_MIN_PORT=%d", c.config.MinPort),
fmt.Sprintf("PLUGIN_MAX_PORT=%d", c.config.MaxPort),
}
stdout_r, stdout_w := io.Pipe()
stderr_r, stderr_w := io.Pipe()
cmd := c.config.Cmd
cmd.Env = append(cmd.Env, os.Environ()...)
cmd.Env = append(cmd.Env, env...)
cmd.Stdin = os.Stdin
cmd.Stderr = stderr_w
cmd.Stdout = stdout_w
log.Printf("[DEBUG] plugin: starting plugin: %s %#v", cmd.Path, cmd.Args)
err = cmd.Start()
if err != nil {
return
}
// Set the process
c.process = cmd.Process
// Make sure the command is properly cleaned up if there is an error
defer func() {
r := recover()
if err != nil || r != nil {
cmd.Process.Kill()
}
if r != nil {
panic(r)
}
}()
// Start goroutine to wait for process to exit
exitCh := make(chan struct{})
go func() {
// Make sure we close the write end of our stderr/stdout so
// that the readers send EOF properly.
defer stderr_w.Close()
defer stdout_w.Close()
// Wait for the command to end.
cmd.Wait()
// Log and make sure to flush the logs write away
log.Printf("[DEBUG] plugin: %s: plugin process exited\n", cmd.Path)
os.Stderr.Sync()
// Mark that we exited
close(exitCh)
// Set that we exited, which takes a lock
c.l.Lock()
defer c.l.Unlock()
c.exited = true
}()
// Start goroutine that logs the stderr
go c.logStderr(stderr_r)
// Start a goroutine that is going to be reading the lines
// out of stdout
linesCh := make(chan []byte)
go func() {
defer close(linesCh)
buf := bufio.NewReader(stdout_r)
for {
line, err := buf.ReadBytes('\n')
if line != nil {
linesCh <- line
}
if err == io.EOF {
return
}
}
}()
// Make sure after we exit we read the lines from stdout forever
// so they don't block since it is an io.Pipe
defer func() {
go func() {
for _ = range linesCh {
}
}()
}()
// Some channels for the next step
timeout := time.After(c.config.StartTimeout)
// Start looking for the address
log.Printf("[DEBUG] plugin: waiting for RPC address for: %s", cmd.Path)
select {
case <-timeout:
err = errors.New("timeout while waiting for plugin to start")
case <-exitCh:
err = errors.New("plugin exited before we could connect")
case lineBytes := <-linesCh:
// Trim the line and split by "|" in order to get the parts of
// the output.
line := strings.TrimSpace(string(lineBytes))
parts := strings.SplitN(line, "|", 4)
if len(parts) < 4 {
err = fmt.Errorf(
"Unrecognized remote plugin message: %s\n\n"+
"This usually means that the plugin is either invalid or simply\n"+
"needs to be recompiled to support the latest protocol.", line)
return
}
// Check the core protocol. Wrapped in a {} for scoping.
{
var coreProtocol int64
coreProtocol, err = strconv.ParseInt(parts[0], 10, 0)
if err != nil {
err = fmt.Errorf("Error parsing core protocol version: %s", err)
return
}
if int(coreProtocol) != CoreProtocolVersion {
err = fmt.Errorf("Incompatible core API version with plugin. "+
"Plugin version: %s, Ours: %d\n\n"+
"To fix this, the plugin usually only needs to be recompiled.\n"+
"Please report this to the plugin author.", parts[0], CoreProtocolVersion)
return
}
}
// Parse the protocol version
var protocol int64
protocol, err = strconv.ParseInt(parts[1], 10, 0)
if err != nil {
err = fmt.Errorf("Error parsing protocol version: %s", err)
return
}
// Test the API version
if uint(protocol) != c.config.ProtocolVersion {
err = fmt.Errorf("Incompatible API version with plugin. "+
"Plugin version: %s, Ours: %d", parts[1], c.config.ProtocolVersion)
return
}
switch parts[2] {
case "tcp":
addr, err = net.ResolveTCPAddr("tcp", parts[3])
case "unix":
addr, err = net.ResolveUnixAddr("unix", parts[3])
default:
err = fmt.Errorf("Unknown address type: %s", parts[3])
}
}
c.address = addr
return
}
// ReattachConfig returns the information that must be provided to NewClient
// to reattach to the plugin process that this client started. This is
// useful for plugins that detach from their parent process.
//
// If this returns nil then the process hasn't been started yet. Please
// call Start or Client before calling this.
func (c *Client) ReattachConfig() *ReattachConfig {
c.l.Lock()
defer c.l.Unlock()
if c.address == nil {
return nil
}
if c.config.Cmd != nil && c.config.Cmd.Process == nil {
return nil
}
// If we connected via reattach, just return the information as-is
if c.config.Reattach != nil {
return c.config.Reattach
}
return &ReattachConfig{
Addr: c.address,
Pid: c.config.Cmd.Process.Pid,
}
}
func (c *Client) logStderr(r io.Reader) {
bufR := bufio.NewReader(r)
for {
line, err := bufR.ReadString('\n')
if line != "" {
c.config.Stderr.Write([]byte(line))
line = strings.TrimRightFunc(line, unicode.IsSpace)
log.Printf("[DEBUG] plugin: %s: %s", filepath.Base(c.config.Cmd.Path), line)
}
if err == io.EOF {
break
}
}
// Flag that we've completed logging for others
close(c.doneLogging)
}
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