112 lines
2.8 KiB
Go
112 lines
2.8 KiB
Go
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// Program jsh exposes a trivial command-shell functionality via JSON-RPC for
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// demonstration purposes.
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//
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// Usage:
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// go build github.com/creachadair/jrpc2/cmd/examples/jsh
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// ./jsh -port 8080
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//
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// See also cmd/examples/jcl/jcl.go.
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package main
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import (
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"bytes"
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"context"
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"flag"
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"fmt"
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"log"
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"net"
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"os"
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"os/exec"
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"github.com/creachadair/jrpc2"
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"github.com/creachadair/jrpc2/code"
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"github.com/creachadair/jrpc2/handler"
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"github.com/creachadair/jrpc2/jctx"
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"github.com/creachadair/jrpc2/server"
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)
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// RunReq is a request to invoke a program.
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type RunReq struct {
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Args []string `json:"args"` // The command line to execute
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Input []byte `json:"input"` // If nonempty, becomes the standard input of the subprocess
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Stderr bool `json:"stderr"` // Whether to capture stderr from the subprocess
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}
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// RunResult is the result of executing a program.
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type RunResult struct {
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Success bool `json:"success"` // Whether the process succeeded (exit status 0)
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Output []byte `json:"output,omitempty"` // The output from the process
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}
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// Run invokes the specified process and returns the result. It is not an RPC
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// error if the process returns a nonzero exit status, unless the process fails
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// to start at all.
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func Run(ctx context.Context, req *RunReq) (*RunResult, error) {
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if len(req.Args) == 0 || req.Args[0] == "" {
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return nil, jrpc2.Errorf(code.InvalidParams, "missing command name")
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}
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if req.Args[0] == "cd" {
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if len(req.Args) != 2 {
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return nil, jrpc2.Errorf(code.InvalidParams, "wrong arguments for cd")
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}
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return &RunResult{
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Success: os.Chdir(req.Args[1]) == nil,
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}, nil
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}
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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cmd := exec.CommandContext(ctx, req.Args[0], req.Args[1:]...)
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if len(req.Input) != 0 {
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cmd.Stdin = bytes.NewReader(req.Input)
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}
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run := cmd.Output
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if req.Stderr {
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run = cmd.CombinedOutput
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}
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out, err := run()
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success := err == nil
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if err != nil {
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if ex, ok := err.(*exec.ExitError); ok && ex.Success() {
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success = true
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} else {
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return nil, err
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}
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}
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return &RunResult{
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Success: success,
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Output: out,
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}, nil
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}
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var (
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port = flag.Int("port", 0, "Service port")
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logging = flag.Bool("log", false, "Enable verbose logging")
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lw *log.Logger
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)
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func main() {
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flag.Parse()
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if *port <= 0 {
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log.Fatal("You must specify a positive --port value")
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} else if *logging {
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lw = log.New(os.Stdout, "", log.LstdFlags|log.Lshortfile)
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}
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lst, err := net.Listen("tcp", fmt.Sprintf("localhost:%d", *port))
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if err != nil {
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log.Fatalln("Listen:", err)
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}
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log.Printf("Listening for connections at %s...", lst.Addr())
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server.Loop(lst, server.NewStatic(handler.Map{
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"Run": handler.New(Run),
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}), &server.LoopOptions{
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ServerOptions: &jrpc2.ServerOptions{
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AllowV1: true,
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Logger: lw,
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DecodeContext: jctx.Decode,
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},
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})
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}
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