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Capture CGO output, realtime.
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| package main | |
| //#include "capture.h" | |
| import "C" | |
| import ( | |
| "bufio" | |
| "fmt" | |
| "log" | |
| "os" | |
| "sync" | |
| "syscall" | |
| ) | |
| func main() { | |
| outc := CaptureCGOOutput(func() error { | |
| _, err := C.hello() | |
| return err | |
| }) | |
| for out := range outc { | |
| if out.Err != nil { | |
| log.Fatal(out.Err) | |
| } | |
| fmt.Printf("%s\n",out.Read) | |
| } | |
| } | |
| var redirectMu sync.Mutex | |
| type RedirectedOutput struct { | |
| Err error | |
| Read []byte | |
| } | |
| func CaptureCGOOutput(call func() error) (outC chan *RedirectedOutput) { | |
| outC = make(chan *RedirectedOutput) | |
| stdout, err := syscall.Dup(syscall.Stdout) | |
| if err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| stderr, err := syscall.Dup(syscall.Stderr) | |
| if err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| r, w, err := os.Pipe() | |
| if err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| go func() { | |
| redirectMu.Lock() | |
| defer redirectMu.Unlock() | |
| defer func() { | |
| C.fflush(nil) | |
| if err := w.Close(); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| } | |
| if err := r.Close(); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| } | |
| }() | |
| if err := syscall.Dup2(int(w.Fd()), syscall.Stdout); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| if err := syscall.Dup2(int(w.Fd()), syscall.Stderr); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| var wg sync.WaitGroup | |
| wg.Add(1) | |
| go func() { | |
| defer wg.Done() | |
| if err := call(); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| } | |
| }() | |
| if err := syscall.Dup2(stdout, syscall.Stdout); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| if err := syscall.Close(stdout); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| if err := syscall.Dup2(stderr, syscall.Stderr); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| if err := syscall.Close(stderr); err != nil { | |
| outC <- &RedirectedOutput{Err: err} | |
| return | |
| } | |
| wg.Wait() | |
| }() | |
| go func() { | |
| br := bufio.NewScanner(r) | |
| br.Split(bufio.ScanLines) | |
| for br.Scan() { | |
| outC<-&RedirectedOutput{Read: br.Bytes()} | |
| } | |
| close(outC) | |
| }() | |
| return | |
| } |
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