package main
import (
_"errors"
"fmt"
"io"
"os"
"syscall"
"time"
"bytes"
_"os/exec"
"github.com/docker/docker/pkg/term"
)
func main() {
Stdin()
}
func Stdin() {
var in io.Reader
in = os.NewFile(uintptr(syscall.Stdin), "/dev/stdin")
_,ok:= term.GetFdInfo(in)
if ok {
fmt.Println("Is terminal \n")
}
reader := bytes.NewBuffer(make([]byte, 10))
for {
data, _:= reader.ReadFrom(in) //很奇怪为什么一直阻塞在这里
fmt.Printf("read from stdin %v \n", data)
time.Sleep(2 * time.Second)
}
}
阻塞在ReadFrom那里,可以看看ReadFrom的具体实现
func (b *Buffer) ReadFrom(r io.Reader) (n int64, err error) {
b.lastRead = opInvalid
// If buffer is empty, reset to recover space.
if b.off >= len(b.buf) {
b.Truncate(0)
}
//因为没有读到标准输出的EOF,所以一直在读
for {
if free := cap(b.buf) - len(b.buf); free < MinRead {
// not enough space at end
newBuf := b.buf
if b.off+free < MinRead {
// not enough space using beginning of buffer;
// double buffer capacity
newBuf = makeSlice(2*cap(b.buf) + MinRead)
}
copy(newBuf, b.buf[b.off:])
b.buf = newBuf[:len(b.buf)-b.off]
b.off = 0
}
m, e := r.Read(b.buf[len(b.buf):cap(b.buf)])
b.buf = b.buf[0 : len(b.buf)+m]
n += int64(m)
if e == io.EOF {
break
}
if e != nil {
return n, e
}
}
return n, nil // err is EOF, so return nil explicitly
}