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copy.go
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copy.go
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//go:build darwin || freebsd || dragonfly || linux
package util
import (
"io"
"os"
"syscall"
)
func Copy(dst io.Writer, src *os.File) func() {
r, w, _ := os.Pipe()
go func() {
copy(dst, src, r)
}()
return func() {
w.Write([]byte("x"))
r.Close()
w.Close()
}
}
func copy(dst io.Writer, src *os.File, finish *os.File) (written int64, err error) {
fd := int(src.Fd())
ffd := int(finish.Fd())
maxfd := ffd + 1
if fd > ffd {
maxfd = fd + 1
}
rfds := &syscall.FdSet{}
buf := make([]byte, 32*1024)
for {
FD_SET(rfds, fd)
FD_SET(rfds, ffd)
es := Select(maxfd, rfds, nil, nil, nil)
if es != nil {
if es == syscall.EINTR {
continue
}
err = es
break
}
if FD_ISSET(rfds, fd) {
nr, er := src.Read(buf)
if nr > 0 {
nw, ew := dst.Write(buf[0:nr])
if nw > 0 {
written += int64(nw)
}
if ew != nil {
err = ew
break
}
if nr != nw {
err = io.ErrShortWrite
break
}
}
if er == io.EOF {
break
}
if er != nil {
err = er
break
}
}
if FD_ISSET(rfds, ffd) {
break
}
}
return written, err
}