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// +build linux
package fifo
import (
"fmt"
"os"
"sync"
"syscall"
"github.com/pkg/errors"
)
const O_PATH = 010000000
type handle struct {
f *os.File
fd uintptr
dev uint64
ino uint64
closeOnce sync.Once
name string
}
func getHandle(fn string) (*handle, error) {
f, err := os.OpenFile(fn, O_PATH, 0)
if err != nil {
return nil, errors.Wrapf(err, "failed to open %v with O_PATH", fn)
}
var (
stat syscall.Stat_t
fd = f.Fd()
)
if err := syscall.Fstat(int(fd), &stat); err != nil {
f.Close()
return nil, errors.Wrapf(err, "failed to stat handle %v", fd)
}
h := &handle{
f: f,
name: fn,
dev: uint64(stat.Dev),
ino: stat.Ino,
fd: fd,
}
// check /proc just in case
if _, err := os.Stat(h.procPath()); err != nil {
f.Close()
return nil, errors.Wrapf(err, "couldn't stat %v", h.procPath())
}
return h, nil
}
func (h *handle) procPath() string {
return fmt.Sprintf("/proc/self/fd/%d", h.fd)
}
func (h *handle) Name() string {
return h.name
}
func (h *handle) Path() (string, error) {
var stat syscall.Stat_t
if err := syscall.Stat(h.procPath(), &stat); err != nil {
return "", errors.Wrapf(err, "path %v could not be statted", h.procPath())
}
if uint64(stat.Dev) != h.dev || stat.Ino != h.ino {
return "", errors.Errorf("failed to verify handle %v/%v %v/%v", stat.Dev, h.dev, stat.Ino, h.ino)
}
return h.procPath(), nil
}
func (h *handle) Close() error {
h.closeOnce.Do(func() {
h.f.Close()
})
return nil
}
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