| // +build linux |
| |
| /* |
| Copyright The containerd Authors. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| */ |
| |
| 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 |
| } |