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354 lines
8.3 KiB
Go
354 lines
8.3 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package samples
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import (
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"bytes"
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"context"
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"path"
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"sync"
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"github.com/jacobsa/ogletest"
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)
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var fToolPath = flag.String(
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"mount_sample",
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"",
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"Path to the mount_sample tool. If unset, we will compile it.")
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var fDebug = flag.Bool("debug", false, "If true, print fuse debug info.")
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// A struct that implements common behavior needed by tests in the samples/
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// directory where the file system is mounted by a subprocess. Use it as an
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// embedded field in your test fixture, calling its SetUp method from your
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// SetUp method after setting the MountType and MountFlags fields.
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type SubprocessTest struct {
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// The type of the file system to mount. Must be recognized by mount_sample.
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MountType string
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// Additional flags to be passed to the mount_sample tool.
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MountFlags []string
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// A list of files to pass to mount_sample. The given string flag will be
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// used to pass the file descriptor number.
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MountFiles map[string]*os.File
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// A context object that can be used for long-running operations.
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Ctx context.Context
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// The directory at which the file system is mounted.
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Dir string
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// Anothing non-nil in this slice will be closed by TearDown. The test will
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// fail if closing fails.
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ToClose []io.Closer
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mountSampleErr <-chan error
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}
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// Mount the file system and initialize the other exported fields of the
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// struct. Panics on error.
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func (t *SubprocessTest) SetUp(ti *ogletest.TestInfo) {
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err := t.initialize(ti.Ctx)
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if err != nil {
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panic(err)
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}
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}
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// Private state for getToolPath.
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var getToolContents_Contents []byte
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var getToolContents_Err error
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var getToolContents_Once sync.Once
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// Implementation detail of getToolPath.
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func getToolContentsImpl() ([]byte, error) {
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// Fast path: has the user set the flag?
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if *fToolPath != "" {
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contents, err := ioutil.ReadFile(*fToolPath)
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if err != nil {
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return nil, fmt.Errorf("Reading mount_sample contents: %v", err)
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}
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return contents, err
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}
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// Create a temporary directory into which we will compile the tool.
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tempDir, err := ioutil.TempDir("", "sample_test")
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if err != nil {
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return nil, fmt.Errorf("TempDir: %v", err)
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}
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toolPath := path.Join(tempDir, "mount_sample")
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// Ensure that we kill the temporary directory when we're finished here.
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defer os.RemoveAll(tempDir)
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// Run "go build".
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cmd := exec.Command(
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"go",
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"build",
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"-o",
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toolPath,
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"github.com/jacobsa/fuse/samples/mount_sample")
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output, err := cmd.CombinedOutput()
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if err != nil {
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return nil, fmt.Errorf(
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"mount_sample exited with %v, output:\n%s",
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err,
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string(output))
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}
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// Slurp the tool contents.
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contents, err := ioutil.ReadFile(toolPath)
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if err != nil {
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return nil, fmt.Errorf("ReadFile: %v", err)
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}
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return contents, nil
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}
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// Build the mount_sample tool if it has not yet been built for this process.
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// Return its contents.
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func getToolContents() ([]byte, error) {
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// Get hold of the binary contents, if we haven't yet.
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getToolContents_Once.Do(func() {
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getToolContents_Contents, getToolContents_Err = getToolContentsImpl()
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})
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return getToolContents_Contents, getToolContents_Err
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}
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func waitForMountSample(
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cmd *exec.Cmd,
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errChan chan<- error,
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stderr *bytes.Buffer) {
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// However we exit, write the error to the channel.
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var err error
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defer func() {
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errChan <- err
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}()
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// Wait for the command.
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err = cmd.Wait()
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if err == nil {
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return
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}
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// Make exit errors nicer.
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if exitErr, ok := err.(*exec.ExitError); ok {
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err = fmt.Errorf(
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"mount_sample exited with %v. Stderr:\n%s",
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exitErr,
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stderr.String())
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return
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}
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err = fmt.Errorf("Waiting for mount_sample: %v", err)
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}
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func waitForReady(readyReader *os.File, c chan<- struct{}) {
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_, err := readyReader.Read(make([]byte, 1))
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if err != nil {
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log.Printf("Readying from ready pipe: %v", err)
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return
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}
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c <- struct{}{}
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}
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// Like SetUp, but doens't panic.
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func (t *SubprocessTest) initialize(ctx context.Context) error {
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// Initialize the context.
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t.Ctx = ctx
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// Set up a temporary directory.
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var err error
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t.Dir, err = ioutil.TempDir("", "sample_test")
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if err != nil {
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return fmt.Errorf("TempDir: %v", err)
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}
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// Build/read the mount_sample tool.
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toolContents, err := getToolContents()
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if err != nil {
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return fmt.Errorf("getTooltoolContents: %v", err)
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}
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// Create a temporary file to hold the contents of the tool.
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toolFile, err := ioutil.TempFile("", "sample_test")
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if err != nil {
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return fmt.Errorf("TempFile: %v", err)
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}
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defer toolFile.Close()
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// Ensure that it is deleted when we leave.
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toolPath := toolFile.Name()
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defer os.Remove(toolPath)
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// Write out the tool contents and make them executable.
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if _, err = toolFile.Write(toolContents); err != nil {
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return fmt.Errorf("toolFile.Write: %v", err)
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}
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if err = toolFile.Chmod(0500); err != nil {
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return fmt.Errorf("toolFile.Chmod: %v", err)
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}
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// Close the tool file to prevent "text file busy" errors below.
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err = toolFile.Close()
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toolFile = nil
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if err != nil {
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return fmt.Errorf("toolFile.Close: %v", err)
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}
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// Set up basic args for the subprocess.
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args := []string{
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"--type",
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t.MountType,
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"--mount_point",
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t.Dir,
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}
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args = append(args, t.MountFlags...)
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// Set up a pipe for the "ready" status.
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readyReader, readyWriter, err := os.Pipe()
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if err != nil {
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return fmt.Errorf("Pipe: %v", err)
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}
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defer readyReader.Close()
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defer readyWriter.Close()
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t.MountFiles["ready_file"] = readyWriter
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// Set up inherited files and appropriate flags.
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var extraFiles []*os.File
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for flag, file := range t.MountFiles {
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// Cf. os/exec.Cmd.ExtraFiles
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fd := 3 + len(extraFiles)
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extraFiles = append(extraFiles, file)
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args = append(args, "--"+flag)
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args = append(args, fmt.Sprintf("%d", fd))
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}
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// Set up a command.
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var stderr bytes.Buffer
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mountCmd := exec.Command(toolPath, args...)
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mountCmd.Stderr = &stderr
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mountCmd.ExtraFiles = extraFiles
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// Handle debug mode.
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if *fDebug {
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mountCmd.Stderr = os.Stderr
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mountCmd.Args = append(mountCmd.Args, "--debug")
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}
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// Start the command.
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if err := mountCmd.Start(); err != nil {
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return fmt.Errorf("mountCmd.Start: %v", err)
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}
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// Launch a goroutine that waits for it and returns its status.
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mountSampleErr := make(chan error, 1)
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go waitForMountSample(mountCmd, mountSampleErr, &stderr)
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// Wait for the tool to say the file system is ready. In parallel, watch for
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// the tool to fail.
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readyChan := make(chan struct{}, 1)
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go waitForReady(readyReader, readyChan)
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select {
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case <-readyChan:
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case err := <-mountSampleErr:
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return err
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}
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// TearDown is no responsible for joining.
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t.mountSampleErr = mountSampleErr
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return nil
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}
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// Unmount the file system and clean up. Panics on error.
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func (t *SubprocessTest) TearDown() {
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err := t.destroy()
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if err != nil {
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panic(err)
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}
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}
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// Like TearDown, but doesn't panic.
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func (t *SubprocessTest) destroy() (err error) {
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// Make sure we clean up after ourselves after everything else below.
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// Close what is necessary.
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for _, c := range t.ToClose {
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if c == nil {
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continue
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}
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ogletest.ExpectEq(nil, c.Close())
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}
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// If we didn't try to mount the file system, there's nothing further to do.
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if t.mountSampleErr == nil {
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return nil
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}
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// In the background, initiate an unmount.
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unmountErrChan := make(chan error)
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go func() {
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unmountErrChan <- unmount(t.Dir)
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}()
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// Make sure we wait for the unmount, even if we've already returned early in
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// error. Return its error if we haven't seen any other error.
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defer func() {
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// Wait.
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unmountErr := <-unmountErrChan
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if unmountErr != nil {
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if err != nil {
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log.Println("unmount:", unmountErr)
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return
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}
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err = fmt.Errorf("unmount: %v", unmountErr)
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return
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}
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// Clean up.
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ogletest.ExpectEq(nil, os.Remove(t.Dir))
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}()
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// Wait for the subprocess.
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if err := <-t.mountSampleErr; err != nil {
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return err
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}
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return nil
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}
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