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-rw-r--r--pkg/test/testutil/BUILD2
-rw-r--r--pkg/test/testutil/sh.go515
2 files changed, 517 insertions, 0 deletions
diff --git a/pkg/test/testutil/BUILD b/pkg/test/testutil/BUILD
index c4b131896..00600a2ad 100644
--- a/pkg/test/testutil/BUILD
+++ b/pkg/test/testutil/BUILD
@@ -6,6 +6,7 @@ go_library(
name = "testutil",
testonly = 1,
srcs = [
+ "sh.go",
"testutil.go",
"testutil_runfiles.go",
],
@@ -15,6 +16,7 @@ go_library(
"//runsc/config",
"//runsc/specutils",
"@com_github_cenkalti_backoff//:go_default_library",
+ "@com_github_kr_pty//:go_default_library",
"@com_github_opencontainers_runtime_spec//specs-go:go_default_library",
],
)
diff --git a/pkg/test/testutil/sh.go b/pkg/test/testutil/sh.go
new file mode 100644
index 000000000..1c77562be
--- /dev/null
+++ b/pkg/test/testutil/sh.go
@@ -0,0 +1,515 @@
+// Copyright 2020 The gVisor 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 testutil
+
+import (
+ "bytes"
+ "context"
+ "fmt"
+ "io"
+ "os"
+ "os/exec"
+ "strings"
+ "syscall"
+ "time"
+
+ "github.com/kr/pty"
+)
+
+// Prompt is used as shell prompt.
+// It is meant to be unique enough to not be seen in command outputs.
+const Prompt = "PROMPT> "
+
+// Simplistic shell string escape.
+func shellEscape(s string) string {
+ // specialChars is used to determine whether s needs quoting at all.
+ const specialChars = "\\'\"`${[|&;<>()*?! \t\n"
+ // If s needs quoting, escapedChars is the set of characters that are
+ // escaped with a backslash.
+ const escapedChars = "\\\"$`"
+ if len(s) == 0 {
+ return "''"
+ }
+ if !strings.ContainsAny(s, specialChars) {
+ return s
+ }
+ var b bytes.Buffer
+ b.WriteString("\"")
+ for _, c := range s {
+ if strings.ContainsAny(string(c), escapedChars) {
+ b.WriteString("\\")
+ }
+ b.WriteRune(c)
+ }
+ b.WriteString("\"")
+ return b.String()
+}
+
+type byteOrError struct {
+ b byte
+ err error
+}
+
+// Shell manages a /bin/sh invocation with convenience functions to handle I/O.
+// The shell is run in its own interactive TTY and should present its prompt.
+type Shell struct {
+ // cmd is a reference to the underlying sh process.
+ cmd *exec.Cmd
+ // cmdFinished is closed when cmd exits.
+ cmdFinished chan struct{}
+
+ // echo is whether the shell will echo input back to us.
+ // This helps setting expectations of getting feedback of written bytes.
+ echo bool
+ // Control characters we expect to see in the shell.
+ controlCharIntr string
+ controlCharEOF string
+
+ // ptyMaster and ptyReplica are the TTY pair associated with the shell.
+ ptyMaster *os.File
+ ptyReplica *os.File
+ // readCh is a channel where everything read from ptyMaster is written.
+ readCh chan byteOrError
+
+ // logger is used for logging. It may be nil.
+ logger Logger
+}
+
+// cleanup kills the shell process and closes the TTY.
+// Users of this library get a reference to this function with NewShell.
+func (s *Shell) cleanup() {
+ s.logf("cleanup", "Shell cleanup started.")
+ if s.cmd.ProcessState == nil {
+ if err := s.cmd.Process.Kill(); err != nil {
+ s.logf("cleanup", "cannot kill shell process: %v", err)
+ }
+ // We don't log the error returned by Wait because the monitorExit
+ // goroutine will already do so.
+ s.cmd.Wait()
+ }
+ s.ptyReplica.Close()
+ s.ptyMaster.Close()
+ // Wait for monitorExit goroutine to write exit status to the debug log.
+ <-s.cmdFinished
+ // Empty out everything in the readCh, but don't wait too long for it.
+ var extraBytes bytes.Buffer
+ unreadTimeout := time.After(100 * time.Millisecond)
+unreadLoop:
+ for {
+ select {
+ case r, ok := <-s.readCh:
+ if !ok {
+ break unreadLoop
+ } else if r.err == nil {
+ extraBytes.WriteByte(r.b)
+ }
+ case <-unreadTimeout:
+ break unreadLoop
+ }
+ }
+ if extraBytes.Len() > 0 {
+ s.logIO("unread", extraBytes.Bytes(), nil)
+ }
+ s.logf("cleanup", "Shell cleanup complete.")
+}
+
+// logIO logs byte I/O to both standard logging and the test log, if provided.
+func (s *Shell) logIO(prefix string, b []byte, err error) {
+ var sb strings.Builder
+ if len(b) > 0 {
+ sb.WriteString(fmt.Sprintf("%q", b))
+ } else {
+ sb.WriteString("(nothing)")
+ }
+ if err != nil {
+ sb.WriteString(fmt.Sprintf(" [error: %v]", err))
+ }
+ s.logf(prefix, "%s", sb.String())
+}
+
+// logf logs something to both standard logging and the test log, if provided.
+func (s *Shell) logf(prefix, format string, values ...interface{}) {
+ if s.logger != nil {
+ s.logger.Logf("[%s] %s", prefix, fmt.Sprintf(format, values...))
+ }
+}
+
+// monitorExit waits for the shell process to exit and logs the exit result.
+func (s *Shell) monitorExit() {
+ if err := s.cmd.Wait(); err != nil {
+ s.logf("cmd", "shell process terminated: %v", err)
+ } else {
+ s.logf("cmd", "shell process terminated successfully")
+ }
+ close(s.cmdFinished)
+}
+
+// reader continuously reads the shell output and populates readCh.
+func (s *Shell) reader(ctx context.Context) {
+ b := make([]byte, 4096)
+ defer close(s.readCh)
+ for {
+ select {
+ case <-s.cmdFinished:
+ // Shell process terminated; stop trying to read.
+ return
+ case <-ctx.Done():
+ // Shell process will also have terminated in this case;
+ // stop trying to read.
+ // We don't print an error here because doing so would print this in the
+ // normal case where the context passed to NewShell is canceled at the
+ // end of a successful test.
+ return
+ default:
+ // Shell still running, try reading.
+ }
+ if got, err := s.ptyMaster.Read(b); err != nil {
+ s.readCh <- byteOrError{err: err}
+ if err == io.EOF {
+ return
+ }
+ } else {
+ for i := 0; i < got; i++ {
+ s.readCh <- byteOrError{b: b[i]}
+ }
+ }
+ }
+}
+
+// readByte reads a single byte, respecting the context.
+func (s *Shell) readByte(ctx context.Context) (byte, error) {
+ select {
+ case <-ctx.Done():
+ return 0, ctx.Err()
+ case r := <-s.readCh:
+ return r.b, r.err
+ }
+}
+
+// readLoop reads as many bytes as possible until the context expires, b is
+// full, or a short time passes. It returns how many bytes it has successfully
+// read.
+func (s *Shell) readLoop(ctx context.Context, b []byte) (int, error) {
+ soonCtx, soonCancel := context.WithTimeout(ctx, 5*time.Second)
+ defer soonCancel()
+ var i int
+ for i = 0; i < len(b) && soonCtx.Err() == nil; i++ {
+ next, err := s.readByte(soonCtx)
+ if err != nil {
+ if i > 0 {
+ s.logIO("read", b[:i-1], err)
+ } else {
+ s.logIO("read", nil, err)
+ }
+ return i, err
+ }
+ b[i] = next
+ }
+ s.logIO("read", b[:i], soonCtx.Err())
+ return i, soonCtx.Err()
+}
+
+// readLine reads a single line. Strips out all \r characters for convenience.
+// Upon error, it will still return what it has read so far.
+// It will also exit quickly if the line content it has read so far (without a
+// line break) matches `prompt`.
+func (s *Shell) readLine(ctx context.Context, prompt string) ([]byte, error) {
+ soonCtx, soonCancel := context.WithTimeout(ctx, 5*time.Second)
+ defer soonCancel()
+ var lineData bytes.Buffer
+ var b byte
+ var err error
+ for soonCtx.Err() == nil && b != '\n' {
+ b, err = s.readByte(soonCtx)
+ if err != nil {
+ data := lineData.Bytes()
+ s.logIO("read", data, err)
+ return data, err
+ }
+ if b != '\r' {
+ lineData.WriteByte(b)
+ }
+ if bytes.Equal(lineData.Bytes(), []byte(prompt)) {
+ // Assume that there will not be any further output if we get the prompt.
+ // This avoids waiting for the read deadline just to read the prompt.
+ break
+ }
+ }
+ data := lineData.Bytes()
+ s.logIO("read", data, soonCtx.Err())
+ return data, soonCtx.Err()
+}
+
+// Expect verifies that the next `len(want)` bytes we read match `want`.
+func (s *Shell) Expect(ctx context.Context, want []byte) error {
+ errPrefix := fmt.Sprintf("want(%q)", want)
+ b := make([]byte, len(want))
+ got, err := s.readLoop(ctx, b)
+ if err != nil {
+ if ctx.Err() != nil {
+ return fmt.Errorf("%s: context done (%w), got: %q", errPrefix, err, b[:got])
+ }
+ return fmt.Errorf("%s: %w", errPrefix, err)
+ }
+ if got < len(want) {
+ return fmt.Errorf("%s: short read (read %d bytes, expected %d): %q", errPrefix, got, len(want), b[:got])
+ }
+ if !bytes.Equal(b, want) {
+ return fmt.Errorf("got %q want %q", b, want)
+ }
+ return nil
+}
+
+// ExpectString verifies that the next `len(want)` bytes we read match `want`.
+func (s *Shell) ExpectString(ctx context.Context, want string) error {
+ return s.Expect(ctx, []byte(want))
+}
+
+// ExpectPrompt verifies that the next few bytes we read are the shell prompt.
+func (s *Shell) ExpectPrompt(ctx context.Context) error {
+ return s.ExpectString(ctx, Prompt)
+}
+
+// ExpectEmptyLine verifies that the next few bytes we read are an empty line,
+// as defined by any number of carriage or line break characters.
+func (s *Shell) ExpectEmptyLine(ctx context.Context) error {
+ line, err := s.readLine(ctx, Prompt)
+ if err != nil {
+ return fmt.Errorf("cannot read line: %w", err)
+ }
+ if strings.Trim(string(line), "\r\n") != "" {
+ return fmt.Errorf("line was not empty: %q", line)
+ }
+ return nil
+}
+
+// ExpectLine verifies that the next `len(want)` bytes we read match `want`,
+// followed by carriage returns or newline characters.
+func (s *Shell) ExpectLine(ctx context.Context, want string) error {
+ if err := s.ExpectString(ctx, want); err != nil {
+ return err
+ }
+ if err := s.ExpectEmptyLine(ctx); err != nil {
+ return fmt.Errorf("ExpectLine(%q): no line break: %w", want, err)
+ }
+ return nil
+}
+
+// Write writes `b` to the shell and verifies that all of them get written.
+func (s *Shell) Write(b []byte) error {
+ written, err := s.ptyMaster.Write(b)
+ s.logIO("write", b[:written], err)
+ if err != nil {
+ return fmt.Errorf("write(%q): %w", b, err)
+ }
+ if written != len(b) {
+ return fmt.Errorf("write(%q): wrote %d of %d bytes (%q)", b, written, len(b), b[:written])
+ }
+ return nil
+}
+
+// WriteLine writes `line` (to which \n will be appended) to the shell.
+// If the shell is in `echo` mode, it will also check that we got these bytes
+// back to read.
+func (s *Shell) WriteLine(ctx context.Context, line string) error {
+ if err := s.Write([]byte(line + "\n")); err != nil {
+ return err
+ }
+ if s.echo {
+ // We expect to see everything we've typed.
+ if err := s.ExpectLine(ctx, line); err != nil {
+ return fmt.Errorf("echo: %w", err)
+ }
+ }
+ return nil
+}
+
+// StartCommand is a convenience wrapper for WriteLine that mimics entering a
+// command line and pressing Enter. It does some basic shell argument escaping.
+func (s *Shell) StartCommand(ctx context.Context, cmd ...string) error {
+ escaped := make([]string, len(cmd))
+ for i, arg := range cmd {
+ escaped[i] = shellEscape(arg)
+ }
+ return s.WriteLine(ctx, strings.Join(escaped, " "))
+}
+
+// GetCommandOutput gets all following bytes until the prompt is encountered.
+// This is useful for matching the output of a command.
+// All \r are removed for ease of matching.
+func (s *Shell) GetCommandOutput(ctx context.Context) ([]byte, error) {
+ return s.ReadUntil(ctx, Prompt)
+}
+
+// ReadUntil gets all following bytes until a certain line is encountered.
+// This final line is not returned as part of the output, but everything before
+// it (including the \n) is included.
+// This is useful for matching the output of a command.
+// All \r are removed for ease of matching.
+func (s *Shell) ReadUntil(ctx context.Context, finalLine string) ([]byte, error) {
+ var output bytes.Buffer
+ for ctx.Err() == nil {
+ line, err := s.readLine(ctx, finalLine)
+ if err != nil {
+ return nil, err
+ }
+ if bytes.Equal(line, []byte(finalLine)) {
+ break
+ }
+ // readLine ensures that `line` either matches `finalLine` or contains \n.
+ // Thus we can be confident that `line` has a \n here.
+ output.Write(line)
+ }
+ return output.Bytes(), ctx.Err()
+}
+
+// RunCommand is a convenience wrapper for StartCommand + GetCommandOutput.
+func (s *Shell) RunCommand(ctx context.Context, cmd ...string) ([]byte, error) {
+ if err := s.StartCommand(ctx, cmd...); err != nil {
+ return nil, err
+ }
+ return s.GetCommandOutput(ctx)
+}
+
+// RefreshSTTY interprets output from `stty -a` to check whether we are in echo
+// mode and other settings.
+// It will assume that any line matching `expectPrompt` means the end of
+// the `stty -a` output.
+// Why do this rather than using `tcgets`? Because this function can be used in
+// conjunction with sub-shell processes that can allocate their own TTYs.
+func (s *Shell) RefreshSTTY(ctx context.Context, expectPrompt string) error {
+ // Temporarily assume we will not get any output.
+ // If echo is actually on, we'll get the "stty -a" line as if it was command
+ // output. This is OK because we parse the output generously.
+ s.echo = false
+ if err := s.WriteLine(ctx, "stty -a"); err != nil {
+ return fmt.Errorf("could not run `stty -a`: %w", err)
+ }
+ sttyOutput, err := s.ReadUntil(ctx, expectPrompt)
+ if err != nil {
+ return fmt.Errorf("cannot get `stty -a` output: %w", err)
+ }
+
+ // Set default control characters in case we can't see them in the output.
+ s.controlCharIntr = "^C"
+ s.controlCharEOF = "^D"
+ // stty output has two general notations:
+ // `a = b;` (for control characters), and `option` vs `-option` (for boolean
+ // options). We parse both kinds here.
+ // For `a = b;`, `controlChar` contains `a`, and `previousToken` is used to
+ // set `controlChar` to `previousToken` when we see an "=" token.
+ var previousToken, controlChar string
+ for _, token := range strings.Fields(string(sttyOutput)) {
+ if controlChar != "" {
+ value := strings.TrimSuffix(token, ";")
+ switch controlChar {
+ case "intr":
+ s.controlCharIntr = value
+ case "eof":
+ s.controlCharEOF = value
+ }
+ controlChar = ""
+ } else {
+ switch token {
+ case "=":
+ controlChar = previousToken
+ case "-echo":
+ s.echo = false
+ case "echo":
+ s.echo = true
+ }
+ }
+ previousToken = token
+ }
+ s.logf("stty", "refreshed settings: echo=%v, intr=%q, eof=%q", s.echo, s.controlCharIntr, s.controlCharEOF)
+ return nil
+}
+
+// sendControlCode sends `code` to the shell and expects to see `repr`.
+// If `expectLinebreak` is true, it also expects to see a linebreak.
+func (s *Shell) sendControlCode(ctx context.Context, code byte, repr string, expectLinebreak bool) error {
+ if err := s.Write([]byte{code}); err != nil {
+ return fmt.Errorf("cannot send %q: %w", code, err)
+ }
+ if err := s.ExpectString(ctx, repr); err != nil {
+ return fmt.Errorf("did not see %s: %w", repr, err)
+ }
+ if expectLinebreak {
+ if err := s.ExpectEmptyLine(ctx); err != nil {
+ return fmt.Errorf("linebreak after %s: %v", repr, err)
+ }
+ }
+ return nil
+}
+
+// SendInterrupt sends the \x03 (Ctrl+C) control character to the shell.
+func (s *Shell) SendInterrupt(ctx context.Context, expectLinebreak bool) error {
+ return s.sendControlCode(ctx, 0x03, s.controlCharIntr, expectLinebreak)
+}
+
+// SendEOF sends the \x04 (Ctrl+D) control character to the shell.
+func (s *Shell) SendEOF(ctx context.Context, expectLinebreak bool) error {
+ return s.sendControlCode(ctx, 0x04, s.controlCharEOF, expectLinebreak)
+}
+
+// NewShell returns a new managed sh process along with a cleanup function.
+// The caller is expected to call this function once it no longer needs the
+// shell.
+// The optional passed-in logger will be used for logging.
+func NewShell(ctx context.Context, logger Logger) (*Shell, func(), error) {
+ ptyMaster, ptyReplica, err := pty.Open()
+ if err != nil {
+ return nil, nil, fmt.Errorf("cannot create PTY: %w", err)
+ }
+ cmd := exec.CommandContext(ctx, "/bin/sh", "--noprofile", "--norc", "-i")
+ cmd.Stdin = ptyReplica
+ cmd.Stdout = ptyReplica
+ cmd.Stderr = ptyReplica
+ cmd.SysProcAttr = &syscall.SysProcAttr{
+ Setsid: true,
+ Setctty: true,
+ Ctty: 0,
+ }
+ cmd.Env = append(cmd.Env, fmt.Sprintf("PS1=%s", Prompt))
+ if err := cmd.Start(); err != nil {
+ return nil, nil, fmt.Errorf("cannot start shell: %w", err)
+ }
+ s := &Shell{
+ cmd: cmd,
+ cmdFinished: make(chan struct{}),
+ ptyMaster: ptyMaster,
+ ptyReplica: ptyReplica,
+ readCh: make(chan byteOrError, 1<<20),
+ logger: logger,
+ }
+ s.logf("creation", "Shell spawned.")
+ go s.monitorExit()
+ go s.reader(ctx)
+ setupCtx, setupCancel := context.WithTimeout(ctx, 5*time.Second)
+ defer setupCancel()
+ // We expect to see the prompt immediately on startup,
+ // since the shell is started in interactive mode.
+ if err := s.ExpectPrompt(setupCtx); err != nil {
+ s.cleanup()
+ return nil, nil, fmt.Errorf("did not get initial prompt: %w", err)
+ }
+ s.logf("creation", "Initial prompt observed.")
+ // Get initial TTY settings.
+ if err := s.RefreshSTTY(setupCtx, Prompt); err != nil {
+ s.cleanup()
+ return nil, nil, fmt.Errorf("cannot get initial STTY settings: %w", err)
+ }
+ return s, s.cleanup, nil
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 11:56:42 +0000