From 4c02aa46c2873eaa89060f97f28a0c41c500ff90 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Tue, 31 Mar 2020 11:15:13 +0200 Subject: attach: fix hang if control path is deleted if the control path file is deleted, libpod hangs waiting for a reader to open it. Attempt to open it as non blocking until it returns an error different than EINTR or EAGAIN. Signed-off-by: Giuseppe Scrivano --- libpod/oci_conmon_linux.go | 37 +++++++++++++++++++++++++++++-------- 1 file changed, 29 insertions(+), 8 deletions(-) (limited to 'libpod/oci_conmon_linux.go') diff --git a/libpod/oci_conmon_linux.go b/libpod/oci_conmon_linux.go index ce888c690..6a0097b8e 100644 --- a/libpod/oci_conmon_linux.go +++ b/libpod/oci_conmon_linux.go @@ -575,13 +575,36 @@ func (r *ConmonOCIRuntime) HTTPAttach(ctr *Container, httpConn net.Conn, httpBuf } } +// isRetryable returns whether the error was caused by a blocked syscall or the +// specified operation on a non blocking file descriptor wasn't ready for completion. +func isRetryable(err error) bool { + if errno, isErrno := errors.Cause(err).(syscall.Errno); isErrno { + return errno == syscall.EINTR || errno == syscall.EAGAIN + } + return false +} + +// openControlFile opens the terminal control file. +func openControlFile(ctr *Container, parentDir string) (*os.File, error) { + controlPath := filepath.Join(parentDir, "ctl") + for i := 0; i < 600; i++ { + controlFile, err := os.OpenFile(controlPath, unix.O_WRONLY|unix.O_NONBLOCK, 0) + if err == nil { + return controlFile, err + } + if !isRetryable(err) { + return nil, errors.Wrapf(err, "could not open ctl file for terminal resize for container %s", ctr.ID()) + } + time.Sleep(time.Second / 10) + } + return nil, errors.Errorf("timeout waiting for %q", controlPath) +} + // AttachResize resizes the terminal used by the given container. func (r *ConmonOCIRuntime) AttachResize(ctr *Container, newSize remotecommand.TerminalSize) error { - // TODO: probably want a dedicated function to get ctl file path? - controlPath := filepath.Join(ctr.bundlePath(), "ctl") - controlFile, err := os.OpenFile(controlPath, unix.O_WRONLY, 0) + controlFile, err := openControlFile(ctr, ctr.bundlePath()) if err != nil { - return errors.Wrapf(err, "could not open ctl file for terminal resize") + return err } defer controlFile.Close() @@ -785,11 +808,9 @@ func (r *ConmonOCIRuntime) ExecContainer(c *Container, sessionID string, options // ExecAttachResize resizes the TTY of the given exec session. func (r *ConmonOCIRuntime) ExecAttachResize(ctr *Container, sessionID string, newSize remotecommand.TerminalSize) error { - // TODO: probably want a dedicated function to get ctl file path? - controlPath := filepath.Join(ctr.execBundlePath(sessionID), "ctl") - controlFile, err := os.OpenFile(controlPath, unix.O_WRONLY, 0) + controlFile, err := openControlFile(ctr, ctr.execBundlePath(sessionID)) if err != nil { - return errors.Wrapf(err, "could not open ctl file for terminal resize for container %s exec session %s", ctr.ID(), sessionID) + return err } defer controlFile.Close() -- cgit v1.2.3-54-g00ecf