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attach: fix hang if control path is deleted

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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 <gscrivan@redhat.com>
This commit is contained in:
Giuseppe Scrivano
2020-03-31 11:15:13 +02:00
parent 88455fe704
commit 4c02aa46c2
2 changed files with 41 additions and 8 deletions
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37
libpod/oci_conmon_linux.go
View File

@@ -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()