Re: [PATCH v2 1/2] qtest: multiple fixes to socket_accept()

[Markus Armbruster <armbru@redhat.com>]

Daniel P. Berrangé <berrange@redhat.com> writes:

> If the very first iteration of the loop breaks early due to the
> dead QEMU process, 'ret' is never initialized. Furthermore the
> listener socket is not closed on success and there is no error
> message printed if timing out after all iterations are complete.
> These problems were introduced by the recent refactoring to check
> QEMU is alive.
>
> CID 1688281
> Reported-by: Markus Armbruster <armbru@redhat.com>
> Fixes: c12ad5378739 ("qtest: fail fast when QEMU terminates early")
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  tests/qtest/libqtest.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
> index 9e7a2d43a18..50487739ef9 100644
> --- a/tests/qtest/libqtest.c
> +++ b/tests/qtest/libqtest.c
> @@ -121,7 +121,7 @@ static int qtest_socket_accept(QTestState *s, int sock)
>  {
>      struct sockaddr_un addr;
>      socklen_t addrlen;
> -    int ret;
> +    int ret = -1;

You need this to make [*] work.

>      size_t i;
>  #ifndef _WIN32
>      struct timeval timeout = { .tv_sec = 0,
> @@ -147,14 +147,13 @@ static int qtest_socket_accept(QTestState *s, int sock)
       for (i = 0; i < ACCEPT_RETRIES ; i++) {
           if (!qtest_probe_child(s)) {
               fprintf(stderr,
                       "child process unexpectedly exited, skipping socket accept\n");

[*] @ret comes from the initialization above in the first iteration
only.  In later iterations, it comes from assignment [**] below.

               goto cleanup;
           }
>  
>          addrlen = sizeof(addr);
>          ret = accept(sock, (struct sockaddr *)&addr, &addrlen);

[**]

> -        if (ret == -1) {
> -            if (errno == EINTR || errno == EAGAIN) {
> -                continue;
> -            } else {
> -                fprintf(stderr, "%s failed: %s\n", __func__, strerror(errno));
> -            }
> +        if (ret == -1 && (errno == EINTR || errno == EAGAIN)) {
> +            continue;
>          }
> -        return ret;
> +        break;
> +    }
> +    if (ret == -1) {

@ret comes from [**], because the loop runs at least once
(ACCEPT_RETRIES is positive).

> +        fprintf(stderr, "%s failed: %s\n", __func__, strerror(errno));
>      }
>  
>   cleanup:

Reviewed-by: Markus Armbruster <armbru@redhat.com>