Re: [Qemu-devel] [PATCH 4/5] qga: handle possible SIGPIPE in guest-file-write

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Quoting Denis V. Lunev (2015-10-01 02:38:02)
> qemu-ga should not exit on guest-file-write to pipe without read end
> but proper error code should be returned. The behavior of the
> spawned process should be default thus SIGPIPE processing should be
> reset to default after fork() but before exec().
> 
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Signed-off-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
> CC: Michael Roth <mdroth@linux.vnet.ibm.com>

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>

> ---
>  qga/commands.c | 18 +++++++++++++++++-
>  qga/main.c     |  6 ++++++
>  2 files changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/qga/commands.c b/qga/commands.c
> index 6efd6aa..199c7c3 100644
> --- a/qga/commands.c
> +++ b/qga/commands.c
> @@ -194,6 +194,22 @@ static void guest_exec_child_watch(GPid pid, gint status, gpointer data)
>      g_spawn_close_pid(pid);
>  }
> 
> +/** Reset ignored signals back to default. */
> +static void guest_exec_task_setup(gpointer data)
> +{
> +#if !defined(G_OS_WIN32)
> +    struct sigaction sigact;
> +
> +    memset(&sigact, 0, sizeof(struct sigaction));
> +    sigact.sa_handler = SIG_DFL;
> +
> +    if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
> +        slog("sigaction() failed to reset child process's SIGPIPE: %s",
> +             strerror(errno));
> +    }
> +#endif
> +}
> +
>  GuestExec *qmp_guest_exec(const char *path,
>                         bool has_arg, strList *arg,
>                         bool has_env, strList *env,
> @@ -219,7 +235,7 @@ GuestExec *qmp_guest_exec(const char *path,
>              G_SPAWN_SEARCH_PATH |
>              G_SPAWN_DO_NOT_REAP_CHILD |
>              G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL,
> -            NULL, NULL, &pid, NULL, NULL, NULL, &gerr);
> +            guest_exec_task_setup, NULL, &pid, NULL, NULL, NULL, &gerr);
>      if (!ret) {
>          error_setg(err, QERR_QGA_COMMAND_FAILED, gerr->message);
>          g_error_free(gerr);
> diff --git a/qga/main.c b/qga/main.c
> index d8e063a..07e3c1c 100644
> --- a/qga/main.c
> +++ b/qga/main.c
> @@ -161,6 +161,12 @@ static gboolean register_signal_handlers(void)
>          g_error("error configuring signal handler: %s", strerror(errno));
>      }
> 
> +    sigact.sa_handler = SIG_IGN;
> +    if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
> +        g_error("error configuring SIGPIPE signal handler: %s",
> +                strerror(errno));
> +    }
> +
>      return true;
>  }
> 
> -- 
> 2.1.4
>