Re: [PATCH 2/2] nbd: disable signals and forking on Windows builds

[Thomas Huth]

On 24/08/2020 19.02, Daniel P. Berrangé wrote:
> Disabling these parts are sufficient to get the qemu-nbd program
> compiling in a Windows build.

Maybe add:
"This also enables compilation of qemu-nbd on macOS again (which got 
disabled by accident during the conversion to the meson build system)"

> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>   meson.build |  7 ++-----
>   qemu-nbd.c  | 10 +++++++++-
>   2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/meson.build b/meson.build
> index df5bf728b5..1071871605 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -1074,12 +1074,9 @@ if have_tools
>                dependencies: [authz, block, crypto, io, qom, qemuutil], 
> install: true)
>     qemu_io = executable('qemu-io', files('qemu-io.c'),
>                dependencies: [block, qemuutil], install: true)
> -  qemu_block_tools += [qemu_img, qemu_io]
> -  if targetos == 'linux' or targetos == 'sunos' or targetos.endswith('bsd')
> -    qemu_nbd = executable('qemu-nbd', files('qemu-nbd.c'),
> +  qemu_nbd = executable('qemu-nbd', files('qemu-nbd.c'),
>                  dependencies: [block, qemuutil], install: true)
> -    qemu_block_tools += [qemu_nbd]
> -  endif
> +  qemu_block_tools += [qemu_img, qemu_io, qemu_nbd]
>   
>     subdir('storage-daemon')
>     subdir('contrib/rdmacm-mux')
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index b102874f0f..c6fd6524d3 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -155,12 +155,13 @@ QEMU_COPYRIGHT "\n"
>       , name);
>   }
>   
> +#ifndef WIN32
>   static void termsig_handler(int signum)
>   {
>       atomic_cmpxchg(&state, RUNNING, TERMINATE);
>       qemu_notify_event();
>   }
> -
> +#endif
>   
>   static int qemu_nbd_client_list(SocketAddress *saddr, QCryptoTLSCreds *tls,
>                                   const char *hostname)
> @@ -587,6 +588,7 @@ int main(int argc, char **argv)
>       unsigned socket_activation;
>       const char *pid_file_name = NULL;
>   
> +#ifndef WIN32
>       /* The client thread uses SIGTERM to interrupt the server.  A signal
>        * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
>        */
> @@ -594,6 +596,7 @@ int main(int argc, char **argv)
>       memset(&sa_sigterm, 0, sizeof(sa_sigterm));
>       sa_sigterm.sa_handler = termsig_handler;
>       sigaction(SIGTERM, &sa_sigterm, NULL);
> +#endif
>   
>   #ifdef CONFIG_POSIX

I wonder why the CONFIG_POSIX does not simply start earlier here ... I 
think you could replace your #ifndef WIN32 with #ifdef CONFIG_POSIX that 
way?

>       signal(SIGPIPE, SIG_IGN);
> @@ -896,6 +899,7 @@ int main(int argc, char **argv)
>   #endif
>   
>       if ((device && !verbose) || fork_process) {
> +#ifndef WIN32
>           int stderr_fd[2];
>           pid_t pid;
>           int ret;
> @@ -959,6 +963,10 @@ int main(int argc, char **argv)
>                */
>               exit(errors);
>           }
> +#else /* WIN32 */
> +        error_report("Unable to fork into background on Windows hosts");
> +        exit(EXIT_FAILURE);
> +#endif /* WIN32 */
>       }
>   
>       if (device != NULL && sockpath == NULL) {

 Thomas