Commit 3c1fa35d authored by Eric Blake's avatar Eric Blake
Browse files

qemu-nbd: Fail earlier for -c/-d on non-linux 



Connecting to a /dev/nbdN device is a Linux-specific action.
We were already masking -c and -d from 'qemu-nbd --help' on
non-linux.  However, while -d fails with a sensible error
message, it took hunting through a couple of files to prove
that.  What's more, the code for -c doesn't fail until after
it has created a pthread and tried to open a device - possibly
even printing an error message with %m on a non-Linux platform
in spite of the comment that %m is glibc-specific.  Make the
failure happen sooner, then get rid of stubs that are no
longer needed because of the early exits.

While at it: tweak the blank newlines in --help output to be
consistent, whether or not built on Linux.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <20181215135324.152629-7-eblake@redhat.com>
Reviewed-by: default avatarRichard W.M. Jones <rjones@redhat.com>
Reviewed-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
parent 6c5c0351

nbd/client.c

+1 −17
Original line number Diff line number Diff line
@@ -1031,23 +1031,7 @@ int nbd_disconnect(int fd) 
    return 0;

}



#else

int nbd_init(int fd, QIOChannelSocket *ioc, NBDExportInfo *info,

	     Error **errp)

{

    error_setg(errp, "nbd_init is only supported on Linux");

    return -ENOTSUP;

}



int nbd_client(int fd)

{

    return -ENOTSUP;

}

int nbd_disconnect(int fd)

{

    return -ENOTSUP;

}

#endif

#endif /* __linux__ */



int nbd_send_request(QIOChannel *ioc, NBDRequest *request)

{

qemu-nbd.c

+19 −2
Original line number Diff line number Diff line
@@ -43,6 +43,12 @@ 
#include "trace/control.h"

#include "qemu-version.h"



#ifdef __linux__

#define HAVE_NBD_DEVICE 1

#else

#define HAVE_NBD_DEVICE 0

#endif



#define SOCKET_PATH                "/var/lock/qemu-nbd-%s"

#define QEMU_NBD_OPT_CACHE         256

#define QEMU_NBD_OPT_AIO           257
@@ -98,11 +104,11 @@ static void usage(const char *name) 
"                            specify tracing options\n"

"  --fork                    fork off the server process and exit the parent\n"

"                            once the server is running\n"

#ifdef __linux__

#if HAVE_NBD_DEVICE

"\n"

"Kernel NBD client support:\n"

"  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"

"  -d, --disconnect          disconnect the specified device\n"

"\n"

#endif

"\n"

"Block device options:\n"
@@ -236,6 +242,7 @@ static void termsig_handler(int signum) 
}





#if HAVE_NBD_DEVICE

static void *show_parts(void *arg)

{

    char *device = arg;
@@ -321,6 +328,7 @@ out: 
    kill(getpid(), SIGTERM);

    return (void *) EXIT_FAILURE;

}

#endif /* HAVE_NBD_DEVICE */



static int nbd_can_accept(void)

{
@@ -814,6 +822,12 @@ int main(int argc, char **argv) 
        }

    }



#if !HAVE_NBD_DEVICE

    if (disconnect || device) {

        error_report("Kernel /dev/nbdN support not available");

        exit(EXIT_FAILURE);

    }

#else /* HAVE_NBD_DEVICE */

    if (disconnect) {

        int nbdfd = open(argv[optind], O_RDWR);

        if (nbdfd < 0) {
@@ -829,6 +843,7 @@ int main(int argc, char **argv) 


        return 0;

    }

#endif



    if ((device && !verbose) || fork_process) {

        int stderr_fd[2];
@@ -1006,6 +1021,7 @@ int main(int argc, char **argv) 
    nbd_export_set_description(exp, export_description);



    if (device) {

#if HAVE_NBD_DEVICE

        int ret;



        ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
@@ -1013,6 +1029,7 @@ int main(int argc, char **argv) 
            error_report("Failed to create client thread: %s", strerror(ret));

            exit(EXIT_FAILURE);

        }

#endif

    } else {

        /* Shut up GCC warnings.  */

        memset(&client_thread, 0, sizeof(client_thread));