[Libguestfs] [PATCH 2/5] p2v: Clean up ugly implementation of --nbd option.
Richard W.M. Jones
rjones at redhat.com
Fri Feb 3 14:21:15 UTC 2017
The previous implementation was pretty ugly. This reimplements things
a bit more cleanly.
---
p2v/nbd.c | 129 ++++++++++++++++++++++++++++++++++----------------------------
1 file changed, 71 insertions(+), 58 deletions(-)
diff --git a/p2v/nbd.c b/p2v/nbd.c
index 519774f..ce90361 100644
--- a/p2v/nbd.c
+++ b/p2v/nbd.c
@@ -36,6 +36,7 @@
#include <libintl.h>
#include <sys/types.h>
#include <sys/socket.h>
+#include <assert.h>
#include "getprogname.h"
@@ -44,14 +45,24 @@
/* How long to wait for the NBD server to start (seconds). */
#define WAIT_NBD_TIMEOUT 10
-/* virt-p2v --nbd option. */
+/* List of servers specified by the --nbd option. */
enum nbd_server {
- NO_SERVER = 0,
+ /* 0 is reserved for "end of list" */
QEMU_NBD = 1,
NBDKIT = 2,
-#define NR_NBD_SERVERS 2
};
-static enum nbd_server nbd_servers[NR_NBD_SERVERS] = { QEMU_NBD, NBDKIT };
+static enum nbd_server *cmdline_servers = NULL;
+
+/* If no --nbd option is passed, we use this standard list instead.
+ * Must match the documentation in virt-p2v(1).
+ */
+static const enum nbd_server standard_servers[] =
+ { QEMU_NBD, NBDKIT, 0 };
+
+/* After testing the list of servers passed by the user, this is
+ * server we decide to use.
+ */
+static enum nbd_server use_server;
static pid_t start_qemu_nbd (int nbd_local_port, const char *device);
static pid_t start_nbdkit (int nbd_local_port, const char *device);
@@ -94,59 +105,70 @@ get_nbd_error (void)
void
set_nbd_option (const char *opt)
{
- size_t i;
- CLEANUP_FREE_STRING_LIST char **strs
- = guestfs_int_split_string (',', opt);
+ size_t i, len;
+ CLEANUP_FREE_STRING_LIST char **strs = NULL;
+
+ if (cmdline_servers != NULL)
+ error (EXIT_FAILURE, 0, _("--nbd option appears multiple times"));
+
+ strs = guestfs_int_split_string (',', opt);
if (strs == NULL)
error (EXIT_FAILURE, errno, _("malloc"));
- if (strs[0] == NULL)
+ len = guestfs_int_count_strings (strs);
+ if (len == 0)
error (EXIT_FAILURE, 0, _("--nbd option cannot be empty"));
- for (i = 0; strs[i] != NULL; ++i) {
- if (i >= NR_NBD_SERVERS)
- error (EXIT_FAILURE, 0, _("too many --nbd servers"));
+ cmdline_servers = malloc (sizeof (enum nbd_server) * (len + 1));
+ if (cmdline_servers == NULL)
+ error (EXIT_FAILURE, errno, _("malloc"));
+ for (i = 0; strs[i] != NULL; ++i) {
if (STREQ (strs[i], "qemu-nbd") || STREQ (strs[i], "qemu"))
- nbd_servers[i] = QEMU_NBD;
+ cmdline_servers[i] = QEMU_NBD;
else if (STREQ (strs[i], "nbdkit"))
- nbd_servers[i] = NBDKIT;
+ cmdline_servers[i] = NBDKIT;
else
error (EXIT_FAILURE, 0, _("--nbd: unknown server: %s"), strs[i]);
}
- for (; i < NR_NBD_SERVERS; ++i)
- nbd_servers[i] = NO_SERVER;
+ assert (i == len);
+ cmdline_servers[i] = 0; /* marks the end of the list */
}
/**
* Test the I<--nbd> option (or built-in default list) to see which
* servers are actually installed and appear to be working.
*
- * If a server is not installed we set the corresponding
- * C<nbd_servers[i] = NO_SERVER>.
+ * Set the C<use_server> global accordingly.
*/
void
test_nbd_servers (void)
{
size_t i;
int r;
+ const enum nbd_server *servers;
- for (i = 0; i < NR_NBD_SERVERS; ++i) {
- switch (nbd_servers[i]) {
- case NO_SERVER:
- /* ignore entry */
- break;
+ if (cmdline_servers != NULL)
+ servers = cmdline_servers;
+ else
+ servers = standard_servers;
+
+ use_server = 0;
+ for (i = 0; servers[i] != 0; ++i) {
+ switch (servers[i]) {
case QEMU_NBD:
r = system ("qemu-nbd --version"
#ifndef DEBUG_STDERR
" >/dev/null 2>&1"
#endif
);
- if (r != 0)
- nbd_servers[i] = NO_SERVER;
+ if (r == 0) {
+ use_server = servers[i];
+ goto finish;
+ }
break;
case NBDKIT:
@@ -155,8 +177,10 @@ test_nbd_servers (void)
" >/dev/null 2>&1"
#endif
);
- if (r != 0)
- nbd_servers[i] = NO_SERVER;
+ if (r == 0) {
+ use_server = servers[i];
+ goto finish;
+ }
break;
default:
@@ -164,52 +188,41 @@ test_nbd_servers (void)
}
}
- for (i = 0; i < NR_NBD_SERVERS; ++i)
- if (nbd_servers[i] != NO_SERVER)
- return;
+ finish:
+ if (use_server == 0) {
+ fprintf (stderr,
+ _("%s: no working NBD server was found, cannot continue.\n"
+ "Please check the --nbd option in the virt-p2v(1) man page.\n"),
+ getprogname ());
+ exit (EXIT_FAILURE);
+ }
- /* If we reach here, there are no servers left, so we have to exit. */
- fprintf (stderr,
- _("%s: no working NBD server was found, cannot continue.\n"
- "Please check the --nbd option in the virt-p2v(1) man page.\n"),
- getprogname ());
- exit (EXIT_FAILURE);
+ /* Release memory used by the --nbd option. */
+ free (cmdline_servers);
+ cmdline_servers = NULL;
}
/**
- * Start the first server found in the C<nbd_servers> list.
+ * Start the NBD server.
*
- * We previously tested all NBD servers (see C<test_nbd_servers>) so
- * we only need to run the first server in the list.
+ * We previously tested all NBD servers (see C<test_nbd_servers>) and
+ * hopefully found one which will work.
*
* Returns the process ID (E<gt> 0) or C<0> if there is an error.
*/
pid_t
start_nbd_server (int port, const char *device)
{
- size_t i;
-
- for (i = 0; i < NR_NBD_SERVERS; ++i) {
- switch (nbd_servers[i]) {
- case NO_SERVER:
- /* ignore */
- break;
+ switch (use_server) {
+ case QEMU_NBD:
+ return start_qemu_nbd (port, device);
- case QEMU_NBD:
- return start_qemu_nbd (port, device);
+ case NBDKIT:
+ return start_nbdkit (port, device);
- case NBDKIT:
- return start_nbdkit (port, device);
-
- default:
- abort ();
- }
+ default:
+ abort ();
}
-
- /* This should never happen because of the checks in
- * test_nbd_servers.
- */
- abort ();
}
/**
--
2.9.3
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