[Libguestfs] [nbdkit PATCH 1/2] nbd: Refactor Unix socket connection
Prepare to add TCP socket support by extracting Unix socket connection
into its own function. While at it, take advantage of nbdkit's
guarantee that .config values have a lifetime longer than the plugin
(no need to malloc 'export'). No semantic change.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
plugins/nbd/nbd.c | 68 ++++++++++++++++++++++++++---------------------
1 file changed, 37 insertions(+), 31 deletions(-)
diff --git a/plugins/nbd/nbd.c b/plugins/nbd/nbd.c
index fd1855e..a826363 100644
--- a/plugins/nbd/nbd.c
+++ b/plugins/nbd/nbd.c
@@ -52,14 +52,16 @@
#include "byte-swapping.h"
#include "cleanup.h"
-static char *sockname = NULL;
-static char *export = NULL;
+/* Connect to server via absolute name of Unix socket */
+static char *sockname;
+
+/* Name of export on remote server, default '', ignored for oldstyle */
+static const char *export;
static void
nbd_unload (void)
{
free (sockname);
- free (export);
}
/* Called for each key=value passed on the command line. This plugin
@@ -75,14 +77,8 @@ nbd_config (const char *key, const char *value)
if (!sockname)
return -1;
}
- else if (strcmp (key, "export") == 0) {
- free (export);
- export = strdup (value);
- if (!export) {
- nbdkit_error ("memory failure: %m");
- return -1;
- }
- }
+ else if (strcmp (key, "export") == 0)
+ export = value;
else {
nbdkit_error ("unknown parameter '%s'", key);
return -1;
@@ -107,11 +103,7 @@ nbd_config_complete (void)
return -1;
}
if (!export)
- export = strdup ("");
- if (!export) {
- nbdkit_error ("memory failure: %m");
- return -1;
- }
+ export = "";
return 0;
}
@@ -846,33 +838,46 @@ nbd_newstyle_haggle (struct handle *h)
}
}
-/* Create the per-connection handle. */
-static void *
-nbd_open (int readonly)
+/* Connect to a Unix socket */
+static int
+nbd_connect_unix(struct handle *h)
{
- struct handle *h;
struct sockaddr_un sock = { .sun_family = AF_UNIX };
- struct old_handshake old;
- uint64_t version;
- h = calloc (1, sizeof *h);
- if (h == NULL) {
- nbdkit_error ("malloc: %m");
- return NULL;
- }
+ nbdkit_debug ("connecting to Unix socket name=%s", sockname);
h->fd = socket (AF_UNIX, SOCK_STREAM, 0);
if (h->fd < 0) {
nbdkit_error ("socket: %m");
- free (h);
- return NULL;
+ return -1;
}
+
/* We already validated length during nbd_config_complete */
assert (strlen (sockname) <= sizeof sock.sun_path);
memcpy (sock.sun_path, sockname, strlen (sockname));
if (connect (h->fd, (const struct sockaddr *) &sock, sizeof sock) < 0) {
nbdkit_error ("connect: %m");
+ return -1;
+ }
+ return 0;
+}
+
+/* Create the per-connection handle. */
+static void *
+nbd_open (int readonly)
+{
+ struct handle *h;
+ struct old_handshake old;
+ uint64_t version;
+
+ h = calloc (1, sizeof *h);
+ if (h == NULL) {
+ nbdkit_error ("malloc: %m");
+ return NULL;
+ }
+ h->fd = -1;
+
+ if (nbd_connect_unix (h) == -1)
goto err;
- }
/* old and new handshake share same meaning of first 16 bytes */
if (read_full (h->fd, &old, offsetof (struct old_handshake, exportsize))) {
@@ -972,7 +977,8 @@ nbd_open (int readonly)
return h;
err:
- close (h->fd);
+ if (h->fd >= 0)
+ close (h->fd);
free (h);
return NULL;
}
--
2.20.1