[Xen-devel] [PATCH 09 of 13 v6] blktap3/libblktapctl: Introduce tap-ctl-open

[Thanos Makatos <thanos.makatos@xxxxxxxxxx>]

The tapback daemon needs to tell the tapdisk which file to open.

Signed-off-by: Thanos Makatos <thanos.makatos@xxxxxxxxxx>

---
Changed since v3:
  * Introduced patch in patch series.

Changed since v4:
  * Use the type:/path/to/file instead of the minor number.

diff --git a/tools/blktap3/control/tap-ctl-open.c 
b/tools/blktap3/control/tap-ctl-open.c
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/control/tap-ctl-open.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2008, XenSource Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of XenSource Inc. nor the names of its contributors
+ *       may be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <getopt.h>
+
+#include "tap-ctl.h"
+
+int
+tap_ctl_open(const int pid, const char *params, int flags,
+             const char * prt_path, const char *secondary)
+{
+    int err;
+    tapdisk_message_t message;
+
+    memset(&message, 0, sizeof(message));
+    message.type = TAPDISK_MESSAGE_OPEN;
+    if (prt_path) {
+        if (strnlen(prt_path, TAPDISK_MESSAGE_OPEN) == TAPDISK_MESSAGE_OPEN)
+            return -ENAMETOOLONG;
+        strcpy(message.u.params.prt_path, prt_path);
+    }
+
+    message.u.params.flags = flags;
+
+    err = snprintf(message.u.params.path,
+                   sizeof(message.u.params.path) - 1, "%s", params);
+    if (err >= sizeof(message.u.params.path)) {
+        EPRINTF("name too long\n");
+        return -ENAMETOOLONG;
+    }
+
+    if (secondary) {
+        err = snprintf(message.u.params.secondary,
+                       sizeof(message.u.params.secondary) - 1, "%s",
+                       secondary);
+        if (err >= sizeof(message.u.params.secondary)) {
+            EPRINTF("secondary image name too long\n");
+            return -ENAMETOOLONG;
+        }
+    }
+
+    err = tap_ctl_connect_send_and_receive(pid, &message, NULL);
+    if (err)
+        return err;
+
+    switch (message.type) {
+    case TAPDISK_MESSAGE_OPEN_RSP:
+        break;
+    case TAPDISK_MESSAGE_ERROR:
+        err = -message.u.response.error;
+        EPRINTF("open failed: %s\n", strerror(err));
+        break;
+    default:
+        EPRINTF("got unexpected result '%s' from %d\n",
+                tapdisk_message_name(message.type), pid);
+        err = -EINVAL;
+    }
+
+    return err;
+}

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