[PATCH v3 10/15] libxl: make libxl_cd_insert "eject" + "insert"

[Wei Liu <wei.liu2@citrix.com>]

A "cdrom insert" is always processed as "eject" + "insert", with JSON
config updated in between. So that we can know the correct state of
CDROM later when we try to retrieve domain configuration: if xenstore is
"empty", then CDROM is "empty"; otherwise use the information presented
in JSON.

Note that libxl_cd_insert doesn't care about the incarnation of "empty"
state so I don't state explictly what is in xenstore.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
change in v3:
clarify "empty" in commit log
---
 tools/libxl/libxl.c |   67 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index fa7d5d5..1fdb2d8 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2662,8 +2662,9 @@ int libxl_device_disk_getinfo(libxl_ctx *ctx, uint32_t domid,
     return 0;
 }
 
-int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid, libxl_device_disk *disk,
-                       const libxl_asyncop_how *ao_how)
+static int libxl__cdrom_insert(libxl_ctx *ctx, uint32_t domid,
+                               libxl_device_disk *disk,
+                               const libxl_asyncop_how *ao_how)
 {
     AO_CREATE(ctx, domid, ao_how);
     int num = 0, i;
@@ -2774,6 +2775,68 @@ out:
     return AO_INPROGRESS;
 }
 
+/*
+ * A "cdrom insert" is always processed as "eject" + "insert", with
+ * updating JSON in between. So that we can know the current state of
+ * CDROM later when we try to retrieve domain configuration: if
+ * xenstore is "empty", then CDROM is "empty"; otherwise use the image
+ * in JSON.
+ *
+ * Note that we don't actually care about the incarnation of "empty"
+ * state so we don't state explicitly what the content in xenstore
+ * should be.
+ *
+ * In order to maintain lock hierarchy, CTX lock is taken when
+ * entering this function.
+ */
+int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid, libxl_device_disk *disk,
+                       const libxl_asyncop_how *ao_how)
+{
+    GC_INIT(ctx);
+    libxl_domain_config d_config;
+    libxl_device_disk empty;
+    int rc;
+    libxl__carefd *lock = NULL;
+
+    CTX_LOCK;
+
+    libxl_domain_config_init(&d_config);
+    libxl_device_disk_init(&empty);
+    empty.format = LIBXL_DISK_FORMAT_EMPTY;
+    empty.vdev = libxl__strdup(NOGC, disk->vdev);
+    empty.is_cdrom = 1;
+
+    rc = libxl__cdrom_insert(ctx, domid, &empty, NULL);
+    if (rc)
+        goto out;
+
+    /* Optimisation: don't insert empty disk twice, and skip
+     * manipulating JSON. */
+    if (disk->format == LIBXL_DISK_FORMAT_EMPTY)
+        goto out;
+
+    lock = libxl__lock_domain_userdata(gc, domid);
+    if (!lock) {
+        rc = ERROR_LOCK_FAIL;
+        goto out;
+    }
+    rc = libxl__get_domain_configuration(gc, domid, &d_config);
+    if (rc) goto out;
+    DEVICE_ADD(disk, disks, domid, disk, COMPARE_DISK, &d_config);
+    rc = libxl__set_domain_configuration(gc, domid, &d_config);
+    if (rc) goto out;
+    libxl__unlock_domain_userdata(lock);
+
+    rc = libxl__cdrom_insert(ctx, domid, disk, ao_how);
+
+out:
+    libxl_device_disk_dispose(&empty);
+    libxl_domain_config_dispose(&d_config);
+    CTX_UNLOCK;
+    GC_FREE;
+    return rc;
+}
+
 /* libxl__alloc_vdev only works on the local domain, that is the domain
  * where the toolstack is running */
 static char * libxl__alloc_vdev(libxl__gc *gc, void *get_vdev_user,
-- 
1.7.10.4