[PATCH v1] libxl: adjust handling of libxl_device_disk objects

[Olaf Hering]

libxl objects are supposed to be initialized and disposed.
Correct the usage of libxl_device_disk objects which are allocated on
the stack. Initialize each one prior usage, and dispose them once done.

Adjust libxlMakeDisk to use an already initialized object, it is owned
by the caller.

Adjust libxlMakeDiskList to initialize the list of objects, before they
are filled by libxlMakeDisk. In case of error, the objects are disposed
by libxl_domain_config_dispose.

The usage of g_new0 is suspicious in the context of libxl because the
memory allocated via glib is released with plain free() inside libxl.

Signed-off-by: Olaf Hering <olaf at aepfle.de>
---
 src/libxl/libxl_conf.c   | 22 +++++++++-------------
 src/libxl/libxl_driver.c |  6 ++++++
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index 3149ee3b4a..2d2aab7e66 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -1114,8 +1114,6 @@ libxlMakeDisk(virDomainDiskDef *l_disk, libxl_device_disk *x_disk)
     int format = virDomainDiskGetFormat(l_disk);
     int actual_type = virStorageSourceGetActualType(l_disk->src);
 
-    libxl_device_disk_init(x_disk);
-
     if (actual_type == VIR_STORAGE_TYPE_NETWORK) {
         if (STRNEQ_NULLABLE(driver, "qemu")) {
             virReportError(VIR_ERR_OPERATION_INVALID, "%s",
@@ -1265,26 +1263,24 @@ libxlMakeDiskList(virDomainDef *def, libxl_domain_config *d_config)
 {
     virDomainDiskDef **l_disks = def->disks;
     int ndisks = def->ndisks;
-    libxl_device_disk *x_disks;
     size_t i;
+    int ret = -1;
+
+    d_config->disks = g_new0(libxl_device_disk, ndisks);
+    d_config->num_disks = ndisks;
 
-    x_disks = g_new0(libxl_device_disk, ndisks);
+    for (i = 0; i < ndisks; i++)
+        libxl_device_disk_init(&d_config->disks[i]);
 
     for (i = 0; i < ndisks; i++) {
-        if (libxlMakeDisk(l_disks[i], &x_disks[i]) < 0)
+        if (libxlMakeDisk(l_disks[i], &d_config->disks[i]) < 0)
             goto error;
     }
 
-    d_config->disks = x_disks;
-    d_config->num_disks = ndisks;
-
-    return 0;
+    ret = 0;
 
  error:
-    for (i = 0; i < ndisks; i++)
-        libxl_device_disk_dispose(&x_disks[i]);
-    VIR_FREE(x_disks);
-    return -1;
+    return ret;
 }
 
 /*
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index d54cd41785..2b844bb3b5 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -2978,6 +2978,7 @@ libxlDomainChangeEjectableMedia(virDomainObj *vm, virDomainDiskDef *disk)
     size_t i;
     int ret = -1;
 
+    libxl_device_disk_init(&x_disk);
     for (i = 0; i < vm->def->ndisks; i++) {
         if (vm->def->disks[i]->bus == disk->bus &&
             STREQ(vm->def->disks[i]->dst, disk->dst)) {
@@ -3018,6 +3019,7 @@ libxlDomainChangeEjectableMedia(virDomainObj *vm, virDomainDiskDef *disk)
     ret = 0;
 
  cleanup:
+    libxl_device_disk_dispose(&x_disk);
     virObjectUnref(cfg);
     return ret;
 }
@@ -3030,6 +3032,7 @@ libxlDomainAttachDeviceDiskLive(virDomainObj *vm, virDomainDeviceDef *dev)
     libxl_device_disk x_disk;
     int ret = -1;
 
+    libxl_device_disk_init(&x_disk);
     switch (l_disk->device)  {
         case VIR_DOMAIN_DISK_DEVICE_CDROM:
             ret = libxlDomainChangeEjectableMedia(vm, l_disk);
@@ -3091,6 +3094,7 @@ libxlDomainAttachDeviceDiskLive(virDomainObj *vm, virDomainDeviceDef *dev)
     }
 
  cleanup:
+    libxl_device_disk_dispose(&x_disk);
     virObjectUnref(cfg);
     return ret;
 }
@@ -3329,6 +3333,7 @@ libxlDomainDetachDeviceDiskLive(virDomainObj *vm, virDomainDeviceDef *dev)
     int idx;
     int ret = -1;
 
+    libxl_device_disk_init(&x_disk);
     switch (dev->data.disk->device)  {
         case VIR_DOMAIN_DISK_DEVICE_DISK:
             if (dev->data.disk->bus == VIR_DOMAIN_DISK_BUS_XEN) {
@@ -3380,6 +3385,7 @@ libxlDomainDetachDeviceDiskLive(virDomainObj *vm, virDomainDeviceDef *dev)
     }
 
  cleanup:
+    libxl_device_disk_dispose(&x_disk);
     virObjectUnref(cfg);
     return ret;
 }