Split qemuDomainChrInsert into two parts

Do the allocation first, then add the actual device.
The second part should never fail. This is good
for live hotplug where we don't want to remove the device
on OOM after the monitor command succeeded.

The only change in behavior is that on failure, the
vmdef->consoles array is freed, not just the first console.

src/conf/domain_conf.c

@@ -12027,15 +12027,27 @@ virDomainChrGetDomainPtrs(const virDomainDef *vmdef,
 
 
 int
-virDomainChrInsert(virDomainDefPtr vmdef,
-                   virDomainChrDefPtr chr)
+virDomainChrPreAlloc(virDomainDefPtr vmdef,
+                     virDomainChrDefPtr chr)
+{
+    virDomainChrDefPtr **arrPtr = NULL;
+    size_t *cntPtr = NULL;
+
+    virDomainChrGetDomainPtrsInternal(vmdef, chr->deviceType, &arrPtr, &cntPtr);
+
+    return VIR_REALLOC_N(*arrPtr, *cntPtr + 1);
+}
+
+void
+virDomainChrInsertPreAlloced(virDomainDefPtr vmdef,
+                             virDomainChrDefPtr chr)
 {
     virDomainChrDefPtr **arrPtr = NULL;
     size_t *cntPtr = NULL;
 
     virDomainChrGetDomainPtrsInternal(vmdef, chr->deviceType, &arrPtr, &cntPtr);
 
-    return VIR_APPEND_ELEMENT(*arrPtr, *cntPtr, chr);
+    ignore_value(VIR_APPEND_ELEMENT_INPLACE(*arrPtr, *cntPtr, chr));
 }
 
 virDomainChrDefPtr

src/conf/domain_conf.h

@@ -2652,8 +2652,11 @@ bool
 virDomainChrEquals(virDomainChrDefPtr src,
                    virDomainChrDefPtr tgt);
 int
-virDomainChrInsert(virDomainDefPtr vmdef,
-                   virDomainChrDefPtr chr);
+virDomainChrPreAlloc(virDomainDefPtr vmdef,
+                     virDomainChrDefPtr chr);
+void
+virDomainChrInsertPreAlloced(virDomainDefPtr vmdef,
+                             virDomainChrDefPtr chr);
 virDomainChrDefPtr
 virDomainChrRemove(virDomainDefPtr vmdef,
                    virDomainChrDefPtr chr);

src/libvirt_private.syms

@@ -153,7 +153,8 @@ virDomainChrDefNew;
 virDomainChrEquals;
 virDomainChrFind;
 virDomainChrGetDomainPtrs;
-virDomainChrInsert;
+virDomainChrInsertPreAlloced;
+virDomainChrPreAlloc;
 virDomainChrRemove;
 virDomainChrSerialTargetTypeFromString;
 virDomainChrSerialTargetTypeToString;

src/qemu/qemu_hotplug.c

@@ -1403,9 +1403,9 @@ int qemuDomainAttachRedirdevDevice(virQEMUDriverPtr driver,
 
 }
 
-int
-qemuDomainChrInsert(virDomainDefPtr vmdef,
-                    virDomainChrDefPtr chr)
+static int
+qemuDomainChrPreInsert(virDomainDefPtr vmdef,
+                       virDomainChrDefPtr chr)
 {
     if (chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_CONSOLE &&
         chr->targetType == VIR_DOMAIN_CHR_CONSOLE_TARGET_TYPE_SERIAL) {
@@ -1420,25 +1420,63 @@ qemuDomainChrInsert(virDomainDefPtr vmdef,
         return -1;
     }
 
-    if (virDomainChrInsert(vmdef, chr) < 0)
+    if (virDomainChrPreAlloc(vmdef, chr) < 0)
         return -1;
 
     /* Due to some crazy backcompat stuff, the first serial device is an alias
      * to the first console too. If this is the case, the definition must be
      * duplicated as first console device. */
-    if (vmdef->nserials == 1 && vmdef->nconsoles == 0) {
-        if ((!vmdef->consoles && VIR_ALLOC(vmdef->consoles) < 0) ||
-            VIR_ALLOC(vmdef->consoles[0]) < 0) {
-            virDomainChrRemove(vmdef, chr);
+    if (vmdef->nserials == 0 && vmdef->nconsoles == 0 &&
+        chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_SERIAL) {
+        if (!vmdef->consoles && VIR_ALLOC(vmdef->consoles) < 0)
+            return -1;
+
+        if (VIR_ALLOC(vmdef->consoles[0]) < 0) {
+            VIR_FREE(vmdef->consoles);
             return -1;
         }
+        vmdef->nconsoles++;
+    }
+    return 0;
+}
+
+static void
+qemuDomainChrInsertPreAlloced(virDomainDefPtr vmdef,
+                              virDomainChrDefPtr chr)
+{
+    virDomainChrInsertPreAlloced(vmdef, chr);
+    if (vmdef->nserials == 1 && vmdef->nconsoles == 0 &&
+        chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_SERIAL) {
         vmdef->nconsoles = 1;
 
         /* Create an console alias for the serial port */
         vmdef->consoles[0]->deviceType = VIR_DOMAIN_CHR_DEVICE_TYPE_CONSOLE;
         vmdef->consoles[0]->targetType = VIR_DOMAIN_CHR_CONSOLE_TARGET_TYPE_SERIAL;
     }
+}
+
+static void
+qemuDomainChrInsertPreAllocCleanup(virDomainDefPtr vmdef,
+                                   virDomainChrDefPtr chr)
+{
+    /* Remove the stub console added by qemuDomainChrPreInsert */
+    if (vmdef->nserials == 0 && vmdef->nconsoles == 1 &&
+        chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_SERIAL) {
+        VIR_FREE(vmdef->consoles[0]);
+        VIR_FREE(vmdef->consoles);
+        vmdef->nconsoles = 0;
+    }
+}
 
+int
+qemuDomainChrInsert(virDomainDefPtr vmdef,
+                    virDomainChrDefPtr chr)
+{
+    if (qemuDomainChrPreInsert(vmdef, chr) < 0) {
+        qemuDomainChrInsertPreAllocCleanup(vmdef, chr);
+        return -1;
+    }
+    qemuDomainChrInsertPreAlloced(vmdef, chr);
     return 0;
 }