qemu: improve detection of UNIX path generated by libvirt

Currently we consider all UNIX paths with specific prefix as generated
by libvirt, but that's a wrong assumption.  Let's make the detection
better by actually checking whether the whole path matches one of the
paths that we generate or generated in the past.

The UNIX path isn't stored in config XML since libvirt-1.3.1.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1446980Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

src/qemu/qemu_domain.c

@@ -3173,24 +3173,58 @@ qemuDomainDefaultNetModel(const virDomainDef *def,
 
 
 /*
- * Clear auto generated unix socket path, i.e., the one which starts with our
- * channel directory.
+ * Clear auto generated unix socket paths:
+ *
+ * libvirt 1.2.18 and older:
+ *     {cfg->channelTargetDir}/{dom-name}.{target-name}
+ *
+ * libvirt 1.2.19 - 1.3.2:
+ *     {cfg->channelTargetDir}/domain-{dom-name}/{target-name}
+ *
+ * libvirt 1.3.3 and newer:
+ *     {cfg->channelTargetDir}/domain-{dom-id}-{short-dom-name}/{target-name}
+ *
+ * The unix socket path was stored in config XML until libvirt 1.3.0.
+ * If someone specifies the same path as we generate, they shouldn't do it.
+ *
+ * This function clears the path for migration as well, so we need to clear
+ * the path even if we are not storing it in the XML.
  */
-static void
+static int
 qemuDomainChrDefDropDefaultPath(virDomainChrDefPtr chr,
                                 virQEMUDriverPtr driver)
 {
-    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    virQEMUDriverConfigPtr cfg;
+    virBuffer buf = VIR_BUFFER_INITIALIZER;
+    char *regexp = NULL;
+    int ret = -1;
 
-    if (chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL &&
-        chr->targetType == VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_VIRTIO &&
-        chr->source->type == VIR_DOMAIN_CHR_TYPE_UNIX &&
-        chr->source->data.nix.path &&
-        STRPREFIX(chr->source->data.nix.path, cfg->channelTargetDir)) {
-        VIR_FREE(chr->source->data.nix.path);
+    if (chr->deviceType != VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL ||
+        chr->targetType != VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_VIRTIO ||
+        chr->source->type != VIR_DOMAIN_CHR_TYPE_UNIX ||
+        !chr->source->data.nix.path) {
+        return 0;
     }
 
+    cfg = virQEMUDriverGetConfig(driver);
+
+    virBufferEscapeRegex(&buf, "^%s", cfg->channelTargetDir);
+    virBufferAddLit(&buf, "/([^/]+\\.)|(domain-[^/]+/)");
+    virBufferEscapeRegex(&buf, "%s$", chr->target.name);
+
+    if (virBufferCheckError(&buf) < 0)
+        goto cleanup;
+
+    regexp = virBufferContentAndReset(&buf);
+
+    if (virStringMatch(chr->source->data.nix.path, regexp))
+        VIR_FREE(chr->source->data.nix.path);
+
+    ret = 0;
+ cleanup:
+    VIR_FREE(regexp);
     virObjectUnref(cfg);
+    return ret;
 }
 
 
@@ -3458,8 +3492,10 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
 
     /* clear auto generated unix socket path for inactive definitions */
     if ((parseFlags & VIR_DOMAIN_DEF_PARSE_INACTIVE) &&
-        dev->type == VIR_DOMAIN_DEVICE_CHR)
-        qemuDomainChrDefDropDefaultPath(dev->data.chr, driver);
+        dev->type == VIR_DOMAIN_DEVICE_CHR) {
+        if (qemuDomainChrDefDropDefaultPath(dev->data.chr, driver) < 0)
+            goto cleanup;
+    }
 
     /* forbid capabilities mode hostdev in this kind of hypervisor */
     if (dev->type == VIR_DOMAIN_DEVICE_HOSTDEV &&
@@ -4245,8 +4281,10 @@ qemuDomainDefFormatBuf(virQEMUDriverPtr driver,
             }
         }
 
-        for (i = 0; i < def->nchannels; i++)
-            qemuDomainChrDefDropDefaultPath(def->channels[i], driver);
+        for (i = 0; i < def->nchannels; i++) {
+            if (qemuDomainChrDefDropDefaultPath(def->channels[i], driver) < 0)
+                goto cleanup;
+        }
     }
 
  format:

tests/qemuxml2argvdata/qemuxml2argv-channel-unix-source-path.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc'>hvm</type>
+  </os>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/channel/QEMUGuest1.org.qemu.guest_agent.0'/>
+      <target type='virtio' name='org.qemu.guest_agent.0'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/channel/domain-QEMUGuest1/org.qemu.guest_agent.1'/>
+      <target type='virtio' name='org.qemu.guest_agent.1'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/channel/domain-1-QEMUGuest1/org.qemu.guest_agent.2'/>
+      <target type='virtio' name='org.qemu.guest_agent.2'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/channel/QEMUGuest1/org.qemu.guest_agent.3'/>
+      <target type='virtio' name='org.qemu.guest_agent.3'/>
+    </channel>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/qemuxml2xmlout-channel-unix-source-path.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <controller type='virtio-serial' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </controller>
+    <channel type='unix'>
+      <target type='virtio' name='org.qemu.guest_agent.0'/>
+      <address type='virtio-serial' controller='0' bus='0' port='1'/>
+    </channel>
+    <channel type='unix'>
+      <target type='virtio' name='org.qemu.guest_agent.1'/>
+      <address type='virtio-serial' controller='0' bus='0' port='2'/>
+    </channel>
+    <channel type='unix'>
+      <target type='virtio' name='org.qemu.guest_agent.2'/>
+      <address type='virtio-serial' controller='0' bus='0' port='3'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/channel/QEMUGuest1/org.qemu.guest_agent.3'/>
+      <target type='virtio' name='org.qemu.guest_agent.3'/>
+      <address type='virtio-serial' controller='0' bus='0' port='4'/>
+    </channel>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -551,6 +551,8 @@ mymain(void)
     DO_TEST("channel-virtio", NONE);
     DO_TEST("channel-virtio-state", NONE);
 
+    DO_TEST_FULL("channel-unix-source-path", WHEN_INACTIVE, GIC_NONE, NONE);
+
     DO_TEST("hostdev-usb-address", NONE);
     DO_TEST("hostdev-pci-address", NONE);
     DO_TEST("hostdev-vfio", NONE);