qemu: Be less aggressive when dropping channel source paths

In v9.7.0-rc1~130 I've shortened the path that's generated for
<channel/> source. With that, I had to adjust regex that matches
all versions of paths we have ever generated so that we can drop
them (see comment around qemuDomainChrDefDropDefaultPath()). But
as it is usually the case with regexes - they are write only. And
while I attempted to make one portion of the path optional
("/target/") I accidentally made regex accept more, which
resulted in libvirt dropping the user provided path and
generating our own instead.

Fixes: d3759d3674ab9453e5fb5a27ab6c28b8ff8d5569
Resolves: https://issues.redhat.com/browse/RHEL-20807
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>

src/qemu/qemu_domain.c

@@ -5447,7 +5447,7 @@ qemuDomainChrMatchDefaultPath(const char *prefix,
     virBufferEscapeRegex(&buf, "^%s", prefix);
     if (infix)
         virBufferEscapeRegex(&buf, "%s", infix);
-    virBufferAddLit(&buf, "/(target/)?([^/]+\\.)|(domain-[^/]+/)|([0-9]+-[^/]+/)");
+    virBufferAddLit(&buf, "/(target/)?(([^/]+\\.)|(domain-[^/]+/)|([0-9]+-[^/]+/))");
     virBufferEscapeRegex(&buf, "%s$", target);
 
     regexp = virBufferContentAndReset(&buf);

tests/qemuxml2argvdata/channel-unix-source-path.x86_64-latest.args

@@ -40,6 +40,14 @@ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
 -device '{"driver":"virtserialport","bus":"virtio-serial0.0","nr":5,"chardev":"charchannel4","id":"channel4","name":"org.qemu.guest_agent.4"}' \
 -chardev socket,id=charchannel5,fd=1729,server=on,wait=off \
 -device '{"driver":"virtserialport","bus":"virtio-serial0.0","nr":6,"chardev":"charchannel5","id":"channel5","name":"org.qemu.guest_agent.5"}' \
+-chardev socket,id=charchannel6,fd=1729,server=on,wait=off \
+-device '{"driver":"virtserialport","bus":"virtio-serial0.0","nr":7,"chardev":"charchannel6","id":"channel6","name":"org.qemu.guest_agent.6"}' \
+-chardev socket,id=charchannel7,fd=1729,server=on,wait=off \
+-device '{"driver":"virtserialport","bus":"virtio-serial0.0","nr":8,"chardev":"charchannel7","id":"channel7","name":"org.qemu.guest_agent.7"}' \
+-chardev socket,id=charchannel8,fd=1729,server=on,wait=off \
+-device '{"driver":"virtserialport","bus":"virtio-serial0.0","nr":9,"chardev":"charchannel8","id":"channel8","name":"org.qemu.guest_agent.8"}' \
+-chardev socket,id=charchannel9,fd=1729,server=on,wait=off \
+-device '{"driver":"virtserialport","bus":"virtio-serial0.0","nr":10,"chardev":"charchannel9","id":"channel9","name":"org.qemu.guest_agent.9"}' \
 -audiodev '{"id":"audio1","driver":"none"}' \
 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
 -msg timestamp=on

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

@@ -32,6 +32,22 @@
       <source mode='bind' path='/var/run/libvirt/qemu/channel/1-QEMUGuest1/org.qemu.guest_agent.5'/>
       <target type='virtio' name='org.qemu.guest_agent.5'/>
     </channel>
+    <channel type="unix">
+      <source mode="bind" path="/1-QEMUGuest1/org.qemu.guest_agent.6"/>
+      <target type="virtio" name="org.qemu.guest_agent.6" state="connected"/>
+    </channel>
+    <channel type="unix">
+      <source mode="bind" path="/tmp/1-QEMUGuest1/org.qemu.guest_agent.7"/>
+      <target type="virtio" name="org.qemu.guest_agent.7" state="connected"/>
+    </channel>
+    <channel type="unix">
+      <source mode="bind" path="/tmp/libvirt/qemu/channel/1-QEMUGuest1/org.qemu.guest_agent.8"/>
+      <target type="virtio" name="org.qemu.guest_agent.8" state="connected"/>
+    </channel>
+    <channel type="unix">
+      <source mode="bind" path="/tmp/org.qemu.guest_agent.9"/>
+      <target type="virtio" name="org.qemu.guest_agent.9" state="connected"/>
+    </channel>
     <memballoon model='none'/>
   </devices>
 </domain>

tests/qemuxml2xmloutdata/channel-unix-source-path-active.x86_64-latest.xml

@@ -54,6 +54,26 @@
       <target type='virtio' name='org.qemu.guest_agent.5'/>
       <address type='virtio-serial' controller='0' bus='0' port='6'/>
     </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/1-QEMUGuest1/org.qemu.guest_agent.6'/>
+      <target type='virtio' name='org.qemu.guest_agent.6'/>
+      <address type='virtio-serial' controller='0' bus='0' port='7'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/1-QEMUGuest1/org.qemu.guest_agent.7'/>
+      <target type='virtio' name='org.qemu.guest_agent.7'/>
+      <address type='virtio-serial' controller='0' bus='0' port='8'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/libvirt/qemu/channel/1-QEMUGuest1/org.qemu.guest_agent.8'/>
+      <target type='virtio' name='org.qemu.guest_agent.8'/>
+      <address type='virtio-serial' controller='0' bus='0' port='9'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/org.qemu.guest_agent.9'/>
+      <target type='virtio' name='org.qemu.guest_agent.9'/>
+      <address type='virtio-serial' controller='0' bus='0' port='10'/>
+    </channel>
     <input type='mouse' bus='ps2'/>
     <input type='keyboard' bus='ps2'/>
     <audio id='1' type='none'/>

tests/qemuxml2xmloutdata/channel-unix-source-path-inactive.x86_64-latest.xml

@@ -49,6 +49,26 @@
       <target type='virtio' name='org.qemu.guest_agent.5'/>
       <address type='virtio-serial' controller='0' bus='0' port='6'/>
     </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/1-QEMUGuest1/org.qemu.guest_agent.6'/>
+      <target type='virtio' name='org.qemu.guest_agent.6'/>
+      <address type='virtio-serial' controller='0' bus='0' port='7'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/1-QEMUGuest1/org.qemu.guest_agent.7'/>
+      <target type='virtio' name='org.qemu.guest_agent.7'/>
+      <address type='virtio-serial' controller='0' bus='0' port='8'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/libvirt/qemu/channel/1-QEMUGuest1/org.qemu.guest_agent.8'/>
+      <target type='virtio' name='org.qemu.guest_agent.8'/>
+      <address type='virtio-serial' controller='0' bus='0' port='9'/>
+    </channel>
+    <channel type='unix'>
+      <source mode='bind' path='/tmp/org.qemu.guest_agent.9'/>
+      <target type='virtio' name='org.qemu.guest_agent.9'/>
+      <address type='virtio-serial' controller='0' bus='0' port='10'/>
+    </channel>
     <input type='mouse' bus='ps2'/>
     <input type='keyboard' bus='ps2'/>
     <audio id='1' type='none'/>