qemu: fix UNIX socket chardevs operating in client mode

When support was adding for passing a pre-opened listener socket to UNIX
chardevs, it accidentally passed the listener socket for client mode
chardevs too with predictable amounts of fail resulting. This affects
libvirt when using QEMU >= 2.12

Expand the unit test coverage to validate that we are only doing FD
passing when operating in server mode.

  https://bugzilla.redhat.com/show_bug.cgi?id=1598440

Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit 1bc1a7e320)

src/qemu/qemu_command.c

@@ -5082,7 +5082,8 @@ qemuBuildChrChardevStr(virLogManagerPtr logManager,
         break;
 
     case VIR_DOMAIN_CHR_TYPE_UNIX:
-        if ((flags & QEMU_BUILD_CHARDEV_UNIX_FD_PASS) &&
+        if (dev->data.nix.listen &&
+            (flags & QEMU_BUILD_CHARDEV_UNIX_FD_PASS) &&
             virQEMUCapsGet(qemuCaps, QEMU_CAPS_CHARDEV_FD_PASS)) {
             if (qemuSecuritySetSocketLabel(secManager, (virDomainDefPtr)def) < 0)
                 goto cleanup;

tests/qemuxml2argvdata/serial-unix-chardev.args

@@ -26,4 +26,6 @@ server,nowait \
 -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
 -chardev socket,id=charserial0,path=/tmp/serial.sock \
 -device isa-serial,chardev=charserial0,id=serial0 \
+-chardev socket,id=charserial1,path=/tmp/serial-server.sock,server,nowait \
+-device isa-serial,chardev=charserial1,id=serial1 \
 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/serial-unix-chardev.x86_64-latest.args

@@ -0,0 +1,36 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-i686 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
+-machine pc,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot strict=on \
+-device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0 \
+-device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 \
+-chardev socket,id=charserial0,path=/tmp/serial.sock \
+-device isa-serial,chardev=charserial0,id=serial0 \
+-chardev socket,id=charserial1,fd=1729,server,nowait \
+-device isa-serial,chardev=charserial1,id=serial1 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x2 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-msg timestamp=on

tests/qemuxml2argvdata/serial-unix-chardev.xml

@@ -25,6 +25,10 @@
       <source mode='connect' path='/tmp/serial.sock'/>
       <target port='0'/>
     </serial>
+    <serial type='unix'>
+      <source mode='bind' path='/tmp/serial-server.sock'/>
+      <target port='1'/>
+    </serial>
     <console type='unix'>
       <source mode='connect' path='/tmp/serial.sock'/>
       <target port='0'/>

tests/qemuxml2argvtest.c

@@ -1335,6 +1335,7 @@ mymain(void)
             QEMU_CAPS_CHARDEV_FILE_APPEND);
     DO_TEST("serial-unix-chardev",
             QEMU_CAPS_DEVICE_ISA_SERIAL);
+    DO_TEST_CAPS_LATEST("serial-unix-chardev");
     DO_TEST("serial-tcp-chardev",
             QEMU_CAPS_DEVICE_ISA_SERIAL);
     DO_TEST("serial-udp-chardev",