esx: Don't crash when parsing unmounted datastore

When parsing disk source in ESX driver (esxParseVMXFileName())
the datastore is traversed through trying to find matching
prefix. But not every datastore has to be mounted. In that case,
esxVI_LookupDatastoreHostMount() returns success and the returned
struct has mountInfo->path set to NULL. This can be deducted from
the following backtrace (which shows that strlen() hidden in
STRSKIP() macro was given NULL pointer).

Thread 1 "virsh" received signal SIGSEGV, Segmentation fault.
__strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:76
76		VPCMPEQ	(%rdi), %ymm0, %ymm1
(gdb) bt full
#0  __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:76
No locals.
#1  0x00007ffff7c292d7 in esxParseVMXFileName (fileName=0x5555557341d0 "/vmfs/volumes/5f64209f-c0af0aa8-70c4-e4434ba73190/msafra-RHEL9-shared-1/msafra-RHEL9-shared-1_1.vmdk", opaque=0x7fffffffcf80,
    out=0x7fffffffc738, allow_missing=false) at ../src/esx/esx_driver.c:172
        data = 0x7fffffffcf80
        propertyNameList = 0x555555738b50
        datastoreList = 0x55555573cf40
        datastore = <optimized out>
        hostMount = 0x555555733640
        datastoreName = 0x55555573e590 "mnecas-nfs-test"
        tmp = <optimized out>
        saveptr = 0x5555556a5b50 ""
        strippedFileName = 0x0
        copyOfFileName = 0x0
        directoryAndFileName = <optimized out>
        ret = -1
        __FUNCTION__ = "esxParseVMXFileName"
#2  0x00007ffff7bd47f4 in virVMXParseDisk (ctx=ctx@entry=0x7fffffffcfb0, xmlopt=xmlopt@entry=0x555555738d80, conf=conf@entry=0x5555556a5b50, device=device@entry=0, busType=<optimized out>, busType@entry=3,
    controllerOrBus=controllerOrBus@entry=1, unit=<optimized out>, def=0x7fffffffc960, vmdef=0x5555557375a0) at ../src/vmx/vmx.c:2553
        tmp = 0x0
        result = -1
        prefix = 0x5555557384d0 "scsi1:0"
        present_name = "scsi1:0.present", '\000' <repeats 16 times>
        present = true
        startConnected_name = "scsi1:0.startConnected\000\000\000\000\000\000\000\000\000"
        startConnected = true
        deviceType_name = "scsi1:0.deviceType", '\000' <repeats 13 times>
        deviceType = 0x555555737f60 "scsi-hardDisk"
        clientDevice_name = "scsi1:0.clientDevice", '\000' <repeats 11 times>
        clientDevice = false
        fileType_name = "scsi1:0.fileType", '\000' <repeats 15 times>
        fileType = 0x0
        fileName_name = "scsi1:0.fileName", '\000' <repeats 15 times>
        fileName = 0x5555557341d0 "/vmfs/volumes/5f64209f-c0af0aa8-70c4-e4434ba73190/msafra-RHEL9-shared-1/msafra-RHEL9-shared-1_1.vmdk"
        writeThrough_name = "scsi1:0.writeThrough", '\000' <repeats 11 times>
        writeThrough = false
        mode_name = "scsi1:0.mode", '\000' <repeats 19 times>
        mode = 0x0
        cleanup = <optimized out>
        __FUNCTION__ = "virVMXParseDisk"
#3  0x00007ffff7bd5f01 in virVMXParseConfig (ctx=0x7fffffffcfb0, xmlopt=0x555555738d80, caps=<optimized out>, vmx=<optimized out>) at ../src/vmx/vmx.c:1749
#4  0x00007ffff7c35319 in esxDomainGetXMLDesc (domain=<optimized out>, flags=0) at ../src/esx/esx_driver.c:2595
#5  0x00007ffff7cc4fd3 in virDomainGetXMLDesc (domain=domain@entry=0x5555557367f0, flags=flags@entry=0) at ../src/libvirt-domain.c:2898
#6  0x0000555555586cca in cmdDumpXML (ctl=0x7fffffffd1d0, cmd=0x5555556a5450) at ../tools/virsh-domain.c:10787
#7  0x00005555555bc7cb in vshCommandRun (ctl=0x7fffffffd1d0, cmd=0x5555556a5450) at ../tools/vsh.c:1383
#8  0x0000555555562fbc in main (argc=<optimized out>, argv=0x7fffffffd5c8) at ../tools/virsh.c:900

The backtrace was trimmed.

To fix this, just check whether mount path is not NULL before
passing it to STRSKIP().

Resolves: https://redhat.atlassian.net/browse/RHEL-213506
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>

src/esx/esx_driver.c

@@ -169,6 +169,9 @@ esxParseVMXFileName(const char *fileName,
             goto cleanup;
         }
 
+        if (!hostMount->mountInfo->path)
+            continue;
+
         tmp = (char *)STRSKIP(fileName, hostMount->mountInfo->path);
 
         if (!tmp)