* src/driver.h src/libvirt.c src/openvz_driver.c src/qemu_driver.c

  src/remote_internal.c src/test.c src/util.c src/util.h
  src/xen_unified.c: added probe interface at the driver level,
  use that to improve default hypervisor selection in the absence
  of a given URI when connecting
Daniel

ChangeLog

+Tue Feb 26 08:02:57 CET 2008 Daniel Veillard <veillard@redhat.com>
+
+	* src/driver.h src/libvirt.c src/openvz_driver.c src/qemu_driver.c
+	  src/remote_internal.c src/test.c src/util.c src/util.h
+	  src/xen_unified.c: added probe interface at the driver level,
+	  use that to improve default hypervisor selection in the absence
+	  of a given URI when connecting
+
 Mon Feb 25 14:53:59 CET 2008 Daniel Veillard <veillard@redhat.com>
 
 	* src/Makefile.am src/util-lib.h: fix done with Jim to allow

src/driver.h

@@ -69,6 +69,8 @@ typedef enum {
 #define VIR_DRV_SUPPORTS_FEATURE(drv,conn,feature)                      \
     ((drv)->supports_feature ? (drv)->supports_feature((conn),(feature)) : 0)
 
+typedef const char *
+	(*virDrvProbe)			(void);
 typedef virDrvOpenStatus
 	(*virDrvOpen)			(virConnectPtr conn,
                              xmlURIPtr uri,
@@ -277,62 +279,63 @@ typedef unsigned long long
  *  - close
  */
 struct _virDriver {
-	int	       no;	/* the number virDrvNo */
-	const char * name;	/* the name of the driver */
-	unsigned long ver;	/* the version of the backend */
-	virDrvOpen			open;
-	virDrvClose			close;
+    int	       no;	/* the number virDrvNo */
+    const char * name;	/* the name of the driver */
+    unsigned long ver;	/* the version of the backend */
+    virDrvProbe			probe;
+    virDrvOpen			open;
+    virDrvClose			close;
     virDrvSupportsFeature   supports_feature;
-	virDrvGetType			type;
-	virDrvGetVersion		version;
+    virDrvGetType			type;
+    virDrvGetVersion		version;
     virDrvGetHostname       getHostname;
     virDrvGetURI            getURI;
-	virDrvGetMaxVcpus		getMaxVcpus;
-	virDrvNodeGetInfo		nodeGetInfo;
-	virDrvGetCapabilities		getCapabilities;
-	virDrvListDomains		listDomains;
-	virDrvNumOfDomains		numOfDomains;
-	virDrvDomainCreateLinux		domainCreateLinux;
-	virDrvDomainLookupByID		domainLookupByID;
-	virDrvDomainLookupByUUID	domainLookupByUUID;
-	virDrvDomainLookupByName	domainLookupByName;
-	virDrvDomainSuspend		domainSuspend;
-	virDrvDomainResume		domainResume;
-	virDrvDomainShutdown		domainShutdown;
-	virDrvDomainReboot		domainReboot;
-	virDrvDomainDestroy		domainDestroy;
-	virDrvDomainGetOSType		domainGetOSType;
-	virDrvDomainGetMaxMemory	domainGetMaxMemory;
-	virDrvDomainSetMaxMemory	domainSetMaxMemory;
-	virDrvDomainSetMemory		domainSetMemory;
-	virDrvDomainGetInfo		domainGetInfo;
-	virDrvDomainSave		domainSave;
-	virDrvDomainRestore		domainRestore;
-	virDrvDomainCoreDump		domainCoreDump;
-	virDrvDomainSetVcpus		domainSetVcpus;
-	virDrvDomainPinVcpu		domainPinVcpu;
-	virDrvDomainGetVcpus		domainGetVcpus;
-	virDrvDomainGetMaxVcpus		domainGetMaxVcpus;
-	virDrvDomainDumpXML		domainDumpXML;
-	virDrvListDefinedDomains	listDefinedDomains;
-	virDrvNumOfDefinedDomains	numOfDefinedDomains;
-	virDrvDomainCreate		domainCreate;
-	virDrvDomainDefineXML           domainDefineXML;
-	virDrvDomainUndefine            domainUndefine;
-	virDrvDomainAttachDevice	domainAttachDevice;
-	virDrvDomainDetachDevice	domainDetachDevice;
-	virDrvDomainGetAutostart	domainGetAutostart;
-	virDrvDomainSetAutostart	domainSetAutostart;
-	virDrvDomainGetSchedulerType	domainGetSchedulerType;
-	virDrvDomainGetSchedulerParameters domainGetSchedulerParameters;
-	virDrvDomainSetSchedulerParameters domainSetSchedulerParameters;
+    virDrvGetMaxVcpus		getMaxVcpus;
+    virDrvNodeGetInfo		nodeGetInfo;
+    virDrvGetCapabilities		getCapabilities;
+    virDrvListDomains		listDomains;
+    virDrvNumOfDomains		numOfDomains;
+    virDrvDomainCreateLinux		domainCreateLinux;
+    virDrvDomainLookupByID		domainLookupByID;
+    virDrvDomainLookupByUUID	domainLookupByUUID;
+    virDrvDomainLookupByName	domainLookupByName;
+    virDrvDomainSuspend		domainSuspend;
+    virDrvDomainResume		domainResume;
+    virDrvDomainShutdown		domainShutdown;
+    virDrvDomainReboot		domainReboot;
+    virDrvDomainDestroy		domainDestroy;
+    virDrvDomainGetOSType		domainGetOSType;
+    virDrvDomainGetMaxMemory	domainGetMaxMemory;
+    virDrvDomainSetMaxMemory	domainSetMaxMemory;
+    virDrvDomainSetMemory		domainSetMemory;
+    virDrvDomainGetInfo		domainGetInfo;
+    virDrvDomainSave		domainSave;
+    virDrvDomainRestore		domainRestore;
+    virDrvDomainCoreDump		domainCoreDump;
+    virDrvDomainSetVcpus		domainSetVcpus;
+    virDrvDomainPinVcpu		domainPinVcpu;
+    virDrvDomainGetVcpus		domainGetVcpus;
+    virDrvDomainGetMaxVcpus		domainGetMaxVcpus;
+    virDrvDomainDumpXML		domainDumpXML;
+    virDrvListDefinedDomains	listDefinedDomains;
+    virDrvNumOfDefinedDomains	numOfDefinedDomains;
+    virDrvDomainCreate		domainCreate;
+    virDrvDomainDefineXML           domainDefineXML;
+    virDrvDomainUndefine            domainUndefine;
+    virDrvDomainAttachDevice	domainAttachDevice;
+    virDrvDomainDetachDevice	domainDetachDevice;
+    virDrvDomainGetAutostart	domainGetAutostart;
+    virDrvDomainSetAutostart	domainSetAutostart;
+    virDrvDomainGetSchedulerType	domainGetSchedulerType;
+    virDrvDomainGetSchedulerParameters domainGetSchedulerParameters;
+    virDrvDomainSetSchedulerParameters domainSetSchedulerParameters;
     virDrvDomainMigratePrepare	domainMigratePrepare;
     virDrvDomainMigratePerform	domainMigratePerform;
     virDrvDomainMigrateFinish	domainMigrateFinish;
     virDrvDomainBlockStats      domainBlockStats;
     virDrvDomainInterfaceStats  domainInterfaceStats;
-	virDrvNodeGetCellsFreeMemory	nodeGetCellsFreeMemory;
-	virDrvNodeGetFreeMemory		getFreeMemory;
+    virDrvNodeGetCellsFreeMemory	nodeGetCellsFreeMemory;
+    virDrvNodeGetFreeMemory		getFreeMemory;
 };
 
 typedef int

src/libvirt.c

@@ -632,9 +632,47 @@ do_open (const char *name,
     virConnectPtr ret = NULL;
     xmlURIPtr uri;
 
-    /* Convert NULL or "" to xen:/// for back compat */
-    if (!name || name[0] == '\0')
-        name = "xen:///";
+    /*
+     *  If no URI is passed, then check for an environment string if not
+     *  available probe the compiled in drivers to find a default hypervisor
+     *  if detectable.
+     */
+    if (!name || name[0] == '\0') {
+        char *defname = getenv("LIBVIRT_DEFAULT_URI");
+        if (defname && *defname) {
+	    DEBUG("Using LIBVIRT_DEFAULT_URI %s", defname);
+            name = defname;
+        } else {
+	    const char *use = NULL;
+	    const char *latest;
+	    int probes = 0;
+	    for (i = 0; i < virNetworkDriverTabCount; i++) {
+	        if ((virDriverTab[i]->probe != NULL) &&
+		    ((latest = virDriverTab[i]->probe()) != NULL)) {
+		    probes++;
+
+		    DEBUG("Probed %s", latest);
+		    /*
+		     * if running a xen kernel, give it priority over
+		     * QEmu emultation
+		     */
+		    if (STREQ(latest, "xen:///")) 
+		        use = latest;
+		    else if (use == NULL)
+		        use = latest;
+		}
+	    }
+	    if (use == NULL) {
+		name = "xen:///";
+	        DEBUG("Could not probe any hypervisor defaulting to %s",
+		      name);
+	    } else {
+		name = use;
+	        DEBUG("Using %s as default URI, %d hypervisor found",
+		      use, probes);
+	    }
+	}
+    }
 
     /* Convert xen -> xen:/// for back compat */
     if (!strcasecmp(name, "xen"))

src/openvz_driver.c

@@ -546,6 +546,15 @@ bail_out5:
     return ret;
 }
 
+static const char *openvzProbe(void)
+{
+#ifdef __linux__
+    if ((getuid() == 0) && (virFileExists("/proc/vz")))
+        return("openvz:///");
+#endif
+    return(NULL);
+}
+
 static virDrvOpenStatus openvzOpen(virConnectPtr conn,
                                  xmlURIPtr uri,
                                  virConnectAuthPtr auth ATTRIBUTE_UNUSED,
@@ -694,6 +703,7 @@ static virDriver openvzDriver = {
     VIR_DRV_OPENVZ,
     "OPENVZ",
     LIBVIR_VERSION_NUMBER,
+    openvzProbe, /* probe */
     openvzOpen, /* open */
     openvzClose, /* close */
     NULL, /* supports_feature */

src/qemu_driver.c

@@ -1388,6 +1388,25 @@ static int qemudMonitorCommand(struct qemud_driver *driver ATTRIBUTE_UNUSED,
     return -1;
 }
 
+/**
+ * qemudProbe:
+ *
+ * Probe for the availability of the qemu driver, assume the
+ * presence of QEmu emulation if the binaries are installed
+ */
+static const char *qemudProbe(void)
+{
+    if ((virFileExists("/usr/bin/qemu")) ||
+        (virFileExists("/usr/bin/qemu-kvm")) ||
+	(virFileExists("/usr/bin/xenner"))) {
+        if (getuid() == 0) {
+	    return("qemu:///system");
+	} else {
+	    return("qemu:///session");
+	}
+    }
+    return(NULL);
+}
 
 static virDrvOpenStatus qemudOpen(virConnectPtr conn,
                                   xmlURIPtr uri,
@@ -2859,6 +2878,7 @@ static virDriver qemuDriver = {
     VIR_DRV_QEMU,
     "QEMU",
     LIBVIR_VERSION_NUMBER,
+    qemudProbe, /* probe */
     qemudOpen, /* open */
     qemudClose, /* close */
     NULL, /* supports_feature */

src/remote_internal.c

@@ -4599,6 +4599,7 @@ static virDriver driver = {
     .no = VIR_DRV_REMOTE,
     .name = "remote",
     .ver = REMOTE_PROTOCOL_VERSION,
+    .probe = NULL,
     .open = remoteOpen,
     .close = remoteClose,
     .supports_feature = remoteSupportsFeature,

src/test.c

@@ -1939,6 +1939,7 @@ static virDriver testDriver = {
     VIR_DRV_TEST,
     "Test",
     LIBVIR_VERSION_NUMBER,
+    NULL, /* probe */
     testOpen, /* open */
     testClose, /* close */
     NULL, /* supports_feature */

src/util.c

@@ -463,6 +463,15 @@ virFileLinkPointsTo (const char *checkLink ATTRIBUTE_UNUSED,
 
 #endif /*! __MINGW32__ */
 
+int virFileExists(const char *path)
+{
+    struct stat st;
+
+    if (stat(path, &st) >= 0)
+        return(1);
+    return(0);
+}
+
 int virFileMakePath(const char *path)
 {
     struct stat st;

src/util.h

@@ -47,6 +47,9 @@ int virFileHasSuffix(const char *str,
 
 int virFileLinkPointsTo(const char *checkLink,
                         const char *checkDest);
+
+int virFileExists(const char *path);
+
 int virFileMakePath(const char *path);
 
 int virFileBuildPath(const char *dir,

src/xen_unified.c

@@ -39,6 +39,7 @@
 #include "xs_internal.h"
 #include "xm_internal.h"
 #include "xml.h"
+#include "util.h"
 
 #define DEBUG(fmt,...) VIR_DEBUG(__FILE__, fmt,__VA_ARGS__)
 
@@ -217,6 +218,24 @@ done:
  * in the low level drivers directly.
  */
 
+static const char *
+xenUnifiedProbe (void)
+{
+#ifdef __linux__
+    if (virFileExists("/proc/xen"))
+        return("xen:///");
+#endif
+#ifdef __sun__
+    FILE *fh;
+
+    if (fh = fopen("/dev/xen/domcaps", "r")) {
+	fclose(fh);
+        return("xen:///");
+    }
+#endif
+    return(NULL);
+}
+
 static int
 xenUnifiedOpen (virConnectPtr conn, xmlURIPtr uri, virConnectAuthPtr auth, int flags)
 {
@@ -1198,6 +1217,7 @@ static virDriver xenUnifiedDriver = {
     .no = VIR_DRV_XEN_UNIFIED,
     .name = "Xen",
     .ver = HV_VERSION,
+    .probe 			= xenUnifiedProbe,
     .open 			= xenUnifiedOpen,
     .close 			= xenUnifiedClose,
     .supports_feature   = xenUnifiedSupportsFeature,