conf: Don't generate clashing machine names for embed driver

So far, when using the qemu:///embed driver, management
applications can't chose whether they want to register their
domains in machined or not. While having that option is certainly
desired, it will require more work. What we can do meanwhile is
to generate names that include part of hash of the root
directory. This is to ensure that if two applications using
different roots but the same domain name (and ID) start the
domain no clashing name for machined is generated.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>

src/conf/domain_conf.c

@@ -62,6 +62,7 @@
 #include "virdomainsnapshotobjlist.h"
 #include "virdomaincheckpointobjlist.h"
 #include "virutil.h"
+#include "vircrypto.h"
 
 #define VIR_FROM_THIS VIR_FROM_DOMAIN
 
@@ -31076,21 +31077,33 @@ virDomainMachineNameAppendValid(virBufferPtr buf,
 
 char *
 virDomainGenerateMachineName(const char *drivername,
+                             const char *root,
                              int id,
                              const char *name,
                              bool privileged)
 {
     virBuffer buf = VIR_BUFFER_INITIALIZER;
 
-    if (privileged) {
     virBufferAsprintf(&buf, "%s-", drivername);
-    } else {
+
+    if (root) {
+        g_autofree char *hash = NULL;
+
+        /* When two embed drivers start two domains with the same @name and @id
+         * we would generate a non-unique name. Include parts of hashed @root
+         * which guarantees uniqueness. The first 8 characters of SHA256 ought
+         * to be enough for anybody. */
+        if (virCryptoHashString(VIR_CRYPTO_HASH_SHA256, root, &hash) < 0)
+            return NULL;
+
+        virBufferAsprintf(&buf, "embed-%.8s-", hash);
+    } else if (!privileged) {
         g_autofree char *username = NULL;
         if (!(username = virGetUserName(geteuid()))) {
             virBufferFreeAndReset(&buf);
             return NULL;
         }
-        virBufferAsprintf(&buf, "%s-%s-", username, drivername);
+        virBufferAsprintf(&buf, "%s-", username);
     }
 
     virBufferAsprintf(&buf, "%d-", id);

src/conf/domain_conf.h

@@ -3649,6 +3649,7 @@ int virDomainDiskSetBlockIOTune(virDomainDiskDefPtr disk,
 
 char *
 virDomainGenerateMachineName(const char *drivername,
+                             const char *root,
                              int id,
                              const char *name,
                              bool privileged);

src/lxc/lxc_domain.c

@@ -406,7 +406,7 @@ virLXCDomainGetMachineName(virDomainDefPtr def, pid_t pid)
     }
 
     if (!ret)
-        ret = virDomainGenerateMachineName("lxc", def->id, def->name, true);
+        ret = virDomainGenerateMachineName("lxc", NULL, def->id, def->name, true);
 
     return ret;
 }

src/qemu/qemu_domain.c

@@ -16424,6 +16424,7 @@ qemuDomainGetMachineName(virDomainObjPtr vm)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
     virQEMUDriverPtr driver = priv->driver;
+    g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
     char *ret = NULL;
 
     if (vm->pid > 0) {
@@ -16433,7 +16434,8 @@ qemuDomainGetMachineName(virDomainObjPtr vm)
     }
 
     if (!ret)
-        ret = virDomainGenerateMachineName("qemu", vm->def->id, vm->def->name,
+        ret = virDomainGenerateMachineName("qemu", cfg->root,
+                                           vm->def->id, vm->def->name,
                                            virQEMUDriverIsPrivileged(driver));
 
     return ret;

tests/virsystemdtest.c

@@ -379,6 +379,7 @@ testGetMachineName(const void *opaque G_GNUC_UNUSED)
 struct testNameData {
     const char *name;
     const char *expected;
+    const char *root;
     int id;
     bool legacy;
 };
@@ -413,8 +414,8 @@ testMachineName(const void *opaque)
     int ret = -1;
     char *actual = NULL;
 
-    if (!(actual = virDomainGenerateMachineName("qemu", data->id,
-                                                data->name, true)))
+    if (!(actual = virDomainGenerateMachineName("qemu", data->root,
+                                                data->id, data->name, true)))
         goto cleanup;
 
     if (STRNEQ(actual, data->expected)) {
@@ -724,30 +725,34 @@ mymain(void)
 
     TEST_SCOPE_NEW("qemu-3-demo", "machine-qemu\\x2d3\\x2ddemo.scope");
 
-# define TEST_MACHINE(_name, _id, machinename) \
+# define TEST_MACHINE(_name, _root, _id, machinename) \
     do { \
         struct testNameData data = { \
-            .name = _name, .expected = machinename, .id = _id, \
+            .name = _name, .expected = machinename, .root = _root, .id = _id, \
         }; \
         if (virTestRun("Test scopename", testMachineName, &data) < 0) \
             ret = -1; \
     } while (0)
 
-    TEST_MACHINE("demo", 1, "qemu-1-demo");
-    TEST_MACHINE("demo-name", 2, "qemu-2-demo-name");
-    TEST_MACHINE("demo!name", 3, "qemu-3-demoname");
-    TEST_MACHINE(".demo", 4, "qemu-4-demo");
-    TEST_MACHINE("bull\U0001f4a9", 5, "qemu-5-bull");
-    TEST_MACHINE("demo..name", 6, "qemu-6-demo.name");
-    TEST_MACHINE("12345678901234567890123456789012345678901234567890123456789", 7,
+    TEST_MACHINE("demo", NULL, 1, "qemu-1-demo");
+    TEST_MACHINE("demo-name", NULL, 2, "qemu-2-demo-name");
+    TEST_MACHINE("demo!name", NULL, 3, "qemu-3-demoname");
+    TEST_MACHINE(".demo", NULL, 4, "qemu-4-demo");
+    TEST_MACHINE("bull\U0001f4a9", NULL, 5, "qemu-5-bull");
+    TEST_MACHINE("demo..name", NULL, 6, "qemu-6-demo.name");
+    TEST_MACHINE("12345678901234567890123456789012345678901234567890123456789", NULL, 7,
                  "qemu-7-123456789012345678901234567890123456789012345678901234567");
-    TEST_MACHINE("123456789012345678901234567890123456789012345678901234567890", 8,
+    TEST_MACHINE("123456789012345678901234567890123456789012345678901234567890", NULL, 8,
                  "qemu-8-123456789012345678901234567890123456789012345678901234567");
-    TEST_MACHINE("kstest-network-device-default-httpks_(c9eed63e-981e-48ec-acdc-56b3f8c5f678)", 100,
+    TEST_MACHINE("kstest-network-device-default-httpks_(c9eed63e-981e-48ec-acdc-56b3f8c5f678)",
+                 NULL, 100,
                  "qemu-100-kstest-network-device-default-httpksc9eed63e-981e-48ec");
-    TEST_MACHINE("kstest-network-device-default-httpks_(c9eed63e-981e-48ec--cdc-56b3f8c5f678)", 10,
+    TEST_MACHINE("kstest-network-device-default-httpks_(c9eed63e-981e-48ec--cdc-56b3f8c5f678)",
+                 NULL, 10,
                  "qemu-10-kstest-network-device-default-httpksc9eed63e-981e-48ec-c");
-    TEST_MACHINE("demo.-.test.", 11, "qemu-11-demo.test");
+    TEST_MACHINE("demo.-.test.", NULL, 11, "qemu-11-demo.test");
+    TEST_MACHINE("demo", "/tmp/root1", 1, "qemu-embed-0991f456-1-demo");
+    TEST_MACHINE("demo", "/tmp/root2", 1, "qemu-embed-95d47ff5-1-demo");
 
 # define TESTS_PM_SUPPORT_HELPER(name, function) \
     do { \