qemu-ga patch queue for hard-freeze

* fix erroneously reporting stale hostname in guest-get-host-name
 * fix regression where guest-shutdown asserts when called
 * fix race condition with guest-fs-freeze/thaw on w32
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Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2020-07-13-tag' into staging

qemu-ga patch queue for hard-freeze

* fix erroneously reporting stale hostname in guest-get-host-name
* fix regression where guest-shutdown asserts when called
* fix race condition with guest-fs-freeze/thaw on w32

# gpg: Signature made Tue 14 Jul 2020 05:47:11 BST
# gpg:                using RSA key CEACC9E15534EBABB82D3FA03353C9CEF108B584
# gpg:                issuer "mdroth@linux.vnet.ibm.com"
# gpg: Good signature from "Michael Roth <flukshun@gmail.com>" [full]
# gpg:                 aka "Michael Roth <mdroth@utexas.edu>" [full]
# gpg:                 aka "Michael Roth <mdroth@linux.vnet.ibm.com>" [full]
# Primary key fingerprint: CEAC C9E1 5534 EBAB B82D  3FA0 3353 C9CE F108 B584

* remotes/mdroth/tags/qga-pull-2020-07-13-tag:
  qga: Use qemu_get_host_name() instead of g_get_host_name()
  util: Introduce qemu_get_host_name()
  qga: fix assert regression on guest-shutdown
  qga-win: Fix QGA VSS Provider service stop failure

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/qemu/osdep.h

@@ -655,4 +655,14 @@ static inline void qemu_reset_optind(void)
 #endif
 }
 
+/**
+ * qemu_get_host_name:
+ * @errp: Error object
+ *
+ * Operating system agnostic way of querying host name.
+ *
+ * Returns allocated hostname (caller should free), NULL on failure.
+ */
+char *qemu_get_host_name(Error **errp);
+
 #endif

qga/commands.c

@@ -515,11 +515,20 @@ int ga_parse_whence(GuestFileWhence *whence, Error **errp)
 GuestHostName *qmp_guest_get_host_name(Error **errp)
 {
     GuestHostName *result = NULL;
-    gchar const *hostname = g_get_host_name();
-    if (hostname != NULL) {
-        result = g_new0(GuestHostName, 1);
-        result->host_name = g_strdup(hostname);
+    g_autofree char *hostname = qemu_get_host_name(errp);
+
+    /*
+     * We want to avoid using g_get_host_name() because that
+     * caches the result and we wouldn't reflect changes in the
+     * host name.
+     */
+
+    if (!hostname) {
+        hostname = g_strdup("localhost");
     }
+
+    result = g_new0(GuestHostName, 1);
+    result->host_name = g_steal_pointer(&hostname);
     return result;
 }
 

qga/main.c

@@ -531,7 +531,11 @@ static int send_response(GAState *s, const QDict *rsp)
     QString *payload_qstr, *response_qstr;
     GIOStatus status;
 
-    g_assert(rsp && s->channel);
+    g_assert(s->channel);
+
+    if (!rsp) {
+        return 0;
+    }
 
     payload_qstr = qobject_to_json(QOBJECT(rsp));
     if (!payload_qstr) {

qga/vss-win32/install.cpp

@@ -19,6 +19,7 @@
 #include <comdef.h>
 #include <comutil.h>
 #include <sddl.h>
+#include <winsvc.h>
 
 #define BUFFER_SIZE 1024
 
@@ -509,26 +510,32 @@ namespace _com_util
     }
 }
 
-/* Stop QGA VSS provider service from COM+ Application Admin Catalog */
-
+/* Stop QGA VSS provider service using Winsvc API  */
 STDAPI StopService(void)
 {
     HRESULT hr;
-    COMInitializer initializer;
-    COMPointer<IUnknown> pUnknown;
-    COMPointer<ICOMAdminCatalog2> pCatalog;
+    SC_HANDLE manager = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS);
+    SC_HANDLE service = NULL;
 
-    int count = 0;
+    if (!manager) {
+        errmsg(E_FAIL, "Failed to open service manager");
+        hr = E_FAIL;
+        goto out;
+    }
+    service = OpenService(manager, QGA_PROVIDER_NAME, SC_MANAGER_ALL_ACCESS);
 
-    chk(QGAProviderFind(QGAProviderCount, (void *)&count));
-    if (count) {
-        chk(CoCreateInstance(CLSID_COMAdminCatalog, NULL, CLSCTX_INPROC_SERVER,
-            IID_IUnknown, (void **)pUnknown.replace()));
-        chk(pUnknown->QueryInterface(IID_ICOMAdminCatalog2,
-            (void **)pCatalog.replace()));
-        chk(pCatalog->ShutdownApplication(_bstr_t(QGA_PROVIDER_LNAME)));
+    if (!service) {
+        errmsg(E_FAIL, "Failed to open service");
+        hr =  E_FAIL;
+        goto out;
+    }
+    if (!(ControlService(service, SERVICE_CONTROL_STOP, NULL))) {
+        errmsg(E_FAIL, "Failed to stop service");
+        hr = E_FAIL;
     }
 
 out:
+    CloseServiceHandle(service);
+    CloseServiceHandle(manager);
     return hr;
 }

util/oslib-posix.c

@@ -794,3 +794,38 @@ void sigaction_invoke(struct sigaction *action,
     }
     action->sa_sigaction(info->ssi_signo, &si, NULL);
 }
+
+#ifndef HOST_NAME_MAX
+# ifdef _POSIX_HOST_NAME_MAX
+#  define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
+# else
+#  define HOST_NAME_MAX 255
+# endif
+#endif
+
+char *qemu_get_host_name(Error **errp)
+{
+    long len = -1;
+    g_autofree char *hostname = NULL;
+
+#ifdef _SC_HOST_NAME_MAX
+    len = sysconf(_SC_HOST_NAME_MAX);
+#endif /* _SC_HOST_NAME_MAX */
+
+    if (len < 0) {
+        len = HOST_NAME_MAX;
+    }
+
+    /* Unfortunately, gethostname() below does not guarantee a
+     * NULL terminated string. Therefore, allocate one byte more
+     * to be sure. */
+    hostname = g_new0(char, len + 1);
+
+    if (gethostname(hostname, len) < 0) {
+        error_setg_errno(errp, errno,
+                         "cannot get hostname");
+        return NULL;
+    }
+
+    return g_steal_pointer(&hostname);
+}

util/oslib-win32.c

@@ -808,3 +808,16 @@ bool qemu_write_pidfile(const char *filename, Error **errp)
     }
     return true;
 }
+
+char *qemu_get_host_name(Error **errp)
+{
+    wchar_t tmp[MAX_COMPUTERNAME_LENGTH + 1];
+    DWORD size = G_N_ELEMENTS(tmp);
+
+    if (GetComputerNameW(tmp, &size) == 0) {
+        error_setg_win32(errp, GetLastError(), "failed close handle");
+        return NULL;
+    }
+
+    return g_utf16_to_utf8(tmp, size, NULL, NULL, NULL);
+}