Changeset 98474 in vbox for trunk/src/VBox/Additions/x11/VBoxClient/display-svga-session.cpp

Timestamp:

Feb 3, 2023 7:20:53 PM (22 months ago)

Author:

vboxsync

Message:

Additions: X11: Add possibility restart VBoxClient processes during Guest Additions update, bugref:10359.

This commit makes VBoxClient processes to temporary release reference to vboxguest kernel module and then
restart itself. So module can be reloaded and newly started VBoxClient instance will utilize updated module.

When VBoxClient starts in demonized mode, it forks a child process which represents actual service. Parent
process continues to run and its main function is to restart child when it crashes or terminates with exit
status != 0. This commit makes child process to catch SIGUSR1 and terminate with exit
status VBGLR3EXITCODERELOAD (currently equal to 2). Parent process will detect this and in turn will release
its reference to vboxguest kernel module, allowing to reload it. The parent process will then wait for SIGUSR1
itself. Once received, it will restart itself (loading new, updated VBoxClient process image). This is a part
of the procedure to install and reload/restart Guest Additions kernel modules and user services without
requiring guest reboot.

File:

• trunk/src/VBox/Additions/x11/VBoxClient/display-svga-session.cpp (modified) (6 diffs)

trunk/src/VBox/Additions/x11/VBoxClient/display-svga-session.cpp

@@ -46 +46 @@
  *
  * Multiple instances of this daemon are allowed to run in parallel
- * with the following limitations (see also vbclSVGASessionPidFileLock()).
+ * with the following limitations.
  * A single user cannot run multiple daemon instances per single TTY device,
  * however, multiple instances are allowed for the user on different
@@ -67 +67 @@
 #include <iprt/linux/sysfs.h>
 
-/** Lock file handle. */
-static RTFILE g_hPidFile;
-/** Full path to PID lock file. */
-static char g_szPidFilePath[RTPATH_MAX];
 
 /** Handle to IPC client connection. */
@@ -117 +113 @@
 
 /**
- * Prevent multiple instances of the service from start.
- *
- * @returns IPRT status code.
- */
-static int vbclSVGASessionPidFileLock(void)
-{
-    int rc;
-
-    /* Allow parallel running instances of the service for processes
-     * which are running in separate X11/Wayland sessions. Compose
-     * custom PID file name based on currently active TTY device. */
-
-    char *pszPidFileName = RTStrAlloc(RTPATH_MAX);
-    if (pszPidFileName)
-    {
-        rc = RTPathUserHome(g_szPidFilePath, sizeof(g_szPidFilePath));
-        if (RT_SUCCESS(rc))
-        {
-            char pszActiveTTY[128];
-            size_t cchRead;
-
-            RT_ZERO(pszActiveTTY);
-
-            RTStrAAppend(&pszPidFileName, ".vboxclient-vmsvga-session");
-
-            rc = RTLinuxSysFsReadStrFile(pszActiveTTY, sizeof(pszActiveTTY) - 1 /* reserve last byte for string termination */,
-                                         &cchRead, "class/tty/tty0/active");
-            if (RT_SUCCESS(rc))
-            {
-                RTStrAAppend(&pszPidFileName, "-");
-                RTStrAAppend(&pszPidFileName, pszActiveTTY);
-            }
-            else
-                VBClLogInfo("cannot detect currently active tty device, "
-                            "multiple service instances for a single user will not be allowed, rc=%Rrc", rc);
-
-            RTStrAAppend(&pszPidFileName, ".pid");
-
-            RTPathAppend(g_szPidFilePath, sizeof(g_szPidFilePath), pszPidFileName);
-
-            VBClLogVerbose(1, "lock file path: %s\n", g_szPidFilePath);
-            rc = VbglR3PidFile(g_szPidFilePath, &g_hPidFile);
-        }
-        else
-            VBClLogError("unable to get user home directory, rc=%Rrc\n", rc);
-
-        RTStrFree(pszPidFileName);
-    }
-    else
-        rc = VERR_NO_MEMORY;
-
-    return rc;
-}
-
-/**
- * Release lock file.
- */
-static void vbclSVGASessionPidFileRelease(void)
-{
-    VbglR3ClosePidFile(g_szPidFilePath, g_hPidFile);
-}
-
-/**
  * @interface_method_impl{VBCLSERVICE,pfnInit}
  */
@@ -192 +125 @@
 
     VBClLogSetLogPrefix(pszLogPrefix);
-
-    rc = vbclSVGASessionPidFileLock();
-    if (RT_FAILURE(rc))
-    {
-        VBClLogVerbose(1, "cannot acquire pid lock, rc=%Rrc\n", rc);
-        return rc;
-    }
 
     rc = RTCritSectInit(&g_hClientCritSect);
@@ -517 +443 @@
     }
 
-    vbclSVGASessionPidFileRelease();
-
     return VINF_SUCCESS;
 }
@@ -526 +450 @@
     "vmsvga-session",                   /* szName */
     "VMSVGA display assistant",         /* pszDescription */
-    NULL,                               /* pszPidFilePath (no pid file lock) */
+    ".vboxclient-vmsvga-session",       /* pszPidFilePathTemplate */
     NULL,                               /* pszUsage */
     NULL,                               /* pszOptions */