* src/vbox/vbox_XPCOMCGlue.[ch]: improve VirtualBox path detection

patch by Pritesh Kothari
Daniel

ChangeLog

@@ -1,3 +1,8 @@
+Wed May  6 15:22:08 CEST 2009 Daniel Veillard <veillard@redhat.com>
+
+	* src/vbox/vbox_XPCOMCGlue.[ch]: improve VirtualBox path detection
+	  patch by Pritesh Kothari
+
 Tue May  5 10:20:27 EDT 2009 Cole Robinson <crobinso@redhat.com>
 
 	* src/qemu_driver.c: Don't throw away StartVM errors when

src/vbox/vbox_XPCOMCGlue.c

@@ -36,6 +36,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <stdarg.h>
 #include <dlfcn.h>
 
 #include "vbox_XPCOMCGlue.h"
@@ -61,41 +62,72 @@
 /** The dlopen handle for VBoxXPCOMC. */
 void *g_hVBoxXPCOMC = NULL;
 /** The last load error. */
+char g_szVBoxErrMsg[256];
+/** Pointer to the VBoxXPCOMC function table. */
 PCVBOXXPCOM g_pVBoxFuncs = NULL;
 /** Pointer to VBoxGetXPCOMCFunctions for the loaded VBoxXPCOMC so/dylib/dll. */
 PFNVBOXGETXPCOMCFUNCTIONS g_pfnGetFunctions = NULL;
 
 
+/**
+ * Wrapper for setting g_szVBoxErrMsg. Can be an empty stub.
+ *
+ * @param   fAlways         When 0 the g_szVBoxErrMsg is only set if empty.
+ * @param   pszFormat       The format string.
+ * @param   ...             The arguments.
+ */
+static void setErrMsg(int fAlways, const char *pszFormat, ...)
+{
+#ifndef LIBVIRT_VERSION
+    if (    fAlways
+        ||  !g_szVBoxErrMsg[0])
+    {
+        va_list va;
+        va_start(va, pszFormat);
+        vsnprintf(g_szVBoxErrMsg, sizeof(g_szVBoxErrMsg), pszFormat, va);
+        va_end(va);
+    }
+#else  /* libvirt */
+    (void)fAlways;
+    (void)pszFormat;
+#endif /* libvirt */
+}
+
+
 /**
  * Try load VBoxXPCOMC.so/dylib/dll from the specified location and resolve all
  * the symbols we need.
  *
  * @returns 0 on success, -1 on failure.
- * @param   pszHome         The director where to try load VBoxXPCOMC from. Can be NULL.
- * @param   fSetAppHome     Whether to set the VBOX_APP_HOME env.var. or not (boolean).
+ * @param   pszHome         The director where to try load VBoxXPCOMC from. Can
+ *                          be NULL.
+ * @param   fSetAppHome     Whether to set the VBOX_APP_HOME env.var. or not
+ *                          (boolean).
  */
 static int tryLoadOne(const char *pszHome, int fSetAppHome)
 {
     size_t      cchHome = pszHome ? strlen(pszHome) : 0;
     size_t      cbBufNeeded;
-    char        szBuf[4096];
+    char        szName[4096];
     int         rc = -1;
 
     /*
      * Construct the full name.
      */
     cbBufNeeded = cchHome + sizeof("/" DYNLIB_NAME);
-    if (cbBufNeeded > sizeof(szBuf))
+    if (cbBufNeeded > sizeof(szName))
     {
+        setErrMsg(1, "path buffer too small: %u bytes needed",
+                  (unsigned)cbBufNeeded);
         return -1;
     }
     if (cchHome)
     {
-        memcpy(szBuf, pszHome, cchHome);
-        szBuf[cchHome] = '/';
+        memcpy(szName, pszHome, cchHome);
+        szName[cchHome] = '/';
         cchHome++;
     }
-    memcpy(&szBuf[cchHome], DYNLIB_NAME, sizeof(DYNLIB_NAME));
+    memcpy(&szName[cchHome], DYNLIB_NAME, sizeof(DYNLIB_NAME));
 
     /*
      * Try load it by that name, setting the VBOX_APP_HOME first (for now).
@@ -108,7 +140,7 @@ static int tryLoadOne(const char *pszHome, int fSetAppHome)
         else
             unsetenv("VBOX_APP_HOME");
     }
-    g_hVBoxXPCOMC = dlopen(szBuf, RTLD_NOW | RTLD_LOCAL);
+    g_hVBoxXPCOMC = dlopen(szName, RTLD_NOW | RTLD_LOCAL);
     if (g_hVBoxXPCOMC)
     {
         PFNVBOXGETXPCOMCFUNCTIONS pfnGetFunctions;
@@ -120,15 +152,21 @@ static int tryLoadOne(const char *pszHome, int fSetAppHome)
             if (g_pVBoxFuncs)
             {
                 g_pfnGetFunctions = pfnGetFunctions;
-                rc = 0;
+                return 0;
             }
+
+            /* bail out */
+            setErrMsg(1, "%.80s: pfnGetFunctions(%#x) failed",
+                      szName, VBOX_XPCOMC_VERSION);
         }
-        if (rc != 0)
-        {
-            dlclose(g_hVBoxXPCOMC);
-            g_hVBoxXPCOMC = NULL;
-        }
+        else
+            setErrMsg(1, "dlsym(%.80s/%.32s): %.128s",
+                      szName, VBOX_GET_XPCOMC_FUNCTIONS_SYMBOL_NAME, dlerror());
+        dlclose(g_hVBoxXPCOMC);
+        g_hVBoxXPCOMC = NULL;
     }
+    else
+        setErrMsg(0, "dlopen(%.80s): %.160s", szName, dlerror());
     return rc;
 }
 
@@ -156,6 +194,7 @@ int VBoxCGlueInit(void)
     /*
      * Try the known standard locations.
      */
+    g_szVBoxErrMsg[0] = '\0';
 #if defined(__gnu__linux__) || defined(__linux__)
     if (tryLoadOne("/opt/VirtualBox", 1) == 0)
         return 0;
@@ -201,5 +240,6 @@ void VBoxCGlueTerm(void)
     }
     g_pVBoxFuncs = NULL;
     g_pfnGetFunctions = NULL;
+    memset(g_szVBoxErrMsg, 0, sizeof(g_szVBoxErrMsg));
 }
 

src/vbox/vbox_XPCOMCGlue.h

@@ -29,6 +29,7 @@
 #ifndef ___VBoxXPCOMC_cglue_h
 #define ___VBoxXPCOMC_cglue_h
 
+/* This has to be the oldest version we support. */
 #include "vbox_CAPI_v2_2.h"
 
 #ifdef __cplusplus
@@ -39,7 +40,7 @@ extern "C" {
 extern void *g_hVBoxXPCOMC;
 /** The last load error. */
 extern char g_szVBoxErrMsg[256];
-/** Pointer to the VBoxXPCOMC function table.  */
+/** Pointer to the VBoxXPCOMC function table. */
 extern PCVBOXXPCOM g_pVBoxFuncs;
 /** Pointer to VBoxGetXPCOMCFunctions for the loaded VBoxXPCOMC so/dylib/dll. */
 extern PFNVBOXGETXPCOMCFUNCTIONS g_pfnGetFunctions;