msi: Handle a NULL and empty szPackagePath in MsiInstallProduct (Coverity 181).

dlls/msi/msi.c

@@ -231,6 +231,12 @@ UINT WINAPI MsiInstallProductW(LPCWSTR szPackagePath, LPCWSTR szCommandLine)
 
     TRACE("%s %s\n",debugstr_w(szPackagePath), debugstr_w(szCommandLine));
 
+    if (!szPackagePath)
+        return ERROR_INVALID_PARAMETER;
+
+    if (!*szPackagePath)
+        return ERROR_PATH_NOT_FOUND;
+
     r = MSI_OpenPackageW( szPackagePath, &package );
     if (r == ERROR_SUCCESS)
     {

dlls/msi/tests/install.c

@@ -1721,6 +1721,21 @@ static void test_MsiInstallProduct(void)
         return;
     }
 
+    /* szPackagePath is NULL */
+    r = MsiInstallProductA(NULL, "INSTALL=ALL");
+    ok(r == ERROR_INVALID_PARAMETER,
+       "Expected ERROR_INVALID_PARAMETER, got %d\n", r);
+
+    /* both szPackagePath and szCommandLine are NULL */
+    r = MsiInstallProductA(NULL, NULL);
+    ok(r == ERROR_INVALID_PARAMETER,
+       "Expected ERROR_INVALID_PARAMETER, got %d\n", r);
+
+    /* szPackagePath is empty */
+    r = MsiInstallProductA("", "INSTALL=ALL");
+    ok(r == ERROR_PATH_NOT_FOUND,
+       "Expected ERROR_PATH_NOT_FOUND, got %d\n", r);
+
     create_test_files();
     create_database(msifile, tables, sizeof(tables) / sizeof(msi_table));