From 984e95fcbdb19c2495851322a4c33f34291ecfab Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Fri, 29 Oct 2021 21:02:54 +0100

Subject: [PATCH] vddk: Simplify detection of VDDK symbols and baseline 6.5

Make all symbols from VDDK 6.5 into required symbols and use a single

error message function if one of these is missing.  The new error is:

  nbdkit: error: required VDDK symbol "VixDiskLib_Wait" is

  missing. VDDK version must be >= 6.5. See nbdkit-vddk-plugin(1) man

  page section "SUPPORTED VERSIONS OF VDDK". Original dlopen error:

  vmware-vix-disklib-distrib/lib64/libvixDiskLib.so.6: undefined

  symbol: VixDiskLib_Wait

Remove the extra check and assert.

Be more consistent about #define OPTIONAL_STUB(fn,ret,args) STUB(fn,ret,args)

when we want the optional and required stubs to do the same thing.

(cherry picked from commit ec0d22e61881efa39a69d02ccb9e4ede8bf95e75)

---

 plugins/vddk/stats.c      |  2 +-

 plugins/vddk/vddk-stubs.h | 45 ++++++++++++++++++---------------------

 plugins/vddk/vddk.c       | 36 ++++++++++++-------------------

 plugins/vddk/vddk.h       |  2 +-

 4 files changed, 37 insertions(+), 48 deletions(-)

diff --git a/plugins/vddk/stats.c b/plugins/vddk/stats.c

index 18a42714..76e0c244 100644

--- a/plugins/vddk/stats.c

+++ b/plugins/vddk/stats.c

@@ -89,7 +89,7 @@ display_stats (void)

   if (!vddk_debug_stats) return;

 #define STUB(fn,ret,args) statlist_append (&stats, stats_##fn)

-#define OPTIONAL_STUB(fn,ret,args) statlist_append (&stats, stats_##fn)

+#define OPTIONAL_STUB(fn,ret,args) STUB(fn,ret,args)

 #include "vddk-stubs.h"

 #undef STUB

 #undef OPTIONAL_STUB

diff --git a/plugins/vddk/vddk-stubs.h b/plugins/vddk/vddk-stubs.h

index 66353691..7d8644c3 100644

--- a/plugins/vddk/vddk-stubs.h

+++ b/plugins/vddk/vddk-stubs.h

@@ -39,10 +39,7 @@

  * function name, return value, arguments.

  */

-/* Required stubs, present in all versions of VDDK that we support.  I

- * have checked that all these exist in at least VDDK 5.5.5 (2015).

- */

-

+/* Required stubs, present in all versions of VDDK since 6.5 (Nov 2016). */

 STUB (VixDiskLib_InitEx,

       VixError,

       (uint32_t major, uint32_t minor,

@@ -103,27 +100,27 @@ STUB (VixDiskLib_Write,

        uint64_t start_sector, uint64_t nr_sectors,

        const unsigned char *buf));

-/* Added in VDDK 6.0, these will be NULL in earlier versions. */

-OPTIONAL_STUB (VixDiskLib_Flush,

-               VixError,

-               (VixDiskLibHandle handle));

-OPTIONAL_STUB (VixDiskLib_ReadAsync,

-               VixError,

-               (VixDiskLibHandle handle,

-                uint64_t start_sector, uint64_t nr_sectors,

-                unsigned char *buf,

-                VixDiskLibCompletionCB callback, void *data));

-OPTIONAL_STUB (VixDiskLib_WriteAsync,

-               VixError,

-               (VixDiskLibHandle handle,

-                uint64_t start_sector, uint64_t nr_sectors,

-                const unsigned char *buf,

-                VixDiskLibCompletionCB callback, void *data));

+/* Added in VDDK 6.0. */

+STUB (VixDiskLib_Flush,

+      VixError,

+      (VixDiskLibHandle handle));

+STUB (VixDiskLib_ReadAsync,

+      VixError,

+      (VixDiskLibHandle handle,

+       uint64_t start_sector, uint64_t nr_sectors,

+       unsigned char *buf,

+       VixDiskLibCompletionCB callback, void *data));

+STUB (VixDiskLib_WriteAsync,

+      VixError,

+      (VixDiskLibHandle handle,

+       uint64_t start_sector, uint64_t nr_sectors,

+       const unsigned char *buf,

+       VixDiskLibCompletionCB callback, void *data));

-/* Added in VDDK 6.5, this will be NULL in earlier versions. */

-OPTIONAL_STUB (VixDiskLib_Wait,

-               VixError,

-               (VixDiskLibHandle handle));

+/* Added in VDDK 6.5. */

+STUB (VixDiskLib_Wait,

+      VixError,

+      (VixDiskLibHandle handle));

 /* Added in VDDK 6.7, these will be NULL for earlier versions: */

 OPTIONAL_STUB (VixDiskLib_QueryAllocatedBlocks,

diff --git a/plugins/vddk/vddk.c b/plugins/vddk/vddk.c

index f967e2d9..271b5ee0 100644

--- a/plugins/vddk/vddk.c

+++ b/plugins/vddk/vddk.c

@@ -63,7 +63,7 @@ NBDKIT_DLL_PUBLIC int vddk_debug_datapath = 1;

  * initialized when the plugin is loaded (by vddk_get_ready).

  */

 #define STUB(fn,ret,args) ret (*fn) args

-#define OPTIONAL_STUB(fn,ret,args) ret (*fn) args

+#define OPTIONAL_STUB(fn,ret,args) STUB(fn,ret,args)

 #include "vddk-stubs.h"

 #undef STUB

 #undef OPTIONAL_STUB

@@ -282,6 +282,17 @@ vddk_config (const char *key, const char *value)

   return 0;

 }

+static void

+missing_required_symbol (const char *fn)

+{

+  nbdkit_error ("required VDDK symbol \"%s\" is missing. "

+                "VDDK version must be >= 6.5. "

+                "See nbdkit-vddk-plugin(1) man page section \"SUPPORTED VERSIONS OF VDDK\". "

+                "Original dlopen error: %s\n",

+                fn, dlerror ());

+  exit (EXIT_FAILURE);

+}

+

 /* Load the VDDK library. */

 static void

 load_library (bool load_error_is_fatal)

@@ -358,32 +369,13 @@ load_library (bool load_error_is_fatal)

 #define STUB(fn,ret,args)                                         \

   do {                                                            \

     fn = dlsym (dl, #fn);                                         \

-    if (fn == NULL) {                                             \

-      nbdkit_error ("required VDDK symbol \"%s\" is missing: %s", \

-                    #fn, dlerror ());                             \

-      exit (EXIT_FAILURE);                                        \

-    }                                                             \

+    if (fn == NULL)                                               \

+      missing_required_symbol (#fn);                              \

   } while (0)

 #define OPTIONAL_STUB(fn,ret,args) fn = dlsym (dl, #fn)

 #include "vddk-stubs.h"

 #undef STUB

 #undef OPTIONAL_STUB

-

-  /* Additionally, VDDK version must be >= 6.5.  This was the first

-   * version which introduced VixDiskLib_Wait symbol so we can check

-   * for that.

-   */

-  if (VixDiskLib_Wait == NULL) {

-    nbdkit_error ("VDDK version must be >= 6.5. "

-                  "See nbdkit-vddk-plugin(1) man page section \"SUPPORTED VERSIONS OF VDDK\".");

-    exit (EXIT_FAILURE);

-  }

-

-  /* Added in VDDK 6.0 so it must always be present.  Since we are

-   * going to call this function unconditionally, fail early and hard

-   * if for some reason it's not present.

-   */

-  assert (VixDiskLib_Flush != NULL);

 }

 static int

diff --git a/plugins/vddk/vddk.h b/plugins/vddk/vddk.h

index be0b3492..0e3dd79e 100644

--- a/plugins/vddk/vddk.h

+++ b/plugins/vddk/vddk.h

@@ -76,7 +76,7 @@ extern int vddk_debug_datapath;

 extern int vddk_debug_stats;

 #define STUB(fn,ret,args) extern ret (*fn) args

-#define OPTIONAL_STUB(fn,ret,args) extern ret (*fn) args

+#define OPTIONAL_STUB(fn,ret,args) STUB(fn,ret,args)

 #include "vddk-stubs.h"

 #undef STUB

 #undef OPTIONAL_STUB

-- 

2.31.1