Merge pull request #2329 in HDFFV/hdf5 from ~DEROBINS/hdf5_der:H5MM_const to develop

* commit '10301154215fb6a22590e80f7b5ed0005f3e1786':
  Minor refactoring to the VFD info free call.
  Updated the 'const memory free' changes based on PR feedback.
  Added a free wrapper that lets us free constant pointers without generating warnings.

10 files changed, 67 insertions, 50 deletions

diff --git a/src/H5Eint.c b/src/H5Eint.c
index e76db82..acd5b28 100644
--- a/src/H5Eint.c
+++ b/src/H5Eint.c
@@ -883,12 +883,12 @@ H5E__clear_entries(H5E_t *estack, size_t nentries)
 
         /* Release strings */
         if(error->func_name)
-            error->func_name = (const char *) H5MM_xfree((void *)error->func_name);        /* Casting away const OK - QAK */
+            error->func_name = (const char *) H5MM_xfree_const(error->func_name);
         if(error->file_name)
-            error->file_name = (const char *) H5MM_xfree((void *)error->file_name);        /* Casting away const OK - QAK */
+            error->file_name = (const char *) H5MM_xfree_const(error->file_name);
         if(error->desc)
-            error->desc = (const char *) H5MM_xfree((void *)error->desc);     /* Casting away const OK - QAK */
-    } /* end for */
+            error->desc = (const char *) H5MM_xfree_const(error->desc);
+    }
 
     /* Decrement number of errors on stack */
     estack->nused -= u;
diff --git a/src/H5FD.c b/src/H5FD.c
index 1a4ab4d..63112bd 100644
--- a/src/H5FD.c
+++ b/src/H5FD.c
@@ -202,7 +202,7 @@ H5FD__free_cls(H5FD_class_t *cls)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_free_cls() */
+} /* end H5FD__free_cls() */
 
 
 /*-------------------------------------------------------------------------
@@ -566,22 +566,22 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_fapl_close
+ * Function:    H5FD_free_driver_info
  *
- * Purpose:     Closes a driver for a dataset transfer property list
+ * Purpose:     Frees a driver's info
  *
  * Return:      SUCCEED/FAIL
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5FD_fapl_close(hid_t driver_id, const void *driver_info)
+H5FD_free_driver_info(hid_t driver_id, const void *driver_info)
 {
     herr_t      ret_value = SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(driver_id > 0) {
+    if(driver_id > 0 && driver_info) {
         H5FD_class_t	*driver;
 
         /* Retrieve the driver for the ID */
@@ -589,19 +589,19 @@ H5FD_fapl_close(hid_t driver_id, const void *driver_info)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a driver ID")
 
         /* Allow driver to free info or do it ourselves */
-        if(driver_info) {
-            if(driver->fapl_free) {
-                if((driver->fapl_free)((void *)driver_info) < 0)        /* Casting away const OK -QAK */
-                    HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "driver free request failed")
-            } /* end if */
-            else
-                driver_info = H5MM_xfree((void *)driver_info);        /* Casting away const OK -QAK */
-        } /* end if */
-    } /* end if */
+        if(driver->fapl_free) {
+            /* Free the const pointer */
+            /* Cast through uintptr_t to de-const memory */
+            if((driver->fapl_free)((void *)(uintptr_t)driver_info) < 0)
+                HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "driver free request failed")
+        }
+        else
+            driver_info = H5MM_xfree_const(driver_info);
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_fapl_close() */
+} /* end H5FD_free_driver_info() */
 
 
 /*-------------------------------------------------------------------------
diff --git a/src/H5FDprivate.h b/src/H5FDprivate.h
index ac08f7f..2e3d3ce 100644
--- a/src/H5FDprivate.h
+++ b/src/H5FDprivate.h
@@ -115,7 +115,7 @@ H5_DLL hsize_t H5FD_sb_size(H5FD_t *file);
 H5_DLL herr_t H5FD_sb_encode(H5FD_t *file, char *name/*out*/, uint8_t *buf);
 H5_DLL herr_t H5FD_sb_load(H5FD_t *file, const char *name, const uint8_t *buf);
 H5_DLL void *H5FD_fapl_get(H5FD_t *file);
-H5_DLL herr_t H5FD_fapl_close(hid_t driver_id, const void *fapl);
+H5_DLL herr_t H5FD_free_driver_info(hid_t driver_id, const void *driver_info);
 H5_DLL hid_t H5FD_register(const void *cls, size_t size, hbool_t app_ref);
 H5_DLL H5FD_t *H5FD_open(const char *name, unsigned flags, hid_t fapl_id,
 		  haddr_t maxaddr);
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 74189c1..0000512 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -273,7 +273,7 @@ H5F_get_access_plist(H5F_t *f, hbool_t app_ref)
 
 done:
     /* Release the copy of the driver info, if it was set up */
-    if(driver_prop_copied && H5FD_fapl_close(driver_prop.driver_id, driver_prop.driver_info) < 0)
+    if(driver_prop_copied && H5FD_free_driver_info(driver_prop.driver_id, driver_prop.driver_info) < 0)
         HDONE_ERROR(H5E_FILE, H5E_CANTCLOSEOBJ, H5I_INVALID_HID, "can't close copy of driver info")
 
     FUNC_LEAVE_NOAPI(ret_value)
diff --git a/src/H5MM.c b/src/H5MM.c
index ac3c26e..94bd542 100644
--- a/src/H5MM.c
+++ b/src/H5MM.c
@@ -566,6 +566,31 @@ H5MM_xfree(void *mem)
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5MM_xfree_const
+ *
+ * Purpose:     H5MM_xfree() wrapper that handles const pointers without
+ *              warnings. Used for freeing buffers that should be regarded
+ *              as const in use but need to be freed when no longer needed.
+ *
+ * Return:      Success:    NULL
+ *              Failure:    never fails
+ *
+ *-------------------------------------------------------------------------
+ */
+void *
+H5MM_xfree_const(const void *mem)
+{
+    /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Cast through uintptr_t to de-const memory */
+    H5MM_xfree((void *)(uintptr_t)mem);
+
+    FUNC_LEAVE_NOAPI(NULL)
+} /* end H5MM_xfree_const() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5MM_memcpy
  *
  * Purpose:     Like memcpy(3) but with sanity checks on the parameters,
diff --git a/src/H5MMprivate.h b/src/H5MMprivate.h
index 2053215..240b931 100644
--- a/src/H5MMprivate.h
+++ b/src/H5MMprivate.h
@@ -45,6 +45,7 @@ H5_DLL void *H5MM_realloc(void *mem, size_t size);
 H5_DLL char *H5MM_xstrdup(const char *s);
 H5_DLL char *H5MM_strdup(const char *s);
 H5_DLL void *H5MM_xfree(void *mem);
+H5_DLL void *H5MM_xfree_const(const void *mem);
 H5_DLL void *H5MM_memcpy(void *dest, const void *src, size_t n);
 #if defined H5_MEMORY_ALLOC_SANITY_CHECK
 H5_DLL void H5MM_sanity_check_all(void);
diff --git a/src/H5Pfapl.c b/src/H5Pfapl.c
index 3668229..9a04c3e 100644
--- a/src/H5Pfapl.c
+++ b/src/H5Pfapl.c
@@ -1158,27 +1158,17 @@ H5P__file_driver_free(void *value)
 
         /* Copy the driver & info, if there is one */
         if(info->driver_id > 0) {
-            if(info->driver_info) {
-                H5FD_class_t *driver;       /* Pointer to driver */
-
-                /* Retrieve the driver for the ID */
-                if(NULL == (driver = (H5FD_class_t *)H5I_object(info->driver_id)))
-                    HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a driver ID")
 
-                /* Allow driver to free info or do it ourselves */
-                if(driver->fapl_free) {
-                    if((driver->fapl_free)((void *)info->driver_info) < 0)      /* Casting away const OK -QAK */
-                        HGOTO_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "driver info free request failed")
-                } /* end if */
-                else
-                    H5MM_xfree((void *)info->driver_info);      /* Casting away const OK -QAK */
-            } /* end if */
+            /* Free the driver info, if it exists */
+            if(info->driver_info)
+                if(H5FD_free_driver_info(info->driver_id, info->driver_info) < 0)
+                    HGOTO_ERROR(H5E_PLIST, H5E_CANTFREE, FAIL, "driver info free request failed")
 
             /* Decrement reference count for driver */
             if(H5I_dec_ref(info->driver_id) < 0)
                 HGOTO_ERROR(H5E_PLIST, H5E_CANTDEC, FAIL, "can't decrement reference count for driver ID")
-        } /* end if */
-    } /* end if */
+        }
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -5407,7 +5397,7 @@ H5P_set_vol(H5P_genplist_t *plist, hid_t vol_id, const void *vol_info)
 
         /* Prepare the VOL connector property */
         vol_prop.connector_id = vol_id;
-        vol_prop.connector_info = (void *)vol_info;
+        vol_prop.connector_info = vol_info;
 
         /* Set the connector ID & info property */
         if(H5P_set(plist, H5F_ACS_VOL_CONN_NAME, &vol_prop) < 0)
diff --git a/src/H5VLcallback.c b/src/H5VLcallback.c
index e4ebb95..5c54b5b 100644
--- a/src/H5VLcallback.c
+++ b/src/H5VLcallback.c
@@ -525,7 +525,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_free_connector_info(hid_t connector_id, void *info)
+H5VL_free_connector_info(hid_t connector_id, const void *info)
 {
     H5VL_class_t *cls;                  /* VOL connector's class struct */
     herr_t ret_value = SUCCEED;         /* Return value */
@@ -543,12 +543,13 @@ H5VL_free_connector_info(hid_t connector_id, void *info)
     if(info) {
         /* Allow the connector to free info or do it ourselves */
         if(cls->info_cls.free) {
-            if((cls->info_cls.free)(info) < 0)
+            /* Cast through uintptr_t to de-const memory */
+            if((cls->info_cls.free)((void *)(uintptr_t)info) < 0)
                 HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "connector info free request failed")
-        } /* end if */
+        }
         else
-            H5MM_xfree(info);
-    } /* end if */
+            H5MM_xfree_const(info);
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 39b0f53..6572faa 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -318,7 +318,7 @@ H5VL__free_cls(H5VL_class_t *cls)
         HGOTO_ERROR(H5E_VOL, H5E_CANTCLOSEOBJ, FAIL, "VOL connector did not terminate cleanly")
 
     /* Release the class */
-    H5MM_xfree((void *)cls->name);      /* Casting away const OK -QAK */
+    H5MM_xfree_const(cls->name);
     H5FL_FREE(H5VL_class_t, cls);
 
 done:
@@ -682,14 +682,14 @@ H5VL_conn_free(const H5VL_connector_prop_t *connector_prop)
         if(connector_prop->connector_id > 0) {
             if(connector_prop->connector_info)
                 /* Free the connector info */
-                if(H5VL_free_connector_info(connector_prop->connector_id, (void *)connector_prop->connector_info) < 0)        /* Casting away const OK - QAK */
+                if(H5VL_free_connector_info(connector_prop->connector_id, connector_prop->connector_info) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to release VOL connector info object")
 
             /* Decrement reference count for connector ID */
             if(H5I_dec_ref(connector_prop->connector_id) < 0)
                 HGOTO_ERROR(H5E_VOL, H5E_CANTDEC, FAIL, "can't decrement reference count for connector ID")
-        } /* end if */
-    } /* end if */
+        }
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1144,7 +1144,7 @@ H5VL_register_connector(const void *_cls, hbool_t app_ref, hid_t vipl_id)
 done:
     if(ret_value < 0 && saved) {
         if(saved->name)
-            H5MM_xfree((void *)(saved->name));  /* Casting away const OK -QAK */
+            H5MM_xfree_const(saved->name);
 
         H5FL_FREE(H5VL_class_t, saved);
     } /* end if */
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index 24ae1f3..3235357 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -44,7 +44,7 @@ typedef struct H5VL_object_t {
 /* Internal structure to hold the connector ID & info for FAPLs */
 typedef struct H5VL_connector_prop_t {
     hid_t       connector_id;           /* VOL connector's ID                                   */
-    void        *connector_info;        /* VOL connector info, for open callbacks               */
+    const void  *connector_info;        /* VOL connector info, for open callbacks               */
 } H5VL_connector_prop_t;
 
 /* Which kind of VOL connector field to use for searching */
@@ -128,7 +128,7 @@ H5_DLL int H5VL_copy_connector_info(const H5VL_class_t *connector, void **dst_in
     const void *src_info);
 H5_DLL herr_t H5VL_cmp_connector_info(const H5VL_class_t *connector, int *cmp_value,
     const void *info1, const void *info2);
-H5_DLL herr_t H5VL_free_connector_info(hid_t connector_id, void *info);
+H5_DLL herr_t H5VL_free_connector_info(hid_t connector_id, const void *info);
 
 /* Attribute functions */
 H5_DLL void *H5VL_attr_create(const H5VL_object_t *vol_obj, const H5VL_loc_params_t *loc_params, const char *attr_name, hid_t type_id, hid_t space_id, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);