Refactor several cache clients to have only one copy of their deserialization

code.

6 files changed, 583 insertions, 442 deletions

diff --git a/src/H5Fsuper_cache.c b/src/H5Fsuper_cache.c
index 0dc504e..8e832d7 100644
--- a/src/H5Fsuper_cache.c
+++ b/src/H5Fsuper_cache.c
@@ -91,6 +91,14 @@ static herr_t H5F__cache_drvrinfo_serialize(const H5F_t *f, void *image, size_t
     void *thing);
 static herr_t H5F__cache_drvrinfo_free_icr(void *thing);
 
+/* Local encode/decode routines */
+static herr_t H5F__superblock_prefix_decode(H5F_super_t *sblock,
+    const uint8_t **image_ref, const H5F_superblock_cache_ud_t *udata,
+    hbool_t extend_eoa);
+static herr_t H5F__drvrinfo_prefix_decode(H5O_drvinfo_t *drvinfo, char *drv_name,
+    const uint8_t **image_ref, H5F_drvrinfo_cache_ud_t *udata,
+    hbool_t extend_eoa);
+
 
 /*********************/
 /* Package Variables */
@@ -148,6 +156,158 @@ H5FL_EXTERN(H5F_super_t);
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5F__superblock_prefix_decode
+ *
+ * Purpose:	Decode a superblock prefix
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              December 15, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5F__superblock_prefix_decode(H5F_super_t *sblock, const uint8_t **image_ref,
+    const H5F_superblock_cache_ud_t *udata, hbool_t extend_eoa)
+{
+    const uint8_t *image = (const uint8_t *)*image_ref; /* Pointer into raw data buffer */
+    htri_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Check arguments */
+    HDassert(sblock);
+    HDassert(image_ref);
+    HDassert(image);
+    HDassert(udata);
+    HDassert(udata->f);
+
+    /* Skip over signature (already checked when locating the superblock) */
+    image += H5F_SIGNATURE_LEN;
+
+    /* Superblock version */
+    sblock->super_vers = *image++;
+    if(sblock->super_vers > HDF5_SUPERBLOCK_VERSION_LATEST)
+        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad superblock version number")
+
+    /* Sanity check */
+    HDassert(((size_t)(image - (const uint8_t *)*image_ref)) == H5F_SUPERBLOCK_FIXED_SIZE);
+
+    /* Determine the size of addresses & size of offsets, for computing the
+     * variable-sized portion of the superblock.
+     */
+    if(sblock->super_vers < HDF5_SUPERBLOCK_VERSION_2) {
+        sblock->sizeof_addr = image[4];
+        sblock->sizeof_size = image[5];
+    } /* end if */
+    else {
+        sblock->sizeof_addr = image[0];
+        sblock->sizeof_size = image[1];
+    } /* end else */
+    if(sblock->sizeof_addr != 2 && sblock->sizeof_addr != 4 &&
+            sblock->sizeof_addr != 8 && sblock->sizeof_addr != 16 && sblock->sizeof_addr != 32)
+        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number in an address")
+    if(sblock->sizeof_size != 2 && sblock->sizeof_size != 4 &&
+            sblock->sizeof_size != 8 && sblock->sizeof_size != 16 && sblock->sizeof_size != 32)
+        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number for object size")
+
+    /* Check for extending the EOA for the file */
+    if(extend_eoa) {
+        size_t variable_size;   /* Variable size of superblock */
+
+        /* Determine the size of the variable-length part of the superblock */
+        variable_size = (size_t)H5F_SUPERBLOCK_VARLEN_SIZE(sblock->super_vers, sblock->sizeof_addr, sblock->sizeof_size);
+        HDassert(variable_size > 0);
+
+        /* Make certain we can read the variable-sized portion of the superblock */
+        if(H5F__set_eoa(udata->f, H5FD_MEM_SUPER, (haddr_t)(H5F_SUPERBLOCK_FIXED_SIZE + variable_size)) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
+    } /* end if */
+
+    /* Update the image buffer pointer */
+    *image_ref = image;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5F__superblock_prefix_decode() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F__drvrinfo_prefix_decode
+ *
+ * Purpose:	Decode a driver info prefix
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              December 15, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5F__drvrinfo_prefix_decode(H5O_drvinfo_t *drvrinfo, char *drv_name,
+    const uint8_t **image_ref, H5F_drvrinfo_cache_ud_t *udata,
+    hbool_t extend_eoa)
+{
+    const uint8_t	*image = (const uint8_t *)*image_ref;   /* Pointer into raw data buffer */
+    unsigned            drv_vers;       /* Version of driver info block */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(drvrinfo);
+    HDassert(image_ref);
+    HDassert(image);
+    HDassert(udata);
+    HDassert(udata->f);
+
+    /* Version number */
+    drv_vers = *image++;
+    if(drv_vers != HDF5_DRIVERINFO_VERSION_0)
+        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad driver information block version number")
+
+    image += 3; /* reserved bytes */
+
+    /* Driver info size */
+    UINT32DECODE(image, drvrinfo->len);
+
+    /* Driver name and/or version */
+    if(drv_name) { 
+        HDmemcpy(drv_name, (const char *)image, (size_t)8);
+        drv_name[8] = '\0';
+        image += 8; /* advance past name/version */
+    } /* end if */
+
+    /* Extend the EOA if required so that we can read the complete driver info block */
+    if(extend_eoa) {
+        haddr_t eoa;                /* Current EOA for the file */
+        haddr_t min_eoa;            /* Minimum EOA needed for reading the driver info */
+
+        /* Get current EOA... */
+        eoa = H5FD_get_eoa(udata->f->shared->lf, H5FD_MEM_SUPER);
+        if(!H5F_addr_defined(eoa))
+            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "driver get_eoa request failed")
+
+        /* ... if it is too small, extend it. */
+        min_eoa = udata->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE + drvrinfo->len;
+
+        /* If it grew, set it */
+        if(H5F_addr_gt(min_eoa, eoa))
+            if(H5FD_set_eoa(udata->f->shared->lf, H5FD_MEM_SUPER, min_eoa) < 0)
+                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
+    } /* end if */
+
+    /* Update the image buffer pointer */
+    *image_ref = image;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5F__drvrinfo_prefix_decode() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5F__cache_superblock_get_initial_load_size
  *
  * Purpose:     Compute the size of the data structure on disk.
@@ -195,10 +355,7 @@ H5F__cache_superblock_get_final_load_size(const void *_image, size_t image_len,
 {
     const uint8_t *image = (const uint8_t *)_image;   			    /* Pointer into raw data buffer */
     H5F_superblock_cache_ud_t *udata = (H5F_superblock_cache_ud_t *)_udata; /* User data */
-    unsigned super_vers;                /* Superblock version */
-    uint8_t sizeof_addr;                /* Size of offsets in the file (in bytes) */
-    uint8_t sizeof_size;                /* Size of lengths in the file (in bytes) */
-    size_t variable_size;               /* Variable size of superblock */
+    H5F_super_t sblock;                 /* Temporary file superblock */
     htri_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
@@ -206,56 +363,20 @@ H5F__cache_superblock_get_final_load_size(const void *_image, size_t image_len,
     /* Check arguments */
     HDassert(image);
     HDassert(udata);
-    HDassert(udata->f);
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
-
-    /* Skip over file signature */
-    image += H5F_SIGNATURE_LEN;
-
-    /* Superblock version */
-    super_vers = *image++;
-    if(super_vers > HDF5_SUPERBLOCK_VERSION_LATEST)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad superblock version number")
-
-    /* Save the version to be used in verify_chksum callback */
-    udata->super_vers = super_vers;
-
-    /* Sanity check */
-    HDassert(((size_t)(image - (const uint8_t *)_image)) == H5F_SUPERBLOCK_FIXED_SIZE);
     HDassert(image_len >= H5F_SUPERBLOCK_FIXED_SIZE + 6);
 
-    /* Determine the size of addresses & size of offsets, for computing the
-     * variable-sized portion of the superblock.
-     */
-    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
-        sizeof_addr = image[4];
-        sizeof_size = image[5];
-    } /* end if */
-    else {
-        sizeof_addr = image[0];
-        sizeof_size = image[1];
-    } /* end else */
-    if(sizeof_addr != 2 && sizeof_addr != 4 &&
-            sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number in an address")
-    if(sizeof_size != 2 && sizeof_size != 4 &&
-            sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad byte number for object size")
-
-    /* Determine the size of the variable-length part of the superblock */
-    variable_size = (size_t)H5F_SUPERBLOCK_VARLEN_SIZE(super_vers, sizeof_addr, sizeof_size);
-    HDassert(variable_size > 0);
+    /* Deserialize the file superblock's prefix */
+    if(H5F__superblock_prefix_decode(&sblock, &image, udata, TRUE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, FAIL, "can't decode file superblock prefix")
 
-    /* Sanity check */
-    HDassert(image_len == (H5F_SUPERBLOCK_FIXED_SIZE + H5F_SUPERBLOCK_MINIMAL_VARLEN_SIZE));
-
-    /* Make certain we can read the variable-sized portion of the superblock */
-    if(H5F__set_eoa(udata->f, H5FD_MEM_SUPER, (haddr_t)(H5F_SUPERBLOCK_FIXED_SIZE + variable_size)) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
+    /* Save the version to be used in verify_chksum callback */
+    udata->super_vers = sblock.super_vers;
 
     /* Set the final size for the cache image */
-    *actual_len = H5F_SUPERBLOCK_FIXED_SIZE + variable_size;
+    *actual_len = H5F_SUPERBLOCK_FIXED_SIZE + 
+            (size_t)H5F_SUPERBLOCK_VARLEN_SIZE(sblock.super_vers, sblock.sizeof_addr, sblock.sizeof_size);
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -325,10 +446,6 @@ H5F__cache_superblock_deserialize(const void *_image, size_t len, void *_udata,
     H5F_super_t         *sblock = NULL; /* File's superblock */
     H5F_superblock_cache_ud_t *udata = (H5F_superblock_cache_ud_t *)_udata; /* User data */
     const uint8_t	*image = (const uint8_t *)_image;       /* Pointer into raw data buffer */
-    size_t              variable_size;  /* Variable size of superblock */
-    unsigned            super_vers;     /* Superblock version */
-    uint8_t             sizeof_addr;    /* Size of offsets in the file (in bytes) */
-    uint8_t             sizeof_size;    /* Size of lengths in the file (in bytes) */
     H5F_super_t         *ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_STATIC
@@ -337,54 +454,18 @@ H5F__cache_superblock_deserialize(const void *_image, size_t len, void *_udata,
     HDassert(image);
     HDassert(udata);
     HDassert(udata->f);
+    HDassert(len >= H5F_SUPERBLOCK_FIXED_SIZE + 6);
 
     /* Allocate space for the superblock */
     if(NULL == (sblock = H5FL_CALLOC(H5F_super_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
-    /* Skip over signature (already checked when locating the superblock) */
-    image += H5F_SIGNATURE_LEN;
-
-    /* Superblock version */
-    super_vers = *image++;
-    if(super_vers > HDF5_SUPERBLOCK_VERSION_LATEST)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad superblock version number")
-
-    /* Record the superblock version */
-    sblock->super_vers = super_vers;
-
-    /* Sanity check */
-    HDassert(((size_t)(image - (const uint8_t *)_image)) == H5F_SUPERBLOCK_FIXED_SIZE);
-    HDassert(len >= H5F_SUPERBLOCK_FIXED_SIZE + 6);
-
-    /* Determine the size of addresses & size of offsets, for computing the
-     * variable-sized portion of the superblock.
-     */
-    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
-        sizeof_addr = image[4];
-        sizeof_size = image[5];
-    } /* end if */
-    else {
-        sizeof_addr = image[0];
-        sizeof_size = image[1];
-    } /* end else */
-    if(sizeof_addr != 2 && sizeof_addr != 4 &&
-            sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number in an address")
-    if(sizeof_size != 2 && sizeof_size != 4 &&
-            sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number for object size")
-    sblock->sizeof_addr = sizeof_addr;
-    sblock->sizeof_size = sizeof_size;
-
-    /* Determine the size of the variable-length part of the superblock */
-    variable_size = (size_t)H5F_SUPERBLOCK_VARLEN_SIZE(super_vers, sizeof_addr, sizeof_size);
-    HDassert(variable_size > 0);
-
-    HDassert(len == (H5F_SUPERBLOCK_FIXED_SIZE + variable_size));
+    /* Deserialize the file superblock's prefix */
+    if(H5F__superblock_prefix_decode(sblock, &image, udata, FALSE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, NULL, "can't decode file superblock prefix")
 
     /* Check for older version of superblock format */
-    if(super_vers < HDF5_SUPERBLOCK_VERSION_2) {
+    if(sblock->super_vers < HDF5_SUPERBLOCK_VERSION_2) {
 	uint32_t    status_flags;	    /* File status flags	   */
 	unsigned    sym_leaf_k;         /* Symbol table leaf node's 'K' value */
 	unsigned    snode_btree_k;      /* B-tree symbol table internal node 'K' value */
@@ -405,21 +486,13 @@ H5F__cache_superblock_deserialize(const void *_image, size_t len, void *_udata,
 	if(HDF5_SHAREDHEADER_VERSION != *image++)
 	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad shared-header format version number")
 
-	/* Size of file addresses */
-	sizeof_addr = *image++;
-	if(sizeof_addr != 2 && sizeof_addr != 4 &&
-		sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
-	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number in an address")
-	sblock->sizeof_addr = sizeof_addr;
-	udata->f->shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */
-
-	/* Size of file sizes */
-	sizeof_size = *image++;
-	if(sizeof_size != 2 && sizeof_size != 4 &&
-		sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
-	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number for object size")
-	sblock->sizeof_size = sizeof_size;
-	udata->f->shared->sizeof_size = sizeof_size;  /* Keep a local copy also */
+	/* Skip over size of file addresses (already decoded) */
+	image++;
+	udata->f->shared->sizeof_addr = sblock->sizeof_addr;  /* Keep a local copy also */
+
+	/* Skip over size of file sizes (already decoded) */
+	image++;
+	udata->f->shared->sizeof_size = sblock->sizeof_size;  /* Keep a local copy also */
 
 	/* Skip over reserved byte */
 	image++;
@@ -452,11 +525,11 @@ H5F__cache_superblock_deserialize(const void *_image, size_t len, void *_udata,
          * If the superblock version # is greater than 0, read in the indexed
          * storage B-tree internal 'K' value
          */
-        if(super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
+        if(sblock->super_vers > HDF5_SUPERBLOCK_VERSION_DEF) {
 	    UINT16DECODE(image, chunk_btree_k);
 
 	    /* Reserved bytes are present only in version 1 */
-	    if(super_vers == HDF5_SUPERBLOCK_VERSION_1)
+	    if(sblock->super_vers == HDF5_SUPERBLOCK_VERSION_1)
 		image += 2;   /* reserved */
 	} /* end if */
 	else
@@ -498,21 +571,13 @@ H5F__cache_superblock_deserialize(const void *_image, size_t len, void *_udata,
     else {
 	uint32_t read_chksum;           /* Checksum read from file  */
 
-       /* Size of file addresses */
-       sizeof_addr = *image++;
-       if(sizeof_addr != 2 && sizeof_addr != 4 &&
-		sizeof_addr != 8 && sizeof_addr != 16 && sizeof_addr != 32)
-	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number in an address")
-	sblock->sizeof_addr = sizeof_addr;
-	udata->f->shared->sizeof_addr = sizeof_addr;  /* Keep a local copy also */
-
-	/* Size of file sizes */
-	sizeof_size = *image++;
-	if(sizeof_size != 2 && sizeof_size != 4 &&
-		sizeof_size != 8 && sizeof_size != 16 && sizeof_size != 32)
-	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number for object size")
-	sblock->sizeof_size = sizeof_size;
-	udata->f->shared->sizeof_size = sizeof_size;  /* Keep a local copy also */
+        /* Skip over size of file addresses (already decoded) */
+        image++;
+	udata->f->shared->sizeof_addr = sblock->sizeof_addr;  /* Keep a local copy also */
+
+	/* Skip over size of file sizes (already decoded) */
+	image++;
+	udata->f->shared->sizeof_size = sblock->sizeof_size;  /* Keep a local copy also */
 
 	/* File status flags (not really used yet) */
 	sblock->status_flags = *image++;
@@ -588,7 +653,7 @@ H5F__cache_superblock_image_len(const void *_thing, size_t *image_len)
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FS__cache_hdf_pre_serialize
+ * Function:    H5FS__cache_superblock_pre_serialize
  *
  * Purpose:	The current use of this function is a cludge to repair an 
  *		oversight in the conversion of the superblock code to use the 
@@ -927,50 +992,24 @@ H5F__cache_drvrinfo_get_final_load_size(const void *_image, size_t image_len,
 {
     const uint8_t *image = (const uint8_t *)_image;   			/* Pointer into raw data buffer */
     H5F_drvrinfo_cache_ud_t *udata = (H5F_drvrinfo_cache_ud_t *)_udata;	/* User data */
-    unsigned drv_vers;          /* Version of driver info block */
-    size_t drvinfo_len;         /* Length of encoded buffer */
-    haddr_t eoa;                /* Current EOA for the file */
-    haddr_t min_eoa;            /* Minimum EOA needed for reading the driver info */
-    htri_t ret_value = SUCCEED; /* Return value */
+    H5O_drvinfo_t drvrinfo;     /* Driver info */
+    herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_STATIC
 
     /* Check arguments */
     HDassert(image);
     HDassert(udata);
-    HDassert(udata->f);
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
-
-    /* Version number */
-    drv_vers = *image++;
-    if(drv_vers != HDF5_DRIVERINFO_VERSION_0)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, FAIL, "bad driver information block version number")
-
-    image += 3; /* reserved bytes */
-
-    /* Driver info size */
-    UINT32DECODE(image, drvinfo_len);
-
-    /* Sanity check */
     HDassert(image_len == H5F_DRVINFOBLOCK_HDR_SIZE);
 
-    /* Extend the EOA if required so that we can read the complete driver info block */
-
-    /* Get current EOA... */
-    if((eoa = H5FD_get_eoa(udata->f->shared->lf, H5FD_MEM_SUPER)) == HADDR_UNDEF)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "driver get_eoa request failed")
-
-    /* ... if it is too small, extend it. */
-    min_eoa = udata->driver_addr + H5F_DRVINFOBLOCK_HDR_SIZE + drvinfo_len;
-
-    /* If it grew, set it */
-    if(H5F_addr_gt(min_eoa, eoa))
-        if(H5FD_set_eoa(udata->f->shared->lf, H5FD_MEM_SUPER, min_eoa) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
+    /* Deserialize the file driver info's prefix */
+    if(H5F__drvrinfo_prefix_decode(&drvrinfo, NULL, &image, udata, TRUE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, FAIL, "can't decode file driver info prefix")
 
     /* Set the final size for the cache image */
-    *actual_len = H5F_DRVINFOBLOCK_HDR_SIZE + drvinfo_len;
+    *actual_len = H5F_DRVINFOBLOCK_HDR_SIZE + drvrinfo.len;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -999,7 +1038,6 @@ H5F__cache_drvrinfo_deserialize(const void *_image, size_t len, void *_udata,
     H5F_drvrinfo_cache_ud_t *udata = (H5F_drvrinfo_cache_ud_t *)_udata;     /* User data */
     const uint8_t	*image = (const uint8_t *)_image;       /* Pointer into raw data buffer */
     char                drv_name[9];    /* Name of driver */
-    unsigned            drv_vers;       /* Version of driver info block */
     H5O_drvinfo_t       *ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_STATIC
@@ -1014,21 +1052,11 @@ H5F__cache_drvrinfo_deserialize(const void *_image, size_t len, void *_udata,
     if(NULL == (drvinfo = (H5O_drvinfo_t *)H5MM_calloc(sizeof(H5O_drvinfo_t))))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTALLOC, NULL, "memory allocation failed for driver info message")
 
-    /* Version number */
-    drv_vers = *image++;
-    if(drv_vers != HDF5_DRIVERINFO_VERSION_0)
-        HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad driver information block version number")
-
-    image += 3; /* reserved bytes */
-
-    /* Driver info size */
-    UINT32DECODE(image, drvinfo->len);
-
-    /* Driver name and/or version */
-    HDstrncpy(drv_name, (const char *)image, (size_t)8);
-    drv_name[8] = '\0';
-    image += 8; /* advance past name/version */
+    /* Deserialize the file driver info's prefix */
+    if(H5F__drvrinfo_prefix_decode(drvinfo, drv_name, &image, udata, FALSE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, NULL, "can't decode file driver info prefix")
 
+    /* Sanity check */
     HDassert(len == (H5F_DRVINFOBLOCK_HDR_SIZE + drvinfo->len));
 
     /* Validate and decode driver information */
diff --git a/src/H5HFcache.c b/src/H5HFcache.c
index f85b344..1e2eb8f 100644
--- a/src/H5HFcache.c
+++ b/src/H5HFcache.c
@@ -69,6 +69,7 @@
 /********************/
 
 /* Local encode/decode routines */
+static herr_t H5HF__hdr_prefix_decode(H5HF_hdr_t *hdr, const uint8_t **image_ref);
 static herr_t H5HF__dtable_encode(H5F_t *f, uint8_t **pp, const H5HF_dtable_t *dtable);
 static herr_t H5HF__dtable_decode(H5F_t *f, const uint8_t **pp, H5HF_dtable_t *dtable);
 
@@ -200,6 +201,52 @@ H5FL_BLK_DEFINE(direct_block);
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5HF__hdr_prefix_decode()
+ *
+ * Purpose:	Decode a fractal heap header's prefix
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	Quincey Koziol
+ *		December 15, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5HF__hdr_prefix_decode(H5HF_hdr_t *hdr, const uint8_t **image_ref)
+{
+    const uint8_t *image = *image_ref;  /* Pointer into into supplied image */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity checks */
+    HDassert(hdr);
+    HDassert(image);
+
+    /* Magic number */
+    if(HDmemcmp(image, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC))
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "wrong fractal heap header signature")
+    image += H5_SIZEOF_MAGIC;
+
+    /* Version */
+    if(*image++ != H5HF_HDR_VERSION)
+        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, FAIL, "wrong fractal heap header version")
+
+    /* General heap information */
+    UINT16DECODE(image, hdr->id_len);              /* Heap ID length */
+    UINT16DECODE(image, hdr->filter_len);          /* I/O filters' encoded length */
+
+    /* Update the image buffer pointer */
+    *image_ref = image;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5HF__hdr_prefix_decode() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5HF__dtable_decode
  *
  * Purpose:	Decodes the metadata for a doubling table
@@ -360,10 +407,10 @@ static herr_t
 H5HF__cache_hdr_get_final_load_size(const void *_image, size_t image_len,
     void *_udata, size_t *actual_len)
 {
-    const uint8_t *image = (const uint8_t *)_image;	/* Pointer into raw data buffer */
-    H5HF_hdr_cache_ud_t *udata = (H5HF_hdr_cache_ud_t *)_udata; /* pointer to user data */
-    unsigned filter_len;        /* Size of I/O filter information (in bytes) */
-    htri_t ret_value = SUCCEED; /* Return value */
+    H5HF_hdr_t hdr;             /* Temporary fractal heap header */
+    const uint8_t *image = (const uint8_t *)_image;       /* Pointer into into supplied image */
+    H5HF_hdr_cache_ud_t *udata = (H5HF_hdr_cache_ud_t *)_udata; /* User data for callback */
+    herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_STATIC
 
@@ -373,25 +420,16 @@ H5HF__cache_hdr_get_final_load_size(const void *_image, size_t image_len,
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
 
-    /* Magic number */
-    if(HDmemcmp(image, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "wrong fractal heap header signature")
-    image += H5_SIZEOF_MAGIC;
-
-    /* Version */
-    if(*image++ != H5HF_HDR_VERSION)
-        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, FAIL, "wrong fractal heap header version")
-
-    /* General heap information */
-    image += 2;                               /* Heap ID length */
-    UINT16DECODE(image, filter_len);          /* I/O filters' encoded length */
+    /* Deserialize the fractal heap header's prefix */
+    if(H5HF__hdr_prefix_decode(&hdr, &image) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, FAIL, "can't decode fractal heap header prefix")
 
     /* Check for I/O filter info on this heap */
-    if(filter_len > 0)
+    if(hdr.filter_len > 0)
         /* Compute the extra heap header size */
         *actual_len += (size_t)(H5F_SIZEOF_SIZE(udata->f)   /* Size of size for filtered root direct block */
                             + (unsigned)4		/* Size of filter mask for filtered root direct block */
-                            + filter_len);         	/* Size of encoded I/O filter info */
+                            + hdr.filter_len);         	/* Size of encoded I/O filter info */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -473,18 +511,9 @@ H5HF__cache_hdr_deserialize(const void *_image, size_t len, void *_udata,
     if(NULL == (hdr = H5HF_hdr_alloc(udata->f)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
-    /* Magic number */
-    if(HDmemcmp(image, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "wrong fractal heap header signature")
-    image += H5_SIZEOF_MAGIC;
-
-    /* Version */
-    if(*image++ != H5HF_HDR_VERSION)
-        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, NULL, "wrong fractal heap header version")
-
-    /* General heap information */
-    UINT16DECODE(image, hdr->id_len);              /* Heap ID length */
-    UINT16DECODE(image, hdr->filter_len);          /* I/O filters' encoded length */
+    /* Deserialize the fractal heap header's prefix */
+    if(H5HF__hdr_prefix_decode(hdr, &image) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, NULL, "can't decode fractal heap header prefix")
 
     /* Heap status flags */
     /* (bit 0: "huge" object IDs have wrapped) */
@@ -1618,10 +1647,6 @@ H5HF__cache_dblock_verify_chksum(const void *_image, size_t len, void *_udata)
     hdr = par_info->hdr;
     HDassert(hdr);
 
-    /* Reset callback context info */
-    udata->decompressed = FALSE;
-    udata->dblk = NULL;
-
     /* Get out if data block is not checksummed */
     if(!(hdr->checksum_dblocks))
 	HGOTO_DONE(TRUE);
@@ -1728,7 +1753,7 @@ H5HF__cache_dblock_deserialize(const void *_image, size_t len, void *_udata,
     H5HF_dblock_cache_ud_t *udata = (H5HF_dblock_cache_ud_t *)_udata;   /* User data for callback */
     H5HF_parent_t       *par_info;      /* Pointer to parent information */
     H5HF_direct_t       *dblock = NULL; /* Direct block info */
-    const uint8_t       *image = _image;/* Pointer into raw data buffer */
+    const uint8_t       *image = (const uint8_t *)_image;/* Pointer into raw data buffer */
     void                *read_buf = NULL; /* Pointer to buffer to decompress */
     haddr_t             heap_addr;      /* Address of heap header in the file */
     void *              ret_value = NULL;       /* Return value */
diff --git a/src/H5HFdblock.c b/src/H5HFdblock.c
index 1272ab0..b34534c 100644
--- a/src/H5HFdblock.c
+++ b/src/H5HFdblock.c
@@ -493,6 +493,10 @@ H5HF_man_dblock_protect(H5HF_hdr_t *hdr, hid_t dxpl_id, haddr_t dblock_addr,
         udata.filter_mask = 0;
     } /* end else */
 
+    /* Reset compression context info */
+    udata.decompressed = FALSE;
+    udata.dblk = NULL;
+
     /* Protect the direct block */
     if(NULL == (dblock = (H5HF_direct_t *)H5AC_protect(hdr->f, dxpl_id, H5AC_FHEAP_DBLOCK, dblock_addr, &udata, flags)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap direct block")
diff --git a/src/H5HGcache.c b/src/H5HGcache.c
index 6bc9860..a83c22b 100644
--- a/src/H5HGcache.c
+++ b/src/H5HGcache.c
@@ -72,6 +72,10 @@ static herr_t H5HG__cache_heap_serialize(const H5F_t *f, void *image,
     size_t len, void *thing); 
 static herr_t H5HG__cache_heap_free_icr(void *thing);
 
+/* Prefix deserialization */
+static herr_t H5HG__hdr_deserialize(H5HG_heap_t *heap, const uint8_t *image,
+    const H5F_t *f);
+
 
 /*********************/
 /* Package Variables */
@@ -108,6 +112,52 @@ const H5AC_class_t H5AC_GHEAP[1] = {{
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5HG__hdr_deserialize()
+ *
+ * Purpose:	Decode a global heap's header
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        FAIL
+ *
+ * Programmer:  Quincey Koziol
+ *              December 15, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5HG__hdr_deserialize(H5HG_heap_t *heap, const uint8_t *image, const H5F_t *f)
+{
+    herr_t ret_value = SUCCEED;                 /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(heap);
+    HDassert(image);
+    HDassert(f);
+
+    /* Magic number */
+    if(HDmemcmp(image, H5HG_MAGIC, (size_t)H5_SIZEOF_MAGIC))
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "bad global heap collection signature")
+    image += H5_SIZEOF_MAGIC;
+
+    /* Version */
+    if(H5HG_VERSION != *image++)
+        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, FAIL, "wrong version number in global heap")
+
+    /* Reserved */
+    image += 3;
+
+    /* Size */
+    H5F_DECODE_LENGTH(f, image, heap->size);
+    HDassert(heap->size >= H5HG_MINSIZE);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5HG__hdr_deserialize() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5HG__cache_heap_get_initial_load_size()
  *
  * Purpose:	Return the initial speculative read size to the metadata 
@@ -154,41 +204,27 @@ H5HG__cache_heap_get_initial_load_size(void H5_ATTR_UNUSED *_udata, size_t *imag
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HG__cache_heap_get_final_load_size(const void *_image, size_t image_len,
-    void *_udata, size_t *actual_len)
+H5HG__cache_heap_get_final_load_size(const void *image, size_t image_len,
+    void *udata, size_t *actual_len)
 {
-    const uint8_t *image = (const uint8_t *)_image;   	/* Pointer into raw data buffer */
-    H5F_t *f = (H5F_t *)_udata;                 /* File pointer -- obtained from user data */
-    size_t heap_size = 0;                       /* Total size of collection      */
-    herr_t ret_value = SUCCEED;                 /* Return value */
+    H5HG_heap_t heap;                   /* Global heap */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
 
     /* Sanity check */
     HDassert(image);
-    HDassert(f);
+    HDassert(udata);
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
-
-    /* Magic number */
-    if(HDmemcmp(image, H5HG_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "bad global heap collection signature")
-    image += H5_SIZEOF_MAGIC;
-
-    /* Version */
-    if(H5HG_VERSION != *image++)
-        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, FAIL, "wrong version number in global heap")
-
-    /* Reserved */
-    image += 3;
-
-    /* Size */
-    H5F_DECODE_LENGTH(f, image, heap_size);
-    HDassert(heap_size >= H5HG_MINSIZE);
     HDassert(image_len == H5HG_MINSIZE);
 
+    /* Deserialize the heap's header */
+    if(H5HG__hdr_deserialize(&heap, (const uint8_t *)image, (const H5F_t *)udata) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, FAIL, "can't decode global heap prefix")
+
     /* Set the final size for the cache image */
-    *actual_len = heap_size;
+    *actual_len = heap.size;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -236,29 +272,13 @@ H5HG__cache_heap_deserialize(const void *_image, size_t len, void *_udata,
     if(NULL == (heap->chunk = H5FL_BLK_MALLOC(gheap_chunk, len)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
-    /* copy the image buffer into the newly allocate chunk */
+    /* Copy the image buffer into the newly allocate chunk */
     HDmemcpy(heap->chunk, _image, len);
 
-    image = heap->chunk;
-
-    /* Magic number */
-    if(HDmemcmp(image, H5HG_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "bad global heap collection signature")
-    image += H5_SIZEOF_MAGIC;
+    /* Deserialize the heap's header */
+    if(H5HG__hdr_deserialize(heap, (const uint8_t *)heap->chunk, f) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, NULL, "can't decode global heap header")
 
-    /* Version */
-    if(H5HG_VERSION != *image++) 
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "wrong version number in global heap")
-
-    /* Reserved */
-    image += 3;
-
-    /* Size */
-    H5F_DECODE_LENGTH(f, image, heap->size);
-    HDassert(heap->size >= H5HG_MINSIZE);
-    HDassert((len == H5HG_MINSIZE) /* first try */ || 
-             ((len == heap->size) && (len > H5HG_MINSIZE))); /* second try */
-    
     /* Decode each object */
     image = heap->chunk + H5HG_SIZEOF_HDR(f);
     nalloc = H5HG_NOBJS(f, heap->size);
diff --git a/src/H5HLcache.c b/src/H5HLcache.c
index 3db239e..b2ca839 100644
--- a/src/H5HLcache.c
+++ b/src/H5HLcache.c
@@ -91,6 +91,10 @@ static herr_t H5HL__cache_datablock_serialize(const H5F_t *f, void *image,
 static herr_t H5HL__cache_datablock_notify(H5C_notify_action_t action, void *_thing);
 static herr_t H5HL__cache_datablock_free_icr(void *thing);
 
+/* Header deserialization */
+static herr_t H5HL__hdr_deserialize(H5HL_t *heap, const uint8_t *image,
+    H5HL_cache_prfx_ud_t *udata);
+
 /* Free list de/serialization */
 static herr_t H5HL__fl_deserialize(H5HL_t *heap);
 static void H5HL__fl_serialize(const H5HL_t *heap);
@@ -147,6 +151,64 @@ const H5AC_class_t H5AC_LHEAP_DBLK[1] = {{
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5HL__hdr_deserialize()
+ *
+ * Purpose:	Decode a local heap's header
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        FAIL
+ *
+ * Programmer:  Quincey Koziol
+ *              December 15, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5HL__hdr_deserialize( H5HL_t *heap, const uint8_t *image,
+    H5HL_cache_prfx_ud_t *udata)
+{
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity checks */
+    HDassert(heap);
+    HDassert(image);
+    HDassert(udata);
+
+    /* Check magic number */
+    if(HDmemcmp(image, H5HL_MAGIC, (size_t)H5_SIZEOF_MAGIC)) 
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "bad local heap signature")
+    image += H5_SIZEOF_MAGIC;
+
+    /* Version */
+    if(H5HL_VERSION != *image++) 
+        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, FAIL, "wrong version number in local heap")
+
+    /* Reserved */
+    image += 3;
+
+    /* Store the prefix's address & length */
+    heap->prfx_addr = udata->prfx_addr;
+    heap->prfx_size = udata->sizeof_prfx;
+
+    /* Heap data size */
+    H5F_DECODE_LENGTH_LEN(image, heap->dblk_size, udata->sizeof_size);
+
+    /* Free list head */
+    H5F_DECODE_LENGTH_LEN(image, heap->free_block, udata->sizeof_size);
+    if(heap->free_block != H5HL_FREE_NULL && heap->free_block >= heap->dblk_size)
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "bad heap free list")
+
+    /* Heap data address */
+    H5F_addr_decode_len(udata->sizeof_addr, &image, &(heap->dblk_addr));
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5HL__hdr_deserialize() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5HL__fl_deserialize
  *
  * Purpose:     Deserialize the free list for a heap data block
@@ -319,32 +381,9 @@ H5HL__cache_prefix_get_final_load_size(const void *_image, size_t image_len,
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
 
-    /* Check magic number */
-    if(HDmemcmp(image, H5HL_MAGIC, (size_t)H5_SIZEOF_MAGIC)) 
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "bad local heap signature")
-    image += H5_SIZEOF_MAGIC;
-
-    /* Version */
-    if(H5HL_VERSION != *image++) 
-        HGOTO_ERROR(H5E_HEAP, H5E_VERSION, FAIL, "wrong version number in local heap")
-
-    /* Reserved */
-    image += 3;
-
-    /* Store the prefix's address & length */
-    heap.prfx_addr = udata->prfx_addr; /* NEED */
-    heap.prfx_size = udata->sizeof_prfx; /* NEED */
-
-    /* Heap data size */
-    H5F_DECODE_LENGTH_LEN(image, heap.dblk_size, udata->sizeof_size); /* NEED */
-
-    /* Free list head */
-    H5F_DECODE_LENGTH_LEN(image, heap.free_block, udata->sizeof_size);
-    if(heap.free_block != H5HL_FREE_NULL && heap.free_block >= heap.dblk_size)
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "bad heap free list");
-
-    /* Heap data address */
-    H5F_addr_decode_len(udata->sizeof_addr, &image, &(heap.dblk_addr)); /* NEED */
+    /* Deserialize the heap's header */
+    if(H5HL__hdr_deserialize(&heap, (const uint8_t *)image, udata) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, FAIL, "can't decode local heap header")
 
     /* Set the final size for the cache image */
     *actual_len = heap.prfx_size;
@@ -398,41 +437,18 @@ H5HL__cache_prefix_deserialize(const void *_image, size_t len, void *_udata,
     HDassert(H5F_addr_defined(udata->prfx_addr));
     HDassert(dirty);
 
-    /* Check magic number */
-    if(HDmemcmp(image, H5HL_MAGIC, (size_t)H5_SIZEOF_MAGIC)) 
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "bad local heap signature")
-    image += H5_SIZEOF_MAGIC;
-
-    /* Version */
-    if(H5HL_VERSION != *image++) 
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "wrong version number in local heap")
-
-    /* Reserved */
-    image += 3;
-    
     /* Allocate space in memory for the heap */
     if(NULL == (heap = H5HL__new(udata->sizeof_size, udata->sizeof_addr, udata->sizeof_prfx)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate local heap structure");
 
+    /* Deserialize the heap's header */
+    if(H5HL__hdr_deserialize(heap, (const uint8_t *)image, udata) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, NULL, "can't decode local heap header")
+
     /* Allocate the heap prefix */
     if(NULL == (prfx = H5HL__prfx_new(heap)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate local heap prefix");
 
-    /* Store the prefix's address & length */
-    heap->prfx_addr = udata->prfx_addr;
-    heap->prfx_size = udata->sizeof_prfx;
-
-    /* Heap data size */
-    H5F_DECODE_LENGTH_LEN(image, heap->dblk_size, udata->sizeof_size);
-
-    /* Free list head */
-    H5F_DECODE_LENGTH_LEN(image, heap->free_block, udata->sizeof_size);
-    if((heap->free_block != H5HL_FREE_NULL) && (heap->free_block >= heap->dblk_size))
-        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "bad heap free list")
-
-    /* Heap data address */
-    H5F_addr_decode_len(udata->sizeof_addr, &image, &(heap->dblk_addr));
-
     /* Check if heap block exists */
     if(heap->dblk_size) {
         /* Check if heap data block is contiguous with header */
diff --git a/src/H5Ocache.c b/src/H5Ocache.c
index d398e41..1067b8c 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -84,6 +84,10 @@ static herr_t H5O__cache_chk_serialize(const H5F_t *f, void *image, size_t len,
 static herr_t H5O__cache_chk_notify(H5AC_notify_action_t action, void *_thing);
 static herr_t H5O__cache_chk_free_icr(void *thing);
 
+/* Prefix routines */
+static herr_t H5O__prefix_deserialize(const uint8_t *image,
+    H5O_cache_ud_t *udata);
+
 /* Chunk routines */
 static herr_t H5O__chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len,
     const uint8_t *image, H5O_common_cache_ud_t *udata, hbool_t *dirty);
@@ -198,13 +202,11 @@ H5O__cache_get_initial_load_size(void H5_ATTR_UNUSED *_udata, size_t *image_len)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5O__cache_get_final_load_size(const void *_image, size_t image_len,
+H5O__cache_get_final_load_size(const void *image, size_t image_len,
     void *_udata, size_t *actual_len)
 {
-    const uint8_t *image = (const uint8_t *)_image;   	/* Pointer into raw data buffer */
     H5O_cache_ud_t *udata = (H5O_cache_ud_t *)_udata;   /* User data for callback */
-    H5O_t *oh = NULL;                   /* Object header read in */
-    htri_t ret_value = SUCCEED;         /* Return value */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
 
@@ -214,136 +216,17 @@ H5O__cache_get_final_load_size(const void *_image, size_t image_len,
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
 
-    /* Allocate space for the new object header data structure */
-    if(NULL == (oh = H5FL_CALLOC(H5O_t)))
-        HGOTO_ERROR(H5E_OHDR, H5E_CANTALLOC, FAIL, "memory allocation failed")
-
-    /* File-specific, non-stored information */
-    oh->sizeof_size = H5F_SIZEOF_SIZE(udata->common.f);
-    oh->sizeof_addr = H5F_SIZEOF_ADDR(udata->common.f);
-
-    /* Check for presence of magic number */
-    /* (indicates version 2 or later) */
-    if(!HDmemcmp(image, H5O_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC)) {
-        /* Magic number */
-        image += H5_SIZEOF_MAGIC;
-
-        /* Version */
-        oh->version = *image++;
-        if(H5O_VERSION_2 != oh->version)
-            HGOTO_ERROR(H5E_OHDR, H5E_VERSION, FAIL, "bad object header version number")
-
-        /* Flags */
-        oh->flags = *image++;
-        if(oh->flags & ~H5O_HDR_ALL_FLAGS)
-            HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "unknown object header status flag(s)")
-
-        /* Number of links to object (unless overridden by refcount message) */
-        oh->nlink = 1;
-
-        /* Time fields */
-        if(oh->flags & H5O_HDR_STORE_TIMES) {
-            uint32_t tmp;       /* Temporary value */
-
-            UINT32DECODE(image, tmp);
-            oh->atime = (time_t)tmp;
-            UINT32DECODE(image, tmp);
-            oh->mtime = (time_t)tmp;
-            UINT32DECODE(image, tmp);
-            oh->ctime = (time_t)tmp;
-            UINT32DECODE(image, tmp);
-            oh->btime = (time_t)tmp;
-        } /* end if */
-        else
-            oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
-
-        /* Attribute fields */
-        if(oh->flags & H5O_HDR_ATTR_STORE_PHASE_CHANGE) {
-            UINT16DECODE(image, oh->max_compact);
-            UINT16DECODE(image, oh->min_dense);
-            if(oh->max_compact < oh->min_dense)
-                HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad object header attribute phase change values")
-        } /* end if */
-        else {
-            oh->max_compact = H5O_CRT_ATTR_MAX_COMPACT_DEF;
-            oh->min_dense = H5O_CRT_ATTR_MIN_DENSE_DEF;
-        } /* end else */
-
-        /* First chunk size */
-        switch(oh->flags & H5O_HDR_CHUNK0_SIZE) {
-            case 0:     /* 1 byte size */
-                udata->chunk0_size = *image++;
-                break;
-
-            case 1:     /* 2 byte size */
-                UINT16DECODE(image, udata->chunk0_size);
-                break;
-
-            case 2:     /* 4 byte size */
-                UINT32DECODE(image, udata->chunk0_size);
-                break;
-
-            case 3:     /* 8 byte size */
-                UINT64DECODE(image, udata->chunk0_size);
-                break;
-
-            default:
-                HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad size for chunk 0")
-        } /* end switch */
-        if(udata->chunk0_size > 0 && udata->chunk0_size < H5O_SIZEOF_MSGHDR_OH(oh))
-            HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad object header chunk size")
-    } /* end if */
-    else {
-        /* Version */
-        oh->version = *image++;
-        if(H5O_VERSION_1 != oh->version)
-            HGOTO_ERROR(H5E_OHDR, H5E_VERSION, FAIL, "bad object header version number")
-
-        /* Flags */
-        oh->flags = H5O_CRT_OHDR_FLAGS_DEF;
-
-        /* Reserved */
-        image++;
-
-        /* Number of messages */
-        UINT16DECODE(image, udata->v1_pfx_nmesgs);
-
-        /* Link count */
-        UINT32DECODE(image, oh->nlink);
-
-        /* Reset unused time fields */
-        oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
-
-        /* Reset unused attribute fields */
-        oh->max_compact = 0;
-        oh->min_dense = 0;
-
-        /* First chunk size */
-        UINT32DECODE(image, udata->chunk0_size);
-        if((udata->v1_pfx_nmesgs > 0 && udata->chunk0_size < H5O_SIZEOF_MSGHDR_OH(oh)) ||
-                (udata->v1_pfx_nmesgs == 0 && udata->chunk0_size > 0))
-            HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad object header chunk size")
-
-        /* Reserved, in version 1 (for 8-byte alignment padding) */
-        image += 4;
-    } /* end else */
+    /* Deserialize the object header prefix */
+    if(H5O__prefix_deserialize((const uint8_t *)image, udata) < 0)
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, FAIL, "can't deserialize object header prefix")
 
-    /* Determine object header prefix length */
-    HDassert((size_t)((const uint8_t *)image - (const uint8_t *)_image) == (size_t)(H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
+    /* Sanity check */
+    HDassert(udata->oh);
 
     /* Set the final size for the cache image */
-    *actual_len = udata->chunk0_size + (size_t)H5O_SIZEOF_HDR(oh);
-
-    /* Save the object header for later use in 'deserialize' callback */
-    udata->oh = oh;
-    oh = NULL;
+    *actual_len = udata->chunk0_size + (size_t)H5O_SIZEOF_HDR(udata->oh);
 
 done:
-    /* Release the [possibly partially initialized] object header on errors */
-    if(ret_value < 0 && oh)
-        if(H5O__free(oh) < 0)
-            HDONE_ERROR(H5E_OHDR, H5E_CANTRELEASE, FAIL, "unable to destroy object header data")
-
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5O__cache_get_final_load_size() */
 
@@ -413,12 +296,11 @@ H5O__cache_verify_chksum(const void *_image, size_t len, void *_udata)
  *-------------------------------------------------------------------------
  */
 static void *
-H5O__cache_deserialize(const void *_image, size_t len, void *_udata,
+H5O__cache_deserialize(const void *image, size_t len, void *_udata,
     hbool_t *dirty)
 {
-    H5O_t          *oh;                 /* Object header read in */
+    H5O_t          *oh = NULL;          /* Object header read in */
     H5O_cache_ud_t *udata = (H5O_cache_ud_t *)_udata;   /* User data for callback */
-    const uint8_t  *image = (const uint8_t *)_image;    /* Pointer into buffer to decode */
     void *          ret_value = NULL;   /* Return value */
 
     FUNC_ENTER_STATIC
@@ -427,11 +309,24 @@ H5O__cache_deserialize(const void *_image, size_t len, void *_udata,
     HDassert(image);
     HDassert(len > 0); 
     HDassert(udata);
-    HDassert(udata->oh);
     HDassert(udata->common.f);
     HDassert(udata->common.cont_msg_info);
     HDassert(dirty);
 
+    /* Check for partially deserialized object header */
+    /* (Object header prefix will be deserialized if the object header came
+     *  through the 'get_final_load_size' callback and not deserialized if
+     *  the object header is coming from a cache image - QAK, 2016/12/14)
+     */
+    if(NULL == udata->oh) {
+        /* Deserialize the object header prefix */
+        if(H5O__prefix_deserialize((const uint8_t *)image, udata) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, NULL, "can't deserialize object header prefix")
+
+        /* Sanity check */
+        HDassert(udata->oh);
+    } /* end if */
+
     /* Retrieve partially deserialized object header from user data */
     oh = udata->oh;
 
@@ -448,7 +343,7 @@ H5O__cache_deserialize(const void *_image, size_t len, void *_udata,
         oh->proxy = NULL;
 
     /* Parse the first chunk */
-    if(H5O__chunk_deserialize(oh, udata->common.addr, udata->chunk0_size, (const uint8_t *)_image, &(udata->common), dirty) < 0)
+    if(H5O__chunk_deserialize(oh, udata->common.addr, udata->chunk0_size, (const uint8_t *)image, &(udata->common), dirty) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, NULL, "can't deserialize first object header chunk")
 
     /* Note that we've loaded the object header from the file */
@@ -717,11 +612,7 @@ H5O__cache_notify(H5AC_notify_action_t action, void *_thing)
             break;
 
         default:
-#ifdef NDEBUG
             HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "unknown action from metadata cache")
-#else /* NDEBUG */
-            HDassert(0 && "Unknown action?!?");
-#endif /* NDEBUG */
     } /* end switch */
 
 done:
@@ -1228,6 +1119,163 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5O__prefix_deserialize()
+ *
+ * Purpose:	Deserialize an object header prefix
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        FAIL
+ *
+ * Programmer:  Quincey Koziol
+ *              December 14, 2016
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O__prefix_deserialize(const uint8_t *_image, H5O_cache_ud_t *udata)
+{
+    const uint8_t *image = (const uint8_t *)_image;   	/* Pointer into raw data buffer */
+    H5O_t *oh = NULL;                   /* Object header read in */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Check arguments */
+    HDassert(image);
+    HDassert(udata);
+
+    /* Allocate space for the new object header data structure */
+    if(NULL == (oh = H5FL_CALLOC(H5O_t)))
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTALLOC, FAIL, "memory allocation failed")
+
+    /* File-specific, non-stored information */
+    oh->sizeof_size = H5F_SIZEOF_SIZE(udata->common.f);
+    oh->sizeof_addr = H5F_SIZEOF_ADDR(udata->common.f);
+
+    /* Check for presence of magic number */
+    /* (indicates version 2 or later) */
+    if(!HDmemcmp(image, H5O_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC)) {
+        /* Magic number */
+        image += H5_SIZEOF_MAGIC;
+
+        /* Version */
+        oh->version = *image++;
+        if(H5O_VERSION_2 != oh->version)
+            HGOTO_ERROR(H5E_OHDR, H5E_VERSION, FAIL, "bad object header version number")
+
+        /* Flags */
+        oh->flags = *image++;
+        if(oh->flags & ~H5O_HDR_ALL_FLAGS)
+            HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "unknown object header status flag(s)")
+
+        /* Number of links to object (unless overridden by refcount message) */
+        oh->nlink = 1;
+
+        /* Time fields */
+        if(oh->flags & H5O_HDR_STORE_TIMES) {
+            uint32_t tmp;       /* Temporary value */
+
+            UINT32DECODE(image, tmp);
+            oh->atime = (time_t)tmp;
+            UINT32DECODE(image, tmp);
+            oh->mtime = (time_t)tmp;
+            UINT32DECODE(image, tmp);
+            oh->ctime = (time_t)tmp;
+            UINT32DECODE(image, tmp);
+            oh->btime = (time_t)tmp;
+        } /* end if */
+        else
+            oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
+
+        /* Attribute fields */
+        if(oh->flags & H5O_HDR_ATTR_STORE_PHASE_CHANGE) {
+            UINT16DECODE(image, oh->max_compact);
+            UINT16DECODE(image, oh->min_dense);
+            if(oh->max_compact < oh->min_dense)
+                HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad object header attribute phase change values")
+        } /* end if */
+        else {
+            oh->max_compact = H5O_CRT_ATTR_MAX_COMPACT_DEF;
+            oh->min_dense = H5O_CRT_ATTR_MIN_DENSE_DEF;
+        } /* end else */
+
+        /* First chunk size */
+        switch(oh->flags & H5O_HDR_CHUNK0_SIZE) {
+            case 0:     /* 1 byte size */
+                udata->chunk0_size = *image++;
+                break;
+
+            case 1:     /* 2 byte size */
+                UINT16DECODE(image, udata->chunk0_size);
+                break;
+
+            case 2:     /* 4 byte size */
+                UINT32DECODE(image, udata->chunk0_size);
+                break;
+
+            case 3:     /* 8 byte size */
+                UINT64DECODE(image, udata->chunk0_size);
+                break;
+
+            default:
+                HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad size for chunk 0")
+        } /* end switch */
+        if(udata->chunk0_size > 0 && udata->chunk0_size < H5O_SIZEOF_MSGHDR_OH(oh))
+            HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad object header chunk size")
+    } /* end if */
+    else {
+        /* Version */
+        oh->version = *image++;
+        if(H5O_VERSION_1 != oh->version)
+            HGOTO_ERROR(H5E_OHDR, H5E_VERSION, FAIL, "bad object header version number")
+
+        /* Flags */
+        oh->flags = H5O_CRT_OHDR_FLAGS_DEF;
+
+        /* Reserved */
+        image++;
+
+        /* Number of messages */
+        UINT16DECODE(image, udata->v1_pfx_nmesgs);
+
+        /* Link count */
+        UINT32DECODE(image, oh->nlink);
+
+        /* Reset unused time fields */
+        oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
+
+        /* Reset unused attribute fields */
+        oh->max_compact = 0;
+        oh->min_dense = 0;
+
+        /* First chunk size */
+        UINT32DECODE(image, udata->chunk0_size);
+        if((udata->v1_pfx_nmesgs > 0 && udata->chunk0_size < H5O_SIZEOF_MSGHDR_OH(oh)) ||
+                (udata->v1_pfx_nmesgs == 0 && udata->chunk0_size > 0))
+            HGOTO_ERROR(H5E_OHDR, H5E_BADVALUE, FAIL, "bad object header chunk size")
+
+        /* Reserved, in version 1 (for 8-byte alignment padding) */
+        image += 4;
+    } /* end else */
+
+    /* Verify object header prefix length */
+    HDassert((size_t)(image - _image) == (size_t)(H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
+
+    /* Save the object header for later use in 'deserialize' callback */
+    udata->oh = oh;
+    oh = NULL;
+
+done:
+    /* Release the [possibly partially initialized] object header on errors */
+    if(ret_value < 0 && oh)
+        if(H5O__free(oh) < 0)
+            HDONE_ERROR(H5E_OHDR, H5E_CANTRELEASE, FAIL, "unable to destroy object header data")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5O__prefix_deserialize() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O__chunk_deserialize
  *
  * Purpose:	Deserialize a chunk for an object header