[svn-r13056] Description:

    Add H5SM_type_shared() internal routine to determine if a particular
type of header message is sharable in a file.

    Correct off-by-one error in computing B-tree record size for densely
stored attributes' name index.

    Further progress toward supporting shared attributes in dense storage.

Tested on:
    Linux/32 2.6 (chicago)
    Linux/64 2.6 (chicago2)

8 files changed, 244 insertions, 76 deletions

diff --git a/src/H5Abtree2.c b/src/H5Abtree2.c
index 47cbaae..dc2478e 100644
--- a/src/H5Abtree2.c
+++ b/src/H5Abtree2.c
@@ -148,10 +148,9 @@ H5A_dense_fh_name_cmp(const void *obj, size_t UNUSED obj_len, void *_udata)
     udata->cmp = HDstrcmp(udata->name, attr->name);
 
     /* Check for correct attribute & callback to make */
-    if(udata->cmp == 0 && udata->found_op) {
+    if(udata->cmp == 0 && udata->found_op)
         if((udata->found_op)(attr, udata->found_op_data) < 0)
             HGOTO_ERROR(H5E_OHDR, H5E_CANTOPERATE, FAIL, "attribute found callback failed")
-    } /* end if */
 
 done:
     /* Release the space allocated for the attrbute */
@@ -250,6 +249,7 @@ H5A_dense_btree2_name_compare(const void *_bt2_udata, const void *_bt2_rec)
         HGOTO_DONE(1)
     else {
         H5A_fh_ud_cmp_t fh_udata;       /* User data for fractal heap 'op' callback */
+        H5HF_t *fheap;                  /* Fractal heap handle to use for finding object */
         herr_t status;                  /* Status from fractal heap 'op' routine */
 
         /* Sanity check */
@@ -267,14 +267,14 @@ H5A_dense_btree2_name_compare(const void *_bt2_udata, const void *_bt2_rec)
         fh_udata.cmp = 0;
 
         /* Check for attribute in shared storage */
-        if(bt2_rec->flags) {
-HDfprintf(stderr, "%s: Shared dense storage for attributes not supported yet!\n", "H5A_dense_btree2_name_compare");
-HDassert(0 && "Shared dense storage for attributes not supported yet!");
-        } /* end if */
+        if(bt2_rec->flags)
+            fheap = bt2_udata->shared_fheap;
+        else
+            fheap = bt2_udata->fheap;
+        HDassert(fheap);
 
         /* Check if the user's link and the B-tree's link have the same name */
-        status = H5HF_op(bt2_udata->fheap, bt2_udata->dxpl_id, bt2_rec->id,
-                H5A_dense_fh_name_cmp, &fh_udata);
+        status = H5HF_op(fheap, bt2_udata->dxpl_id, bt2_rec->id, H5A_dense_fh_name_cmp, &fh_udata);
         HDassert(status >= 0);
 
         /* Callback will set comparison value */
@@ -308,8 +308,8 @@ H5A_dense_btree2_name_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_n
 
     /* Encode the record's fields */
     UINT32ENCODE(raw, nrecord->hash)
-    HDmemcpy(raw, nrecord->id, (size_t)H5A_DENSE_FHEAP_ID_LEN);
     *raw++ = nrecord->flags;
+    HDmemcpy(raw, nrecord->id, (size_t)H5A_DENSE_FHEAP_ID_LEN);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5A_dense_btree2_name_encode() */
@@ -337,8 +337,8 @@ H5A_dense_btree2_name_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_n
 
     /* Decode the record's fields */
     UINT32DECODE(raw, nrecord->hash)
-    HDmemcpy(nrecord->id, raw, (size_t)H5A_DENSE_FHEAP_ID_LEN);
     nrecord->flags = *raw++;
+    HDmemcpy(nrecord->id, raw, (size_t)H5A_DENSE_FHEAP_ID_LEN);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5A_dense_btree2_name_decode() */
diff --git a/src/H5Adense.c b/src/H5Adense.c
index 8dea1b7..e2a3d76 100644
--- a/src/H5Adense.c
+++ b/src/H5Adense.c
@@ -40,6 +40,7 @@
 #include "H5Eprivate.h"		/* Error handling		  	*/
 #include "H5MMprivate.h"	/* Memory management			*/
 #include "H5Opkg.h"		/* Object headers			*/
+#include "H5SMprivate.h"	/* Shared object header messages        */
 
 
 /****************/
@@ -65,8 +66,8 @@
 #define H5A_CORDER_BT2_MERGE_PERC       40
 #define H5A_CORDER_BT2_SPLIT_PERC       100
 
-/* Size of stack buffer for serialized attribute */
-#define H5A_ATTR_BUF_SIZE               128
+/* Size of stack buffer for serialized messages */
+#define H5A_MESG_BUF_SIZE               128
 
 
 /******************/
@@ -457,6 +458,7 @@ HDfprintf(stderr, "%s: oh->attr_fheap_addr = %a\n", FUNC, oh->attr_fheap_addr);
     if(H5HF_get_id_len(fheap, &fheap_id_len) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGETSIZE, FAIL, "can't get fractal heap ID length")
     HDassert(fheap_id_len == H5A_DENSE_FHEAP_ID_LEN);
+    HDassert(fheap_id_len == H5SM_FHEAP_ID_LEN);        /* Need to be interchangable -QAK */
 #ifdef QAK
 HDfprintf(stderr, "%s: fheap_id_len = %Zu\n", FUNC, fheap_id_len);
 #endif /* QAK */
@@ -467,6 +469,7 @@ HDfprintf(stderr, "%s: fheap_id_len = %Zu\n", FUNC, fheap_id_len);
 
     /* Create the name index v2 B-tree */
     bt2_rrec_size = 4 +                 /* Name's hash value */
+            1 +                         /* Message flags */
             fheap_id_len;               /* Fractal heap ID */
     if(H5B2_create(f, dxpl_id, H5A_BT2_NAME,
             (size_t)H5A_NAME_BT2_NODE_SIZE, bt2_rrec_size,
@@ -574,6 +577,7 @@ H5A_dense_open(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const char *name)
     udata.f = f;
     udata.dxpl_id = dxpl_id;
     udata.fheap = fheap;
+    udata.shared_fheap = NULL;
     udata.name = name;
     udata.name_hash = H5_checksum_lookup3(name, HDstrlen(name), 0);
     udata.flags = 0;
@@ -612,10 +616,13 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, unsigned mesg_flags,
     const H5A_t *attr)
 {
     H5A_bt2_ud_ins_t udata;             /* User data for v2 B-tree insertion */
-    H5HF_t *fheap = NULL;               /* Fractal heap handle */
-    size_t attr_size;                   /* Size of serialized attribute in the heap */
-    uint8_t attr_buf[H5A_ATTR_BUF_SIZE]; /* Buffer for serializing attribute */
-    void *attr_ptr = NULL;              /* Pointer to serialized attribute */
+    H5HF_t *fheap = NULL;               /* Fractal heap handle for attributes */
+    H5HF_t *shared_fheap = NULL;        /* Fractal heap handle for shared header messages */
+    uint8_t id[H5A_DENSE_FHEAP_ID_LEN]; /* Heap ID of attribute to insert    */
+    H5O_shared_t sh_mesg;               /* Shared object header message */
+    uint8_t attr_buf[H5A_MESG_BUF_SIZE]; /* Buffer for serializing message */
+    void *attr_ptr = NULL;              /* Pointer to serialized message */
+    htri_t attr_sharable;               /* Flag indicating attributes are sharable */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5A_dense_insert, FAIL)
@@ -627,48 +634,79 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, unsigned mesg_flags,
     HDassert(oh);
     HDassert(attr);
 
-    /* Check for inserting shared attribute */
-    if(mesg_flags & H5O_MSG_FLAG_SHARED) {
-/* XXX: fix me */
-HDfprintf(stderr, "%s: inserting shared attributes in dense storage not supported yet!\n", FUNC);
-HGOTO_ERROR(H5E_ATTR, H5E_UNSUPPORTED, FAIL, "inserting shared attributes in dense storage not supported yet")
-    } /* end if */
+    /* Check if attributes are shared in this file */
+    if((attr_sharable = H5SM_type_shared(f, H5O_ATTR_ID, dxpl_id)) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "can't determine if attributes are shared")
 
-    /* Find out the size of buffer needed for serialized attribute */
-    if((attr_size = H5O_msg_raw_size(f, H5O_ATTR_ID, attr)) == 0)
-        HGOTO_ERROR(H5E_ATTR, H5E_CANTGETSIZE, FAIL, "can't get attribute size")
+    /* Get handle for shared object heap, if attributes are sharable */
+    if(attr_sharable) {
+        haddr_t shared_fheap_addr;      /* Address of fractal heap to use */
 
-    /* Allocate space for serialized attribute, if necessary */
-    if(attr_size > sizeof(attr_buf)) {
-        if(NULL == (attr_ptr = H5FL_BLK_MALLOC(ser_attr, attr_size)))
-            HGOTO_ERROR(H5E_ATTR, H5E_NOSPACE, FAIL, "memory allocation failed")
-    } /* end if */
-    else
-        attr_ptr = attr_buf;
+        /* Retrieve the address of the shared object's fractal heap */
+        if(HADDR_UNDEF == (shared_fheap_addr = H5SM_get_fheap_addr(f, H5O_ATTR_ID, dxpl_id)))
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "can't get shared object heap address")
 
-    /* Create serialized form of attribute */
-    if(H5O_msg_encode(f, H5O_ATTR_ID, attr_ptr, attr) < 0)
-	HGOTO_ERROR(H5E_ATTR, H5E_CANTENCODE, FAIL, "can't encode attribute")
+        /* Open the fractal heap for shared header messages */
+        if(NULL == (shared_fheap = H5HF_open(f, dxpl_id, shared_fheap_addr)))
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
+    } /* end if */
 
     /* Open the fractal heap */
     if(NULL == (fheap = H5HF_open(f, dxpl_id, oh->attr_fheap_addr)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
-    /* Insert the serialized attribute into the fractal heap */
-    if(H5HF_insert(fheap, dxpl_id, attr_size, attr_ptr, udata.id) < 0)
-        HGOTO_ERROR(H5E_ATTR, H5E_CANTINSERT, FAIL, "unable to insert attribute into fractal heap")
+    /* Check for inserting shared attribute */
+    if(mesg_flags & H5O_MSG_FLAG_SHARED) {
+        /* Sanity check */
+        HDassert(attr_sharable);
+
+        /* Get the shared information for the attribute */
+        HDmemset(&sh_mesg, 0, sizeof(sh_mesg));
+        if(H5O_attr_get_share(attr, &sh_mesg) < 0)
+            HGOTO_ERROR(H5E_ATTR, H5E_BADMESG, FAIL, "can't get shared message")
+
+        /* Use heap ID for shared message heap */
+        udata.id = (const uint8_t *)&sh_mesg.u.heap_id;
+    } /* end if */
+    else {
+        size_t attr_size;                   /* Size of serialized attribute in the heap */
+
+        /* Find out the size of buffer needed for serialized message */
+        if((attr_size = H5O_msg_raw_size(f, H5O_ATTR_ID, attr)) == 0)
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTGETSIZE, FAIL, "can't get message size")
+
+        /* Allocate space for serialized message, if necessary */
+        if(attr_size > sizeof(attr_buf)) {
+            if(NULL == (attr_ptr = H5FL_BLK_MALLOC(ser_attr, attr_size)))
+                HGOTO_ERROR(H5E_ATTR, H5E_NOSPACE, FAIL, "memory allocation failed")
+        } /* end if */
+        else
+            attr_ptr = attr_buf;
+
+        /* Create serialized form of attribute or shared message */
+        if(H5O_msg_encode(f, H5O_ATTR_ID, attr_ptr, attr) < 0)
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTENCODE, FAIL, "can't encode attribute")
+
+        /* Insert the serialized attribute into the fractal heap */
+        if(H5HF_insert(fheap, dxpl_id, attr_size, attr_ptr, id) < 0)
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTINSERT, FAIL, "unable to insert attribute into fractal heap")
+
+        /* Use heap ID for attribute heap */
+        udata.id = id;
+    } /* end else */
 
     /* Create the callback information for v2 B-tree record insertion */
     udata.common.f = f;
     udata.common.dxpl_id = dxpl_id;
     udata.common.fheap = fheap;
+    udata.common.shared_fheap = shared_fheap;
     udata.common.name = attr->name;
     udata.common.name_hash = H5_checksum_lookup3(attr->name, HDstrlen(attr->name), 0);
     udata.common.flags = mesg_flags;
     udata.common.corder = -1;   /* XXX: None yet */
     udata.common.found_op = NULL;
     udata.common.found_op_data = NULL;
-    /* udata.id already set in H5HF_insert() call */
+    /* udata.id already set */
 
     /* Insert attribute into 'name' tracking v2 B-tree */
     if(H5B2_insert(f, dxpl_id, H5A_BT2_NAME, oh->name_bt2_addr, &udata) < 0)
@@ -676,6 +714,8 @@ HGOTO_ERROR(H5E_ATTR, H5E_UNSUPPORTED, FAIL, "inserting shared attributes in den
 
 done:
     /* Release resources */
+    if(shared_fheap && H5HF_close(shared_fheap, dxpl_id) < 0)
+        HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "can't close fractal heap")
     if(fheap && H5HF_close(fheap, dxpl_id) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "can't close fractal heap")
     if(attr_ptr && attr_ptr != attr_buf)
@@ -769,10 +809,12 @@ H5A_dense_write(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const H5A_t *attr)
 {
     H5A_bt2_ud_common_t udata;          /* User data for v2 B-tree modify */
     H5A_bt2_od_wrt_t op_data;           /* "Op data" for v2 B-tree modify */
+    H5HF_t *shared_fheap = NULL;        /* Fractal heap handle for shared header messages */
     H5HF_t *fheap = NULL;               /* Fractal heap handle */
     size_t attr_size;                   /* Size of serialized attribute in the heap */
-    uint8_t attr_buf[H5A_ATTR_BUF_SIZE]; /* Buffer for serializing attribute */
+    uint8_t attr_buf[H5A_MESG_BUF_SIZE]; /* Buffer for serializing attribute */
     void *attr_ptr = NULL;              /* Pointer to serialized attribute */
+    htri_t attr_sharable;               /* Flag indicating attributes are sharable */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5A_dense_write, FAIL)
@@ -784,6 +826,23 @@ H5A_dense_write(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const H5A_t *attr)
     HDassert(oh);
     HDassert(attr);
 
+    /* Check if attributes are shared in this file */
+    if((attr_sharable = H5SM_type_shared(f, H5O_ATTR_ID, dxpl_id)) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "can't determine if attributes are shared")
+
+    /* Get handle for shared object heap, if attributes are sharable */
+    if(attr_sharable) {
+        haddr_t shared_fheap_addr;      /* Address of fractal heap to use */
+
+        /* Retrieve the address of the shared object's fractal heap */
+        if(HADDR_UNDEF == (shared_fheap_addr = H5SM_get_fheap_addr(f, H5O_ATTR_ID, dxpl_id)))
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "can't get shared object heap address")
+
+        /* Open the fractal heap for shared header messages */
+        if(NULL == (shared_fheap = H5HF_open(f, dxpl_id, shared_fheap_addr)))
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
+    } /* end if */
+
     /* Find out the size of buffer needed for serialized attribute */
     if((attr_size = H5O_msg_raw_size(f, H5O_ATTR_ID, attr)) == 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGETSIZE, FAIL, "can't get attribute size")
@@ -808,6 +867,7 @@ H5A_dense_write(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const H5A_t *attr)
     udata.f = f;
     udata.dxpl_id = dxpl_id;
     udata.fheap = fheap;
+    udata.shared_fheap = shared_fheap;
     udata.name = attr->name;
     udata.name_hash = H5_checksum_lookup3(attr->name, HDstrlen(attr->name), 0);
     udata.flags = 0;
@@ -827,6 +887,8 @@ H5A_dense_write(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const H5A_t *attr)
 
 done:
     /* Release resources */
+    if(shared_fheap && H5HF_close(shared_fheap, dxpl_id) < 0)
+        HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "can't close fractal heap")
     if(fheap && H5HF_close(fheap, dxpl_id) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "can't close fractal heap")
     if(attr_ptr && attr_ptr != attr_buf)
@@ -1151,6 +1213,7 @@ H5A_dense_remove(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const char *name)
     udata.f = f;
     udata.dxpl_id = dxpl_id;
     udata.fheap = fheap;
+    udata.shared_fheap = NULL;
     udata.name = name;
     udata.name_hash = H5_checksum_lookup3(name, HDstrlen(name), 0);
     udata.flags = 0;
@@ -1209,6 +1272,7 @@ H5A_dense_exists(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, const char *name)
     udata.f = f;
     udata.dxpl_id = dxpl_id;
     udata.fheap = fheap;
+    udata.shared_fheap = NULL;
     udata.name = name;
     udata.name_hash = H5_checksum_lookup3(name, HDstrlen(name), 0);
     udata.flags = 0;
diff --git a/src/H5Apkg.h b/src/H5Apkg.h
index 11dd43d..a3b0e70 100644
--- a/src/H5Apkg.h
+++ b/src/H5Apkg.h
@@ -96,6 +96,7 @@ typedef struct H5A_bt2_ud_common_t {
     H5F_t       *f;                     /* Pointer to file that fractal heap is in */
     hid_t       dxpl_id;                /* DXPL for operation                */
     H5HF_t      *fheap;                 /* Fractal heap handle               */
+    H5HF_t      *shared_fheap;          /* Fractal heap handle for shared messages */
     const char  *name;                  /* Name of attribute to compare      */
     uint32_t    name_hash;              /* Hash of name of attribute to compare */
     uint8_t     flags;                  /* Flags for attribute storage location */
@@ -111,7 +112,7 @@ typedef struct H5A_bt2_ud_common_t {
 typedef struct H5A_bt2_ud_ins_t {
     /* downward */
     H5A_bt2_ud_common_t common;         /* Common info for B-tree user data (must be first) */
-    uint8_t id[H5A_DENSE_FHEAP_ID_LEN]; /* Heap ID of attribute to insert    */
+    const uint8_t *id;                  /* Heap ID of attribute to insert    */
 } H5A_bt2_ud_ins_t;
 
 /* Data structure to hold table of attributes for an object */
diff --git a/src/H5Oattribute.c b/src/H5Oattribute.c
index 7d5e496..17d6dcd 100644
--- a/src/H5Oattribute.c
+++ b/src/H5Oattribute.c
@@ -161,7 +161,9 @@ H5O_attr_to_dense_cb(H5O_t *oh, H5O_mesg_t *mesg/*in,out*/,
     unsigned UNUSED sequence, unsigned *oh_flags_ptr, void *_udata/*in,out*/)
 {
     H5O_iter_cvt_t *udata = (H5O_iter_cvt_t *)_udata;   /* Operator user data */
-    herr_t ret_value = H5_ITER_CONT;   /* Return value */
+    H5A_t shared_attr;                  /* Copy of shared attribute */
+    H5A_t *attr;                        /* Pointer to attribute to insert */
+    herr_t ret_value = H5_ITER_CONT;    /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5O_attr_to_dense_cb)
 
@@ -169,11 +171,23 @@ H5O_attr_to_dense_cb(H5O_t *oh, H5O_mesg_t *mesg/*in,out*/,
     HDassert(oh);
     HDassert(mesg);
 
+    /* Check for shared attribute */
+    if(mesg->flags & H5O_MSG_FLAG_SHARED) {
+        /* Read the shared attribute in */
+        if(NULL == H5O_shared_read(udata->f, udata->dxpl_id, mesg->native, H5O_MSG_ATTR, &shared_attr))
+	    HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, H5_ITER_ERROR, "unable to read shared attribute")
+
+        /* Point attribute to insert at shared attribute read in */
+        attr = &shared_attr;
+    } /* end if */
+    else
+        attr = mesg->native;
+
     /* Insert attribute into dense storage */
-    if(H5A_dense_insert(udata->f, udata->dxpl_id, oh, mesg->flags, mesg->native) < 0)
+    if(H5A_dense_insert(udata->f, udata->dxpl_id, oh, mesg->flags, attr) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, H5_ITER_ERROR, "unable to add to dense storage")
 
-    /* Convert message into a null message */
+    /* Convert message into a null message in the header */
     if(H5O_release_mesg(udata->f, udata->dxpl_id, oh, mesg, TRUE, FALSE) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTDELETE, H5_ITER_ERROR, "unable to convert into null message")
 
@@ -181,6 +195,10 @@ H5O_attr_to_dense_cb(H5O_t *oh, H5O_mesg_t *mesg/*in,out*/,
     *oh_flags_ptr |= H5AC__DIRTIED_FLAG;
 
 done:
+    /* Release copy of shared attribute */
+    if(attr == &shared_attr)
+        H5O_attr_reset(&shared_attr);
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5O_attr_to_dense_cb() */
 
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index e0c7292..a87c3ba 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -217,7 +217,7 @@ struct H5O_t {
     haddr_t     attr_fheap_addr;        /* Address of fractal heap for storing "dense" attributes */
     haddr_t     name_bt2_addr;          /* Address of v2 B-tree for indexing names of attributes */
 
-    /* Message management (stored, indirectly) */
+    /* Message management (stored, in chunks) */
     size_t	nmesgs;			/*number of messages		     */
     size_t	alloc_nmesgs;		/*number of message slots	     */
     H5O_mesg_t	*mesg;			/*array of messages		     */
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 3c95953..5e84ff6 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -47,7 +47,7 @@ typedef struct H5O_t H5O_t;
 
 /* JAMES: should these be in H5SM_private?  or renamed? */
 /* JAMES: causes errors encoding/decoding if this is wrong.  Can't be constant. */
-#define H5SM_FHEAP_ID_LEN 6
+#define H5SM_FHEAP_ID_LEN 7
 
 /* JAMES: not great? */
 typedef uint64_t H5SM_fheap_id_t;
diff --git a/src/H5SM.c b/src/H5SM.c
index 2654483..0e7ba0e 100755
--- a/src/H5SM.c
+++ b/src/H5SM.c
@@ -40,7 +40,7 @@
 #define H5SM_FHEAP_MAN_WIDTH                     4
 #define H5SM_FHEAP_MAN_START_BLOCK_SIZE          1024
 #define H5SM_FHEAP_MAN_MAX_DIRECT_SIZE           (64 * 1024)
-#define H5SM_FHEAP_MAN_MAX_INDEX                 20
+#define H5SM_FHEAP_MAN_MAX_INDEX                 32
 #define H5SM_FHEAP_MAN_START_ROOT_ROWS           1
 #define H5SM_FHEAP_CHECKSUM_DBLOCKS              TRUE
 #define H5SM_FHEAP_MAX_MAN_SIZE                  (4 * 1024)
@@ -62,6 +62,7 @@ static herr_t H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id,
         H5SM_index_header_t *header, unsigned type_id, const H5O_shared_t * mesg,
         unsigned *cache_flags);
 static hsize_t H5SM_find_in_list(H5F_t *f, H5SM_list_t *list, const H5SM_mesg_key_t *key);
+static herr_t H5SM_type_to_flag(unsigned type_id, unsigned *type_flag);
 static ssize_t H5SM_get_index(const H5SM_master_table_t *table, unsigned type_id);
 
 
@@ -217,13 +218,9 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5SM_get_index
- *
- * Purpose:     Get the index number for a given message type.
+ * Function:    H5SM_type_to_flag
  *
- *              Returns the number of the index in the supplied table
- *              that holds messages of type type_id, or negative if
- *              there is no index for this message type.
+ * Purpose:     Get the shared message flag for a given message type.
  *
  * Return:      Non-negative on success/Negative on failure
  *
@@ -232,36 +229,67 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static ssize_t
-H5SM_get_index(const H5SM_master_table_t *table, unsigned type_id)
+static herr_t
+H5SM_type_to_flag(unsigned type_id, unsigned *type_flag)
 {
-    ssize_t x;
-    unsigned type_flag;
-    ssize_t ret_value = FAIL;
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5SM_get_index)
+    FUNC_ENTER_NOAPI_NOINIT(H5SM_type_to_flag)
 
     /* Translate the H5O type_id into an H5SM type flag */
-    switch(type_id)
-    {
+    switch(type_id) {
         case H5O_SDSPACE_ID:
-            type_flag = H5O_MESG_SDSPACE_FLAG;
+            *type_flag = H5O_MESG_SDSPACE_FLAG;
             break;
         case H5O_DTYPE_ID:
-            type_flag = H5O_MESG_DTYPE_FLAG;
+            *type_flag = H5O_MESG_DTYPE_FLAG;
             break;
         case H5O_FILL_NEW_ID:
-            type_flag = H5O_MESG_FILL_FLAG;
+            *type_flag = H5O_MESG_FILL_FLAG;
             break;
         case H5O_PLINE_ID:
-            type_flag = H5O_MESG_PLINE_FLAG;
+            *type_flag = H5O_MESG_PLINE_FLAG;
             break;
         case H5O_ATTR_ID:
-            type_flag = H5O_MESG_ATTR_FLAG;
+            *type_flag = H5O_MESG_ATTR_FLAG;
             break;
         default:
             HGOTO_ERROR(H5E_OHDR, H5E_BADTYPE, FAIL, "unknown message type ID")
-    }
+    } /* end switch */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5SM_type_to_flag() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5SM_get_index
+ *
+ * Purpose:     Get the index number for a given message type.
+ *
+ *              Returns the number of the index in the supplied table
+ *              that holds messages of type type_id, or negative if
+ *              there is no index for this message type.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  James Laird
+ *              Tuesday, October 10, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+static ssize_t
+H5SM_get_index(const H5SM_master_table_t *table, unsigned type_id)
+{
+    ssize_t x;
+    unsigned type_flag;
+    ssize_t ret_value = FAIL;
+
+    FUNC_ENTER_NOAPI_NOINIT(H5SM_get_index)
+
+    /* Translate the H5O type_id into an H5SM type flag */
+    if(H5SM_type_to_flag(type_id, &type_flag) < 0)
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't map message type to flag")
 
     /* Search the indexes until we find one that matches this flag or we've
      * searched them all.
@@ -284,6 +312,57 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5SM_type_shared
+ *
+ * Purpose:     Check if a given message type is shared in a file.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              Tuesday, December 12, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5SM_type_shared(H5F_t *f, unsigned type_id, hid_t dxpl_id)
+{
+    H5SM_master_table_t *table = NULL;  /* Shared object master table */
+    unsigned type_flag;                 /* Flag corresponding to message type */
+    size_t u;                           /* Local index variable */
+    htri_t ret_value = FALSE;           /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5SM_type_shared)
+
+    /* Translate the H5O type_id into an H5SM type flag */
+    if(H5SM_type_to_flag(type_id, &type_flag) < 0)
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "can't map message type to flag")
+
+    /* Look up the master SOHM table */
+    if(H5F_addr_defined(f->shared->sohm_addr)) {
+        if(NULL == (table = H5AC_protect(f, dxpl_id, H5AC_SOHM_TABLE, f->shared->sohm_addr, NULL, NULL, H5AC_READ)))
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTPROTECT, FAIL, "unable to load SOHM master table")
+    } /* end if */
+    else
+        /* No shared messages of any type */
+        HGOTO_DONE(FALSE)       
+
+    /* Search the indexes until we find one that matches this flag or we've
+     * searched them all.
+     */
+    for(u = 0; u < table->num_indexes; u++)
+        if(table->indexes[u].mesg_types & type_flag)
+            HGOTO_DONE(TRUE)
+
+done:
+    /* Release the master SOHM table */
+    if(table && H5AC_unprotect(f, dxpl_id, H5AC_SOHM_TABLE, f->shared->sohm_addr, table, H5AC__NO_FLAGS_SET) < 0)
+	HDONE_ERROR(H5E_OHDR, H5E_CANTUNPROTECT, FAIL, "unable to close SOHM master table")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5SM_type_shared() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5SM_get_fheap_addr
  *
  * Purpose:     Gets the address of the fractal heap used to store
@@ -299,14 +378,14 @@ done:
 haddr_t
 H5SM_get_fheap_addr(H5F_t *f, unsigned type_id, hid_t dxpl_id)
 {
-    H5SM_master_table_t *table = NULL;
-    ssize_t index_num; /* Which index */
+    H5SM_master_table_t *table = NULL;  /* Shared object master table */
+    ssize_t index_num;                  /* Which index */
     haddr_t ret_value;
 
     FUNC_ENTER_NOAPI(H5SM_get_fheap_addr, FAIL)
 
     /* Look up the master SOHM table */
-    if(NULL == (table = H5AC_protect(f, dxpl_id, H5AC_SOHM_TABLE, f->shared->sohm_addr, NULL, NULL, H5AC_WRITE)))
+    if(NULL == (table = H5AC_protect(f, dxpl_id, H5AC_SOHM_TABLE, f->shared->sohm_addr, NULL, NULL, H5AC_READ)))
 	HGOTO_ERROR(H5E_CACHE, H5E_CANTPROTECT, HADDR_UNDEF, "unable to load SOHM master table")
 
     /* JAMES! */
@@ -317,8 +396,8 @@ H5SM_get_fheap_addr(H5F_t *f, unsigned type_id, hid_t dxpl_id)
 
 done:
     /* Release the master SOHM table */
-    if (table && H5AC_unprotect(f, dxpl_id, H5AC_SOHM_TABLE, f->shared->sohm_addr, table, H5AC__NO_FLAGS_SET) < 0)
-	HGOTO_ERROR(H5E_CACHE, H5E_CANTUNPROTECT, HADDR_UNDEF, "unable to close SOHM master table")
+    if(table && H5AC_unprotect(f, dxpl_id, H5AC_SOHM_TABLE, f->shared->sohm_addr, table, H5AC__NO_FLAGS_SET) < 0)
+	HDONE_ERROR(H5E_CACHE, H5E_CANTUNPROTECT, HADDR_UNDEF, "unable to close SOHM master table")
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5SM_get_fheap_addr() */
@@ -343,7 +422,9 @@ H5SM_create_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id)
     haddr_t tree_addr=HADDR_UNDEF;   /* Address of SOHM B-tree */
     H5HF_create_t fheap_cparam;      /* Fractal heap creation parameters */
     H5HF_t *fheap = NULL;
+#ifndef NDEBUG
     size_t fheap_id_len;             /* Size of a fractal heap ID */
+#endif /* NDEBUG */
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(H5SM_create_index, FAIL)
@@ -393,8 +474,12 @@ H5SM_create_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id)
     if(H5HF_get_heap_addr(fheap, &(header->heap_addr )) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTGETSIZE, FAIL, "can't get fractal heap address")
 
+#ifndef NDEBUG
+    /* Sanity check ID length */
     if(H5HF_get_id_len(fheap, &fheap_id_len) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTGETSIZE, FAIL, "can't get fractal heap ID length")
+    HDassert(fheap_id_len == H5SM_FHEAP_ID_LEN);
+#endif /* NDEBUG */
 
 done:
     /* Close the fractal heap if one has been created */
@@ -773,7 +858,7 @@ H5SM_write_mesg(H5F_t *f, hid_t dxpl_id, H5SM_index_header_t *header,
 
     /* Change the original message passed in to reflect that it's now shared */
     if(H5O_msg_set_share(type_id, &shared, mesg) < 0)
-        HGOTO_ERROR (H5E_OHDR, H5E_BADMESG, FAIL, "unable to set sharing information")
+        HGOTO_ERROR(H5E_OHDR, H5E_BADMESG, FAIL, "unable to set sharing information")
 
 done:
     /* Release the fractal heap if we opened it */
@@ -1000,7 +1085,6 @@ H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id, H5SM_index_header_t *header, uns
             /* Remember the btree address for this index; we'll overwrite the
              * address in the index header
              */
-            haddr_t btree_addr = header->index_addr;
             H5SM_index_header_t temp_header;
 
             /* The protect callback expects a header corresponding to the list
@@ -1100,8 +1184,8 @@ H5SM_get_info(H5F_t *f, unsigned *index_flags, unsigned *minsizes,
 
 done:
     /* Release the master SOHM table if we took it out of the cache */
-    if (table && H5AC_unprotect(f, dxpl_id, H5AC_SOHM_TABLE, table_addr, table, H5AC__NO_FLAGS_SET) < 0)
-	HGOTO_ERROR(H5E_CACHE, H5E_CANTRELEASE, FAIL, "unable to close SOHM master table")
+    if(table && H5AC_unprotect(f, dxpl_id, H5AC_SOHM_TABLE, table_addr, table, H5AC__NO_FLAGS_SET) < 0)
+	HDONE_ERROR(H5E_CACHE, H5E_CANTRELEASE, FAIL, "unable to close SOHM master table")
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5SM_get_info() */
diff --git a/src/H5SMprivate.h b/src/H5SMprivate.h
index 1c90e80..2308167 100755
--- a/src/H5SMprivate.h
+++ b/src/H5SMprivate.h
@@ -48,6 +48,7 @@ H5_DLL htri_t H5SM_try_share(H5F_t *f, hid_t dxpl_id, unsigned type_id,
 H5_DLL herr_t H5SM_try_delete(H5F_t *f, hid_t dxpl_id, unsigned type_id, const H5O_shared_t *mesg);
 H5_DLL herr_t H5SM_get_info(H5F_t *f, unsigned *index_flags, unsigned *minsizes,
                   unsigned *list_to_btree, unsigned *btree_to_list, hid_t dxpl_id);
+H5_DLL htri_t H5SM_type_shared(H5F_t *f, unsigned type_id, hid_t dxpl_id);
 H5_DLL haddr_t H5SM_get_fheap_addr(H5F_t *f, unsigned type_id, hid_t dxpl_id);
 
 #endif /*_H5SMprivate_H*/