[svn-r14234] Description:

	Add H5Aexists and H5Aexists_by_name API routines, to match H5Lexists.

Tested on:
        FreeBSD/32 6.2 (duty) in debug mode
        FreeBSD/64 6.2 (liberty) w/C++ & FORTRAN, in debug mode
        Linux/32 2.6 (kagiso) w/PGI compilers, w/C++ & FORTRAN, w/threadsafe,
                                in debug mode
        Linux/64-amd64 2.6 (smirom) w/default API=1.6.x, w/C++ & FORTRAN,
                                in production mode
        Linux/64-ia64 2.6 (cobalt) w/Intel compilers, w/C++ & FORTRAN,
                                in production mode
        Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
                                w/szip filter, in production mode
        Mac OS X/32 10.4.10 (amazon) in debug mode
        Linux/64-ia64 2.4 (tg-login3) w/parallel, w/FORTRAN, in production mode

4 files changed, 121 insertions, 8 deletions

diff --git a/src/H5A.c b/src/H5A.c
index acd6307..4a09fde 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -2486,3 +2486,108 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5A_nameof() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Aexists
+ *
+ * Purpose:	Checks if an attribute with a given name exists on an opened
+ *              object.
+ *
+ * Return:	Success:	TRUE/FALSE
+ * 		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 1, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5Aexists(hid_t obj_id, const char *attr_name)
+{
+    H5G_loc_t   loc;                    /* Object location */
+    htri_t	ret_value;              /* Return value */
+
+    FUNC_ENTER_API(H5Aexists, FAIL)
+    H5TRACE2("t", "i*s", obj_id, attr_name);
+
+    /* check arguments */
+    if(H5I_ATTR == H5I_get_type(obj_id))
+	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "location is not valid for an attribute")
+    if(H5G_loc(obj_id, &loc) < 0)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a location")
+    if(!attr_name || !*attr_name)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no attribute name")
+
+    /* Check if the attribute exists */
+    if((ret_value = H5O_attr_exists(loc.oloc, attr_name, H5AC_ind_dxpl_id)) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to determine if attribute exists")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5Aexists() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Aexists_by_name
+ *
+ * Purpose:	Checks if an attribute with a given name exists on an object.
+ *
+ * Return:	Success:	TRUE/FALSE
+ * 		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 1, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
+    hid_t lapl_id)
+{
+    H5G_loc_t   loc;                    /* Object location */
+    H5G_loc_t   obj_loc;                /* Location used to open group */
+    H5G_name_t  obj_path;            	/* Opened object group hier. path */
+    H5O_loc_t   obj_oloc;            	/* Opened object object location */
+    hbool_t     loc_found = FALSE;      /* Entry at 'obj_name' found */
+    htri_t	ret_value;              /* Return value */
+
+    FUNC_ENTER_API(H5Aexists_by_name, FAIL)
+    H5TRACE4("t", "i*s*si", loc_id, obj_name, attr_name, lapl_id);
+
+    /* check arguments */
+    if(H5I_ATTR == H5I_get_type(loc_id))
+	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "location is not valid for an attribute")
+    if(H5G_loc(loc_id, &loc) < 0)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a location")
+    if(!obj_name || !*obj_name)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no object name")
+    if(!attr_name || !*attr_name)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no attribute name")
+    if(H5P_DEFAULT == lapl_id)
+        lapl_id = H5P_LINK_ACCESS_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(lapl_id, H5P_LINK_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not link access property list ID")
+
+    /* Set up opened group location to fill in */
+    obj_loc.oloc = &obj_oloc;
+    obj_loc.path = &obj_path;
+    H5G_loc_reset(&obj_loc);
+
+    /* Find the object's location */
+    if(H5G_loc_find(&loc, obj_name, &obj_loc/*out*/, lapl_id, H5AC_ind_dxpl_id) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_NOTFOUND, FAIL, "object not found")
+    loc_found = TRUE;
+
+    /* Check if the attribute exists */
+    if((ret_value = H5O_attr_exists(obj_loc.oloc, attr_name, H5AC_ind_dxpl_id)) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to determine if attribute exists")
+
+done:
+    /* Release resources */
+    if(loc_found && H5G_loc_free(&obj_loc) < 0)
+        HDONE_ERROR(H5E_ATTR, H5E_CANTRELEASE, FAIL, "can't free location")
+
+    FUNC_LEAVE_API(ret_value)
+} /* H5Aexists_by_name() */
+
diff --git a/src/H5Apublic.h b/src/H5Apublic.h
index c320a91..3586bad 100644
--- a/src/H5Apublic.h
+++ b/src/H5Apublic.h
@@ -45,7 +45,7 @@ H5_DLL hid_t   H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id,
     hid_t space_id, hid_t acpl_id, hid_t aapl_id);
 H5_DLL hid_t   H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     hid_t type_id, hid_t space_id, hid_t acpl_id, hid_t aapl_id, hid_t lapl_id);
-H5_DLL hid_t   H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id);
+H5_DLL hid_t   H5Aopen(hid_t obj_id, const char *attr_name, hid_t aapl_id);
 H5_DLL hid_t   H5Aopen_by_name(hid_t loc_id, const char *obj_name,
     const char *attr_name, hid_t aapl_id, hid_t lapl_id);
 H5_DLL hid_t   H5Aopen_by_idx(hid_t loc_id, const char *obj_name, 
@@ -81,6 +81,9 @@ H5_DLL herr_t  H5Adelete_by_name(hid_t loc_id, const char *obj_name,
     const char *attr_name, hid_t lapl_id);
 H5_DLL herr_t  H5Adelete_by_idx(hid_t loc_id, const char *obj_name,
     H5_index_t idx_type, H5_iter_order_t order, hsize_t n, hid_t lapl_id);
+H5_DLL htri_t H5Aexists(hid_t obj_id, const char *attr_name);
+H5_DLL htri_t H5Aexists_by_name(hid_t obj_id, const char *obj_name,
+    const char *attr_name, hid_t lapl_id);
 
 /* Symbols defined for compatibility with previous versions of the HDF5 API.
  * 
diff --git a/src/H5L.c b/src/H5L.c
index d8fb0eb..78a78f2 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -794,14 +794,14 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t
+htri_t
 H5Lexists(hid_t loc_id, const char *name, hid_t lapl_id)
 {
     H5G_loc_t	loc;
-    herr_t ret_value = SUCCEED;
+    htri_t ret_value;
 
     FUNC_ENTER_API(H5Lexists, FAIL)
-    H5TRACE3("e", "i*si", loc_id, name, lapl_id);
+    H5TRACE3("t", "i*si", loc_id, name, lapl_id);
 
     /* Check arguments */
     if(H5G_loc(loc_id, &loc))
diff --git a/src/H5Oattribute.c b/src/H5Oattribute.c
index 5c0a91a..5c9f875 100644
--- a/src/H5Oattribute.c
+++ b/src/H5Oattribute.c
@@ -61,8 +61,6 @@ typedef struct {
 /* User data for iteration when opening an attribute */
 typedef struct {
     /* down */
-    H5F_t *f;                   /* Pointer to file attribute is in */
-    hid_t dxpl_id;              /* DXPL for operation */
     const char *name;           /* Name of attribute to open */
 
     /* up */
@@ -117,6 +115,15 @@ typedef struct {
     hbool_t found;              /* Found attribute to delete */
 } H5O_iter_rm_t;
 
+/* User data for iteration when checking if an attribute exists */
+typedef struct {
+    /* down */
+    const char *name;           /* Name of attribute to open */
+
+    /* up */
+    hbool_t found;              /* Found attribute */
+} H5O_iter_xst_t;
+
 
 /********************/
 /* Package Typedefs */
@@ -483,8 +490,6 @@ H5O_attr_open_by_name(const H5O_loc_t *loc, const char *name, hid_t dxpl_id)
         H5O_mesg_operator_t op;         /* Wrapper for operator */
 
         /* Set up user data for callback */
-        udata.f = loc->file;
-        udata.dxpl_id = dxpl_id;
         udata.name = name;
         udata.attr = NULL;