[svn-r20676] Purpose:

    - HDFFV-5928 - GMQS: h5diff problem and improvement on comparsing the same objects

Description:
    Fixed:
    1) adding h5tools_is_obj_same() function to check if two given IDs or paths point to the same object. This function can be very useful for other tools and applications.
    2) using h5tools_is_obj_same() at h5diff() and diff() in h5diff.c. If two paths point to the same object, there is no need to check the details of the object since we know there is no difference. The fix will increase the performance by skipping the content comparison. It also fixed the problem of reporting difference for some cases of comparing the same file, e.g. empty files or files with incomparable objects the same file.

    Test update:
    Updat prvious test cases (171, 172, 530) affected by this fix, so they
    still perfrom originally intended testing without bypassing.

Tested:
 jam (linux32-LE), koala (linux64-LE), heiwa (linuxppc64-BE), tejeda (mac32-LE), linew (solaris-BE), cmake

13 files changed, 186 insertions, 51 deletions

diff --git a/tools/h5diff/CMakeLists.txt b/tools/h5diff/CMakeLists.txt
index 0969a23..bb267eb 100644
--- a/tools/h5diff/CMakeLists.txt
+++ b/tools/h5diff/CMakeLists.txt
@@ -735,10 +735,10 @@ ADD_H5_TEST (h5diff_16_3 1 -v -p 0.02 ${FILE1} ${FILE1} g1/dset9 g1/dset10)
 ADD_H5_TEST (h5diff_17 1 -v ${FILE1} ${FILE2})   
 
 # 1.7 test 32-bit INFINITY
-ADD_H5_TEST (h5diff_171 0 -v ${FILE1} ${FILE1} /g1/fp19)
+ADD_H5_TEST (h5diff_171 0 -v ${FILE1} ${FILE1} /g1/fp19 /g1/fp19_COPY)
 
 # 1.7 test 64-bit INFINITY
-ADD_H5_TEST (h5diff_172 0 -v ${FILE1} ${FILE1} /g1/fp20)
+ADD_H5_TEST (h5diff_172 0 -v ${FILE1} ${FILE1} /g1/fp20 /g1/fp20_COPY)
 
 # 1.8 quiet mode 
 ADD_H5_TEST (h5diff_18 1 -q ${FILE1} ${FILE2}) 
@@ -1199,7 +1199,7 @@ ADD_H5_TEST (h5diff_484 0 -v --exclude-path "/dset3" ${EXCLUDE_FILE1_1} ${EXCLUD
 # ##############################################################################
 # # diff various multiple vlen and fixed strings in a compound type dataset
 # ##############################################################################
-ADD_H5_TEST (h5diff_530 0 -v  ${COMP_VL_STRS_FILE} ${COMP_VL_STRS_FILE})
+ADD_H5_TEST (h5diff_530 0 -v  ${COMP_VL_STRS_FILE} ${COMP_VL_STRS_FILE} /group /group_copy)
 
   
 ENDIF (BUILD_TESTING)
diff --git a/tools/h5diff/h5diffgentest.c b/tools/h5diff/h5diffgentest.c
index 3363b39..3ef01a0 100644
--- a/tools/h5diff/h5diffgentest.c
+++ b/tools/h5diff/h5diffgentest.c
@@ -129,7 +129,7 @@ static int test_group_recurse(const char *fname1, const char *fname2);
 static int test_group_recurse2(void);
 static int test_exclude_obj1(const char *fname1, const char *fname2);
 static int test_exclude_obj2(const char *fname1, const char *fname2);
-static int test_comp_vlen_strings(const char *fname1);
+static int test_comp_vlen_strings(const char *fname1, const char *grp_name, int is_file_new);
 static int test_attributes_verbose_level(const char *fname1, const char *fname2);
 
 /* called by test_attributes() and test_datasets() */
@@ -194,7 +194,8 @@ int main(void)
     test_exclude_obj2(EXCLUDE_FILE2_1, EXCLUDE_FILE2_2);
 
     /* diff various multiple vlen and fixlen string types in a compound dataset */
-    test_comp_vlen_strings(COMP_VL_STRS_FILE );
+    test_comp_vlen_strings(COMP_VL_STRS_FILE, "group", 1);
+    test_comp_vlen_strings(COMP_VL_STRS_FILE, "group_copy", 0);
 
     return 0;
 }
@@ -430,7 +431,9 @@ int test_basic(const char *fname1, const char *fname2, const char *fname3)
         data20[3] = data20[4] = data20[5] = -log(0);
 
         write_dset(gid1,1,dims1,"fp19",H5T_NATIVE_FLOAT,data19);
+        write_dset(gid1,1,dims1,"fp19_COPY",H5T_NATIVE_FLOAT,data19);
         write_dset(gid1,1,dims1,"fp20",H5T_NATIVE_DOUBLE,data20);
+        write_dset(gid1,1,dims1,"fp20_COPY",H5T_NATIVE_DOUBLE,data20);
     }
 
     /*-------------------------------------------------------------------------
@@ -3309,11 +3312,12 @@ out:
 #define FIXLEN_STR_ARRY_SIZE 30
 #define COMP_RANK 1
 #define COMP_DIM 1
-static int test_comp_vlen_strings(const char *fname1)
+static int test_comp_vlen_strings(const char *fname1, const char *grp_name, int is_file_new)
 {
     int i;
 
     hid_t    fid1;      /* file id */
+    hid_t    gid;
 
     /* compound1 datatype */
     typedef struct comp1_t
@@ -3604,10 +3608,34 @@ static int test_comp_vlen_strings(const char *fname1)
     /*-----------------------------------------------------------------------
     * Create file(s)
     *------------------------------------------------------------------------*/
-    fid1 = H5Fcreate (fname1, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
-    if (fid1 < 0)
+    if (is_file_new == 1)
     {
-        fprintf(stderr, "Error: %s> H5Fcreate failed.\n", fname1);
+        fid1 = H5Fcreate (fname1, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+        if (fid1 < 0)
+        {
+            fprintf(stderr, "Error: %s> H5Fcreate failed.\n", fname1);
+            status = FAIL;
+            goto out;
+        }
+    }
+    else
+    {
+        fid1 = H5Fopen (fname1, H5F_ACC_RDWR, H5P_DEFAULT);
+        if (fid1 < 0)
+        {
+            fprintf(stderr, "Error: %s> H5Fopen failed.\n", fname1);
+            status = FAIL;
+            goto out;
+        }
+    }
+
+    /*-----------------------------------------------------------------------
+    * Create group 
+    *------------------------------------------------------------------------*/
+    gid = H5Gcreate2(fid1, grp_name, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    if (gid < 0)
+    {
+        fprintf(stderr, "Error: %s> H5Gcreate2 failed.\n", fname1);
         status = FAIL;
         goto out;
     }
@@ -3827,7 +3855,7 @@ static int test_comp_vlen_strings(const char *fname1)
 
 
     /* Write data to compound 1 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset1", tid1_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset1", tid1_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid1_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp1_buf);
     if (status < 0)
     {
@@ -3838,7 +3866,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 2 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset2", tid2_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset2", tid2_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid2_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp2_buf);
     if (status < 0)
     {
@@ -3849,7 +3877,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 3 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset3", tid3_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset3", tid3_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid3_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp3_buf);
     if (status < 0)
     {
@@ -3860,7 +3888,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 4 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset4", tid4_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset4", tid4_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid4_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp4_buf);
     if (status < 0)
     {
@@ -3871,7 +3899,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 5 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset5", tid5_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset5", tid5_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid5_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp5_buf);
     if (status < 0)
     {
@@ -3882,7 +3910,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 6 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset6", tid6_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset6", tid6_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid6_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp6_buf);
     if (status < 0)
     {
@@ -3893,7 +3921,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 7 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset7", tid7_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset7", tid7_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid7_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp7_buf);
     if (status < 0)
     {
@@ -3904,7 +3932,7 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 8 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset8", tid8_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset8", tid8_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     status = H5Dwrite(did_comp, tid8_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp8_buf);
     if (status < 0)
     {
@@ -3915,12 +3943,12 @@ static int test_comp_vlen_strings(const char *fname1)
     H5Dclose(did_comp);
 
     /* Write data to compound 9 dataset buffer */
-    did_comp = H5Dcreate2(fid1, "Compound_dset9", tid9_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+    did_comp = H5Dcreate2(gid, "Compound_dset9", tid9_comp, sid_comp, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
 
     /* obj references */
-    status=H5Rcreate(&(comp9_buf.objref1),fid1,"/Compound_dset2",H5R_OBJECT,-1);
-    status=H5Rcreate(&(comp9_buf.objref2),fid1,"/Compound_dset3",H5R_OBJECT,-1);
-    status=H5Rcreate(&(comp9_buf.objref3),fid1,"/Compound_dset4",H5R_OBJECT,-1);
+    status=H5Rcreate(&(comp9_buf.objref1),gid,"Compound_dset2",H5R_OBJECT,-1);
+    status=H5Rcreate(&(comp9_buf.objref2),gid,"Compound_dset3",H5R_OBJECT,-1);
+    status=H5Rcreate(&(comp9_buf.objref3),gid,"Compound_dset4",H5R_OBJECT,-1);
 
     status = H5Dwrite(did_comp, tid9_comp, H5S_ALL, H5S_ALL, H5P_DEFAULT, &comp9_buf);
     if (status < 0)
@@ -3940,6 +3968,8 @@ out:
     *-----------------------------------------------------------------------*/
     if(fid1)
         H5Fclose(fid1);
+    if(gid)
+        H5Gclose(gid);
     /* vlen string */
     if(tid_vlen_str)
         H5Tclose(tid_vlen_str);
diff --git a/tools/h5diff/testfiles/h5diff_17.txt b/tools/h5diff/testfiles/h5diff_17.txt
index 5cb604d..5e48dae 100644
--- a/tools/h5diff/testfiles/h5diff_17.txt
+++ b/tools/h5diff/testfiles/h5diff_17.txt
@@ -23,8 +23,10 @@ file1     file2
     x           /g1/fp17       
     x           /g1/fp18       
     x           /g1/fp19       
+    x           /g1/fp19_COPY  
     x           /g1/fp2        
     x           /g1/fp20       
+    x           /g1/fp20_COPY  
     x           /g1/ld         
            x    /g2            
            x    /g2/dset1      
diff --git a/tools/h5diff/testfiles/h5diff_171.txt b/tools/h5diff/testfiles/h5diff_171.txt
index 5314a79..aabe16a 100644
--- a/tools/h5diff/testfiles/h5diff_171.txt
+++ b/tools/h5diff/testfiles/h5diff_171.txt
@@ -1,3 +1,3 @@
-dataset: </g1/fp19> and </g1/fp19>
+dataset: </g1/fp19> and </g1/fp19_COPY>
 0 differences found
 EXIT CODE: 0
diff --git a/tools/h5diff/testfiles/h5diff_172.txt b/tools/h5diff/testfiles/h5diff_172.txt
index 0269194..852f7b5 100644
--- a/tools/h5diff/testfiles/h5diff_172.txt
+++ b/tools/h5diff/testfiles/h5diff_172.txt
@@ -1,3 +1,3 @@
-dataset: </g1/fp20> and </g1/fp20>
+dataset: </g1/fp20> and </g1/fp20_COPY>
 0 differences found
 EXIT CODE: 0
diff --git a/tools/h5diff/testfiles/h5diff_530.txt b/tools/h5diff/testfiles/h5diff_530.txt
index bd2b435..73d736e 100644
--- a/tools/h5diff/testfiles/h5diff_530.txt
+++ b/tools/h5diff/testfiles/h5diff_530.txt
@@ -1,7 +1,7 @@
 
-file1     file2
+group1   group2
 ---------------------------------------
-    x      x    /              
+    x      x                   
     x      x    /Compound_dset1
     x      x    /Compound_dset2
     x      x    /Compound_dset3
@@ -12,24 +12,24 @@ file1     file2
     x      x    /Compound_dset8
     x      x    /Compound_dset9
 
-group  : </> and </>
+group  : </group> and </group_copy>
 0 differences found
-dataset: </Compound_dset1> and </Compound_dset1>
+dataset: </group/Compound_dset1> and </group_copy/Compound_dset1>
 0 differences found
-dataset: </Compound_dset2> and </Compound_dset2>
+dataset: </group/Compound_dset2> and </group_copy/Compound_dset2>
 0 differences found
-dataset: </Compound_dset3> and </Compound_dset3>
+dataset: </group/Compound_dset3> and </group_copy/Compound_dset3>
 0 differences found
-dataset: </Compound_dset4> and </Compound_dset4>
+dataset: </group/Compound_dset4> and </group_copy/Compound_dset4>
 0 differences found
-dataset: </Compound_dset5> and </Compound_dset5>
+dataset: </group/Compound_dset5> and </group_copy/Compound_dset5>
 0 differences found
-dataset: </Compound_dset6> and </Compound_dset6>
+dataset: </group/Compound_dset6> and </group_copy/Compound_dset6>
 0 differences found
-dataset: </Compound_dset7> and </Compound_dset7>
+dataset: </group/Compound_dset7> and </group_copy/Compound_dset7>
 0 differences found
-dataset: </Compound_dset8> and </Compound_dset8>
+dataset: </group/Compound_dset8> and </group_copy/Compound_dset8>
 0 differences found
-dataset: </Compound_dset9> and </Compound_dset9>
+dataset: </group/Compound_dset9> and </group_copy/Compound_dset9>
 0 differences found
 EXIT CODE: 0
diff --git a/tools/h5diff/testfiles/h5diff_90.txt b/tools/h5diff/testfiles/h5diff_90.txt
index fb23843..9965ab0 100644
--- a/tools/h5diff/testfiles/h5diff_90.txt
+++ b/tools/h5diff/testfiles/h5diff_90.txt
@@ -30,7 +30,6 @@ dataset: </g1/dset4> and </g1/dset4>
 group  : </g2> and </g2>
 0 differences found
 dataset: </g2/dset1> and </g2/dset1>
-Not comparable: </g2/dset1> or </g2/dset1> is an empty dataset
 0 differences found
 dataset: </g2/dset2> and </g2/dset2>
 0 differences found
@@ -47,10 +46,5 @@ dataset: </g2/dset7> and </g2/dset7>
 dataset: </g2/dset8> and </g2/dset8>
 0 differences found
 dataset: </g2/dset9> and </g2/dset9>
-Not comparable: </g2/dset9> or </g2/dset9> is an empty dataset
 0 differences found
---------------------------------
-Some objects are not comparable
---------------------------------
-Use -c for a list of objects.
 EXIT CODE: 0
diff --git a/tools/h5diff/testfiles/h5diff_basic1.h5 b/tools/h5diff/testfiles/h5diff_basic1.h5
index 4f3cf9a..d97017e 100644
--- a/tools/h5diff/testfiles/h5diff_basic1.h5
+++ b/tools/h5diff/testfiles/h5diff_basic1.h5
diff --git a/tools/h5diff/testfiles/h5diff_comp_vl_strs.h5 b/tools/h5diff/testfiles/h5diff_comp_vl_strs.h5
index dac510f..4ad6f19 100644
--- a/tools/h5diff/testfiles/h5diff_comp_vl_strs.h5
+++ b/tools/h5diff/testfiles/h5diff_comp_vl_strs.h5
diff --git a/tools/h5diff/testh5diff.sh b/tools/h5diff/testh5diff.sh
index cb213dc..5087350 100755
--- a/tools/h5diff/testh5diff.sh
+++ b/tools/h5diff/testh5diff.sh
@@ -365,10 +365,10 @@ TOOLTEST h5diff_16_3.txt -v -p 0.02 $FILE1 $FILE1 g1/dset9 g1/dset10
 TOOLTEST h5diff_17.txt -v $FILE1 $FILE2   
 
 # 1.7 test 32-bit INFINITY
-TOOLTEST h5diff_171.txt -v $FILE1 $FILE1 /g1/fp19
+TOOLTEST h5diff_171.txt -v $FILE1 $FILE1 /g1/fp19 /g1/fp19_COPY
 
 # 1.7 test 64-bit INFINITY
-TOOLTEST h5diff_172.txt -v $FILE1 $FILE1 /g1/fp20
+TOOLTEST h5diff_172.txt -v $FILE1 $FILE1 /g1/fp20 /g1/fp20_COPY
 
 # 1.8 quiet mode 
 TOOLTEST h5diff_18.txt -q $FILE1 $FILE2 
@@ -832,7 +832,7 @@ TOOLTEST h5diff_484.txt -v --exclude-path "/dset3" $EXCLUDE_FILE1_1 $EXCLUDE_FIL
 # ##############################################################################
 # # diff various multiple vlen and fixed strings in a compound type dataset
 # ##############################################################################
-TOOLTEST h5diff_530.txt -v  $COMP_VL_STRS_FILE $COMP_VL_STRS_FILE
+TOOLTEST h5diff_530.txt -v  $COMP_VL_STRS_FILE $COMP_VL_STRS_FILE /group /group_copy
 
 # ##############################################################################
 # # END
diff --git a/tools/lib/h5diff.c b/tools/lib/h5diff.c
index a4d8469..4f82906 100644
--- a/tools/lib/h5diff.c
+++ b/tools/lib/h5diff.c
@@ -932,6 +932,19 @@ hsize_t h5diff(const char *fname1,
     /* if both obj1 and obj2 are group */
     if (obj1type == H5TRAV_TYPE_GROUP && obj2type == H5TRAV_TYPE_GROUP)
     {
+
+        /* 
+         * Use h5tools_is_obj_same() to improve performance by skipping 
+         * comparing details of same objects. If verbose options is used,
+         * need to traverse thorugh the list of objects in the group and
+         * print out object information. Details of same objects will be 
+         * skipped at diff() function.
+         */
+         if(!(options->m_verbose || options->m_report)) {
+             if (h5tools_is_obj_same(file1_id,obj1fullname,file2_id,obj2fullname)!=0)
+                 goto out;
+         }
+
         /* 
          * traverse group1 
          */
@@ -1773,6 +1786,7 @@ hsize_t diff(hid_t file1_id,
     int     ret;
     int     is_dangle_link1 = 0;
     int     is_dangle_link2 = 0;
+    int     is_hard_link = 0;
     hsize_t nfound = 0;
 
 
@@ -1834,6 +1848,58 @@ hsize_t diff(hid_t file1_id,
     /* found dangling link */
     if (is_dangle_link1 || is_dangle_link2)
         goto out2;
+  
+    /* 
+     * Use h5tools_is_obj_same() to improve performance by skipping 
+     * comparing details of same objects,
+     * 
+     * check if two paths point to the same object for hard links or 
+     * the option of follow link is used. h5tools_is_obj_same() is not
+     * needed for other cases.
+     */
+    is_hard_link = (type==H5TRAV_TYPE_DATASET ||
+                    type==H5TRAV_TYPE_NAMED_DATATYPE ||
+                    type==H5TRAV_TYPE_GROUP);
+     if (options->follow_links || is_hard_link)
+     {
+        if (h5tools_is_obj_same(file1_id, path1, file2_id, path2)!=0)
+        {
+            /* print information is only verbose option is used */
+            if(options->m_verbose || options->m_report)
+            {
+                switch(type)
+                {
+                case H5TRAV_TYPE_DATASET:
+                    do_print_objname("dataset", path1, path2, options);
+                    break; 
+                case H5TRAV_TYPE_NAMED_DATATYPE:
+                    do_print_objname("datatype", path1, path2, options);
+                    break;
+                case H5TRAV_TYPE_GROUP:
+                    do_print_objname("group", path1, path2, options);
+                    break;
+                case H5TRAV_TYPE_LINK:
+                    do_print_objname("link", path1, path2, options);
+                    break;
+                case H5TRAV_TYPE_UDLINK:
+                    if(linkinfo1.linfo.type == H5L_TYPE_EXTERNAL && linkinfo2.linfo.type == H5L_TYPE_EXTERNAL)
+                        do_print_objname("external link", path1, path2, options);
+                    else
+                        do_print_objname ("user defined link", path1, path2, options);
+                    break; 
+                default:
+                    parallel_print("Comparison not supported: <%s> and <%s> are of type %s\n",
+                        path1, path2, get_type(type) );
+                    options->not_cmp = 1;
+                    break;
+                } /* switch(type)*/
+
+                print_found(nfound);
+            } /* if(options->m_verbose || options->m_report) */
+
+            goto out2;
+        } /* h5tools_is_obj_same */
+    }
 
     switch(type)
     {
diff --git a/tools/lib/h5tools.c b/tools/lib/h5tools.c
index bf85bc2..3e72bdd 100644
--- a/tools/lib/h5tools.c
+++ b/tools/lib/h5tools.c
@@ -626,11 +626,11 @@ h5tools_ncols(const char *s)
  *
  * Purpose: Recursive check for any variable length data in given type.
  *
- * Return: 
+ * Return:
  *    TRUE : type conatains any variable length data
  *    FALSE : type doesn't contain any variable length data
  *    Negative value: error occur
- * 
+ *
  * Programmer: Jonathan Kim  March 18, 2011
  *-------------------------------------------------------------------------
  */
@@ -658,7 +658,7 @@ done:
  *
  * Purpose: Recursive check for variable length string of a datatype.
  *
- * Return: 
+ * Return:
  *    TRUE : type conatains any variable length string
  *    FALSE : type doesn't contain any variable length string
  *    Negative value: error occur
@@ -848,7 +848,7 @@ h5tools_region_simple_prefix(FILE *stream, const h5tool_format_t *info,
     }
 
     /* Calculate new prefix */
-    h5tools_str_region_prefix(&prefix, info, elmtno, ptdata, ctx->ndims, 
+    h5tools_str_region_prefix(&prefix, info, elmtno, ptdata, ctx->ndims,
             ctx->p_max_idx, ctx);
 
     /* Write new prefix to output */
@@ -2419,7 +2419,7 @@ h5tools_dump_simple_subset(FILE *stream, const h5tool_format_t *info, hid_t dset
     /* Terminate the output */
     if (ctx.cur_column) {
         fputs(OPT(info->line_suf, ""), stdout);
-        putc('\n', stdout); 
+        putc('\n', stdout);
         fputs(OPT(info->line_sep, ""), stdout);
     }
 
@@ -2527,7 +2527,7 @@ h5tools_dump_simple_dset(FILE *stream, const h5tool_format_t *info,
         vl_data = TRUE;
     if (H5Tdetect_class(p_type, H5T_VLEN) == TRUE)
         vl_data = TRUE;
- 
+
     /*
      * Determine the strip mine size and allocate a buffer. The strip mine is
      * a hyperslab whose size is manageable.
@@ -2545,7 +2545,7 @@ h5tools_dump_simple_dset(FILE *stream, const h5tool_format_t *info,
         }
     }
 
-    if(!sm_nbytes) 
+    if(!sm_nbytes)
         goto done;
 
     assert(sm_nbytes == (hsize_t)((size_t)sm_nbytes)); /*check for overflow*/
@@ -4323,3 +4323,45 @@ hbool_t h5tools_is_zero(const void *_mem, size_t size)
     return TRUE;
 }
 
+/*-------------------------------------------------------------------------
+ * Function:    h5tools_is_obj_same
+ *
+ * Purpose: Check if two given object IDs or link names point to the same object.
+ *
+ * Parameters:
+ *             hid_t loc_id1: location of the first object
+ *             char *name1:   link name of the first object.
+ *                             Use "." or NULL if loc_id1 is the object to be compared.
+ *             hid_t loc_id2: location of the second object
+ *             char *name1:   link name of the first object.
+ *                             Use "." or NULL if loc_id2 is the object to be compared.
+ *
+ * Return:  TRUE if it is the same object; FALSE otherwise.
+ *
+ * Programmer: Peter Cao
+ *             4/27/2011
+  *
+ *-------------------------------------------------------------------------
+ */
+hbool_t h5tools_is_obj_same(hid_t loc_id1, const char *name1,
+		                    hid_t loc_id2, const char *name2)
+{
+    H5O_info_t oinfo1,  oinfo2;
+    hbool_t ret_val = 0;
+
+    if ( name1 && strcmp(name1, "."))
+    	H5Oget_info_by_name(loc_id1, name1, &oinfo1, H5P_DEFAULT);
+    else
+    	H5Oget_info(loc_id1, &oinfo1);
+
+    if ( name2 && strcmp(name2, "."))
+    	H5Oget_info_by_name(loc_id2, name2, &oinfo2, H5P_DEFAULT);
+    else
+    	H5Oget_info(loc_id2, &oinfo2);
+
+    if (oinfo1.fileno == oinfo2.fileno && oinfo1.addr==oinfo2.addr)
+    	ret_val = 1;
+
+    return ret_val;
+}
+
diff --git a/tools/lib/h5tools.h b/tools/lib/h5tools.h
index d08edf7..89e07fa 100644
--- a/tools/lib/h5tools.h
+++ b/tools/lib/h5tools.h
@@ -555,6 +555,7 @@ H5TOOLS_DLL hid_t    h5tools_get_big_endian_type(hid_t type);
 
 H5TOOLS_DLL htri_t   h5tools_detect_vlen(hid_t tid);
 H5TOOLS_DLL htri_t   h5tools_detect_vlen_str(hid_t tid);
+H5TOOLS_DLL hbool_t   h5tools_is_obj_same(hid_t loc_id1, const char *name1, hid_t loc_id2, const char *name2);
 
 H5TOOLS_DLL void     h5tools_dump_simple_data(FILE *stream, const h5tool_format_t *info, hid_t container,
                          h5tools_context_t *ctx/*in,out*/, unsigned flags,