Merge pull request #1653 in HDFFV/hdf5 from ~KOZIOL/hdf5:get_fileno to develop

* commit 'd7e1464058515d07b838741f65a77977224814de':
  Add C++, Java, and FORTRAN wrappers and tests for H5Fget_fileno
  Add trace macro.
  Add H5Fget_fileno() API routine.

18 files changed, 471 insertions, 1 deletions

diff --git a/c++/src/C2Cppfunction_map.htm b/c++/src/C2Cppfunction_map.htm
index b53ea15..2d779a3 100644
--- a/c++/src/C2Cppfunction_map.htm
+++ b/c++/src/C2Cppfunction_map.htm
@@ -7666,6 +7666,42 @@ normal'><span style='font-size:14.0pt;mso-bidi-font-size:11.0pt;line-height:
   normal'><o:p>&nbsp;</o:p></p>
   </td>
  </tr>
+ <tr style='mso-yfti-irow:180'>
+  <td width=263 style='width:197.2pt;border:solid windowtext 1.0pt;border-top:
+  none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
+  padding:0in 5.4pt 0in 5.4pt'>
+  <p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
+  normal'>H5Fget_fileno</p>
+  </td>
+  <td width=474 valign=top style='width:355.2pt;border-top:none;border-left:
+  none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
+  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
+  mso-border-alt:solid windowtext .5pt;padding:0in 5.4pt 0in 5.4pt'>
+  <p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
+  normal'>unsigned long H5File::getFileNum()</p>
+  </td>
+  <td width=35 valign=top style='width:26.05pt;border-top:none;border-left:
+  none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
+  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
+  mso-border-alt:solid windowtext .5pt;padding:0in 5.4pt 0in 5.4pt'>
+  <p class=MsoNormal align=center style='margin-bottom:0in;margin-bottom:.0001pt;
+  text-align:center;line-height:normal'><o:p>&nbsp;</o:p></p>
+  </td>
+  <td width=42 valign=top style='width:31.45pt;border-top:none;border-left:
+  none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
+  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
+  mso-border-alt:solid windowtext .5pt;padding:0in 5.4pt 0in 5.4pt'>
+  <p class=MsoNormal align=center style='margin-bottom:0in;margin-bottom:.0001pt;
+  text-align:center;line-height:normal'><o:p>&nbsp;</o:p></p>
+  </td>
+  <td width=169 valign=top style='width:126.65pt;border-top:none;border-left:
+  none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
+  mso-border-top-alt:solid windowtext .5pt;mso-border-left-alt:solid windowtext .5pt;
+  mso-border-alt:solid windowtext .5pt;padding:0in 5.4pt 0in 5.4pt'>
+  <p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
+  normal'><o:p>&nbsp;</o:p></p>
+  </td>
+ </tr>
  <tr style='mso-yfti-irow:181'>
   <td width=263 style='width:197.2pt;border:solid windowtext 1.0pt;border-top:
   none;mso-border-top-alt:solid windowtext .5pt;mso-border-alt:solid windowtext .5pt;
diff --git a/c++/src/H5File.cpp b/c++/src/H5File.cpp
index 719c1ba..b9ecded 100644
--- a/c++/src/H5File.cpp
+++ b/c++/src/H5File.cpp
@@ -580,6 +580,27 @@ hsize_t H5File::getFileSize() const
 }
 
 //--------------------------------------------------------------------------
+// Function:    H5File::getFileNum
+///\brief       Returns the file number of the HDF5 file.
+///\return      File number
+///\exception   H5::FileIException
+///\par Description
+///             This function is called after an existing file is opened in
+///             order to retrieve the unique 'file number' for the file.
+// Programmer   Quincey Koziol - April 13, 2019
+//--------------------------------------------------------------------------
+unsigned long H5File::getFileNum() const
+{
+    unsigned long fileno = 0;
+    herr_t ret_value = H5Fget_fileno(id, &fileno);
+    if (ret_value < 0)
+    {
+        throw FileIException("H5File::getFileNum", "H5Fget_fileno failed");
+    }
+    return (fileno);
+}
+
+//--------------------------------------------------------------------------
 // Function:    H5File::getId
 ///\brief       Get the id of this file
 ///\return      File identifier
diff --git a/c++/src/H5File.h b/c++/src/H5File.h
index 332685e..1b1227f 100644
--- a/c++/src/H5File.h
+++ b/c++/src/H5File.h
@@ -69,6 +69,9 @@ class H5_DLLCPP H5File : public Group {
         // Returns the file size of the HDF5 file.
         hsize_t getFileSize() const;
 
+        // Returns the 'file number' of the HDF5 file.
+        unsigned long getFileNum() const;
+
         // Determines if a file, specified by its name, is in HDF5 format
         static bool isHdf5(const char* name);
         static bool isHdf5(const H5std_string& name);
diff --git a/c++/test/tfile.cpp b/c++/test/tfile.cpp
index a2bf1c2..055cf23 100644
--- a/c++/test/tfile.cpp
+++ b/c++/test/tfile.cpp
@@ -412,6 +412,64 @@ static void test_file_size()
 
 
 /*-------------------------------------------------------------------------
+ * Function:    test_file_num
+ *
+ * Purpose      Test file number.
+ *
+ * Return       None
+ *
+ * Programmer   Quincey Koziol
+ *              April, 2019
+ *-------------------------------------------------------------------------
+ */
+static void test_file_num()
+{
+    // Output message about test being performed
+    SUBTEST("File Number");
+
+    hid_t        fapl_id;
+    fapl_id = h5_fileaccess(); // in h5test.c, returns a file access template
+
+    try {
+        // Use the file access template id to create a file access prop.
+        // list object to pass in H5File::H5File
+        FileAccPropList fapl(fapl_id);
+
+        // Create two files
+        H5File file1(FILE1, H5F_ACC_TRUNC, FileCreatPropList::DEFAULT, fapl);
+        H5File file2(FILE2, H5F_ACC_TRUNC, FileCreatPropList::DEFAULT, fapl);
+
+        // Open the first file again
+        H5File file3(FILE1, H5F_ACC_RDWR);
+
+        // Get file numbers
+        unsigned long file_num1 = file1.getFileNum();
+        unsigned long file_num2 = file2.getFileNum();
+        unsigned long file_num3 = file3.getFileNum();
+
+        // Check file numbers
+        if (file_num1 == file_num2)
+            issue_fail_msg("test_file_num()", __LINE__, __FILE__, "getFileNum() returned wrong value");
+        if (file_num1 != file_num3)
+            issue_fail_msg("test_file_num()", __LINE__, __FILE__, "getFileNum() returned wrong value");
+
+        PASSED();
+    }   // end of try block
+
+    catch (Exception& E)
+    {
+        issue_fail_msg("test_file_num()", __LINE__, __FILE__, E.getCDetailMsg());
+    }
+
+    // use C test utility routine to close property list.
+    herr_t ret = H5Pclose(fapl_id);
+    if (ret < 0)
+        issue_fail_msg("test_file_num()", __LINE__, __FILE__, "H5Pclose failed");
+
+}   // test_file_num()
+
+
+/*-------------------------------------------------------------------------
  * Function:    test_file_name
  *
  * Purpose      Test getting file's name.
@@ -966,6 +1024,7 @@ void test_file()
     test_file_create();      // Test file creation (also creation templates)
     test_file_open();        // Test file opening
     test_file_size();        // Test file size
+    test_file_num();         // Test file number
     test_file_name();        // Test getting file's name
     test_file_attribute();   // Test file attribute feature
     test_libver_bounds();    // Test format version
diff --git a/fortran/src/H5Ff.c b/fortran/src/H5Ff.c
index a4e786e..12fb7ed 100644
--- a/fortran/src/H5Ff.c
+++ b/fortran/src/H5Ff.c
@@ -632,6 +632,40 @@ done:
       return ret_value;
 }
 
+/****if* H5Ff/h5fget_fileno_c
+ * NAME
+ *  h5fget_fileno_c
+ * PURPOSE
+ *  Call H5Fget_fileno to get file number
+ * INPUTS
+ *  file_id - file identifier
+ * OUTPUTS
+ *  fileno - file number for open file
+ * RETURNS
+ *  0 on success, -1 on failure
+ * AUTHOR
+ *  Quincey Koziol
+ *  Saturday, April 13, 2019
+ * SOURCE
+*/
+int_f
+h5fget_fileno_c(hid_t_f *file_id, int_f *fileno)
+/******/
+{
+    unsigned long fileno_c;
+    herr_t ret_value=0;          /* Return value */
+
+     /*
+      * Call H5Fget_filesize function
+      */
+     if ((ret_value = H5Fget_fileno((hid_t)*file_id, &fileno_c)) < 0)
+         HGOTO_DONE(FAIL);
+      *fileno = (hsize_t_f)fileno_c;
+
+done:
+      return ret_value;
+}
+
 /****if* H5Ff/h5fget_file_image_c
  * NAME
  *  h5fget_file_image_c
diff --git a/fortran/src/H5Fff.F90 b/fortran/src/H5Fff.F90
index cc51f37..ac3a1c0 100644
--- a/fortran/src/H5Fff.F90
+++ b/fortran/src/H5Fff.F90
@@ -886,6 +886,44 @@ CONTAINS
     hdferr = h5fget_filesize_c(file_id, size)
   END SUBROUTINE h5fget_filesize_f
 
+!****s* H5F/h5fget_fileno_f
+!
+! NAME
+!  h5fget_fileno_f
+!
+! PURPOSE
+!  Retrieves the file number of the HDF5 file.
+!
+! INPUTS
+!  file_id 	 - file identifier
+! OUTPUTS
+!  fileno 	 - file number
+!  hdferr 	 - Returns 0 if successful and -1 if fails
+!
+! AUTHOR
+!  Quincey Koziol
+!  April 13, 2019
+!
+! SOURCE
+  SUBROUTINE h5fget_fileno_f(file_id, fileno, hdferr)
+    IMPLICIT NONE
+    INTEGER(HID_T), INTENT(IN) :: file_id  ! file identifier
+    INTEGER, INTENT(OUT) :: fileno         ! File number
+    INTEGER, INTENT(OUT) :: hdferr         ! Error code: 0 on success,
+                                           !   	 -1 if fail
+!*****
+    INTERFACE
+       INTEGER FUNCTION h5fget_fileno_c(file_id, fileno) &
+            BIND(C,NAME='h5fget_fileno_c')
+         IMPORT :: HID_T, HSIZE_T
+         IMPLICIT NONE
+         INTEGER(HID_T), INTENT(IN) :: file_id
+         INTEGER, INTENT(OUT) :: fileno
+       END FUNCTION h5fget_fileno_c
+    END INTERFACE
+    hdferr = h5fget_fileno_c(file_id, fileno)
+  END SUBROUTINE h5fget_fileno_f
+
 !****s* H5F (F03)/h5fget_file_image_f_F03
 !
 ! NAME
diff --git a/fortran/src/H5f90proto.h b/fortran/src/H5f90proto.h
index 554ad0f..b357715 100644
--- a/fortran/src/H5f90proto.h
+++ b/fortran/src/H5f90proto.h
@@ -91,6 +91,7 @@ H5_FCDLL int_f h5fget_file_image_c(hid_t_f *file_id, void *buf_ptr, size_t_f *bu
 H5_FCDLL int_f h5fflush_c(hid_t_f *obj_id, int_f *scope);
 H5_FCDLL int_f h5fget_name_c(hid_t_f *obj_id, size_t_f *size, _fcd buf, size_t_f *buflen);
 H5_FCDLL int_f h5fget_filesize_c(hid_t_f *file_id, hsize_t_f *size);
+H5_FCDLL int_f h5fget_fileno_c(hid_t_f *file_id, int_f *fileno);
 
 /*
  * Functions from H5Sf.c
diff --git a/fortran/test/tH5F.F90 b/fortran/test/tH5F.F90
index 2501996..b898c21 100644
--- a/fortran/test/tH5F.F90
+++ b/fortran/test/tH5F.F90
@@ -105,6 +105,10 @@ CONTAINS
           INTEGER(SIZE_T) :: obj_count
           INTEGER(HID_T) :: t1, t2, t3, t4
 
+          ! File numbers
+          INTEGER  :: file_num1
+          INTEGER  :: file_num2
+
           !
           !data buffers
           !
@@ -287,6 +291,18 @@ CONTAINS
           IF(obj_count.NE.2)THEN
              total_error = total_error + 1
           ENDIF  
+
+          !
+          !Check file numbers
+          !
+          CALL h5fget_fileno_f(file1_id, file_num1, error)
+               CALL check("h5fget_fileno_f",error,total_error)
+          CALL h5fget_fileno_f(file2_id, file_num2, error)
+               CALL check("h5fget_fileno_f",error,total_error)
+          IF(file_num1 .EQ. file_num2) THEN
+               write(*,*) "file numbers aren't supposed to match"
+          END IF
+
           !
           !mount the second file under the first file's "/G" group.
           !
@@ -431,6 +447,8 @@ CONTAINS
           INTEGER, DIMENSION(4,6) :: dset_data, data_out
           INTEGER(HSIZE_T), DIMENSION(2) :: data_dims
           INTEGER(HSIZE_T)  :: file_size
+          INTEGER  :: file_num1
+          INTEGER  :: file_num2
           CHARACTER(LEN=80) :: file_name
           INTEGER(SIZE_T) :: name_size
 
@@ -499,6 +517,17 @@ CONTAINS
               CALL check("h5fget_filesize_f",error,total_error)
 
          !
+         !Check file numbers
+         !
+         CALL h5fget_fileno_f(file_id, file_num1, error)
+              CALL check("h5fget_fileno_f",error,total_error)
+         CALL h5fget_fileno_f(reopen_id, file_num2, error)
+              CALL check("h5fget_fileno_f",error,total_error)
+         IF(file_num1 .NE. file_num2) THEN
+              write(*,*) "file numbers don't match"
+         END IF
+
+         !
          !Open the dataset based on the reopen_id.
          !
          CALL h5dopen_f(reopen_id, dsetname, dset_id, error)
diff --git a/java/src/hdf/hdf5lib/H5.java b/java/src/hdf/hdf5lib/H5.java
index d107ad8..e874732 100644
--- a/java/src/hdf/hdf5lib/H5.java
+++ b/java/src/hdf/hdf5lib/H5.java
@@ -2968,6 +2968,19 @@ public class H5 implements java.io.Serializable {
     public synchronized static native int H5Fget_intent(long file_id) throws HDF5LibraryException;
 
     /**
+     * H5Fget_fileno retrieves the "file number" for an open file.
+     *
+     * @param file_id
+     *            IN: File identifier for a currently-open HDF5 file
+     *
+     * @return the unique file number for the file.
+     *
+     * @exception HDF5LibraryException
+     *                - Error from the HDF-5 Library.
+     **/
+    public synchronized static native long H5Fget_fileno(long file_id) throws HDF5LibraryException;
+
+    /**
      * H5Fget_mdc_hit_rate queries the metadata cache of the target file to obtain its hit rate (cache hits / (cache
      * hits + cache misses)) since the last time hit rate statistics were reset.
      *
diff --git a/java/src/jni/h5fImp.c b/java/src/jni/h5fImp.c
index d145c6a..26c1d17 100644
--- a/java/src/jni/h5fImp.c
+++ b/java/src/jni/h5fImp.c
@@ -275,6 +275,26 @@ done:
 
 /*
  * Class:     hdf_hdf5lib_H5
+ * Method:    H5Fget_fileno
+ * Signature: (J)J
+ */
+JNIEXPORT jlong JNICALL
+Java_hdf_hdf5lib_H5_H5Fget_1fileno
+    (JNIEnv *env, jclass cls, jlong file_id)
+{
+    unsigned long fileno = 0;
+
+    UNUSED(cls);
+
+    if (H5Fget_intent((hid_t)file_id, &fileno) < 0)
+        H5_LIBRARY_ERROR(ENVONLY);
+
+done:
+    return (jlong)fileno;
+} /* end Java_hdf_hdf5lib_H5_H5Fget_1intent */
+
+/*
+ * Class:     hdf_hdf5lib_H5
  * Method:    H5Fclose
  * Signature: (J)I
  */
diff --git a/java/src/jni/h5fImp.h b/java/src/jni/h5fImp.h
index 410a249..fc02c76 100644
--- a/java/src/jni/h5fImp.h
+++ b/java/src/jni/h5fImp.h
@@ -104,6 +104,15 @@ Java_hdf_hdf5lib_H5_H5Fget_1intent
 
 /*
  * Class:     hdf_hdf5lib_H5
+ * Method:    H5Fget_fileno
+ * Signature: (J)J
+ */
+JNIEXPORT jlong JNICALL
+Java_hdf_hdf5lib_H5_H5Fget_1fileno
+  (JNIEnv*, jclass, jlong);
+
+/*
+ * Class:     hdf_hdf5lib_H5
  * Method:    H5Fclose
  * Signature: (J)I
  */
diff --git a/java/test/TestH5F.java b/java/test/TestH5F.java
index e4f9a30..a86fddb 100644
--- a/java/test/TestH5F.java
+++ b/java/test/TestH5F.java
@@ -14,6 +14,7 @@
 package test;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
@@ -32,6 +33,7 @@ import org.junit.rules.TestName;
 public class TestH5F {
     @Rule public TestName testname = new TestName();
     private static final String H5_FILE = "testF.h5";
+    private static final String H5_FILE2 = "testF2.h5";
 
     private static final int COUNT_OBJ_FILE = 1;
     private static final int COUNT_OBJ_DATASET = 0;
@@ -48,6 +50,7 @@ public class TestH5F {
             HDF5Constants.H5F_OBJ_DATATYPE, HDF5Constants.H5F_OBJ_ATTR,
             HDF5Constants.H5F_OBJ_ALL };
     long H5fid = -1;
+    long H5fid2 = -1;
 
     private final void _deleteFile(String filename) {
         File file = new File(filename);
@@ -66,6 +69,10 @@ public class TestH5F {
         H5fid = H5.H5Fcreate(H5_FILE, HDF5Constants.H5F_ACC_TRUNC,
                 HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT);
         H5.H5Fflush(H5fid, HDF5Constants.H5F_SCOPE_LOCAL);
+
+        H5fid2 = H5.H5Fcreate(H5_FILE2, HDF5Constants.H5F_ACC_TRUNC,
+                HDF5Constants.H5P_DEFAULT, HDF5Constants.H5P_DEFAULT);
+        H5.H5Fflush(H5fid2, HDF5Constants.H5F_SCOPE_LOCAL);
     }
 
     @After
@@ -74,7 +81,12 @@ public class TestH5F {
             try {H5.H5Fclose(H5fid);} catch (Exception ex) {}
             H5fid = -1;
         }
+        if (H5fid2 > 0) {
+            try {H5.H5Fclose(H5fid2);} catch (Exception ex) {}
+            H5fid2 = -1;
+        }
         _deleteFile(H5_FILE);
+        _deleteFile(H5_FILE2);
         System.out.println();
     }
 
@@ -223,6 +235,124 @@ public class TestH5F {
     }
 
     @Test
+    public void testH5Fget_fileno_same() {
+        long fileno1 = 0;
+        long fileno2 = 0;
+        long fid1 = -1;
+        long fid2 = -1;
+
+        if (H5fid > 0) {
+            try {H5.H5Fclose(H5fid);} catch (Exception ex) {}
+            H5fid = -1;
+        }
+
+        try {
+            fid1 = H5.H5Fopen(H5_FILE, HDF5Constants.H5F_ACC_RDWR,
+                    HDF5Constants.H5P_DEFAULT);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fopen: " + err);
+        }
+
+        try {
+            fid2 = H5.H5Fopen(H5_FILE, HDF5Constants.H5F_ACC_RDWR,
+                    HDF5Constants.H5P_DEFAULT);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fopen: " + err);
+        }
+
+        try {
+            fileno1 = H5.H5Fget_fileno(fid1);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fget_fileno: " + err);
+        }
+
+        try {
+            fileno2 = H5.H5Fget_fileno(fid2);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fget_fileno: " + err);
+        }
+
+        assertEquals(fileno1, fileno2);
+
+        try {
+            H5.H5Fclose(fid1);
+        }
+        catch (Exception ex) {
+        }
+
+        try {
+            H5.H5Fclose(fid2);
+        }
+        catch (Exception ex) {
+        }
+    }
+
+    @Test
+    public void testH5Fget_fileno_diff() {
+        long fileno1 = 0;
+        long fileno2 = 0;
+        long fid1 = -1;
+        long fid2 = -1;
+
+        if (H5fid > 0) {
+            try {H5.H5Fclose(H5fid);} catch (Exception ex) {}
+            H5fid = -1;
+        }
+        if (H5fid2 > 0) {
+            try {H5.H5Fclose(H5fid2);} catch (Exception ex) {}
+            H5fid2 = -1;
+        }
+
+        try {
+            fid1 = H5.H5Fopen(H5_FILE, HDF5Constants.H5F_ACC_RDWR,
+                    HDF5Constants.H5P_DEFAULT);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fopen: " + err);
+        }
+
+        try {
+            fid2 = H5.H5Fopen(H5_FILE2, HDF5Constants.H5F_ACC_RDWR,
+                    HDF5Constants.H5P_DEFAULT);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fopen: " + err);
+        }
+
+        try {
+            fileno1 = H5.H5Fget_fileno(fid1);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fget_fileno: " + err);
+        }
+
+        try {
+            fileno2 = H5.H5Fget_fileno(fid2);
+        }
+        catch (Throwable err) {
+            fail("H5.H5Fget_fileno: " + err);
+        }
+
+        assertNotEquals(fileno1, fileno2);
+
+        try {
+            H5.H5Fclose(fid1);
+        }
+        catch (Exception ex) {
+        }
+
+        try {
+            H5.H5Fclose(fid2);
+        }
+        catch (Exception ex) {
+        }
+    }
+
+    @Test
     public void testH5Fget_obj_count() {
         long count = -1;
 
diff --git a/java/test/testfiles/JUnit-TestH5F.txt b/java/test/testfiles/JUnit-TestH5F.txt
index 16a423e..791e82d 100644
--- a/java/test/testfiles/JUnit-TestH5F.txt
+++ b/java/test/testfiles/JUnit-TestH5F.txt
@@ -7,8 +7,10 @@ JUnit version 4.11
 .testH5Fget_intent_rdonly
 .testH5Fget_create_plist
 .testH5Fget_obj_count
+.testH5Fget_fileno_same
+.testH5Fget_fileno_diff
 
 Time:  XXXX
 
-OK (8 tests)
+OK (10 tests)
 
diff --git a/src/H5F.c b/src/H5F.c
index 9df8140..779c940 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -921,6 +921,42 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5Fget_fileno
+ *
+ * Purpose:     Public API to retrieve the file's 'file number' that uniquely
+ *              identifies each open file.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Fget_fileno(hid_t file_id, unsigned long *fileno)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "i*Ul", file_id, fileno);
+
+    /* If no fileno pointer was passed in, exit quietly */
+    if(fileno) {
+        H5VL_object_t   *vol_obj;                      /* File info */
+
+        /* Get the internal file structure */
+        if(NULL == (vol_obj = (H5VL_object_t *)H5I_object(file_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
+
+        /* Get the flags */
+        if((ret_value = H5VL_file_get(vol_obj, H5VL_FILE_GET_FILENO, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, fileno)) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "unable to get file's 'file number'")
+    } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Fget_fileno() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5Fget_freespace
  *
  * Purpose:     Retrieves the amount of free space in the file.
diff --git a/src/H5Fpublic.h b/src/H5Fpublic.h
index 8274654..52f1ee2 100644
--- a/src/H5Fpublic.h
+++ b/src/H5Fpublic.h
@@ -236,6 +236,7 @@ H5_DLL herr_t H5Fclose(hid_t file_id);
 H5_DLL hid_t  H5Fget_create_plist(hid_t file_id);
 H5_DLL hid_t  H5Fget_access_plist(hid_t file_id);
 H5_DLL herr_t H5Fget_intent(hid_t file_id, unsigned *intent);
+H5_DLL herr_t H5Fget_fileno(hid_t file_id, unsigned long *fileno);
 H5_DLL ssize_t H5Fget_obj_count(hid_t file_id, unsigned types);
 H5_DLL ssize_t H5Fget_obj_ids(hid_t file_id, unsigned types, size_t max_objs, hid_t *obj_id_list);
 H5_DLL herr_t H5Fget_vfd_handle(hid_t file_id, hid_t fapl, void **file_handle);
diff --git a/src/H5VLnative_file.c b/src/H5VLnative_file.c
index 624cd30..8903911 100644
--- a/src/H5VLnative_file.c
+++ b/src/H5VLnative_file.c
@@ -228,6 +228,19 @@ H5VL__native_file_get(void *obj, H5VL_file_get_t get_type,
                 break;
             }
 
+        /* H5Fget_fileno */
+        case H5VL_FILE_GET_FILENO:
+            {
+                unsigned long *fileno = HDva_arg(arguments, unsigned long *);
+                unsigned long my_fileno = 0;
+
+                f = (H5F_t *)obj;
+                H5F_GET_FILENO(f, my_fileno);
+                *fileno = my_fileno;    /* sigh */
+
+                break;
+            }
+
         /* H5Fget_name */
         case H5VL_FILE_GET_NAME:
             {
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index cf6246b..da31a97 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -114,6 +114,7 @@ typedef enum H5VL_file_get_t {
     H5VL_FILE_GET_FAPL,                     /* file access property list	*/
     H5VL_FILE_GET_FCPL,	                    /* file creation property list	*/
     H5VL_FILE_GET_INTENT,	            /* file intent           		*/
+    H5VL_FILE_GET_FILENO,	            /* file number           		*/
     H5VL_FILE_GET_NAME,	                    /* file name             		*/
     H5VL_FILE_GET_OBJ_COUNT,	            /* object count in file	       	*/
     H5VL_FILE_GET_OBJ_IDS	            /* object ids in file     		*/
diff --git a/test/tfile.c b/test/tfile.c
index 430bc85..acf2bd6 100644
--- a/test/tfile.c
+++ b/test/tfile.c
@@ -1921,6 +1921,7 @@ test_file_open_overlap(void)
     hid_t sid;
     ssize_t nobjs;      /* # of open objects */
     unsigned intent;
+    unsigned long fileno1, fileno2;     /* File number */
     herr_t ret;         /* Generic return value */
 
     /* Output message about test being performed */
@@ -1939,6 +1940,19 @@ test_file_open_overlap(void)
     CHECK(ret, FAIL, "H5Fget_intent");
     VERIFY(intent, H5F_ACC_RDWR, "H5Fget_intent");
 
+    /* Check the file numbers */
+    fileno1 = 0;
+    ret = H5Fget_fileno(fid1, &fileno1);
+    CHECK(ret, FAIL, "H5Fget_fileno");
+    fileno2 = 0;
+    ret = H5Fget_fileno(fid2, &fileno2);
+    CHECK(ret, FAIL, "H5Fget_fileno");
+    VERIFY(fileno1, fileno2, "H5Fget_fileno");
+
+    /* Check that a file number pointer of NULL is ignored */
+    ret = H5Fget_fileno(fid1, NULL);
+    CHECK(ret, FAIL, "H5Fget_fileno");
+
     /* Create a group in file */
     gid = H5Gcreate2(fid1, GROUP1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(gid, FAIL, "H5Gcreate2");
@@ -2652,6 +2666,7 @@ test_userblock_file_size(void)
     hid_t fcpl2_id;
     hsize_t dims[2] = {3, 4};
     hsize_t filesize1, filesize2, filesize;
+    unsigned long fileno1, fileno2;     /* File number */
     herr_t ret;         /* Generic return value */
 
     /* Output message about test being performed */
@@ -2669,6 +2684,15 @@ test_userblock_file_size(void)
     file2_id = H5Fcreate(FILE2, H5F_ACC_TRUNC, fcpl2_id, H5P_DEFAULT);
     CHECK(file2_id, FAIL, "H5Fcreate");
 
+    /* Check the file numbers */
+    fileno1 = 0;
+    ret = H5Fget_fileno(file1_id, &fileno1);
+    CHECK(ret, FAIL, "H5Fget_fileno");
+    fileno2 = 0;
+    ret = H5Fget_fileno(file2_id, &fileno2);
+    CHECK(ret, FAIL, "H5Fget_fileno");
+    CHECK(fileno1, fileno2, "H5Fget_fileno");
+
     /* Create groups */
     group1_id = H5Gcreate2(file1_id, GROUP1, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(group1_id, FAIL, "H5Gcreate2");