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<html>
<head><title>
HDF5/H5E API Specification
</title>

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<hr>
<!-- #EndLibraryItem --><center>
<h1>H5E: Error Interface</h1>
</center>

<h2>Error API Functions</h2>

These functions provide error handling capabilities in the HDF5 environment.

<p>
<strong>The C Interfaces:</strong>

<table border=0>
<tr><td valign=top>
<ul>
    <li><a href="#Error-Clear">H5Eclear</a>
    <li><a href="#Error-Print">H5Eprint</a>
    <li><a href="#Error-Push">H5Epush</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#Error-SetAuto">H5Eset_auto</a>
    <li><a href="#Error-GetAuto">H5Eget_auto</a>
    <li><a href="#Error-Walk">H5Ewalk</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#Error-WalkCB">H5Ewalk_cb</a>
    <li><a href="#Error-GetMajor">H5Eget_major</a>
    <li><a href="#Error-GetMinor">H5Eget_minor</a>
</ul>
</td></tr>
</table>
<br>

<i>Alphabetical Listing</i>

<table border="0">
  <tr>
    <td valign="top">
	<ul>
      <li><a href="#Error-Clear">H5Eclear</a>
      <li><a href="#Error-GetAuto">H5Eget_auto</a>
      <li><a href="#Error-GetMajor">H5Eget_major</a>
	</ul>     
    </td>
    
    <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
    
    <td valign="top">
	<ul>
      <li><a href="#Error-GetMinor">H5Eget_minor</a>
      <li><a href="#Error-Print">H5Eprint</a>
      <li><a href="#Error-Push">H5Epush</a>
	</ul>
    </td>
    
    <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
    
    <td valign="top">
	<ul>
      <li><a href="#Error-SetAuto">H5Eset_auto</a>
      <li><a href="#Error-Walk">H5Ewalk</a>
      <li><a href="#Error-WalkCB">H5Ewalk_cb</a>
	</ul>
    </td>
  </tr>
</table>

<br>
<strong>The FORTRAN90 Interfaces:</strong>
<br>
In general, each FORTRAN90 subroutine performs exactly the same task 
as the corresponding C function.  
<br>

<table border=0>
<tr><td valign=top>
<ul>
    <li><a href="#Error-Clear">h5eclear_f</a>
    <li><a href="#Error-Print">h5eprint_f</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#Error-SetAuto">h5eset_auto_f</a>
<!--<li><a href="#Error-GetAuto">h5eget_auto_f</a>                    -->
<!--<li><a href="#Error-Walk">h5ewalk_f</a>                          -->
<!--<li><a href="#Error-WalkCB">h5ewalk_cb_f</a>                     -->
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#Error-GetMajor">h5eget_major_f</a>
    <li><a href="#Error-GetMinor">h5eget_minor_f</a>
</ul>
</td></tr>
</table>

<p>
The Error interface provides error handling in the form of a stack.  
The <code>FUNC_ENTER()</code> macro clears the error stack whenever 
an interface function is entered.  
When an error is detected, an entry is pushed onto the stack.  
As the functions unwind, additional entries are pushed onto the stack. 
The API function will return some indication that an error occurred and 
the application can print the error stack.
<p>
Certain API functions in the H5E package, such as <code>H5Eprint</code>,
do not clear the error stack.  Otherwise, any function which
does not have an underscore immediately after the package name
will clear the error stack.  For instance, <code>H5Fopen</code> 
clears the error stack while <code>H5F_open</code> does not.
<p>
An error stack has a fixed maximum size.  
If this size is exceeded then the stack will be truncated and only the
inner-most functions will have entries on the stack. 
This is expected to be a rare condition. 
<p>
Each thread has its own error stack, but since
multi-threading has not been added to the library yet, this
package maintains a single error stack. The error stack is
statically allocated to reduce the complexity of handling
errors within the H5E package.    

<!-- NEW PAGE -->
<!-- HEADER RIGHT " " -->
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Eclear" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-Clear">H5Eclear</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Eclear</code>(<code>void</code>)
<dt><strong>Purpose:</strong>
    <dd>Clears the error stack for the current thread.
<dt><strong>Description:</strong>
    <dd><code>H5Eclear</code> clears the error stack for the current thread.
        <p>
        The stack is also cleared whenever an API function is called, 
	  with certain exceptions (for instance, <code>H5Eprint</code>).
        <p>
        <code>H5Eclear</code> can fail if there are problems initializing 
        the library.
<dt><strong>Parameters:</strong>
    <dl>
        <dt>None
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong> h5eclear_f
    <dd>
	<pre>
SUBROUTINE h5eclear_f(hdferr) 
  IMPLICIT NONE
  INTEGER, INTENT(OUT) :: hdferr  ! Error code

END SUBROUTINE h5eclear_f
	</pre>		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Eget_auto" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-GetAuto">H5Eget_auto</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Eget_auto</code>(<em>H5E_auto_t *</em> <code>func</code>,
        <em>void **</em><code>client_data</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the current settings for the automatic error stack
        traversal function and its data.  
<dt><strong>Description:</strong>
    <dd><code>H5Eget_auto</code> returns the current settings for the 
        automatic error stack traversal function, <code>func</code>, 
        and its data, <code>client_data</code>.  Either (or both) 
        arguments may be null in which case the value is not returned.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5E_auto_t *</em> <code>func</code>
            <dd>OUT: Current setting for the function to be called upon an 
                error condition.
        <dt><em>void **</em><code>client_data</code>
            <dd>OUT: Current setting for the data passed to the error function.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong>
    <dd>None.
	
<!--
	<pre>
SUBROUTINE
	</pre>
-->		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Eget_major" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-GetMajor">H5Eget_major</a>
<dt><strong>Signature:</strong>
    <dd><em>const char *</em> <code>H5Eget_major</code>(<em>H5E_major_t</em> <code>n</code>)
<dt><strong>Purpose:</strong>
    <dd>Returns a character string describing an error specified by a 
        major error number.
<dt><strong>Description:</strong>
    <dd>Given a major error number, <code>H5Eget_major</code> returns a 
        constant character string that describes the error.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5E_major_t</em> <code>n</code>
            <dd>IN: Major error number.
    </dl>
<dt><strong>Returns:</strong>
    <dd> Returns a character string describing the error if successful.
         Otherwise returns "Invalid major error number."
<dt><strong>Fortran90 Interface:</strong> h5eget_major_f
    <dd>
	<pre>
SUBROUTINE h5eget_major_f(error_no, name, hdferr)
  INTEGER, INTENT(IN) :: error_no         !Major error number
  CHARACTER(LEN=*), INTENT(OUT) :: name   ! File name
  INTEGER, INTENT(OUT) :: hdferr          ! Error code

END SUBROUTINE h5eget_major_f
	</pre>		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Eget_minor" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-GetMinor">H5Eget_minor</a>
<dt><strong>Signature:</strong>
    <dd><em>const char *</em> <code>H5Eget_minor</code>(<em>H5E_minor_t</em> <code>n</code>)
<dt><strong>Purpose:</strong>
    <dd>Returns a character string describing an error specified by a 
        minor error number.
<dt><strong>Description:</strong>
    <dd>Given a minor error number, <code>H5Eget_minor</code> returns a 
        constant character string that describes the error.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5E_minor_t</em> <code>n</code>
            <dd>IN: Minor error number.
    </dl>
<dt><strong>Returns:</strong>
    <dd> Returns a character string describing the error if successful.
         Otherwise returns "Invalid minor error number."
<dt><strong>Fortran90 Interface:</strong> h5eget_minor_f
    <dd>
	<pre>
SUBROUTINE h5eget_minor_f(error_no, name, hdferr)
  INTEGER, INTENT(IN) :: error_no         !Major error number
  CHARACTER(LEN=*), INTENT(OUT) :: name   ! File name
  INTEGER, INTENT(OUT) :: hdferr          ! Error code

END SUBROUTINE h5eget_minor_f
	</pre>		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Eprint" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-Print">H5Eprint</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Eprint</code>(<em>FILE *</em> <code>stream</code>)
<dt><strong>Purpose:</strong>
    <dd>Prints the error stack in a default manner.  
<dt><strong>Description:</strong>
    <dd><code>H5Eprint</code> prints the error stack on the specified 
        stream, <code>stream</code>.  
        Even if the error stack is empty, a one-line message will be printed:
        <br>&nbsp;&nbsp;&nbsp;&nbsp;
	  <code>HDF5-DIAG: Error detected in thread 0.</code>
        <p>
        <code>H5Eprint</code> is a convenience function for 
        <code>H5Ewalk</code> with a function that prints error messages.  
        Users are encouraged to write their own more specific error handlers.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>FILE *</em> <code>stream</code>
            <dd>IN: File pointer, or stderr if NULL.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong> h5eprint_f
    <dd>
	<pre>
SUBROUTINE h5eprint_f(hdferr, name)
  CHARACTER(LEN=*), OPTIONAL, INTENT(IN) :: name ! File name
  INTEGER, INTENT(OUT) :: hdferr                 ! Error code

END SUBROUTINE h5eprint_f
	</pre>		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Epush" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-Push">H5Epush</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Epush</code>(
            <em>const char *</em><code>file</code>,
            <em>const char *</em><code>func</code>,
            <em>unsigned</em> <code>line</code>,
            <em>H5E_major_t</em> <code>maj_num</code>,
            <em>H5E_minor_t</em> <code>min_num</code>,
            <em>const char *</em><code>str</code>
            )
<dt><strong>Purpose:</strong>
    <dd>Pushes new error record onto error stack.
<dt><strong>Description:</strong>
    <dd><code>H5Epush</code> pushes a new error record onto the 
        error stack for the current thread.  
        <p>
        The error has major and minor numbers <code>maj_num</code> and 
        <code>min_num</code>, 
        the function <code>func</code> where the error was detected,
        the name of the file <code>file</code> where the error was detected, 
        the line <code>line</code> within that file, 
        and an error description string <code>str</code>.  
        <p>
        The function name, file name, and error description strings 
        must be statically allocated.   
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>const char *</em><code>file</code>,
            <dd>IN: Name of the file in which the error was detected.
        <dt><em>const char *</em><code>func</code>,
            <dd>IN: Name of the function in which the error was detected.
        <dt><em>unsigned</em> <code>line</code>,
            <dd>IN: Line within the file at which the error was detected.
        <dt><em>H5E_major_t</em> <code>maj_num</code>,
            <dd>IN: Major error number.
        <dt><em>H5E_minor_t</em> <code>min_num</code>,
            <dd>IN: Minor error number.
        <dt><em>const char *</em><code>str</code>
            <dd>IN: Error description string.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong>
    <dd>None.
	
<!--
	<pre>
SUBROUTINE
	</pre>
-->		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Eset_auto" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-SetAuto">H5Eset_auto</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Eset_auto</code>(<em>H5E_auto_t</em> <code>func</code>,
        <em>void *</em><code>client_data</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Turns automatic error printing on or off.
<dt><strong>Description:</strong>
    <dd><code>H5Eset_auto</code> turns on or off automatic printing of 
        errors.  When turned on (non-null <code>func</code> pointer), 
        any API function which returns an error indication will 
        first call <code>func</code>, passing it <code>client_data</code>
        as an argument.
        <p>
        When the library is first initialized the auto printing function 
	  is set to <code>H5Eprint</code> (cast appropriately) and
	  <code>client_data</code> is the standard error stream pointer,
	  <code>stderr</code>.
        <p>
        Automatic stack traversal is always in the 
        <code>H5E_WALK_DOWNWARD</code> direction. 
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5E_auto_t</em> <code>func</code>
            <dd>IN: Function to be called upon an error condition.
        <dt><em>void *</em><code>client_data</code>
            <dd>IN: Data passed to the error function.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong> h5eset_auto_f
    <dd>
	<pre>
SUBROUTINE h5eset_auto_f(printflag, hdferr)
  INTEGER, INTENT(IN) :: printflag  !flag to turn automatic error
                                    !printing on or off
                                    !possible values are:
                                    !printon (1)
                                    !printoff(0)
  INTEGER, INTENT(OUT) :: hdferr    ! Error code

END SUBROUTINE h5eset_auto_f
	</pre>		
		
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        <img src="Graphics/Java.gif"> 
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<!-- HEADER RIGHT "H5Ewalk" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-Walk">H5Ewalk</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Ewalk</code>(<em>H5E_direction_t</em> <code>direction</code>,
        <em>H5E_walk_t</em> <code>func</code>,
        <em>void *</em> <code>client_data</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Walks the error stack for the current thread, calling a specified
        function.
<dt><strong>Description:</strong>
    <dd><code>H5Ewalk</code> walks the error stack for the current thread 
        and calls the specified function for each error along the way.
        <p>
        <code>direction</code> determines whether the stack is walked 
        from the inside out or the outside in.  
        A value of <code>H5E_WALK_UPWARD</code> means begin with the
        most specific error and end at the API; 
        a value of <code>H5E_WALK_DOWNWARD</code> means to start at the 
        API and end at the inner-most function where the error was first 
        detected.
        <p>
        <code>func</code> will be called for each error in the error stack. 
        Its arguments will include an index number (beginning at zero 
        regardless of stack traversal direction), an error stack entry, 
        and the <code>client_data</code> pointer passed to 
        <code>H5E_print</code>.
        The <code>H5E_walk_t</code> prototype is as follows:
        <dir>
        <p>
        <code>typedef</code> <em>herr_t</em> <code>(*H5E_walk_t)(</code><em>int</em> <code>n,</code> 
            <em>H5E_error_t *</em><code>err_desc,</code> 
            <em>void *</em><code>client_data)</code>
        <p>
        where the parameters have the following meanings:
            <dl>
            <dt><em>int</em> <code>n</code>
                <dd>Indexed position of the error in the stack.
            <dt><em>H5E_error_t *</em><code>err_desc</code>
                <dd>Pointer to a data structure describing the error.
                    <em>(This structure is currently described only in the
                        source code file </em><code>hdf5/src/H5Epublic.h</code><em>.  
                        That file also contains the definitive list of major 
                        and minor error codes.  That information will 
                        eventually be presented as an appendix to this 
                        <cite>Reference Manual</cite>.)</em>
            <dt><em>void *</em><code>client_data</code>
                <dd>Pointer to client data in the format expected by 
                    the user-defined function.
            </dl>
        </dir>
        <p>
        <code>H5Ewalk</code> can fail if there are problems initializing 
        the library.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5E_direction_t</em> <code>direction</code>
            <dd>IN: Direction in which the error stack is to be walked.
        <dt><em>H5E_walk_t</em> <code>func</code>
            <dd>IN: Function to be called for each error encountered.
        <dt><em>void *</em> <code>client_data</code>
            <dd>IN: Data to be passed with <code>func</code>.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong>
    <dd>None.
	
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	<pre>
SUBROUTINE
	</pre>
-->		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
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<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Ewalk_cb" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Error-WalkCB">H5Ewalk_cb</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Ewalk_cb</code>(<em>int</em> <code>n</code>,
        <em>H5E_error_t *</em><code>err_desc</code>,
        <em>void</em> <code>*client_data</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Default error stack traversal callback function
        that prints error messages to the specified output stream.
<dt><strong>Description:</strong>
    <dd><code>H5Ewalk_cb</code> is a default error stack traversal callback
        function that prints error messages to the specified output stream.
        It is not meant to be called directly but rather as an
        argument to the <code>H5Ewalk</code> function.  
        This function is called also by <code>H5Eprint</code>.  
        Application writers are encouraged to use this function as a 
        model for their own error stack walking functions.
        <p>
        <code>n</code> is a counter for how many times this function 
        has been called for this particular traversal of the stack.  
        It always begins at zero for the first error on the stack 
        (either the top or bottom error, or even both, depending on 
        the traversal direction and the size of the stack).
        <p>
        <code>err_desc</code> is an error description.  It contains all the
        information about a particular error. 
        <p>
        <code>client_data</code> is the same pointer that was passed as the
        <code>client_data</code> argument of <code>H5Ewalk</code>.  
        It is expected to be a file pointer (or stderr if NULL). 
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>int</em> <code>n</code>
            <dd>IN/OUT: Number of times this function has been called 
                for this traversal of the stack.
        <dt><em>H5E_error_t *</em><code>err_desc</code>
            <dd>OUT: Error description.
        <dt><em>void</em> <code>*client_data</code>
            <dd>IN: A file pointer, or stderr if NULL.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Fortran90 Interface:</strong>
    <dd>None.
	
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	<pre>
SUBROUTINE
	</pre>
-->		
		
		<!--<dt><strong>Non-C API(s):</strong>
    	<dd>
        
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
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