H5E: Error Interface

Error API Functions

The C Interfaces:

H5Eset_auto H5Eget_auto H5Eclear

H5Eprint H5Ewalk H5Ewalk_cb

H5Eget_major H5Eget_minor

The FORTRAN90 Interfaces:
In general, each FORTRAN90 subroutine performs exactly the same task as the corresponding C function. The links below go to the C function descriptions, which serve as general descriptions for both. A button, under Non-C API(s) at the end of the C function description, opens an external browser window displaying the FORTRAN90-specific information. You will probably want to adjust the size and location of this external window so that both browser windows are visible and to facilitate moving easily between them.

h5eset_auto_f h5eclear_f

h5eprint_f

h5eget_major_f h5eget_minor_f

The Error interface provides error handling in the form of a stack. The FUNC_ENTER() 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.

Certain API functions in the H5E package, such as H5Eprint(), 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, H5Fopen() clears the error stack while H5F_open() does not.

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.

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.

Name: H5Eset_auto

Signature:

herr_t H5Eset_auto(H5E_auto_t func, void *client_data )

Purpose:

Turns automatic error printing on or off.

Description:

H5Eset_auto turns on or off automatic printing of errors. When turned on (non-null func pointer), any API function which returns an error indication will first call func, passing it client_data as an argument.

When the library is first initialized the auto printing function is set to H5Eprint() (cast appropriately) and client_data is the standard error stream pointer, stderr.

Automatic stack traversal is always in the H5E_WALK_DOWNWARD direction.

Parameters:

H5E_auto_t func

Function to be called upon an error condition.

void *client_data

Data passed to the error function.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Non-C API(s):

Name: H5Eget_auto

Signature:

herr_t H5Eget_auto(H5E_auto_t * func, void **client_data )

Purpose:

Returns the current settings for the automatic error stack traversal function and its data.

Description:

H5Eget_auto returns the current settings for the automatic error stack traversal function, func, and its data, client_data. Either (or both) arguments may be null in which case the value is not returned.

Parameters:

H5E_auto_t * func

Current setting for the function to be called upon an error condition.

void **client_data

Current setting for the data passed to the error function.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5Eclear

Signature:

herr_t H5Eclear(void)

Purpose:

Clears the error stack for the current thread.

Description:

H5Eclear clears the error stack for the current thread.

The stack is also cleared whenever an API function is called, with certain exceptions (for instance, H5Eprint()).

H5Eclear can fail if there are problems initializing the library.

Parameters:

None

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Non-C API(s):

Name: H5Eprint

Signature:

herr_t H5Eprint(FILE * stream)

Purpose:

Prints the error stack in a default manner.

Description:

H5Eprint prints the error stack on the specified stream, stream. Even if the error stack is empty, a one-line message will be printed:
     HDF5-DIAG: Error detected in thread 0.

H5Eprint is a convenience function for H5Ewalk() with a function that prints error messages. Users are encouraged to write there own more specific error handlers.

Parameters:

FILE * stream

File pointer, or stderr if NULL.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Non-C API(s):

Name: H5Ewalk

Signature:

herr_t H5Ewalk(H5E_direction_t direction, H5E_walk_t func, void * client_data )

Purpose:

Walks the error stack for the current thread, calling a specified function.

Description:

H5Ewalk walks the error stack for the current thread and calls the specified function for each error along the way.

direction determines whether the stack is walked from the inside out or the outside in. A value of H5E_WALK_UPWARD means begin with the most specific error and end at the API; a value of H5E_WALK_DOWNWARD means to start at the API and end at the inner-most function where the error was first detected.

func 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 client_data pointer passed to H5E_print. The H5E_walk_t prototype is as follows:

typedef herr_t (*H5E_walk_t)(int n, H5E_error_t *err_desc, void *client_data)

where the parameters have the following meanings:

int n

Indexed position of the error in the stack.

H5E_error_t *err_desc

Pointer to a data structure describing the error. (This structure is currently described only in the source code file hdf5/src/H5Epublic.h. That file also contains the definitive list of major and minor error codes. That information will eventually be presented as an appendix to this Reference Manual.)

void *client_data

Pointer to client data in the format expected by the user-defined function.

H5Ewalk can fail if there are problems initializing the library.

Parameters:

H5E_direction_t direction

Direction in which the error stack is to be walked.

H5E_walk_t func

Function to be called for each error encountered.

void * client_data

Data to be passed with func.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5Ewalk_cb

Signature:

herr_t H5Ewalk_cb(int n, H5E_error_t *err_desc, void *client_data )

Purpose:

Default error stack traversal callback function that prints error messages to the specified output stream.

Description:

H5Ewalk_cb 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 H5Ewalk() function. This function is called also by H5Eprint(). Application writers are encouraged to use this function as a model for their own error stack walking functions.

n 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).

err_desc is an error description. It contains all the information about a particular error.

client_data is the same pointer that was passed as the client_data argument of H5Ewalk(). It is expected to be a file pointer (or stderr if null).

Parameters:

int n

Number of times this function has been called for this traversal of the stack.

H5E_error_t *err_desc

Error description.

void *client_data

A file pointer, or stderr if null.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5Eget_major

Signature:

const char * H5Eget_major(H5E_major_t n)

Purpose:

Returns a character string describing an error specified by a major error number.

Description:

Given a major error number, H5Eget_major returns a constant character string that describes the error.

Parameters:

H5E_major_t n

Major error number.

Returns:

Returns a character string describing the error if successful. Otherwise returns "Invalid major error number."

Non-C API(s):

Name: H5Eget_minor

Signature:

const char * H5Eget_minor(H5E_minor_t n)

Purpose:

Returns a character string describing an error specified by a minor error number.

Description:

Given a minor error number, H5Eget_minor returns a constant character string that describes the error.

Parameters:

H5E_minor_t n

Minor error number.

Returns:

Returns a character string describing the error if successful. Otherwise returns "Invalid minor error number."

Non-C API(s):