Provides error handling in the form of a stack. The FUNC_ENTER() macro clears the error stack whenever an API 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 doesn't 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.
H5Eset_auto(H5E_auto_t func,
void *client_data
)
func pointer),
any API function which returns an error indication will
first call func, passing it client_data
as an argument.
The default values before this function is called are H5Eprint() with client data being the standard error stream, stderr.
Automatic stack traversal is always in the H5E_WALK_DOWNWARD direction.
UG: If func is not a null pointer, then the function to
which it points will be called automatically when an API
function is about to return an indication of failure. The
function is called with a single argument, the
client_data pointer. 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.
UG signature line reads
herr_t H5Eset_auto (herr_t(*func)(void*),
void *client_data).
The UG signature line for H5Eget_auto reads similarly.
func
client_data
H5Eget_auto(H5E_auto_t * func,
void **client_data
)
UG: This function returns the current automatic error traversal settings through the func and client_data arguments. Either (or both) arguments may be null pointers in which case the corresponding information is not returned.
func
client_data
H5Eclear(void)
This function can fail if there are problems initializing the library.
UG: The error stack can be explicitly cleared by calling this
function. The stack is also cleared whenever an API function
is called, with certain exceptions (for instance,
H5Eprint()).
param
H5Eprint(FILE * stream)
UG: The error stack is printed on the specified stream. Even if
the error stack is empty a one-line message will be printed:
HDF5-DIAG: Error detected in thread 0.
stream
H5Ewalk(H5E_direction_t direction,
H5E_walk_t func,
void * client_data
)
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.
It's 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.
H5Ewalk can fail if there are problems initializing the library.
UG: The error stack is traversed and func is called for
each member of the stack. Its arguments are an integer
sequence number beginning at zero (regardless of
direction), a pointer to an error description record,
and the client_data pointer. If direction
is H5E_WALK_UPWARD then traversal begins at the
inner-most function that detected the error and concludes with
the API function. The opposite order is
H5E_WALK_DOWNWARD.
direction
func
client_data
func.
H5Ewalk_cb(int n,
H5E_error_t *err_desc,
void *client_data
)
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).
n
err_desc
*client_data
stderr if null.
H5Eget_major(H5E_major_t n)
n
H5Eget_minor(H5E_minor_t n)
n