4.1 Progress handler

It is often useful to retrieve some feedback while long running operations are performed.

Data type: gcry_handler_progress_t

Progress handler functions have to be of the type gcry_handler_progress_t, which is defined as:

void (*gcry_handler_progress_t) (void *, const char *, int, int, int)

The following function may be used to register a handler function for this purpose.

Function: void gcry_set_progress_handler (gcry_handler_progress_t cb, void *cb_data)

This function installs cb as the ‘Progress handler’ function. It may be used only during initialization. cb must be defined as follows:

void
my_progress_handler (void *cb_data, const char *what,
                     int printchar, int current, int total)
{
  /* Do something.  */
}

A description of the arguments of the progress handler function follows.

cb_data

The argument provided in the call to gcry_set_progress_handler.

what

A string identifying the type of the progress output. The following values for what are defined:

need_entropy

Not enough entropy is available. total holds the number of required bytes.

wait_dev_random

Waiting to re-open a random device. total gives the number of seconds until the next try.

primegen

Values for printchar:

\n

Prime generated.

!

Need to refresh the pool of prime numbers.

<, >

Number of bits adjusted.

^

Searching for a generator.

.

Fermat test on 10 candidates failed.

:

Restart with a new random value.

+

Rabin Miller test passed.