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#include <libserialport.h>
#include <stdio.h>
#include <stdlib.h>
/* Example of how to handle errors from libserialport.
*
* This example file is released to the public domain. */
/* Pointers used in the program to resources that may need to be freed. */
struct sp_port **port_list = NULL;
struct sp_port_config *config = NULL;
struct sp_port *port = NULL;
/* Example of a function to clean up and exit the program with a given return code. */
void end_program(int return_code)
{
/* Free any structures we allocated. */
if (port_list != NULL)
sp_free_port_list(port_list);
if (config != NULL)
sp_free_config(config);
if (port != NULL)
sp_free_port(port);
/* Exit with the given return code. */
exit(return_code);
}
/* Example of a helper function for error handling. */
int check(enum sp_return result)
{
int error_code;
char *error_message;
switch (result) {
/* Handle each of the four negative error codes that can be returned.
*
* In this example, we will end the program on any error, using
* a different return code for each possible class of error. */
case SP_ERR_ARG:
/* When SP_ERR_ARG is returned, there was a problem with one
* or more of the arguments passed to the function, e.g. a null
* pointer or an invalid value. This generally implies a bug in
* the calling code. */
printf("Error: Invalid argument.\n");
end_program(1);
case SP_ERR_FAIL:
/* When SP_ERR_FAIL is returned, there was an error from the OS,
* which we can obtain the error code and message for. These
* calls must be made in the same thread as the call that
* returned SP_ERR_FAIL, and before any other system functions
* are called in that thread, or they may not return the
* correct results. */
error_code = sp_last_error_code();
error_message = sp_last_error_message();
printf("Error: Failed: OS error code: %d, message: '%s'\n",
error_code, error_message);
/* The error message should be freed after use. */
sp_free_error_message(error_message);
end_program(2);
case SP_ERR_SUPP:
/* When SP_ERR_SUPP is returned, the function was asked to do
* something that isn't supported by the current OS or device,
* or that libserialport doesn't know how to do in the current
* version. */
printf("Error: Not supported.\n");
end_program(3);
case SP_ERR_MEM:
/* When SP_ERR_MEM is returned, libserialport wasn't able to
* allocate some memory it needed. Since the library doesn't
* normally use any large data structures, this probably means
* the system is critically low on memory and recovery will
* require very careful handling. The library itself will
* always try to handle any allocation failure safely.
*
* In this example, we'll just try to exit gracefully without
* calling printf, which might need to allocate further memory. */
end_program(4);
case SP_OK:
default:
/* A return value of SP_OK, defined as zero, means that the
* operation succeeded. */
printf("Operation succeeded.\n");
/* Some fuctions can also return a value greater than zero to
* indicate a numeric result, such as the number of bytes read by
* sp_blocking_read(). So when writing an error handling wrapper
* function like this one, it's helpful to return the result so
* that it can be used. */
return result;
}
}
int main(int argc, char **argv)
{
/* Call some functions that should not result in errors. */
printf("Getting list of ports.\n");
check(sp_list_ports(&port_list));
printf("Creating a new port configuration.\n");
check(sp_new_config(&config));
/* Now make a function call that will result in an error. */
printf("Trying to find a port that doesn't exist.\n");
check(sp_get_port_by_name("NON-EXISTENT-PORT", &port));
/* We could now clean up and exit normally if an error hadn't occured. */
end_program(0);
}
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