[PATCH wayland v3] Add support for direct file reading and writing in wayland-scanner.

[Bill Spitzak]

This is my suggested alteration of the patch to allow 3 arguments, there 
is a * in front of my changed or added lines:

>> -	if (argc != 2)
  * +    if (argc < 2 || argc > 4)
>>   		usage(EXIT_FAILURE);
>>   	else if (strcmp(argv[1], "help") == 0 || strcmp(argv[1], "--help") == 0)
>>   		usage(EXIT_SUCCESS);
>> @@ -1273,6 +1275,20 @@ int main(int argc, char *argv[])
>>   	else
>>   		usage(EXIT_FAILURE);
>>
>> +	if (argc == 4) {
>> +		input = fopen(argv[2], "r");
>> +		if (input == NULL) {
>> +			fprintf(stderr, "Could not open input file: %s\n",
>> +				strerror(errno));
>> +			exit(EXIT_FAILURE);
>> +		}
  * +    }
  * +    if (argc > 2) {
>> +		if (freopen(argv[3], "w", stdout) == NULL) {
>> +			fprintf(stderr, "Could not open output file: %s\n",
>> +				strerror(errno));
>> +			exit(EXIT_FAILURE);
>> +		}

The dashes are not a big deal and not worth adding.

Note there are no actual switches to this program, instead it's action 
is controlled by it's first argument, which does not have a dash in 
front of it. It's more like part of the command name. Since there are no 
switches I don't see an option parsing library being useful.