Demonstrate logging errors, info messages, etc. with SDL2 logging facilities

log.c

/* build this with
   cc log.c -o log `sdl2-config --cflags --libs`

   run with
   ./log -l <loglevel>

   And you will only see log messages that are at least that priority.
*/

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>

#include <SDL2/SDL.h>

static void setLogPriority(const char *arg);

int main(int argc, char **argv)
{
	(void)SDL_Init(SDL_INIT_VIDEO);

	int option;
	while((option = getopt(argc, argv, "l:")) != -1) {
		switch(option) {
		case 'l':
			setLogPriority(optarg);
			break;
		case '?':
			fprintf(stderr, "unknown option '%c'\n", optopt);
			break;
		}
	}

	/* These are all in the APPLICATION category, but we can still log errors etc */
	SDL_LogCritical(SDL_LOG_CATEGORY_APPLICATION, "Critical\n");
	SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Error\n");
	SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Warning\n");
	SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Info\n");
	SDL_LogDebug(SDL_LOG_CATEGORY_APPLICATION, "Debug\n");
	SDL_LogVerbose(SDL_LOG_CATEGORY_APPLICATION, "Verbose\n");

	SDL_Quit();
	return 0;
}

static void setLogPriority(const char *arg)
{
	SDL_LogPriority priority = SDL_LOG_PRIORITY_VERBOSE;

	if(strncasecmp("debug", arg, strlen("debug")) == 0) {
		priority = SDL_LOG_PRIORITY_DEBUG;
	} else if(strncasecmp("info", arg, strlen("info")) == 0) {
		priority = SDL_LOG_PRIORITY_INFO;
	} else if(strncasecmp("warn", arg, strlen("warn")) == 0) {
		priority = SDL_LOG_PRIORITY_WARN;
	} else if(strncasecmp("error", arg, strlen("error")) == 0) {
		priority = SDL_LOG_PRIORITY_ERROR;
	} else if(strncasecmp("critical", arg, strlen("critical")) == 0) {
		priority = SDL_LOG_PRIORITY_CRITICAL;
	}

	SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, priority);
}