Logical logging for C11

log.h

//
//  Logging facility
//

// Expecting to be included:
//  <stdio.h>
//  <inttypes.h>

#define _overload7(one, two, three, four, five, six, seven, x, ...)  x

#define _log7(arg0, arg1, arg2, arg3, arg4, arg5, arg6) \
	do { \
		_log_(arg0); _log_(arg1); _log_(arg2); _log_(arg3); \
		_log_(arg4); _log_(arg5); \
		_log(arg6); \
	} while(0)
#define _log6(arg0, arg1, arg2, arg3, arg4, arg5) \
	do { \
		_log_(arg0); _log_(arg1); _log_(arg2); _log_(arg3); \
		_log_(arg4); _log(arg5); \
	} while(0)
#define _log5(arg0, arg1, arg2, arg3, arg4) \
	do { \
		_log_(arg0); _log_(arg1); _log_(arg2); _log_(arg3); \
		_log(arg4); \
	} while(0)
#define _log4(arg0, arg1, arg2, arg3) \
	do { \
		_log_(arg0); _log_(arg1); _log_(arg2); _log(arg3); \
	} while(0)
#define _log3(arg0, arg1, arg2) \
	do { \
		_log_(arg0); _log_(arg1); _log(arg2); \
	} while(0)
#define _log2(arg0, arg1) \
	do { \
		_log_(arg0); _log(arg1); \
	} while(0)
#define _log(x)  fprintf(stderr, _log_format(x), x)
#define _log_(x) _log(x), fputc(0x20, stderr)

#ifndef _log_prologue
#    define _log_prologue
#endif
#ifndef _log_epilogue
#    define _log_epilogue fputc(0xa, stderr)
#endif
#ifndef _panic_prologue
#    define _panic_prologue
#endif
#ifndef _panic_epilogue
#    define _panic_epilogue fputc(0xa, stderr)
#endif

#define _force_pointer_decay(x) ((void)0,x)

#define _log_format(x) \
	_Generic(_force_pointer_decay(x), \
		uint8_t: "%" PRIu8, \
		uint16_t: "%" PRIu16, \
		uint32_t: "%" PRIu32, \
		uint64_t: "%" PRIu64, \
		int8_t: "%" PRId8, \
		int16_t: "%" PRId16, \
		int32_t: "%" PRId32, \
		int64_t: "%" PRId64, \
		size_t: "%zu", \
		ssize_t: "%zd", \
		char: "%c", \
		const char: "%c", \
		char *: "%s", \
		const char *: "%s", \
		float: "%f", \
		double: "%lf", \
		void *: "%p", \
		default: "%p" \
	)

#define log(...) \
	do { \
		_log_prologue; \
		_overload7(__VA_ARGS__, \
			_log7, _log6, _log5, _log4, \
			_log3, _log2, _log \
		)(__VA_ARGS__); \
		_log_epilogue; \
	} while(0)

#define panic(...) \
	do { \
		_panic_prologue; \
		_overload7(__VA_ARGS__, \
			_log7, _log6, _log5, _log4, \
			_log3, _log2, _log \
		)(__VA_ARGS__); \
		_panic_epilogue; \
	} while(0)