printf2.c

#include <assert.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>

#include "printf2.h"

size_t
vfprintf2(FILE *stream, const char *format, va_list ap)
{
	typedef size_t (*pp_print)(FILE *stream, va_list *);

	va_list ap2;
	va_copy(ap2, ap);
	size_t n = 0;
	while (ferror(stream) == 0) {
		char c;

		switch (c = *(format++)) {
		case '\0':
			goto done;
		case '%':
			switch (c = *(format++)) {
			case '\0':
				goto done;
			case '%':
				if (fputc('%', stream) != 0) {
					n++;
				}
				break;
			case 'B': {
				const char *s = va_arg(ap2, int) != 0 ? "true" : "false";
				n += fwrite(s, strlen(s), 1, stream);
				break;
			}
			case 'c':
				if (fputc(va_arg(ap2, int), stream) != 0) {
					n++;
				}
				break;
			case 's': {
				const char *s = va_arg(ap2, const char *);
				n += fwrite(s, strlen(s), 1, stream);
				break;
			}
			case 't': {
				pp_print pr = va_arg(ap2, pp_print);
				n += pr(stream, &ap2);
				break;
			}
			default:
				assert(0);
			}
			break;
		default:
			if (fputc((int) c, stream) != 0) {
				n++;
			}
			break;
		}
	}
done:
	va_end(ap2);
	return n;
}

size_t
fprintf2(FILE *stream, const char *format, ...)
{
	va_list ap;
	va_start(ap, format);
	size_t n = vfprintf2(stream, format, ap);
	va_end(ap);
	return n;
}

size_t
printf2(const char *format, ...)
{
	va_list ap;
	va_start(ap, format);
	size_t n = vfprintf2(stdout, format, ap);
	va_end(ap);
	return n;
}