gists/c-programming/asprintf.c

#include "asprintf.h"

ssize_t asprintf(char** strp, char* format, ...) {
	va_list args;
	va_start(args, format);

	ssize_t size = (ssize_t) vsnprintf(NULL, 0, format, args);
	if (size < 0) {
		va_end(args);
		return -1;
	}

	*strp = malloc(size + 1);
	if (*strp == NULL) {
		va_end(args);
		return -1;
	}

	ssize_t result = (ssize_t) vsnprintf(*strp, size + 1, format, args);
	va_end(args);

	if (result < 0) {
		free(*strp);
		return -1;
	}

	return result;
}