alloc_sprintf.c

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include "alloc_sprintf.h"

char *alloc_sprintf(const char *message, ...) {
  char *res = NULL;
  va_list ap;
  int size = 0;

	va_start(ap, message);
  size = vsnprintf(res, 0, message, ap);
	va_end(ap);

  size++;

  res = xmalloc(size);

	va_start(ap, message);
  size = vsnprintf(res, size, message, ap);
  // this should never happen in my use cases, I think
  // I hope, I pray to Yog-Sothoth every day
  if (size < 0) {
    res = xrealloc(res, 1);
    res[0] = '\0';
    return res;
  }
  va_end(ap);

  return res;
}