opkg-lede/libopkg/sprintf_alloc.c

/* sprintf_alloc.c -- like sprintf with memory allocation

   Copyright (C) 2010 Ubiq Technologies <graham.gower@gmail.com>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
*/

#include <stdarg.h>

#include "sprintf_alloc.h"
#include "libbb/libbb.h"

void sprintf_alloc(char **str, const char *fmt, ...)
{
	va_list ap;
	int n;
	unsigned int size = 0;

	*str = NULL;

	for (;;) {
		va_start(ap, fmt);
		n = vsnprintf(*str, size, fmt, ap);
		va_end(ap);

		if (n < 0) {
			fprintf(stderr, "%s: encountered an output or encoding"
				" error during vsnprintf.\n", __FUNCTION__);
			exit(EXIT_FAILURE);
		}

		if (n < size)
			break;

		/* Truncated, try again with more space. */
		size = n + 1;
		*str = xrealloc(*str, size);
	}
}