snprintf/snprintf.c

   1 /*      $OpenBSD: snprintf.c,v 1.16 2009/10/22 01:23:16 guenther Exp $ */
   2 /*
   3  * SPDX-License-Identifier: BSD-3-Clause
   4  *
   5  * Copyright (C) 1990, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * Chris Torek.
  10  */
  11
  12 #include <limits.h>
  13 #include <stddef.h>
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <stdarg.h>
  17 #include "local.h"
  18 #include "ust_snprintf.h"
  19
  20 #define DUMMY_LEN       1
  21
  22 int ust_safe_vsnprintf(char *str, size_t n, const char *fmt, va_list ap)
  23 {
  24         int ret;
  25         char dummy[DUMMY_LEN];
  26         LTTNG_UST_LFILE f;
  27         struct __lttng_ust_sfileext fext;
  28
  29         /* While snprintf(3) specifies size_t stdio uses an int internally */
  30         if (n > INT_MAX)
  31                 n = INT_MAX;
  32         /* Stdio internals do not deal correctly with zero length buffer */
  33         if (n == 0) {
  34                 str = dummy;
  35                 n = DUMMY_LEN;
  36         }
  37         _FILEEXT_SETUP(&f, &fext);
  38         f._file = -1;
  39         f._flags = __SWR | __SSTR;
  40         f._bf._base = f._p = (unsigned char *)str;
  41         f._bf._size = f._w = n - 1;
  42         ret = ust_safe_vfprintf(&f, fmt, ap);
  43         *f._p = '\0';
  44         return (ret);
  45 }
  46
  47 int ust_safe_snprintf(char *str, size_t n, const char *fmt, ...)
  48 {
  49         va_list ap;
  50         int ret;
  51
  52         va_start(ap, fmt);
  53         ret = ust_safe_vsnprintf(str, n, fmt, ap);
  54         va_end(ap);
  55
  56         return ret;
  57 }