vsnprintf.c 2.3 KB

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  1. /* $OpenBSD: vsnprintf.c,v 1.15 2009/11/09 00:18:28 kurt Exp $ */
  2. /*-
  3. * Copyright (c) 1990, 1993
  4. * The Regents of the University of California. All rights reserved.
  5. *
  6. * This code is derived from software contributed to Berkeley by
  7. * Chris Torek.
  8. *
  9. * Redistribution and use in source and binary forms, with or without
  10. * modification, are permitted provided that the following conditions
  11. * are met:
  12. * 1. Redistributions of source code must retain the above copyright
  13. * notice, this list of conditions and the following disclaimer.
  14. * 2. Redistributions in binary form must reproduce the above copyright
  15. * notice, this list of conditions and the following disclaimer in the
  16. * documentation and/or other materials provided with the distribution.
  17. * 3. Neither the name of the University nor the names of its contributors
  18. * may be used to endorse or promote products derived from this software
  19. * without specific prior written permission.
  20. *
  21. * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24. * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31. * SUCH DAMAGE.
  32. */
  33. #include <limits.h>
  34. #include <stdio.h>
  35. #include <string.h>
  36. #include "local.h"
  37. int
  38. vsnprintf(char *str, size_t n, const char *fmt, __va_list ap)
  39. {
  40. int ret;
  41. char dummy;
  42. FILE f;
  43. struct __sfileext fext;
  44. _FILEEXT_SETUP(&f, &fext);
  45. /* While snprintf(3) specifies size_t stdio uses an int internally */
  46. if (n > INT_MAX)
  47. n = INT_MAX;
  48. /* Stdio internals do not deal correctly with zero length buffer */
  49. if (n == 0) {
  50. str = &dummy;
  51. n = 1;
  52. }
  53. f._file = -1;
  54. f._flags = __SWR | __SSTR;
  55. f._bf._base = f._p = (unsigned char *)str;
  56. f._bf._size = f._w = n - 1;
  57. ret = __vfprintf(&f, fmt, ap);
  58. *f._p = '\0';
  59. return (ret);
  60. }