contrib/sendmail-8.14/libsm/snprintf.c

   1 /*
   2  * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * By using this file, you agree to the terms and conditions set
  11  * forth in the LICENSE file which can be found at the top level of
  12  * the sendmail distribution.
  13  */
  14
  15 #include <sm/gen.h>
  16 SM_RCSID("@(#)$Id: snprintf.c,v 1.24 2006/10/12 21:50:10 ca Exp $")
  17 #include <limits.h>
  18 #include <sm/varargs.h>
  19 #include <sm/io.h>
  20 #include <sm/string.h>
  21 #include "local.h"
  22
  23 /*
  24 **  SM_SNPRINTF -- format a string to a memory location of restricted size
  25 **
  26 **      Parameters:
  27 **              str -- memory location to place formatted string
  28 **              n -- size of buffer pointed to by str, capped to
  29 **                      a maximum of INT_MAX
  30 **              fmt -- the formatting directives
  31 **              ... -- the data to satisfy the formatting
  32 **
  33 **      Returns:
  34 **              Failure: -1
  35 **              Success: number of bytes that would have been written
  36 **                      to str, not including the trailing '\0',
  37 **                      up to a maximum of INT_MAX, as if there was
  38 **                      no buffer size limitation.  If the result >= n
  39 **                      then the output was truncated.
  40 **
  41 **      Side Effects:
  42 **              If n > 0, then between 0 and n-1 bytes of formatted output
  43 **              are written into 'str', followed by a '\0'.
  44 */
  45
  46 int
  47 #if SM_VA_STD
  48 sm_snprintf(char *str, size_t n, char const *fmt, ...)
  49 #else /* SM_VA_STD */
  50 sm_snprintf(str, n, fmt, va_alist)
  51         char *str;
  52         size_t n;
  53         char *fmt;
  54         va_dcl
  55 #endif /* SM_VA_STD */
  56 {
  57         int ret;
  58         SM_VA_LOCAL_DECL
  59         SM_FILE_T fake;
  60
  61         /* While snprintf(3) specifies size_t stdio uses an int internally */
  62         if (n > INT_MAX)
  63                 n = INT_MAX;
  64         SM_VA_START(ap, fmt);
  65
  66         /* XXX put this into a static? */
  67         fake.sm_magic = SmFileMagic;
  68         fake.f_file = -1;
  69         fake.f_flags = SMWR | SMSTR;
  70         fake.f_cookie = &fake;
  71         fake.f_bf.smb_base = fake.f_p = (unsigned char *)str;
  72         fake.f_bf.smb_size = fake.f_w = n ? n - 1 : 0;
  73         fake.f_timeout = SM_TIME_FOREVER;
  74         fake.f_timeoutstate = SM_TIME_BLOCK;
  75         fake.f_close = NULL;
  76         fake.f_open = NULL;
  77         fake.f_read = NULL;
  78         fake.f_write = NULL;
  79         fake.f_seek = NULL;
  80         fake.f_setinfo = fake.f_getinfo = NULL;
  81         fake.f_type = "sm_snprintf:fake";
  82         ret = sm_io_vfprintf(&fake, SM_TIME_FOREVER, fmt, ap);
  83         if (n > 0)
  84                 *fake.f_p = '\0';
  85         SM_VA_END(ap);
  86         return ret;
  87 }