contrib/sendmail-8.13.7/libsm/vsnprintf.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: vsnprintf.c,v 1.23 2001/09/11 04:04:49 gshapiro Exp $")
  17 #include <limits.h>
  18 #include <sm/io.h>
  19 #include "local.h"
  20
  21 /*
  22 **  SM_VSNPRINTF -- format data for "output" into a string
  23 **
  24 **      Assigned 'str' to a "fake" file pointer. This allows common
  25 **      o/p formatting function sm_vprintf() to be used.
  26 **
  27 **      Parameters:
  28 **              str -- location for output
  29 **              n -- maximum size for o/p
  30 **              fmt -- format directives
  31 **              ap -- data unit vectors for use by 'fmt'
  32 **
  33 **      Results:
  34 **              result from sm_io_vfprintf()
  35 **
  36 **      Side Effects:
  37 **              Limits the size ('n') to INT_MAX.
  38 */
  39
  40 int
  41 sm_vsnprintf(str, n, fmt, ap)
  42         char *str;
  43         size_t n;
  44         const char *fmt;
  45         SM_VA_LOCAL_DECL
  46 {
  47         int ret;
  48         char dummy;
  49         SM_FILE_T fake;
  50
  51         /* While snprintf(3) specifies size_t stdio uses an int internally */
  52         if (n > INT_MAX)
  53                 n = INT_MAX;
  54
  55         /* Stdio internals do not deal correctly with zero length buffer */
  56         if (n == 0)
  57         {
  58                 str = &dummy;
  59                 n = 1;
  60         }
  61         fake.sm_magic = SmFileMagic;
  62         fake.f_timeout = SM_TIME_FOREVER;
  63         fake.f_timeoutstate = SM_TIME_BLOCK;
  64         fake.f_file = -1;
  65         fake.f_flags = SMWR | SMSTR;
  66         fake.f_bf.smb_base = fake.f_p = (unsigned char *)str;
  67         fake.f_bf.smb_size = fake.f_w = n - 1;
  68         fake.f_close = NULL;
  69         fake.f_open = NULL;
  70         fake.f_read = NULL;
  71         fake.f_write = NULL;
  72         fake.f_seek = NULL;
  73         fake.f_setinfo = fake.f_getinfo = NULL;
  74         fake.f_type = "sm_vsnprintf:fake";
  75         ret = sm_io_vfprintf(&fake, SM_TIME_FOREVER, fmt, ap);
  76         *fake.f_p = 0;
  77         return ret;
  78 }