usr/src/cmd/sendmail/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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  16
  17 #include <sm/gen.h>
  18 SM_RCSID("@(#)$Id: snprintf.c,v 1.24 2006/10/12 21:50:10 ca Exp $")
  19 #include <limits.h>
  20 #include <sm/varargs.h>
  21 #include <sm/io.h>
  22 #include <sm/string.h>
  23 #include "local.h"
  24
  25 /*
  26 **  SM_SNPRINTF -- format a string to a memory location of restricted size
  27 **
  28 **      Parameters:
  29 **              str -- memory location to place formatted string
  30 **              n -- size of buffer pointed to by str, capped to
  31 **                      a maximum of INT_MAX
  32 **              fmt -- the formatting directives
  33 **              ... -- the data to satisfy the formatting
  34 **
  35 **      Returns:
  36 **              Failure: -1
  37 **              Success: number of bytes that would have been written
  38 **                      to str, not including the trailing '\0',
  39 **                      up to a maximum of INT_MAX, as if there was
  40 **                      no buffer size limitation.  If the result >= n
  41 **                      then the output was truncated.
  42 **
  43 **      Side Effects:
  44 **              If n > 0, then between 0 and n-1 bytes of formatted output
  45 **              are written into 'str', followed by a '\0'.
  46 */
  47
  48 int
  49 #if SM_VA_STD
  50 sm_snprintf(char *str, size_t n, char const *fmt, ...)
  51 #else /* SM_VA_STD */
  52 sm_snprintf(str, n, fmt, va_alist)
  53         char *str;
  54         size_t n;
  55         char *fmt;
  56         va_dcl
  57 #endif /* SM_VA_STD */
  58 {
  59         int ret;
  60         SM_VA_LOCAL_DECL
  61         SM_FILE_T fake;
  62
  63         /* While snprintf(3) specifies size_t stdio uses an int internally */
  64         if (n > INT_MAX)
  65                 n = INT_MAX;
  66         SM_VA_START(ap, fmt);
  67
  68         /* XXX put this into a static? */
  69         fake.sm_magic = SmFileMagic;
  70         fake.f_file = -1;
  71         fake.f_flags = SMWR | SMSTR;
  72         fake.f_cookie = &fake;
  73         fake.f_bf.smb_base = fake.f_p = (unsigned char *)str;
  74         fake.f_bf.smb_size = fake.f_w = n ? n - 1 : 0;
  75         fake.f_timeout = SM_TIME_FOREVER;
  76         fake.f_timeoutstate = SM_TIME_BLOCK;
  77         fake.f_close = NULL;
  78         fake.f_open = NULL;
  79         fake.f_read = NULL;
  80         fake.f_write = NULL;
  81         fake.f_seek = NULL;
  82         fake.f_setinfo = fake.f_getinfo = NULL;
  83         fake.f_type = "sm_snprintf:fake";
  84         ret = sm_io_vfprintf(&fake, SM_TIME_FOREVER, fmt, ap);
  85         if (n > 0)
  86                 *fake.f_p = '\0';
  87         SM_VA_END(ap);
  88         return ret;
  89 }