compiler/stdc/vsnprintf.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     C99 function vsnprintf().
   6 */
   7 /* Original source from libnix */
   8
   9 #include <stdarg.h>
  10 #include <stddef.h>
  11
  12 struct data
  13 {
  14     char * str;
  15     size_t n;
  16 };
  17
  18 static int _vsnprintf_uc (int c, struct data * data)
  19 {
  20     if (data->n)
  21     {
  22         *(data->str) ++ = c;
  23         data->n --;
  24     }
  25
  26     return 1;
  27 }
  28
  29 /*****************************************************************************
  30
  31     NAME */
  32 #include <stdio.h>
  33
  34         int vsnprintf (
  35
  36 /*  SYNOPSIS */
  37         char        * str,
  38         size_t      n,
  39         const char * format,
  40         va_list      args)
  41
  42 /*  FUNCTION
  43         Format a list of arguments and put them into the string str.
  44         The function makes sure that no more than n characters (including
  45         the terminal 0 byte) are written into str.
  46         If n is zero, nothing is written, and s may be a null pointer. Otherwise,
  47         output characters beyond the n-1st are discarded rather than being written
  48         to the array, and a null character is written at the end of the characters
  49         actually written into the array. If copying takes place between objects
  50         that overlap, the behavior is undefined.
  51
  52     INPUTS
  53         str - The formatted result is stored here
  54         n - The size of str
  55         format - A printf() format string.
  56         args - A list of arguments for the format string.
  57
  58     RESULT
  59         Function returns the number of characters that would have been
  60         written had n been sufficiently large, not counting the terminating null
  61         character, or a negative value if an encoding error occurred. Thus, the
  62         null-terminated output has been completely written if and only if the
  63         returned value is nonnegative and less than n.
  64
  65     NOTES
  66
  67     EXAMPLE
  68
  69     BUGS
  70
  71     SEE ALSO
  72         printf(), sprintf(), fprintf(), vprintf(), vfprintf(), snprintf(),
  73         vsnprintf()
  74
  75     INTERNALS
  76
  77 ******************************************************************************/
  78 {
  79     int rc;
  80     struct data data;
  81
  82     if (str == NULL && n != 0) n = 0;
  83
  84     data.n = n;
  85     data.str = str;
  86
  87     rc = __vcformat (&data, (void *)_vsnprintf_uc, format, args);
  88
  89     if (data.n)
  90     {
  91         *(data.str) = 0;
  92     }
  93     else if ( n != 0 )
  94     {
  95         str[n-1] = 0;
  96     }
  97
  98     return rc;
  99 } /* vsnprintf */
 100