libiberty/vprintf-support.c

   1 /* Estimate the length of the string generated by a vprintf-like
   2    function.  Used by vasprintf and xvasprintf.
   3    Copyright (C) 1994-2024 Free Software Foundation, Inc.
   4
   5 This file is part of the libiberty library.
   6 Libiberty is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public
   8 License as published by the Free Software Foundation; either
   9 version 2 of the License, or (at your option) any later version.
  10
  11 Libiberty is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with libiberty; see the file COPYING.LIB.  If not, write
  18 to the Free Software Foundation, Inc., 51 Franklin Street - Fifth
  19 Floor, Boston, MA 02110-1301, USA.  */
  20
  21 #ifdef HAVE_CONFIG_H
  22 #include "config.h"
  23 #endif
  24 #include <ansidecl.h>
  25 #include <stdarg.h>
  26 #if !defined (va_copy) && defined (__va_copy)
  27 # define va_copy(d,s)  __va_copy((d),(s))
  28 #endif
  29 #include <stdio.h>
  30 #ifdef HAVE_STRING_H
  31 #include <string.h>
  32 #endif
  33 #ifdef HAVE_STDLIB_H
  34 #include <stdlib.h>
  35 #else
  36 extern unsigned long strtoul ();
  37 #endif
  38 #include "libiberty.h"
  39
  40 int
  41 libiberty_vprintf_buffer_size (const char *format, va_list args)
  42 {
  43   const char *p = format;
  44   /* Add one to make sure that it is never zero, which might cause malloc
  45      to return NULL.  */
  46   int total_width = strlen (format) + 1;
  47   va_list ap;
  48
  49 #ifdef va_copy
  50   va_copy (ap, args);
  51 #else
  52   memcpy ((void *) &ap, (void *) &args, sizeof (va_list));
  53 #endif
  54
  55   while (*p != '\0')
  56     {
  57       if (*p++ == '%')
  58         {
  59           while (strchr ("-+ #0", *p))
  60             ++p;
  61           if (*p == '*')
  62             {
  63               ++p;
  64               total_width += abs (va_arg (ap, int));
  65             }
  66           else
  67             total_width += strtoul (p, (char **) &p, 10);
  68           if (*p == '.')
  69             {
  70               ++p;
  71               if (*p == '*')
  72                 {
  73                   ++p;
  74                   total_width += abs (va_arg (ap, int));
  75                 }
  76               else
  77               total_width += strtoul (p, (char **) &p, 10);
  78             }
  79           while (strchr ("hlL", *p))
  80             ++p;
  81           /* Should be big enough for any format specifier except %s and floats.  */
  82           total_width += 30;
  83           switch (*p)
  84             {
  85             case 'd':
  86             case 'i':
  87             case 'o':
  88             case 'u':
  89             case 'x':
  90             case 'X':
  91             case 'c':
  92               (void) va_arg (ap, int);
  93               break;
  94             case 'f':
  95             case 'e':
  96             case 'E':
  97             case 'g':
  98             case 'G':
  99               (void) va_arg (ap, double);
 100               /* Since an ieee double can have an exponent of 307, we'll
 101                  make the buffer wide enough to cover the gross case. */
 102               total_width += 307;
 103               break;
 104             case 's':
 105               total_width += strlen (va_arg (ap, char *));
 106               break;
 107             case 'p':
 108             case 'n':
 109               (void) va_arg (ap, char *);
 110               break;
 111             }
 112           p++;
 113         }
 114     }
 115 #ifdef va_copy
 116   va_end (ap);
 117 #endif
 118   return total_width;
 119 }