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) 1994-2025 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           int prec = 0;
  60           while (strchr ("-+ #0", *p))
  61             ++p;
  62           if (*p == '*')
  63             {
  64               ++p;
  65               total_width += abs (va_arg (ap, int));
  66             }
  67           else
  68             total_width += strtoul (p, (char **) &p, 10);
  69           if (*p == '.')
  70             {
  71               ++p;
  72               if (*p == '*')
  73                 {
  74                   ++p;
  75                   total_width += abs (va_arg (ap, int));
  76                 }
  77               else
  78               total_width += strtoul (p, (char **) &p, 10);
  79             }
  80           do
  81             {
  82               switch (*p)
  83                 {
  84                 case 'h':
  85                   ++p;
  86                   continue;
  87                 case 'l':
  88                 case 'L':
  89                   ++prec;
  90                   ++p;
  91                   continue;
  92                 case 'z':
  93                   prec = 3;
  94                   ++p;
  95                   continue;
  96                 case 't':
  97                   prec = 4;
  98                   ++p;
  99                   continue;
 100 #ifdef _WIN32
 101                 case 'I':
 102                   if (p[1] == '6' && p[2] == '4')
 103                     {
 104                       prec = 2;
 105                       p += 3;
 106                       continue;
 107                     }
 108                   break;
 109 #endif
 110                 default:
 111                   break;
 112                 }
 113               break;
 114             }
 115           while (1);
 116
 117           /* Should be big enough for any format specifier except %s and floats.  */
 118           total_width += 30;
 119           switch (*p)
 120             {
 121             case 'd':
 122             case 'i':
 123             case 'o':
 124             case 'u':
 125             case 'x':
 126             case 'X':
 127               switch (prec)
 128                 {
 129                 case 0: (void) va_arg (ap, int); break;
 130                 case 1: (void) va_arg (ap, long int); break;
 131                 case 2: (void) va_arg (ap, long long int); break;
 132                 case 3: (void) va_arg (ap, size_t); break;
 133                 case 4: (void) va_arg (ap, ptrdiff_t); break;
 134                 }
 135               break;
 136             case 'c':
 137               (void) va_arg (ap, int);
 138               break;
 139             case 'f':
 140             case 'e':
 141             case 'E':
 142             case 'g':
 143             case 'G':
 144               if (!prec)
 145                 {
 146                   (void) va_arg (ap, double);
 147                   /* Since an ieee double can have an exponent of 308, we'll
 148                      make the buffer wide enough to cover the gross case. */
 149                   total_width += 308;
 150                 }
 151               else
 152                 {
 153                   (void) va_arg (ap, long double);
 154                   total_width += 4932;
 155                 }
 156               break;
 157             case 's':
 158               total_width += strlen (va_arg (ap, char *));
 159               break;
 160             case 'p':
 161             case 'n':
 162               (void) va_arg (ap, char *);
 163               break;
 164             }
 165           p++;
 166         }
 167     }
 168 #ifdef va_copy
 169   va_end (ap);
 170 #endif
 171   return total_width;
 172 }