dlfcn/eval.c

   1 /* You don't really want to know what this hack is for.
   2    Copyright (C) 1996, 1997, 2000, 2001 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <ctype.h>
  22 #include <dlfcn.h>
  23 #include <errno.h>
  24 #include <limits.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <unistd.h>
  29
  30 static void *funcall (char **stringp) __attribute_noinline__;
  31 static void *eval (char **stringp);
  32
  33
  34 long int weak_function
  35 __strtol_internal (const char *nptr, char **endptr, int base, int group)
  36 {
  37   unsigned long int result = 0;
  38   long int sign = 1;
  39
  40   while (*nptr == ' ' || *nptr == '\t')
  41     ++nptr;
  42
  43   if (*nptr == '-')
  44     {
  45       sign = -1;
  46       ++nptr;
  47     }
  48   else if (*nptr == '+')
  49     ++nptr;
  50
  51   if (*nptr < '0' || *nptr > '9')
  52     {
  53       if (endptr != NULL)
  54         *endptr = (char *) nptr;
  55       return 0L;
  56     }
  57
  58   assert (base == 0);
  59   base = 10;
  60   if (*nptr == '0')
  61     {
  62       if (nptr[1] == 'x' || nptr[1] == 'X')
  63         {
  64           base = 16;
  65           nptr += 2;
  66         }
  67       else
  68         base = 8;
  69     }
  70
  71   while (*nptr >= '0' && *nptr <= '9')
  72     {
  73       unsigned long int digval = *nptr - '0';
  74       if (result > LONG_MAX / 10
  75           || (sign > 0 ? result == LONG_MAX / 10 && digval > LONG_MAX % 10
  76               : (result == ((unsigned long int) LONG_MAX + 1) / 10
  77                  && digval > ((unsigned long int) LONG_MAX + 1) % 10)))
  78         {
  79           errno = ERANGE;
  80           return sign > 0 ? LONG_MAX : LONG_MIN;
  81         }
  82       result *= base;
  83       result += digval;
  84       ++nptr;
  85     }
  86
  87   return (long int) result * sign;
  88 }
  89
  90
  91 static void *
  92 funcall (char **stringp)
  93 {
  94   void *args[strlen (*stringp)], **ap = args;
  95   void *argcookie = &args[1];
  96
  97   do
  98     {
  99       /* Evaluate the next token.  */
 100       *ap++ = eval (stringp);
 101
 102       /* Whitespace is irrelevant.  */
 103       while (isspace (**stringp))
 104         ++*stringp;
 105
 106       /* Terminate at closing paren or end of line.  */
 107     } while (**stringp != '\0' && **stringp != ')');
 108   if (**stringp != '\0')
 109     /* Swallow closing paren.  */
 110     ++*stringp;
 111
 112   if (args[0] == NULL)
 113     {
 114       static const char unknown[] = "Unknown function\n";
 115       write (1, unknown, sizeof unknown - 1);
 116       return NULL;
 117     }
 118
 119   /* Do it to it.  */
 120   __builtin_return (__builtin_apply (args[0],
 121                                      &argcookie,
 122                                      (char *) ap - (char *) &args[1]));
 123 }
 124
 125 static void *
 126 eval (char **stringp)
 127 {
 128   void *value;
 129   char *p = *stringp, c;
 130
 131   /* Whitespace is irrelevant.  */
 132   while (isspace (*p))
 133     ++p;
 134
 135   switch (*p)
 136     {
 137     case '"':
 138       /* String constant.  */
 139       value = ++p;
 140       do
 141         if (*p == '\\')
 142           {
 143             switch (*strcpy (p, p + 1))
 144               {
 145               case 't':
 146                 *p = '\t';
 147                 break;
 148               case 'n':
 149                 *p = '\n';
 150                 break;
 151               }
 152             ++p;
 153           }
 154       while (*p != '\0' && *p++ != '"');
 155       if (p[-1] == '"')
 156         p[-1] = '\0';
 157       break;
 158
 159     case '(':
 160       *stringp = ++p;
 161       return funcall (stringp);
 162
 163     default:
 164       /* Try to parse it as a number.  */
 165       value = (void *) __strtol_internal (p, stringp, 0, 0);
 166       if (*stringp != p)
 167         return value;
 168
 169       /* Anything else is a symbol that produces its address.  */
 170       value = p;
 171       do
 172         ++p;
 173       while (*p != '\0' && !isspace (*p) && (!ispunct (*p) || *p == '_'));
 174       c = *p;
 175       *p = '\0';
 176       value = dlsym (NULL, value);
 177       *p = c;
 178       break;
 179     }
 180
 181   *stringp = p;
 182   return value;
 183 }
 184
 185
 186 extern void _start (void) __attribute__ ((noreturn));
 187 void
 188 __attribute__ ((noreturn))
 189 _start (void)
 190 {
 191   char *buf = NULL;
 192   size_t bufsz = 0;
 193
 194   while (__getdelim (&buf, &bufsz, '\n', stdin) > 0)
 195     {
 196       char *p = buf;
 197       eval (&p);
 198     }
 199
 200   exit (0);
 201 }