summaryrefslogtreecommitdiff
path: root/libc/dlfcn/eval.c
blob: f40f5eab21e5b103ec9483fc71cdbbb81150cd3e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
/* You don't really want to know what this hack is for.
   Copyright (C) 1996, 1997, 2000, 2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <ctype.h>
#include <dlfcn.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void *funcall (char **stringp) __attribute_noinline__;
static void *eval (char **stringp);


long int weak_function
__strtol_internal (const char *nptr, char **endptr, int base, int group)
{
  unsigned long int result = 0;
  long int sign = 1;

  while (*nptr == ' ' || *nptr == '\t')
    ++nptr;

  if (*nptr == '-')
    {
      sign = -1;
      ++nptr;
    }
  else if (*nptr == '+')
    ++nptr;

  if (*nptr < '0' || *nptr > '9')
    {
      if (endptr != NULL)
	*endptr = (char *) nptr;
      return 0L;
    }

  assert (base == 0);
  base = 10;
  if (*nptr == '0')
    {
      if (nptr[1] == 'x' || nptr[1] == 'X')
	{
	  base = 16;
	  nptr += 2;
	}
      else
	base = 8;
    }

  while (*nptr >= '0' && *nptr <= '9')
    {
      unsigned long int digval = *nptr - '0';
      if (result > LONG_MAX / 10
	  || (sign > 0 ? result == LONG_MAX / 10 && digval > LONG_MAX % 10
	      : (result == ((unsigned long int) LONG_MAX + 1) / 10
		 && digval > ((unsigned long int) LONG_MAX + 1) % 10)))
	{
	  errno = ERANGE;
	  return sign > 0 ? LONG_MAX : LONG_MIN;
	}
      result *= base;
      result += digval;
      ++nptr;
    }

  return (long int) result * sign;
}


static void *
funcall (char **stringp)
{
  void *args[strlen (*stringp)], **ap = args;
  void *argcookie = &args[1];

  do
    {
      /* Evaluate the next token.  */
      *ap++ = eval (stringp);

      /* Whitespace is irrelevant.  */
      while (isspace (**stringp))
	++*stringp;

      /* Terminate at closing paren or end of line.  */
    } while (**stringp != '\0' && **stringp != ')');
  if (**stringp != '\0')
    /* Swallow closing paren.  */
    ++*stringp;

  if (args[0] == NULL)
    {
      static const char unknown[] = "Unknown function\n";
      write (1, unknown, sizeof unknown - 1);
      return NULL;
    }

  /* Do it to it.  */
  __builtin_return (__builtin_apply (args[0],
				     &argcookie,
				     (char *) ap - (char *) &args[1]));
}

static void *
eval (char **stringp)
{
  void *value;
  char *p = *stringp, c;

  /* Whitespace is irrelevant.  */
  while (isspace (*p))
    ++p;

  switch (*p)
    {
    case '"':
      /* String constant.  */
      value = ++p;
      do
	if (*p == '\\')
	  {
	    switch (*strcpy (p, p + 1))
	      {
	      case 't':
		*p = '\t';
		break;
	      case 'n':
		*p = '\n';
		break;
	      }
	    ++p;
	  }
      while (*p != '\0' && *p++ != '"');
      if (p[-1] == '"')
	p[-1] = '\0';
      break;

    case '(':
      *stringp = ++p;
      return funcall (stringp);

    default:
      /* Try to parse it as a number.  */
      value = (void *) __strtol_internal (p, stringp, 0, 0);
      if (*stringp != p)
	return value;

      /* Anything else is a symbol that produces its address.  */
      value = p;
      do
	++p;
      while (*p != '\0' && !isspace (*p) && (!ispunct (*p) || *p == '_'));
      c = *p;
      *p = '\0';
      value = dlsym (NULL, value);
      *p = c;
      break;
    }

  *stringp = p;
  return value;
}


extern void _start (void) __attribute__ ((noreturn));
void
__attribute__ ((noreturn))
_start (void)
{
  char *buf = NULL;
  size_t bufsz = 0;

  while (__getdelim (&buf, &bufsz, '\n', stdin) > 0)
    {
      char *p = buf;
      eval (&p);
    }

  exit (0);
}