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#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include <dlfcn.h>
static void *funcall (char **stringp);
static void *eval (char **stringp);
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 (p, stringp, 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;
}
void
_start (void)
{
char *buf = NULL;
size_t bufsz = 0;
while (getline (&buf, &bufsz, stdin) > 0)
{
char *p = buf;
eval (&p);
}
exit (0);
}
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