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-rw-r--r--elf/eval.c110
1 files changed, 110 insertions, 0 deletions
diff --git a/elf/eval.c b/elf/eval.c
new file mode 100644
index 0000000000..91415bb6b6
--- /dev/null
+++ b/elf/eval.c
@@ -0,0 +1,110 @@
+#include <stdio.h>
+#include <ctype.h>
+#include <stdlib.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;
+
+ /* 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));
+ 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);
+}